History of Technology Volume 1: Volume 1, 1976 9781350017337, 9781350016606, 9781350017344

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History of Technology Volume 1, 1976

Edited by A. Rupert Hall and Norman Smith

Bloomsbury Academic An imprint of Bloomsbury Publishing Plc LON DON • OX F O R D • N E W YO R K • N E W D E L H I • SY DN EY

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www.bloomsbury.com BLOOMSBURY, T&T CLARK and the Diana logo are trademarks of Bloomsbury Publishing Plc First published 1976 by Mansell Publishing Ltd Copyright © A. Rupert Hall and Norman Smith and Contributors, 1976 The electronic edition published 2016 A. Rupert Hall and Norman Smith and Contributors have asserted their right under the Copyright, Designs and Patents Act, 1988, to be identified as the Authors of this work. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage or retrieval system, without prior permission in writing from the publishers. No responsibility for loss caused to any individual or organization acting on or refraining from action as a result of the material in this publication can be accepted by Bloomsbury or the authors. ISBN: HB: 978-1-3500-1733-7 ePDF: 978-1-3500-1734-4 ePub: 978-1-3500-1735-1 Series: History of Technology, volume 1 Typeset by Preface Ltd., Salisbury, Wiltshire

C o n t e n t s

Preface D.S.L. CARDWELL and RICHARD L. HILLS Thermodynamics and Practical Engineering in the Nineteenth Century

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JACQUES HEYMAN Couplet's Engineering Memoirs, 1726—33

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NORMAN A. F. SMITH Attitudes t o Roman Engineering and the Question of the Inverted Siphon

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R. A. BUCHANAN The Promethean Revolution: Science, Technology and History

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M. DAUMAS The History of Technology: its Aims, its Limits, its Methods. Translated and introduced by A. RUPERT HALL

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KEITH DAWSON Electromagnetic Telegraphy: Early Ideas, Proposals and Apparatus

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MARIE BOAS HALL The Strange Case of Aluminium

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G. HOLLISTER-SHORT Leads and Lags in late Seventeenth-Century English Technology

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The Contributors

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P r e f a c e

We hope that no elaborate apology is needed for publishing the following collection of papers as a separate volume, nor for our aspiring to follow it with others in subsequent years. It is true that a number of outstanding journals are devoted t o the history of engineering and technology, notably the Transactions of the Newcomen Society in this country and Technology and Culture in the United States, b u t (in various ways) all such historical periodicals published in Britain seem to be limited in their topical coverage, and it certainly does n o t appear t h a t there are over-numerous opportunities for publishing the more general kind of paper on the history of technology, such as we hope to find room for here, as well as technical articles. We shall also particularly welcome contributions on the history of technology before the 'Industrial Revolution'. The first three papers in this volume were presented at a Symposium on the History of Technology organized by the British Society for the History of Science and held at Imperial College on 30 November 1974. We are grateful t o their authors for permitting us t o print them here, and look forward to the repetition of such Symposia in future years. It is not, of course, our intention t o publish in these volumes only the work of historians of technology connected with Imperial College. We shall welcome contributions to our enterprise from any quarter, which should be addressed to us, at the Department of History of Science and Technology, Imperial College, London SW7. A. RUPERT HALL NORMAN A. F. SMITH

T h e r m o d y n a m i c s P r a c t i c a l

E n g i n e e r i n g

N i n e t e e n t h

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D. S. L. CARDWELL and RICHARD L. HILLS From the eighteenth century onward the efficiency of steamengines was measured by the work they could do per given weight — usually a bushel* —of coal burned. By 1800 engineers could note that since the first Newcomen engine of 1712 the efficiency, or ' d u t y ' as they called it, of engines had increased six-fold: from about 5 million ft. lbs. per bushel to 30 million, which Watt himself thought was about the limit. This measure of the duty of engines was particularly applicable to pumping engines, whose work could easily be measured by the weight of water, in pounds, lifted so many feet up a mine shaft. In other words, there was a natural relationship between the measure of work and the actual job done by the engine. 1 Of the detailed causes of this dramatic improvement in efficiency the mine owners probably knew little and cared less. The main exceptions were to be found in the south west of the country, in Cornwall, where a large number of steam-engines were concentrated in one area; all doing exactly the same job: pumping water out of mines. The mine owners and engineers worked in, we may assume, some degree of rivalry, friendly or otherwise; and uniquely for a major British industrial area, coal was most expensive, as it had to be imported by sea from South Wales. Coal economy was therefore all-important. The circumstances in Cornwall were, in fact, exceptional, in Britain and in the world. For the Cornish mining area could boast of engineers without equals anywhere else: the Hornblowers, Trevithick, the Harveys, Arthur Woolf and many others, t o say nothing of distinguished foreign residents like James Watt and William Murdoch, his assistant. The genius of the Cornish engineers flowered when Watt's grip was relaxed after 1800, and his network of patents on the condensing steam-engine lapsed. In particular, the high-pressure engine was developed and proved most successful. In 1804 Arthur *The bushel, the weight of a sack of coal, was about 90 lbs., although it varied somewhat from district to district.

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Woolf patented his high-pressure compound engine. In this machine steam was expanded in a small, high-pressure cylinder and then, down to condenser pressure, in a large, low-pressure cylinder. 2 By 1815 such an engine had reached double the duty of the best Watt engine. Of course this owed much to many detailed improvements, not least to Murdoch's plunger-pole pump. But Woolf's success got wide publicity, particularly in the Philosophical Magazine, then edited by his friend Alexander Tilloch, and in the monthly statements of Lean's Engine Reporter.3 It was the remarkable and well publicised performances of the Cornish engines that Sadi Carnot used as strong supporting evidence for his conception of an ideal heat-engine cycle (1824). But the evidence did not justify his conclusion; at best it did not refute it. The most important reason was simply that the Cornish engines were systematically improved, in a competitive situation and in a social context that made such improvements easily possible, and perhaps even inevitable. The details made the whole. It is not necessary to give an account here of Carnot's arguments. Starting from the axioms that perpetual motion is impossible and that wherever there is a difference in temperature there is the possibility of generating motive power, he based his ideal cycle on three assertions. The first was that in an ideal engine there should be no direct, and therefore wasteful, contact between hot and cold bodies or components. This was an analogue of the argument used by his father, Lazare Carnot, in discussing the water-engine: the driving agent should act on the machine without shock, and leave it without velocity, or energy. The second was that the most efficient engine would be the one that made use of the greatest available pressure drop (water-engine), or temperature drop in the case of a heat engine. And the last was that Watt's expansive principle, which implied the adiabatic lowering of temperature, should be used to bring the temperature of the working substance (steam) down from that of the boiler to that of the condenser, in order to make the most complete use of the temperature difference that is available. An engine working on a cycle that exactly fulfilled these conditions would be fully reversible, and Carnot demonstrated, rigorously, that no engine could be more efficient than a reversible one. Carnot's ideas were effectively ignored apart from the isolated exceptions of Clapeyron, Holtzmann, and Lewis Gordon, until that most perceptive of all scientists, William Thomson, later Lord Kelvin, realized their importance, and with his great flair for winning friends and influencing people, succeeded in bringing them to the attention of the scientific world. Let us, however, return for a moment to the Cornish engines. The 1820s and 1830s were their heyday. Thereafter the best performances levelled off, and then gently declined. 4 There were

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several reasons for this. One was the widespread realization that thermomechanical — one can hardly say thermodynamic — efficiency was not the only criterion. A less efficient engine that seldom broke down was a better investment than a more efficient one that was always breaking down. Again, it was reasonable to suppose that the price of coal at the Cornish ports fell progressively as the early nineteenth century inflation was mastered, and as railways and steamships became more common. Nevertheless, the Cornish engine gained a reputation that has endured to the present day, even though the industry has all but vanished and the few surviving engine-houses are objects of antiquarian interest only. The establishment, within a few years after 1850, of the science of thermodynamics on the basis of the dynamical theory of heat through the geniuses of Joule, Rankine, Clausius and Thomson, marked a dramatic reversal in the comparative states of science and technology. After 1850 science was decisively in the lead. This was made quite apparent by a series of meetings at the Institution of Civil Engineers in 1852 and 1853. To explain this it is necessary briefly to recount the history of the air-engine. The prehistory of this machine was a sad story of inventions, few of any real merit, very much on the margins of power technology, competing unsuccessfully with the ever triumphant, the ever diversifying steam-engine; the machine whose exciting possibilities attracted so much of the engineering talent of the day, thus leaving the air-engine at the mercy of the amateurs, the cranks, the incompetent, and the incurably optimistic. The desideratum that few recognized — Sir George Cayley was one obvious exception — was a role for the air-engine that the steam-engine could not fulfil. The first practicable air-engine was invented by the Rev. Robert Stirling in 1816. In subsequent years he and his brother James improved their machine, patents being granted in 1827 and 1840. In principle its operation was quite simple, and as it has recently been described in some detail by Professor Daub, 5 it is not necessary to do more than give a brief outline of its main features, and those of its famous rival, the Ericsson engine. A large cylinder containing compressed air is heated at one end so that the air acts on a piston causing it to do useful work. The cylinder also contains a bulky, cylindrical displacer piston which thereupon moves to the hot end, causing the air to be displaced to the other end via a 'regenerator' consisting of many thin strips of metal. The regenerator is hot where the hot air enters it and cold where the air leaves it. At the cold end of the cylinder the air pressure is much lower. The working piston returns to its initial position and the displacer piston then forces the air back through the regenerator so that it picks up heat as it goes. The cycle is such that the heating and cooling phases are at constant volume, while

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the expansion and compression (or return) phases are isothermal. The regenerator ensures that hot air is never in contact with cold metal, and vice versa. Such an engine on such a cycle can be made reversible and can therefore approximate to the conditions laid down by Sadi Camot. It is almost certain, nevertheless, that neither of the Stirling brothers had ever heard of Carnot, or read his book. In 1826 Lt. John Ericsson, a Swede, came to London with his own idea for an air-engine. This, too, incorporated a regenerator, although it did not have a displacer piston. Ericsson's engine was patented in 1833, and in an improved version in 1850; the name of the patentee being given as Edward Dunn, a ship's captain from New York, resident in London. Ericsson had no doubts about the purpose of his engine: it was to revolutionize sea transport. Clumsy, dangerous boilers would no longer be required. The caloric engine — the antiquated name for heat should be noted — would do the job safely and efficiently. All that was needed was to impart a certain amount of caloric, or heat, to air so that it expanded, and then withdraw the heat, storing it in the regenerator as the air contracted, until it was required for the next cycle. In fact with efficient insulation you should not need any more heat after the initial warming up: the caloric engine would continue to work without combustibles. People would soon be boasting that they had crossed the Atlantic by 'caloric'. 6 Even James Stirling had claimed in 1845 that the power of their engine was 'theoretically infinite'. 7 Ericsson was even less inhibited and practically claimed the invention of perpetual motion, by virtue of the reiterated use of caloric. The descriptions of these engines and the claims made on their behalf as presented to the Institution of Civil Engineers evidently bewildered men like I. K. Brunei, and Robert Stephenson. 8 They were far too sensible to accept what amounted to claims to have invented perpetual motion machines; but they did not know how to refute such claims. Ironically, had they known their Carnot they would not have been troubled by these claims, for Carnot showed that no heat engine can work without a flow of heat from the hot body, or furnace, to the cold body. Such a flow of heat occurs in the Stirling and in the Ericsson engines and effectively prevents any 'perpetual motion' of the kind envisaged by Ericsson, or James Stirling. No doubt they felt some gratitude to one Benjamin Cheverton/when he took up the challenge in 1853. 9 Cheverton argued that caloric is only a force, and he dismissed, scornfully, the absurd perpetual motion claims. As a heating agent caloric is, he argued, conserved; but when mechanical force is derived from its action, then some caloric is transformed into that mechanical force and it is no longer conserved in the form of

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heat, or caloric. He went on: It is in the declination from a higher to a lower degree of temperature — it is in the aspect of a vis-viva force in caloric that mechanical action is developed. That is, the force of caloric is related to vis viva and a fall — that is, a fall in temperature — is necessary for the generation of mechanical action. This enables him to solve a problem. X units of heat at a high temperature is applied to a large amount of water; it will raise the temperature by only a small amount: At°; applied to a small amount of water it will raise the temperature T9 a large amount, and yield some mechanical power. We get power in one case but not in the other; do we get power for nothing? No, for our calculation does not take account of the heat transformed into work in the second case. If we still insist on the conservation of caloric then we are faced with the absurdity that we can get power for nothing; with that is, the fallacy of perpetual motion. Cheverton was insistent that 'it is only in the reduction of temperature that force is elicited'. It is the function of the regenerator to conserve heat that would otherwise be wasted; that is, it has the same function as the then familiar technique of using exhaust steam to pre-heat boiler feed water. Cheverton concluded by remarking that even if all the caloric given off by the burning coals were to be absorbed by the boiler of a steam engine there would still be a wasteful gap between the temperature of the furnace and that of the ordinary boiler; even of the boilers of Mr. Perkin's ultra-high pressure engines. He did not, of course, recognize the difference between the potentially very efficient Stirling engine cycle, and the less efficient Ericsson engine. Nevertheless, there were some extremely interesting points about Cheverton's paper. In the first place although Cheverton never mentioned Carnot, Joule or Thomson his arguments are uncannily like theirs. The recognition that heat and work are interchangeable; the emphasis on the apparent paradox that the same amount of heat can produce either a negligible amount of warming up, or considerable heating plus the performance of work; and finally the clear recognition that work depends on the temperature drop, coupled with the criticism that even Perkins' boiler did not utilize more than a small fraction of the total temperature difference: all these are very close to the arguments of Joule, Carnot and Thomson. 1 0 Did Cheverton know of their work? If he did, why didn't he mention them? It was evident from the subsequent discussion that no one else present made these, to us obvious, connections: not even Michael Faraday, I. K. Brunei, or C. W. Siemens. And then there was the element of mystery about Cheverton

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himself. He said that he had had thirty years' experience of steam-engines; but his name is not known in the familiar annals of steam power technology. He made only one contribution to the Minutes of Proceedings of the Institution of Civil Engineers: there is no obituary notice of him in the subsequent volumes of Minutes of Proceedings11 he did not belong to the Institution of Mechanical Engineers and he is not in either DNB or Who Was Who. He is, in short, a mystery figure. In view of the interest Cheverton's paper had aroused C. W. Siemens was asked to explain the new theory of heat to the Institution. This he did soon afterwards, but his own understanding was not quite what it might have been. In particular he did not understand the significance of the absolute scale of temperature in measuring the efficiency of a heat engine. Merely multiplying the heat imparted to an engine by Joule's equivalent does not give the amount of work theoretically obtainable under ideal circumstances unless the condenser temperature is absolute zero, or — 273° C. Accordingly the steam engines of the day were measured against the impossible standard of a more than perfect engine, indeed a thermodynamically impossible engine. 1 2 Professor Lynwood Bryant has pointed out that this famous discussion revealed the differences in levels of understanding — from the naive, 'practical' or commonsense engineers to comparative sophisticates like Siemens who had some knowledge of current science. 1 3 We would like to suggest here that it shows something else as well: it reveals a considerable culture gap between London on the one hand and Glasgow on the other. We suggest that in those days, before everything became standardized and uniform over the whole country local influences would be much stronger than they could be today. The Glasgow of the early 1850s was the Glasgow of William Thomson, W. J. Macquorn Rankine, Lewis Gordon and James Thomson. It is reasonable to suppose that these men could easily have solved the problems that so puzzled the London engineers. But the debate also raised another topic. As Lynwood Bryant remarks, a strong incentive for the invention of the early air-engines of Ericsson and Stirling was the desirability of devising an efficient and safe marine engine. In this they were unsuccessful, and the steam-engine continued to reign supreme. But now under interesting and rapidly changing circumstances. High-pressure steam was only slowly and reluctantly adopted for marine engines. And this is something of a puzzle when the advantages of high-pressure steam are considered; high-pressure steam-engines could be made powerful, small and economical thus releasing valuable space for profit-earning cargo. There seemed to have been several reasons why, in fact, they were unpopular.

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1. The power required goes up as the cube of the speed so there was, in economic terms, a strong disincentive to the use of high speed engines; this in turn meant a preference for slow, low-pressure engines. 2. There was a very real fear of boiler explosions. Well publicised disasters on the Thames and the Mississippi did nothing t o lessen anxiety about high-pressure steam, after all, the penalties for an explosion at sea were likely to be far more severe than for a similar explosion on land. 3. Boilers were designed t o fit neatly into hulls, which in effect meant rectangular and therefore low-pressure boilers, rather than cylindrical and high-pressure ones. 4. Sea-water was commonly used in marine boilers and this, too, made high pressure practice impossible. Experiments were made with surface condensers — an added expense and complication by the way — but these were n o t generally adopted until after 1850. 5. Improvements such as the introduction of more efficient screw propellers in place of paddlewheels, and iron hulls in place of wooden ones tended to obscure the question of engine efficiency. 14 6. Finally, there are two reasons that were not made explicit at the time but which were, we may infer, of some weight. In the first place shipowners were quite unaccustomed to judge engines by their thermo-mechanical efficiencies. The only rival for the marine steam-engine was the wind, which was quite free. Mine owners, on the other hand, had for centuries been adept at costing out the rival forms of power: wind, water, animal muscle, and finally steam. And the last reason was simply the lack of technical resources for repairs and so forth in ports other than those of Europe and North America. However, with the wider adoption of steamships marine engineers began to pay increased attention to fuel economy and comparative trials became increasingly common. Accordingly the efficiency of marine engines began t o improve rapidly. It was said that it doubled in the decade I860—70, 1 5 and increased sharply again in the next decade. In fact the marine engine seems to have gone through roughly the same phase of dramatic improvement that the Cornish engine went through more than half a century before. And this contrasts with other types of engine. Records are hard to come by — there is a vast field for study here, virtually untouched — but as far as we can see the average level of thermal efficiency of ordinary rotative steam-engines remained abysmal throughout the century. Examples quoted by Sir Frederick Bramwell showed that, in the Birmingham area, for example, the duty of rotative engines in 1885 was of the same order as that of

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the first Newcomen engines, a century and a half earlier. 1 6 The findings of the Manchester Steam Users' Association (an organization run by engine and boiler insurance companies) confirmed that engines in the Manchester area were little, if any, better. Of course the ordinary, backyard rotative engine did not operate under the best, or even reasonable conditions for maximum efficiency; nevertheless the record is surprising. Only perhaps in the cases of pumping and marine engines were direct and large scale comparisons of duty possible, for these were the only engines that ran for long periods uniformly and with more or less constant loads.* In the cases of all other engines variations in load or running conditions made comparisons difficult, and comparative abundance and cheapness of coal might make them superfluous. A textbook, published at the end of the century, makes this point very clearly: l 7 . . . .where other conditions than the above obtain, that is, where cost of maintenance, attendance, repairs, depreciation, loss through stoppages, etc., all have to be considered, as is the case in most stationary work, in estimating the real commercial economy, it is doubtful whether even the most up-to-date stationary engineering will adopt the extremely high pressures used by marine engineers for the sake of maximum steam economy as such, and as distinguished from all-round economy, though probably superheating will continue to increase in favour. And the author quotes a pamphlet by Hick, Hargreaves & Co. of Bolton who state: Experience has shown that whilst two cylinder compound engines have great advantages in the way of simplicity and reliability, they can compete very closely even in steam-engine economy per I.H.P. with the best triple-expansion engines, and that they actually afford the least expensive and most satisfactory method of driving a factory when all the items of expense are taken into account. When we turn to consider the scientific aspects of the development of the marine steam-engine, indeed of all steamengines, during this period we are confronted by the commanding figure of W. J. Macquorn Rankine.'Industry', wrote Liddell Hart, 'is the proverbial birthright of the the Lowland Scot'. Certainly Rankine was no exception. Born in 1820 in Edinburgh, he was educated at Ayr Academy and Glasgow High School, b u t as he suffered from ill health much of his subsequent education was private. At the age of fourteen he read Newton's Principia, and, on *This would certainly be true of mail and ferry steamers carrying passengers and only a small cargo over long distances on regular and scheduled services.

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entering Edinburgh Univerity in 1836, he studied a wide range of sciences as well as reading extensively in philosophy; he was also an accomplished classical scholar and a good pianist. On leaving University he found his metier in the employ of various railway companies, and as a surveyor to the Loch Katrine water scheme. In 1855 Lewis Gordon resigned the Regius Chair of Civil Engineering at Glasgow University 1 8 and Rankine was invited to succeed him. During the ten years 1859—1869 Rankine in an astonishing burst of creativity produced four masterly textbooks of engineering: A manual of the steam-engine and other prime movers; A manual of civil engineering; A treatise on shipbuilding; and On machinery and millwork. He also introduced the key concepts of potential and actual energy (he was a sound Aristotelean, hence his invention of appropriate dichotomous terms) which were later, and not altogether happily, retitled by Thomson and Tait potential and kinetic energy. And his contribution to the philosophy of science won him the approval of Pierre Duhem as one of the only two worthy 'English' scientists: the other being Newton. 1 9 Rankine, who never married, died prematurely in 1872. It is, of course, with Rankine's thermodynamics that we shall be concerned. And at this stage I must refer to the important work now being done on this subject by Mr. Keith Hutchison of Oxford. We shall not, therefore, deal with the abstruse aspects of Rankine's thermodynamics; we shall concentrate only on the practical consequences. Now his interest in this subject dates effectively from 1850, and it is worth noting that by the time he had published his great Manual of the steam engine, which went through many editions and is really the first modern and scientific book on the steam-engine, he had already worked out his ideas on thermodynamics to the extent of having arrived at what he called the thermodynamic function, which Clausius was later to call the entropy. As we have seen, it is a basic axiom of thermodynamics that the efficiency of a heat engine depends directly on the temperature difference over which it works. In practical terms this means that it is wasteful to burn coal in the furnace at 1,000° C and use the heat to generate steam at only 100° C; to get the best out of the engine you must raise the temperature of the steam as high as you can; as close as possible to that of the burning coal. In the days before Rankine this was by no means self-evident. Many engineers argued that there was no advantage in high-pressure — and therefore high-temperature — steam and they based their arguments on hard, practical experience. After all, there could be a multitude of reasons why a high-pressure/high-temperature engine might be less efficient in practice than a theoretically inferior low-pressure/low-temperature engine. In fact as late as 1839 the British Government had been advised by a leading firm of

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engineers that 'there was no economy in working a marine engine with high-pressure steam'. 2 ° The point then about thermodynamics, and particularly Rankine's thermodynamics, is that it cleared the way ahead for designers of engines, particularly marine engines. It showed them unambiguously what to aim for; it laid down the conditions for progress, subject always to the limitations of design and the physical properties of steam. And it is curious that the point seems to have been conveyed in a very personal way. For two of Rankine's closest friends were James Robert Napier (1791—1869), the great pioneer of Clyde marine engineering — than whom no man did more to improve the steam navigation of the world 2 l and J o h n Elder (1824—1869) of the shipbuilding firm of Randolph & Elder. Rankine collaborated with Napier in the improvement of Stirling's engine; significantly, as Professor Daub has shown, 2 2 the Stirling engine, working on a constant volume cycle, could in theory attain the maximum possible efficiency between the working temperatures, while at the same time using a much smaller expansion than would be required by an engine working on a Carnot cycle between the same temperatures. A smaller expansion meant a smaller engine: a point of considerable importance t o marine engineering. Unfortunately contemporary metallurgy was not capable of supplying the suitable materials for such an engine: there was no Bessemer steel in those days. In the 1850s the steam-engine was therefore the only feasible way of approaching the thermodynamic conditions for maximum efficiency. Unfortunately, there were certain rather obvious difficulties in expanding high-pressure steam down to reasonably low pressures and temperatures. The mechanical difficulties of enormous ratios of expansion in a single cylinder were obvious enough; the new thermodynamics, however, indicated that the specific heat of saturated steam was negative which meant that as it expanded adiabatically it would condense, and n o t superheat as the old conservation of heat theory had forecast. This meant that water would accumulate in the cylinder; and when the exhaust ports were opened so that the pressure fell sharply to that of the condenser the water would re-evaporate, and exhaust into the condenser, carrying heat with it. This was obviously wasteful. The old engineers had noticed the accumulation of water in the cylinder but had ascribed it to 'priming', t h a t is water being carried over from the boiler by the flow of steam. There were several answers to this problem. The most obvious perhaps was to effect the expansion in two or more stages; that is, compounding: a high-pressure cylinder followed by intermediate, or low-pressure cylinders so that the expansion, and therefore the temperature fall per cylinder, was reduced appreciably. These cylinders could be steam jacketed to counteract any tendency on

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the part of steam to condense, and finally the steam could be superheated. Compound marine engines designed in accordance with these principles first appeared in 1856 through the enterprise of the firm of Randolph & Elder. John Elder gave accounts of these engines in the British Association Reports of 1858, 1859 and 1860. All were for the Royal Mail steamers on the South American run. Rankine, in his obituary notice of John Elder, published only a few months before his own death, explicitly ascribes the invention and introduction of these engines to John Elder's knowledge of thermodynamics, 2 3 a knowledge that he must have gained from Rankine himself. This was the beginning of the drive to get much higher efficiencies in marine engines, and we think there can be little doubt that its success owed a great deal to the close relationship between Rankine, on the one hand, and Robert Napier and John Elder on the other. The triple expansion engine came in somewhat later*. An added incentive towards these improvements may have been the price of coal in ports like Valparaiso, Callao, and Panama. But it is interesting to reflect that there was, if not a mistake, certainly a lacuna in Rankine's arguments and reasoning. Carnot's axiom was, of course, entirely correct and the whole history of all heat engines has been guided by it up to the present day. But the water in the cylinder was not primarily due to the'negative specific heat of steam. Oddly enough the proper cause had been pointed out by an engineer called Combes as early as 1 8 4 3 . 2 4 The explanation is simple: the cylinder walls are inevitably cooled as the steam expands and this effect is particularly marked near the exhaust ports. The cooled metal of the cylinders naturally condenses a high proportion of the incoming stearii for the next cycle: this proportion can be as high as 30 per cent or more. Nevertheless, the remedy will be the same as that advocated by Rankine and his immediate disciples: compound expansive engines with steam jackets, and perhaps superheating. 2 5 From the Clyde shipyards and Glasgow University the scene now shifts to Mulhouse, or Muhlhausen — that Franco-German Manchester — and its Societe Industrielle. Gustave Adolphe Hirn (1815—1890), a leading member of the Societe, was an industrialist and engineer, and like Rankine a man of wide and considerable scientific attainments. 26 As early as 1845 he had convinced himself of the truth of the dynamical theory of heat, and had set out to prove it. But he found that Joule had already done so. In the following decade he commenced his well-known experiments to demonstrate that heat is actually consumed in the operation of *Long before the end of the nineteenth century the era of the high-speed, high efficiency * ocean greyhound* had begun.

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a steam-engine. Some writers have professed t o find it odd that it took such a long time for this to be proved; alternatively, that it was a long time before anyone thought of doing it. Dr. A. J. Pacey's recent paper, however, has shown that the passage of heat through a heat engine had been measured before the end of the eighteenth century; 2 7 and the critics underestimate the great difficulties involved in making such measurements. The thermodynamic efficiencies of heat engines were, up to Hirn's time so small that the actual consumption of heat was effectively hidden among other losses of equal or greater magnitude. In any case the actual proof required not merely a demonstration of loss — anything could account for that — but the added demonstration that such loss was always equal t o the magnitude of the work done divided by Joule's equivalent: that is, that the missing heat was actually converted into work. This Hirn succeeded in doing in a masterly series of experiments described in his Exposition analytique et experimentale, de la theorie mecanique de la chaleur.28 The third edition incidentally was published in 1875 when Hirn had presumably become a German, b u t the copy that originally belonged t o Joule, and is now in our library at UMIST, is inscribed by Hirn in French, and his address is given as 'Logelbach, pr&s Colmar'. Hirn's demonstration was in fact part of a great series of experiments carried out by him and his collaborators, O. Hallauer, W. Grosseteste, G. Leloutre and others in which n o t only was the dynamical theory of heat confirmed b u t all the sources of loss and inefficiency in steam-engines meticulously examined and measured. It was confirmed for example that the water in the cylinder was due t o cold metal condensing the incoming steam. The efficiency of the steam jacket, or 'chemise a vapeur' was studied and the limits of expansion examined. In this way a new and critical analytic approach to the steam-engine, based on the dynamical theory of heat and the principles of thermodynamics, was pioneered in France. It was all reported in the pages of the Bulletin de la Societe Industrielle de Mulhouse (1826— ) and for the first time in over a hundred and fifty years the British found themselves copying the French in practical matters relating t o steam power. As early as 1839 a Mr. Parkes had objected to the common, time-honoured practice of indicating the efficiency of an engine by expressing the work done per given weight of coal consumed. 2 9 His complaint seems to have been ignored however, even though he pointed out that such a practice obscured the important differences that underlay the comparison of engine efficiencies: one machine might have a much better boiler, or a better engineman than another and so, even though it might in itself be less efficient in the long run, it might appear the better machine. It was only after the development of thermodynamics and the work

D. S. L. Cardwell and Richard L. Hills

13

of Hirn that this point seems t o have been taken up again. In England Bryan Donkin, a member of an old-established engineering family, was perhaps the first t o attempt to use a more rational measure of the performance of engines. 3 0 He measured the efficiencies of engines by dividing the heat rejected into condenser by the indicated work: the smaller this fraction, the better the engine. A superior measure was t o take the number of thermal units used per horse power hour: this was the way favoured by Hirn and his disciples. The acceptance of the principles of thermodynamics meant therefore new techniques in engine design, new standards of efficiency and new and exact measurements of the various significant processes in the steam-engine. The last of the new techniques of measurement that I shall mention was due t o yet another formidable, although now very little known, Scotsman, John Macfarlane Gray. Macfarlane Gray (1831—1908) was the son of a Kincardine draper, and as a youth he was apprenticed to that trade; it did not suit him so he transferred his allegiance to a Leith engineering firm. During this time he managed to teach himself Greek and Hebrew as well as mathematics and mechanics. Thereafter he went t o various Clyde shipbuilding firms, being employed on the design of marine engines. In 1866 he became quite famous through his invention of the remote controlled steam steering gear for the Great Eastern.31 In those days it was said that an armoured cruiser travelling at speed might require up to a hundred men t o put the helm over t o alter course. With steam steering gear the number of men was reduced to two, and the time required to make a full 360° turn substantially reduced. At about this time Macfarlane Gray entered the service of the Board of Trade as Chief Examiner of Marine Engineers. This had the unfortunate consequence of severely reducing his publications. He was President of the Institution of Naval Architects in 1870, and Vice-President in 1904. Macfarlane Gray's major contribution was what he called the 'theta-phi', or entropy-temperature, diagram. 3 2 This complemented the familiar indicator diagram for it denoted the heat energy entering and leaving the steam while the latter indicated the mechanical work done by or on the steam. Macfarlane Gray plotted the absolute temperature as the vertical ordinate and the entropy as the abscissae (see Figure 1). From the definition of entropy the area under a section of the water, steam, or latent heat lines gives the heat energy either imparted to the working substance or the heat energy abstracted from it. In the case of a perfect engine working on a Carnot cycle the isothermals and adiabatics — or isentropic lines — are straight lines so that the cycle on the theta-phi diagram appears as a rectangle. The advantage so far as practical steam-engines are concerned, are that

14

Thermodynamics

and Practical Engineering \Steam

Water/

Tor 0 (Absolute temperature)

,

Ti„ y

^

Tn,

/

D

< ^ ^ ^ > ^

E

\ ,A

B

< ^

C S or (^(entropy)

Figure 1 The entropy-temperature diagram as it appeared in many late nineteenth century engineering textbooks. the theta-phi diagram shows the efficiency of the engine, and indicates the wastages in a way that the pv indicator diagram cannot do; it also reveals clearly the dependence of engine efficiency on the temperature range over which it works, and shows the degree of wetness of the steam after expansion. There can be no doubt that Macfarlane Gray's theta-phi diagram was derived from his reading of Rankine and contacts with him. That he used the term 'entropy' rather than 'thermodynamic function' merely shows the influence of his fellow Scots, and near neighbours, William Thomson and P. G. Tait. Let us suppose that water at temperature T 0 , sufficient for one cycle of an ordinary steam-engine, is heated up so that its temperature rises to Tx and its entropy increases by l o g T j / T o . When it reaches Tx the water begins to boil and, as the pressure is kept constant (isothermal expansion), it continues to evaporate until at point A it is all in the form of steam. This is the point of cut-off when the steam in the cylinder is allowed to expand adiabatically. The adiabatic or isentropic expansion is indicated by the vertical line AB which cuts the isothermal T 0 at B. The steam is now wet, having condensed FB/FT 0 of its weight, and its conversion entirely into water is effected by isothermal compression at T 0 . When the steam is all condensed it is returned to the boiler for the next cycle. The shaded area T 0 T X AB indicates the work done by the heat in one cycle of the engine. In actual practice cylinder losses and

D. S. L. Cardwell and Richard L. Hills

15

incomplete expansion reduce this area by amounts that can be ascertained. Tx ABE is the diagram that would be obtained for an engine working on a Carnot cycle (two adiabatics and two isothermals). Macfarlane Gray stated that he first began to use the theta-phi diagram in 1875 although he did not publish an account of it until 1889. 3 3 In the meantime one of the disciples he had acquired was Peter William Willans (1851—1892), who was in business as an engine-maker at Thames Ditton. Willans was killed by an accidental fall from his dog-cart while at the prime of his life. 3 4 He had already read two significant papers before the Institution of Civil Engineers, and had a third in preparation. 35 These papers described in meticulous detail tests he had carried out on his own high-speed compound engine. Willans concluded that for maximum efficiency at the higher temperature ranges the engine should run at high speed and have an appropriate number of stages of expansion. The Willans engine was found to be most useful for driving that new machine that was meeting a new, and rapidly growing demand, the electric dynamo. And so the theta-phi diagram passed into common use at the end of the nineteenth century. Willans, who had started off as a severely practical engineer, was converted to it and to the analytical approach by Macfarlane Gray himself, as well as by Captain Riall Sankey, R.E., and Colonel R. E. Crompton. However, as is well known, the theta-phi, or entropy-temperature diagram was first invented by Josiah Willard Gibbs who published his account of it in the Transactions of the Connecticut Academy of Arts and Science.36 And two years later Professor Carl von Linde* of the Munich Technische Hochschule gave an account of what he called the 'heat-weight' — temperature diagram (see Figure 2 ) . 3 7 The expression 'heat-weight' requires clarification. Linde had attended Zurich Polytechnic where he had come in contact with Clausius, Reuleux and Gustav Zeuner. The last named had, in his Gfiindzuge der mechanischen wdrmetheorie (editions from 1860 onward) done for Germans what Him and Rankine had done for Frenchmen and Britons: that is, write a definitive textbook on thermodynamics for engineers. Zeuner had envisaged the operation of heat engines in terms of an hydraulic analogy, just as Carnot had done, nearly forty years before. 3 8 For Carnot caloric *Linde has the vicarious distinction of having inspired Rudolf Diesel to invent his engine by pointing out the main features of the Carnot cycle to a class of students that included Diesel, and by going on to comment that no feasible engine could possibly approximate to the efficiency of the Carnot cycle. Linde's own work was concerned mainly with refrigeration and he is known for his invention of a method of producing very low temperatures by means of the Joule-Thomson effect.

288

Figure 2. von LindeV heat-weight' temperature diagram

D. S. L. Cardwell and Richard L. Hills

17

was an acceptable analogue of ponderable water; but as the caloric theory was long discredited Zeuner substituted the notion of 'heat-weight', which some interpreted as equivalent to the entropy.* The work done by a weight of water W x , falling hx — h 0 feet is equal to Wx (hj — h 0 ) . And the work done by a quantity of heat Qi applied to an analogous fall in temperature is Qi /Ti (T x — T 0 ) . If, then, we take the temperature fall as analogous to the difference in height, then the 'heat-weight' ( Q i / T j ) is analogous to the weight, Wj. The expressions for both the water and the heat engines can be generalized to cover more complicated engines involving varying quantities of driving agent and a number of different falls. 3 9 This attempt to extend the hydraulic analogy did not find favour with other writers! In fact, much of the work published towards the end of the nineteenth century seems rather archaic. This is true of Willan's papers, and particularly true of Daniel Kinnear Clark's massive four-volume work: The steam engine: a treatise on steam engines and boilers (1889—90). The engines described in such detail were already outmoded, and in the next few decades were to be completely superseded. It was the end of an era. For, in 1884 C. A. Parsons had introduced the steam turbine, which in conjunction with the dynamo was to spell the end of the nineteenth century reciprocating engine. 4 ° And the diesel and other forms of internal combustion engine were soon to oust all the smaller steam-engines. Nevertheless, the basic principles remained unchanged; the thermodynamics worked out by Rankine, his contemporaries and their immediate successors was no less applicable to the new engines than it had been to the old ones. It is true that Richard Mollier introduced the entropy-total heat diagram which is particularly suitable for dealing with turbines, but this was a development from the main theme, not a basic change. In conclusion we think it is quite clear that by the 1870s the British were beginning to lose their decisive lead in power technology. Rankine died in 1872. In 1873 Gibbs introduced the entropy-temperature diagram. Thereafter it was as reasonable to expect the next advance from Zurich, or Munich, or Mulhausen, or M.I.T., as it was from Glasgow or Manchester. Parsons — a very highly privileged engineer — was the exception that proves the rule. A significant clue to the reason for this change was put forward by an engineer attending a meeting of Institution of Civil

*This of course was misleading, for entropy is a state function of a body. For Clausius' criticism, see his Mechanical theory of heat, translated by Walter R. Browne (London, 1879), pp. 341—345.

18

Thermodynamics

and Practical

Engineering

Engineers to discuss the Willans engine (1893): The danger which, as many thought, now threatened English engineering, lay in the more thorough education and superior mathematical knowledge of so many foreign engineers. But this raises questions outside the scope of this paper. Notes 1. D. S. L. Card well, 'Les Debuts de la Thermodynamique', La Recherche, No. 48 (September, 1974), p. 726. 2. Jonathan Hornblower had, as early as 1781, invented a two-cylinder compound engine. It was not a success — the engineering techniques of the time were not sufficiently advanced to enable such a machine to be made with the necessary precision. And in any case the courts held that it violated Watt's patent. 3. Joel Lean, a much respected Cornish engineer, commenced publication of the Monthly Engine Reporter in 1811. It appeared regularly until 1880 and gave details of the great majority of engines in the county, their fuel consumption and the work they did every month. 4. W. Morshead, Jr., * On the duty of the Cornish pumping engines'. Minutes of Proceedings of the Institution of Civil Engineers, vol. 23 (1863—4), p. 45. Morshead showed that the duty of Cornish engines fell by about 25 per cent during the period 1841 to 1860. 5. Edward E. Daub, "The regenerator principle in the Stirling and Ericsson hot air engines', British Journal for the History of Science, vol. 7 (November, 1974), p. 259. 6. Ibid. The source of this extravagant hope, quoted by Daub, was the Boston Evening Transcript 7. James Stirling, * Description of Stirling's improved air engine', M.P.I.C.E., vol. 4 (1845), p. 348. 8. See the discussions following W. W. Poingdestre's paper * Description of Sir George Cayley's air engine', M.P.I.C.E., vol. 9 (1850), p. 194; and following B. Cheverton's paper, op. cit. (9). 9. Benjamin Cheverton, 'On the use of hot air as a motive power', M.P.I.C.E., vol. 12 (1852-3), p. 312. 10. Collected scientific papers of James Prescott Joule, vol. 1 (Physical Society, London, 1881; Dawson Reprint, 1963), p. 123 et seq.; Sadi Carnot Reflexions sur la puissance mo trice du feu (Paris, 1824; Blanchard Reprint, 1953); William Thomson, 'An Account of Carnot's theory of the motive power of heat' (1849), in Mathematical and physical papers of Sir William Thomson, vol. 1 (Cambridge, 1884). 11. See 'Memoirs of deceased members' in Subject Indexes of M.P.I.C.E. (1885), (1895), (1909), (1920) and (1930). 12. Joule himself made this mistake. See Joule, op. cit. (10), pp. 156—7. An engine whose condenser was not at absolute zero and which nevertheless converted all the input heat into useful work would directly contravene the second law of thermodynamics. 13. Lynwood Bryant, 'The role of thermodynamics in the evolution of the heat engine', Technology and Culture, vol. 14 (April, 1973), p. 152. 14. (1) to (5) are given by Frederick J. Bramwell, 'On the progress effected in the economy of fuel in steam navigation', Proceedings of the Institution of Mechanical Engineers (1872), p. 125. 15. Ibid. See the statements of J. L. K. Jamieson and C. W. Siemens. Also F. C. Marshall 'On the progress and development of the marine engine', PJ.M.E. (1881), p. 449.

D. S. L. Cardwell and Richard L. Hills

19

16. George E. Davies, A handbook of chemical engineering, vol. 1 (Manchester, 1901), p. 265 et seq., p. 291. 17. William Ripper, Steam engine theory and practice (London, 1901), p. 307. 18. Lewis Gordon (1815—1876), was perhaps the first British convert to Sadi Carnot's ideas. See Sylvanus Thompson, The life of William Thomson, Lord Kelvin, Vol. 1 (London, 1910), p. 133. Gordon, who was born in Edinburgh, studied engineering at Freiburg and seems to have had some connection with the Ecole Poly technique. He travelled extensively in Europe, studying mines and mining techniques. Subsequently he became an assistant to M. I. Brunei on the Thames Tunnel project, and from 1840 until 1855 he held the Regius Chair of Civil Engineering at Glasgow University. James Thomson (William Thomson's brother) was one of his students at Glasgow. On resigning his Chair he went into business, manufacturing submarine electric cables. We are indebted to Mr. Keith Hutchison for this additional information. 19. Pierre Duhem, The aim and structure of physical theory (Princeton University Press, 1954), pp. 52—3, 317, 326—7, 333. 20. F. J. Bramwell, op. cit. (note 14). 21. Obituary notice of David Napier, Engineering (3 December, 1869), p. 365. 22. Daub, op. cit. (note 5). 23. W. J. M. Rankine, Biography of John Elder (1824—1869), Transactions of the Institution of Engineers and Shipbuilders in Scotland, vol. 15 (1871-2), p. 15. 24. Charles Combes, 'Memoire contenant la discussion de quelques observations relatives au mode d'action de la vapeur dans les machines, principalement dans les machines d'epuisement a detente usitees dans la Comte de Cornwall', Comptes Rendus, vol. 16 (1843), p. 649; and 'Notes sur Pinfluence des enveloppes dans les machines a vapeur', Comptes Rendus, vol. 17 (1843), p. 1165. 25. The old Cornish engineers had reduced the temperature difference in the cylinder by commoning the top and bottom ends after expansion and during the return stroke. See P. W. Willans, * Steam engine trials', M.P.I.C.E., vol. 114 (1893), p. 2, and comment by Mr. Wingfield in subsequent discussion. An account of this technique will be found in W. Ripper, op. cit. (note 17), pp. 318—9. 26. For a biographical sketch of Him see Memoirs and Proceedings of the Manchester Literary and Philosophical Society, 4th series, vol. 33 (1890), p. 159. The Manchester 'Lit. & Phil.' was the only British institution to honour Hirn. 27. A. J. Pacey, 'Some early heat engine concepts and the conservation of heat', B.J.H.S., vol. 7 (July, 1974), p. 135. 28. G. A. Hirn, 'Exposition analytique . . .' (Paris, 1862). 29. J. G. Mair, 'The independent testing of steam engines and the measurement of the heat used', M.P.I.C.E., vol. 70 (1882—3), p. 313; and 'Results of some engine tests', M.P.I.C.E., vol. 79 (1884—5), p. 323. 30. Engineering, vol. 7 (21 May, 1869), pp. 334, 341; and vol. 37 (15 February, 1884), p. 154. 31. Obituary notice, Engineering, vol. 85 (17 January, 1908), pp. 87—9. It is of interest that Gray must have been with the Clydeside firm of McNab at about the time when they built the first receiver compound engine (1860). 32. Accounts of the 'theta-phi' diagram can be found in, for example, John Perry, The steam engine, and gas and oil engines (London, 1900); William Ripper, op. cit. (17); J. A. Ewing, The steam engine and other heat engines (Cambridge, 1894); J. H. Cotterill, The steam engine considered as a thermodynamic machine (London, 2nd edition, 1890) and H. A. Golding,

20

Thermodynamics

and Practical

Engineering

The theta-phi diagram, practically applied to steam, gas, oil and air engines (Manchester, 1893). 33. J. Macfarlane Gray, 'The ether pressure theory of thermodynamics applied to steam', P.I.M.E. (1889), p. 339; and 'The rationalisation of Regnault's experiments on steam', Ibid., p. 399. 34. Obituary notice, Engineering, vol. 53 (1893), p. 661. 35. P. W. Willans, 'Economy trials of a non-condensing steam engine: Simple, Compound and Triple', M.P.I.C.E., vol. 93 (1888), p. 128; and, 'Reply by author to the correspondence', M.P.I.C.E., vol. 96 (1889), p. 230; and op. cit. (25). 36. Reprinted in The collected papers of J. Willard Gibbs, vol. 1 (Yale University Press, 1948), p. 1. 37. See Schroeter's contribution to the discussion following Willans' paper, op. cit. (25). 38. For Carnot's use of the hydraulic analogy, see D. S. L. Cardwell, From Watt to Clausius (Heinemann, London, 1971), p. 181 et seq. And, D. S. L. Cardwell, 'Power technology and the advance of science, 1700—1825', Technology and Culture, vol. 6 (Spring, 1965), p. 188. 39. J. A. Ewing, op. cit. (32), p. 92—3. 40. It is worth remarking that in the Parsons turbine the steam expands in stages from high to low pressure. There is thus an analogy between the turbine and the double, or triple expansion reciprocating engines. But in the case of the turbine the basic reason for using multistage expansion was to bring the pressure drop, per stage, down to a reasonable level so that the blades did not have to rotate at an impossibly high speed in order to develop power efficiently.

C o u p l e t ' s M e m o i r s ,

E n g i n e e r i n g 1 7 2 6 - 3 3

JACQUES HEYMAN Couplet, alias Couplet de Tartreaux, alias Tartereaux (Pierre), whose place and date of birth are unrecorded, was the son of Claude-Antoine Couplet, permanent Treasurer of the Academie Royale des Sciences, and was admitted t o the Academie as his father's pupil on 4 April 1696; he became in his turn permanent Treasurer in March 1717; he died in Paris on 23 December 1743; he was Professeur Royal de Mathematiques des Pages de la Grande Ecurie. This is almost the total information in the official Index of the Academie; Maindron's list 2 adds nothing Biographique1 further, although his earlier history 3 catches sight of Couplet once or twice. There appears to have been no Eloge at his death, and this is most unusual; Dortous de Mairan's collection 4 of Eloges for the Academicians who died in 1 7 4 1 , 1742 and 1743 contains no mention of Pierre Couplet. Couplet's publications seem to have been entirely in the Memoires of the Academie. He wrote a short note in 1700 relating some experiences on a journey, and submitted some astronomical observations in 1 7 0 1 , but nothing further for a quarter of a century. Then, from 1726 t o 1 7 3 3 , the Academie published in each year a full-length memoir by Couplet. The first three papers discuss the calculation of the thrust of soil against a retaining wall, and the next two the thrust of arches; finally there were three single memoirs on the shape of timber roofs, on the flow of water in long pipe-lines, and on the haulage of carts and sledges. These contributions t o five different problems in engineering science will be described. Claude-Antoine Couplet By contrast with his son, C. Couplet has a full Eloge (in the Histoire of the Academie for 1722: he died on 25 July of that year). He was born in 1642 and became the pupil of Jacques Bu(h)ot, a mathematician, terrestrial geographer, and Royal Engineer; in 1665 he married Buot's step-daughter. Buot himself was chosen in 1666 as one of the founder members of the Academie des Sciences, and it is perhaps no surprise to find that when the founder members were joined almost immediately by some 'young men fit to aid them in their work and one day to succeed them', 5 C. Couplet was included in the list. The young

22

Couplet's Engineering Memoirs,

1726—33

Couplet was given charge of the * Cabinet des Machines'; this mechanics laboratory was, like C. Couplet, housed in the Observatory in the Paris suburb of Saint-Jacques. C. Couplet bought from Buot in 1670 the office of Professeur de Mathematiques des Pages de la Grande Ecurie, the office which he passed later to his son. The Grande Ecurie housed the King's horses at Versailles, together with the Master of the Horse and the pages; the stables were also a sort of public school for the sons of the nobility. 6 C. Couplet's appointment came at a time when Louis XIV was gradually transforming Versailles into the permanent home for the Court (the final installation was in 1682); in the 1670s pipe-lines for water were being laid, and C. Couplet had abundant opportunity to learn and practise the virtually new sciences of hydraulics and surveying. Indeed, from the evidence of the Eloge C. Couplet's technical skills lay entirely in these two fields; a good half of the Eloge describes one of his major works, the bringing of water to the village of Coulanges-la-Vineuse, near Auxerre in Burgundy. His only publication, 7 in 1699, was a description of a levelling instrument, with instructions for its manufacture and use; C. Couplet assumes that the reader is acquainted with La Hire's standard text. 8 The merit of the new instrument lay in the fact that it could be used by unskilled assistants; time and again in the proceedings of the Academie there is evidence of the wish to simplify scientific theory and apparatus so that they can be put more easily to practical use. The same year of 1699 saw a 'second birth' of the Academie as a body established by royal authority; Louis XIV granted statutes governing its composition and procedure. At the same time the Academie started its regular annual publication of a volume of proceedings, the first part of each volume, the Histoire, consisting of analytical commentaries of the second part, the Memoires. (Also included in the Histoire are some minutes of meetings, Eloges, and other matters.) The statutes were followed within two days by a letter from Ponchartrain, Minister and Secretary of State, naming the stipendiary Academicians, the foreign members and the Associate Academicians, and four pupils; Fontenelle was confirmed as permanent Secretary and C. Couplet as permanent Treasurer. He held his office as Treasurer until he was aged 75, when he handed over to his son and retired on pension. Four years later he had two successive attacks of apoplexy, followed by partial paralysis, and he could speak and swallow only with difficulty for the last two years of his life. It is clear that he had been held in esteem by his colleagues, as the close of the Eloge (by Fontenelle) perhaps shows: 'He was Treasurer of the Academie, a title that is too grandiose and that is in fact wrong; he was rather the opposite

Jacques

Heyman

23

of a Treasurer; he had no money in his hands, but himself made advances of sums which were large when measured by his own fortune, and which he recovered only with difficulty. He has left a son who has succeeded him worthily in this office.' Pierre Couplet Pierre Couplet was a fils a papa. The very scanty biographical information that exists comes from his own letter published by the Academie in 1700, in which he comments on his own youth; he would have been very young when his father nominated him as his pupil in 1696, and still young when he was named in the 1699 list as one of the four pupils in the renewed Academie. His father must have secured his succession as permanent Treasurer, and he passed on also the job of schoolmaster at Versailles. Thus Couplet occupied most of the offices of his father, and, like his father, he was versed in the art of surveying. In 1700 he accompanied Cassini II on the expedition to measure the arc of the meridian in France. (The results of the survey are presented in the Suite of the Memoires of the Academie for 1718, and the results have been analysed by Todhunter. 9 ) In 1701 observations of an eclipse of the moon were reported to the Academie; one of the observers (stationed in France and Spain) was Couplet, and Cassini I compared and analysed the observations. 1 ° Previously, in 1700, the Academie published extracts from several letters written by Couplet from Portugal and Brazil to M. l'Abbe Bignon, President of the Academie. These extracts, put together in the form of a Memoire, are of some interest, although not perhaps entirely in the way Couplet intended; they give an autobiographical glimpse, and a view also emerges of a young man certain of his own scientific strength. He says that he had attended meetings of the Academie for several years, and felt he should travel; in 1697, after debating whether to go east or west, he set off for the West Indies. He stayed a while in Lisbon to learn Portuguese, and then went to Brazil, back to Portugal, and so home to France after two-and-a-half-years' absence. On his journey he made various astronomical observations, and he remarks first on the longitude of Lisbon. On the 7 May 1698 he observed an eclipse of the first satellite of Jupiter; Cassini (I?) did the same at the Observatory in Paris. Couplet compares the difference in times at which the eclipse started, and calculates the difference in longitude between Lisbon and Paris as 12° 57' 45". He quotes other published values, and states that the official maps all underestimate the difference between the meridians. In fact the actual difference is about 11°27'; previous values were better than that of Couplet. Not only was Couplet's observation wrong, but he is quite uncritical about the accuracy to which he pretends. To be sure,

24

Couplet's Engineering Memoirs,

1726—33

the final 45 seconds of arc is really % minute; the time difference, 51 min 51 sec, has merely been reduced to arc measure (1 minute of time = 15 minutes of arc). However Wi degrees of arc, Couplet's error, corresponds to only 6 minutes in time, and this seems to be entirely excusable in the simultaneous observation in Paris and Lisbon of an eclipse of the first satellite of Jupiter in 1698. Errors of this sort were repeated in Couplet's other observations. Before leaving Paris he had regulated his clock at the Observatory (or perhaps his father had done it for him), and he found that at Lisbon it lost 2 min 13 sec a day. He checked this with a seconds pendulum, and concluded finally that such a pendulum should be 2x/2 lines shorter in Lisbon than in Paris (the ligne was the twelfth part of an inch). (The measurement of the length of a seconds pendulum was of course common; Newton gave three lengths — at Paris, Goree and Cayenne — in the first edition of the Principia, and many more in the second and third.) Couplet offers no comment on the rather wide discrepancy between his observations; if the pendulum were really 2lA lines shorter then his clock should have lost about 4 min rather than 2 min a day. Similarly, his observation in Paraiba (Joao Pessoa) in Brazil that the seconds pendulum should be shortened by 3% lines conflicts with the evidence of time lost by his clock, and the factor is again about two. Couplet had reached Paraiba in March 1698, and he quotes other physical constants, for example the magnetic declination (5°35'W) and the latitude deduced from observations of the sun (6°38'S; the actual value is 7 ° l l ' S ) . Almost the whole of the short Memo ire is in fact a miscellany of inaccurate geographical information. Couplet has perhaps some excuse; on the very last leg of his journey, on his return to France, he was shipwrecked off the coast of Picardy (on 25 November 1699) and lost all his books, instruments, and specimens. All that survived from his two-and-a-half-years' voyage were the letters written to the Abbe Bignon and to Cassini. Natural history was of course not out of place in the proceedings of the Academie, and Couplet ends his Memoire with the description of a poisonous snake called by the Portuguese the snake with two heads. Not that it actually has two heads, says Couplet, who examined several; there is a swelling at the end of the tail which had been mistaken for a second head. The snake's reputation as being extremely poisonous was verified by Couplet; he developed a persistent rash merely from handling the skins. The kinds of amateur error made by Couplet in his observations were not in fact excused by the Academie. The report in the Histoire for 1700 politely declines to believe Couplet's observations of the lengths of the seconds pendulum, which conflicted

Jacques Hey man

25

with estimates from other latitudes (for example Cayenne, quoted by Newton). Couplet certainly did not have accurate and delicate enough instruments with him, but it is difficult to escape the conclusion that as an experimental scientist he was arrogant, clumsy, unskilled and perhaps unlucky; he seems certainly to have been accident-prone. He was then silent for a quarter of a century before presenting his series of major Memoires, all but one theoretical. He succeeded his father as permanent Treasurer of the Academie in 1717, and from the glimpse that Maindron gives 11 there was evidently some scandal attaching to his administration. From 1666 to 1696 there had been no proper treasurer, and C. Couplet administered the office from 1696 to 1717, Pierre Couplet taking over until his death in 1743. Maindron says that the younger Couplet's accounts were severely questioned, and only finally approved after investigation. No auditing had been done at all from 1666 to 1725, but in the latter year, as a result of the objections to Couplet's accounts, a Treasury Committee was established. In future, no money could be spent without written authority from three of the four members of the committee; the committee survived until five years after Couplet's death, when other arrangements were made. The Memoires on earth pressure 1 7 2 6 , 1 7 2 7 , 1 7 2 8 The thrust of soil against a retaining wall was to become one of the 'classic' problems of the eighteenth century, and has indeed never been solved completely 1 2 ' 2 3 , even in its simplest form. The problem had been thrown into prominence by Vauban's system of defence, which required deep cuttings; Vauban himself had published empirical tables from which could be read the required thickness and batter for walls of from 10 ft. to 80 ft. in height. Couplet wished to tackle this problem theoretically. He starts his first Memoire by noting that only two writers had carried out research on the subject (Bullet 1 4 in 1691 and Gautier 15 in 1717). In fact Gautier adds little to Bullet's work, which was based on the idea that sand could be treated as an assemblage of small rigid spheres. Bullet supposed that the natural slope of such an assemblage would be 60° (Fig. 1); for the sake of safety, however, he proposed to take an angle of 45° in his calculations. Thus if a soil is cut vertically as at AB (Fig. 2), and retained by a wall, and this wall is suddenly removed, then the earth will fall to form the inclined surface J5C, corresponding to the assumed natural slope; what is needed is the calculation of the force required to balance the thrust of the wedge CAB. Bullet quotes a 'standard result' of the principles of statics: The force required to hold a ball on an inclined 45 slope is l / \ / 2 of the weight of the ball. By extension to the whole mass, a force equal to l / \ / 2 of the weight of the triangle CAB must be resisted

26

Couplet's Engineering Memoirs,

Figure 1. After Bullet (1691)

1726—33

Figure 2. After Bullet (1691) 10'

36'

V—-1

1 16' x Figure 3. After Bullet (1691)

by the wall. Thus if AB = AC = 6 toises, then the force will be proportional to 1 A / 2 (18) = 13 toises;2 the retaining wall must have this same area. Since 1 toise = 6 ft., Fig. 3 shows one possible design of wall (with a batter of 1 in 6). Couplet in his first memoir adopts the 'smooth' theory of Bullet, stating that his second memoir will deal with the practically important problem of a rough retaining wall. However, his immediate concern is to correct Bullet's errors. First, the slope of 60° is wrong; Fig.l shows a two-dimensional configuration, whereas in reality spheres will pack as tetrahedra (Couplet's Figs. 10 and 11 in Fig. 4). Secondly, Bullet's factor of l / v / 2 gives the inclined thrust (Fig. 5, Couplet's Fig. 3) rather than the horizontal thrust. In his third criticism Couplet glimpses a crucial idea of which he makes no further use: the failure plane need not coincide with

Jacques Heyman

27

Figure 4. From Couplet (1726) the plane of natural slope. (Gadroy 1 6 observed this twenty years later and Coulomb 1 7 first made use of it analytically in 1773.) In Bullet's 60° configuration, Couplet imagines one ball D to be outside the natural slope CB (Couplet's Fig. 7 in Fig. 4). This ball will slide not on CB but on an imaginary plane LK, and the force necessary to hold it in place will depend on the slope of LK. By contrast, Couplet shows that the smooth wedge theory implies a constant horizontal thrust against the smooth retaining wall independent of the slope, and that the thrust is proportional to V2h2, where h is the height of the wall. Couplet handles all this well, and is clearly adept at simple statics in a way which Bullet had not been thirty years earlier. Equally he sorts out the geometry of the tetrahedron with economy and skill. He has some difficulty in deciding whether AK in his Fig. 10 (Fig. 4) or AD in his Fig. 11 represents the natural

28

Couplet's Engineering Memoirs,

1726—33

Figure 5. From Couplet (1726) slope. He does not resolve this point, but shows that in either case the thrust of the soil against a smooth wall will be the same. Finally, he uses the idea of moment of a force (a quantity which he calls ene!rgie), illustrated in Fig. 4 (Couplet's Fig. 12), to calculate the overturning moment on a retaining wall. With an expression for such an overturning moment, it is of course simple to equate it to the corresponding upsetting moment for a wall. In his Fig. 13, Couplet considers the wall to overturn about its toe Q, and he proceeds correctly to the design of the wall. Indeed the rest of the paper (and its greater part) consists in the application of Couplet's basic result for overturning moment to the design of walls of ten different profiles. In fact, Couplet makes a mistake in the very last stage of his analysis. In establishing his basic value of overturning moment, he states that the lever arm of the horizontal thrust is 2/3 of the height of the wall; i.e. in Couplet's Fig. 13, the thrust acts along DF. He has assumed, without comment, that the wedge ABC of retained soil must achieve equilibrium under the action of three forces all passing through the centroid of the triangle. This assumption is carried through to the second Memoire of 1727, where Couplet attempts to take account of the effect of friction of the soil against the retaining wall. He is well aware that the frictionless model is too crude to serve in practice; the results of the frictionless theory are notably at variance with the

Jacques Heyman

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dimensions of retaining walls established through experience. The effect of wall friction is to allow the soil thrust to act in an inclined direction and no longer horizontally, so that the overturning moment on the wall is considerably reduced. The direction of thrust is not known a priori, and Couplet merely asserts, without comment, that it is parallel to the natural slope of the soil. Thus both position and direction of the thrust are assumed by Couplet, and mechanics is really at a discount in this second paper; once again Couplet applies himself to the geometry of solid figures, and the evaluation of the various dimensions needed to establish the value of overturning moment. He is still unable to decide whether the face or the edge of a tetrahedron should be considered to be the natural slope, and indeed he adds a third packing arrangement, that of the square-based pyramid, which gives him a greater overturning moment than the other two. He finally presents his results in the form of three tables, one for each of the assumptions of natural slope; the choice of table for practical application depends on the observation of the natural slope of the soil in question. The profiles of the resulting retaining walls are much slimmer than those of the first Memoire, and similar to those of Gautier (which in turn were slimmer than those of Bullet). The third Memoire, of 1728, contains little of scientific interest. Couplet applies his theory to the calculation of the profiles of retaining walls when these are buttressed. The masonry is supposed to be so solid that local failure cannot occur, and overturning of the wall must therefore be accompanied by overturning of the buttresses. Couplet's main interest seems to be to involve the reader in some fierce algebra, but he does obtain solutions, and the problem is, of course, of real practical importance. Taken together, the three papers seem somewhat diffuse. However, Couplet is clearly competent in solid geometry, and he handles the notion of force (having both magnitude and direction) fairly well; he uses his simple 'applied mathematics' to study a problem that, as he says, only Bullet and Gautier had tackled previously (and it was to be another half century before the next theoretical paper was published, by Coulomb 1 7 in 1773). The essential parameter which has survived since the eighteenth century in the design of retaining walls is the overturning moment due to soil thrust. It is difficult to know whether this parameter was common currency in 1726, or whether Couplet introduced it himself. Certainly Belidor1 8 , in 1729, arrived (semi-empirically) at the same value of overturning moment as Couplet, and he used this value to give tables of dimensions for a range of retaining walls. However, whoever was responsible for the parameter, Couplet

30

Couplet's Engineering Memoirs,

1726—33

was able through its use to publish tables giving an engineering solution to the retaining-wall problem. Some further economies were possible, but Couplet's tables could be used with confidence for any practical design. The Memoires on arch thrust 1 7 2 9 , 1 7 3 0 Having found, if not the solution, then a solution to the problem of the thrust of soil, Couplet turned his attention to the thrust of arches. His single memoir on arch thrust was divided into two parts and published in successive years. The first part examines the problem on the assumption that the voussoirs of the arch are perfectly smooth; this had been La Hire's assumption of 1695. Although La Hire1 9 had in the course of his analysis developed the powerful tool of the funicular polygon, the frictionless assumption leads to an evident absurdity, and La Hire could only conclude rather lamely that friction would confer stability on an arch which he had 'demonstrated' to be unstable. In 1712, however, La Hire2 ° advanced arch theory considerably by adopting a more 'monolithic' approach to the problem. More precisely, he observed that a weak arch would tend to crack at points about half-way between the springings and the crown, and that the arch could then be regarded, not as an assemblage of voussoirs, but as being made up of a small number of much larger blocks. Although he did not describe the weak joints as hinges, he clearly saw that the line of thrust was compelled to be tangential to the intrados at these joints, and was thus constrained both in position and in direction. If the hinge points are known, then the thrust in the arch can be calculated by statics, and the necessary width of the abutments to sustain that thrust can be determined. The calculation of size of abutments was in fact the purpose of arch analysis, just as the calculations of soil thrust were needed to determine the size of retaining walls. Couplet, indeed, starts his two Memoires on arches by referring to his own work on soil thrusts; he states that not only are the two problems analagous, but so also are the solutions. The first Memoire, assuming the frictionless hypothesis throughout, repeats some of La Hire's work, and consists of little more than an examination of lines of thrust and the calculation of corresponding forces. Couplet knows that this part of the work is of little practical value, and that the important problem is concerned with arches in which the voussoirs are prevented from slipping one on another. He excuses the frictionless hypothesis by stating that all previous writers had made that assumption (which is not true), and that he wishes to compare these first results with those resulting from the frictional hypothesis. However, there is one interesting calculation towards the end of the first memoir on the force on centering; such a calculation is

Jacques Heyman

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Figure 6. From Couplet (1729) of obvious constructional importance, and Pitot 2 1 three years previously had given practical details of timber centres and attempted a theoretical analysis. The problem posed by Couplet is that of a semicircular arch of uniform frictionless voussoirs resting on a smooth centre; the final keystone (of very small width) has not been placed. In this state, Couplet determines the voussoir joint, say MV in Fig. 6, above which the voussoirs will require support from the centering, and below which they will be self-supporting. Couplet is hampered in his analysis by the fact that techniques for dealing with components of forces were not well developed, but he manages this part of the work correctly, and deduces that the dividing joint lies at 30° from the abutment. While this result seems reasonable, he fails to notice that the bottom group of voussoirs is not in fact in equilibrium, but requires a tensile force to be developed between them and the centering. The second memoir is of very different calibre; it is Couplet's best scientific paper, and a major contribution to arch theory. The 1730 Histoire is clear about the quality of the work, and starts with a forceful summary of Couplet's aims and methods:

32

Couplet's Engineering Memoirs,

1726—33

M. Couplet continues his theory of arches, which he presented in 1729 only on the hypothesis of perfectly smooth voussoirs, a hypothesis which is merely mathematical and in reality false. Here he recovers the truth, that the voussoirs interlock one with another on their surfaces, and moreover interlock so that they will not give way to any force whose effect would be to make one surface slide on another; an assumption which is not quite true, but mathematics can never come to the aid of engineering unless something is assumed which is more definite and more unambiguous than the truth. Couplet in his own introduction is precise about his assumption that the voussoirs cannot slip; while they are locked against sliding, no resistance is offered to separation during collapse of the arch. He makes no mention of the strength of the stone of which the voussoirs are made, and by implication he assumes that ambient stresses are low so that crushing strength is of small importance. Thus Couplet's study is based upon premises which lead to a particularly simple form of limit analysis of masonry; if it can be assumed that stone has infinite compressive strength, zero tensile strength, and that sliding failure does not occur, then the theorems of simple plastic theory may be applied. 2 2 In particular, the 'safe theorem' applied to an arch states that if any line of thrust can be found which lies within the masonry and which equilibrates the applied dead and superimposed loading, then the arch cannot collapse under that loading. This is all that is needed to demonstrate that an arch is stable. To demonstrate that an arch can become unstable, it is necessary to construct a pattern of hinges (of La Hire's type of weak joint) that corresponds to a mechanism of collapse. Thus the usual duality of approach to structural problems carries through to masonry; there is the approach through equilibrium ('statics') and through deformation ('mechanism'). Couplet's proof of his first theorem in his second paper contains precisely these aspects of duality of structural behaviour. The theorem states that an arch will not collapse if the chord of half the extrados does not cut the intrados, but lies within the thickness of the arch. Couplet has in mind an arch of negligible self-weight subjected to a single point load at the crown A (Fig. 7). Whatever the value of the load, it can communicate directly with the abutments B and C, following the straight thrust lines AFB and AGC. Further, says Couplet, for the arch to collapse the angle BAC must open, and this can only happen by a spread of the abutments, which is ruled out by hypothesis; there is in fact no arrangement of hinges in the extrados and intrados which is at the same time compatible with a thrust line for the load and which gives rise to a mechanism of collapse. (The idea of a mechanism is

Jacques Hey man

33

Figure 7. From Couplet (1730) not discussed by Couplet at this point; as will be seen, however, he envisaged a mechanism as the failure mode. Eccentric loading is not considered; a load acting away from the crown on the same arch, BAC;IKL in Fig. 7, can in fact give rise to a mechanism.) Couplet then remarks on the behaviour of the thinner arch BAQODEP. If the crown A is loaded sufficiently, then the angle DAE could now open and the angles ADB and AEC could close, it being supposed that the portions BMDO and CNEP have insufficient mass to resist overturning. However, the mode of collapse could be inhibited if the haunches are loaded. Couplet notes that such superimposed load is sometimes omitted in tall arches, such as are used in churches, in order to reduce the thrust on the buttresses; when such arches fail, the weakest point is often half-way between springing and crown. With these preliminaries in mind, Couplet tackles his first problem, namely to find the least thickness to be given to a semi-circular arch, carrying its own weight only. The arch, says Couplet, will collapse by breaking into four pieces, attached to each other by hinges (Fig. 8). The hinges T and K at the haunches are placed at 45° from the springings and, by considering the equilibrium of the arch in this state, a single equation can be found relating the thickness of the arch to its radius. Couplet obtains this equation (a cubic) and solves it numerically to obtain

34

Couplet's Engineering Memoirs,

1726—33

Figure 8. From Couplet (1730) the required ratio of thickness to mean radius t/R as 0.101. Couplet's statics are evident in Fig. 8; for the equilibrium of the piece AK of the arch, the horizontal thrust at A combined with the weight acting through H leads to a thrust at K in the line GK. Now GK is not tangential to the intrados at K; Couplet misses this point, but his analysis is otherwise completely valid. (Coulomb, fifty years later, 17 was the first to break away from the idea of postulated failure modes, both in the retaining wall and in the arch problem; for the latter, he allowed the position of the intrados hinges to be determined by the use of calculus. He noted that the calculations are insensitive to the precise position of these hinges; in the present example of the semi-circular arch, the hinge actually forms at about 31° from the springing rather than at 45°, but the correct value of t/R is increased only to 0.106 from Couplet's value of 0.101.) Couplet then repeats his analysis for a circular arch embracing 120° rather than 180°. He assumes again that the haunch hinges form half-way between springing and crown, and he obtains the minimum thickness t/R = 0.0195; the correct value is 0.0226, but again Couplet's error is trivial. Couplet's third problem is concerned with the determination of the arch thrust. Although the work is essentially a repetition of that of La Hire, it repays a brief study in the light of Couplet's previous solutions. He now abandons the 'collapse analysis', and

Jacques Hey man

35

Figure 9. From Couplet (1730) works from a static thrust line in the arch; specifically (Fig. 9), he uses the centre line SX of the arch. Thus the thrust at the crown acts horizontally at S, and the weight of the half arch in the line LR; a simple triangulation of forces then gives the magnitude of the abutment thrust, acting in the line LX. Couplet notes correctly that this line is not necessarily perpendicular to the voussoir joint BN at the abutment, so that frictional forces must certainly be called into play. The calculation of abutment thrust is of course necessary for the solution of Couplet's fourth and final problem, namely to dimension the piers of the arch so that the whole structure is stable. As a specific example, Couplet finds the base EF of the pier (Fig. 9), such that the line of thrust passes through a given point H in that base. This contribution of Couplet is remarkable. He had clear notions of lines of thrust and of mechanisms of collapse caused by the formation of hinges, he stated explicitly the simplifying assumptions necessary for his analysis, and he used these ideas to obtain an essentially complete and correct solution to the problem of arch design. His work had an immediate impact, and found its way into standard texts (e.g. that of Frezier2 3 ) ; two years later Danyzy 2 4 obtained experimental confirmation of the correctness of Couplet's approach. It is only unfortunate that the work was

36

Couplet's Engineering Memoirs,

1726—33

slowly forgotten, so that fifty years later Coulomb, in seeming ignorance of Couplet's contribution, had to rediscover much of the theory. The Memoire on mansard roofs, 1731 The cross-section of a simple roof system consists of two straight rafters meeting at a ridge, and resting at their lower ends on wall-plates. The rafters will tend to take up a permanent bend because of the weight of the roofing material, and to prevent this, a purlin, running from gable to gable of the building, or spanning between main frames, is often used to support the rafters at about mid-length. However, these purlins themselves become permanently bent under the loading, and Couplet's memoir is concerned with a remedy for this defect. He proposes that, instead of having straight rafters, the roof should be constructed in mansard form; in Fig. 10, which shows half the cross-section of the roof, the rafter ABC connects the ridge A to the wall-plate C. Couplet restricts his analysis to the case where AB = BC (the discontinuity in the rafter half-way between ridge and wall-plate is reminiscent of the hinge point in an arch half-way between crown and springing). A purlin is still connected to the rafters at B, and Couplet seeks the position of B (for given dimensions AD = a, DC = 6) such that no load is imposed on the purlin. Thus the roof system will be theoretically in equilibrium even with hinges connecting the members at A, B and C (and at the corresponding points in the

T

I> S G Figure 10. From Couplet (1731)

4

C

Jacques Hey man

37

other half of the roof); the function of the purlin at B will then be only to hold the rafters in position. The problem is an exercise in simple statics. Couplet assumes a roofing material of uniform weight per unit area, and he obtains after a page or two the correct result: ( a 2 + 2 b 2 ) - ( a 4 + a 2 b 2 + b4)1/2 He gives two numerical examples, for a = b and for a = 2/3b; he also gives a graphical construction for locating B in the general case. He then makes other calculations, including that for the value of the horizontal thrust on a wall-plate. Finally, Couplet has a brief analytical discussion of roofs with straight rafters, and he concludes in his Scholie that a steep roof is better than a shallow, not only for structural reasons (the horizontal thrust is less) but also for practical reasons (rain-water runs off faster; the tiles are less likely to be lifted by wind). Francois Mansard had invented the roof which bears his name less than a hundred years before Couplet was writing, but Couplet gives no hint as to the reasons for the invention, that is, whether they were structural or 'architectural'. Certainly the mansarded form allows the easier incorporation of attic rooms; on the other hand Gwilt, 2 5 at the turn of the present century, is clear about the equilibrium (albeit 'tottering') of the broken rafters — the very problem solved by Couplet. Thus it is difficult to say whether Couplet was pointing to a structural advantage (the load-free purlin) of a form devised for other reasons, or whether he was arriving analytically at a result already known in practice. In either case, Couplet shows himself again to be reasonably adept at solving problems in statics; the problem itself is in this case not very weighty. The Memoire on water flow, 1732 The unit of water flow in ancient Rome was the quinaria. Grimal 26 states that in modern units the quinaria is about 0.47 litre/sec or 40 m 3 /day; Herschel2 7 has the measure at about half this, say 25 (English) pints/min. The difficulty in precise enumeration arises because a quinaria was not a measure of volume, but the diameter of a pipe attached to the public water system and through which the supply was drawn. The quinaria is equal to five quarters of a Roman digit, the digit being the sixteenth part of a Roman foot; thus the quinaria is, very closely, one inch. Taxes were levied on the number of quinariae attached to the public supply, and not on the actual water drawn, but the measure is not so crude or arbitrary as might first appear. First, it was well

38

Couplet's Engineering Memoirs,

1726—33

known that, other things being equal, discharge would be more nearly proportional to area rather than diameter of pipe; although the quinaria was derived from a linear measure it was in fact, at least at the time of Frontinus (A.D. 97), used as a square measure. Second, the Romans were quite aware that discharge would depend on the precise level and way in which the tapping was made, and no water was allowed to be taken from the conduits themselves, but only from delivery tanks at the ends of the aqueducts. Finally, the tapping pipes were strictly controlled, and consisted of a short bronze ajutage of fixed diameter, followed by 50 ft. of lead pipe also of a fixed diameter. (It had been found that a simple lead tapping was likely to be unlawfully enlarged by the tax-paying consumer; there is, according to Herschel, no truth in the story that some especially sophisticated consumers had enlarged the tails of their lead tappings into diffusers in order to increase the discharge.) Despite these controls, Frontinus found that the system, when he succeeded to the post of curator aquarum in A.D. 97, was subject to many abuses, and his De Aquis is, among other things, an exposure of these abuses. Paris had its first aqueduct in the time of Julian, some 250 years later, and Coulomb, in 1784, succeeded to a post (Intendant des eaux et fontaines du roi) very much like that of Frontinus; the problems of taxation, litigation, leaking and construction of new supplies were present in the eighteenth as well as in the first century. Moreover, in Coulomb's time and, fifty years earlier, in that of Couplet, the measurement of flow was the pouce, the direct descendant of the quinaria. Mariotte 2 8 in 1686 had established a standard for this 'inch'; it was the discharge obtained in 1 minute from a circular hole of 1 inch diameter in a thin plate (1 ligne thick) whose centre-line was situated 7 lignes below the free surface of the water. (The ligne being the twelfth part of an inch, the centre of the hole was n /i 2 in. below the surface, and the top of the hole was submerged by yt 2 in.) In this situation, Mariotte reckoned the pouce to be equal to 13% Paris pints/min. After some discussion of the evidence, Couplet in his memoir on water flow concludes that a better value for the pouce d'eau is 13V3 Paris pints/min, each pint containing 48 cubic inches. Having settled on this standard, Couplet then constructs tables for help in determining experimentally the strength of a given source of water. He proposes the use of a standard vessel of capacity 12 (St. Denis) pints (= l S 2 ^ Paris pints); the time taken to fill this vessel should be noted using a half-second pendulum, and the corresponding flow can then be found from the table. (There is an overlong discussion of the difference in length of a pendulum in Paris and in an equatorial region, say Paraiba, and Couplet quotes his own findings of thirty-four years earlier. He

Jacques Hey man

39

concludes that the error introduced by using a' Paris' pendulum in Paraiba, namely 14 seconds in an hour (about 0.4%), is of no consequence. The error is, in fact, greater than Couplet's own correction of Mariotte's value of the pouce by 2 in 3 /min to 640 in 3 /min). Couplet's table is constructed for 1(1)94, 95(5)165 and 168 half-seconds, 1(1)20, 25(5)60 minutes, and 1(1)12 hours. A time of 12 hours to fill the standard vessel corresponds to a flow of one-quarter ligne, or 37 pints/day; a time of 84 seconds corresponds to a flow of 1 pouce. As an example of the different units that Couplet judges to be of convenience, if the time taken to fill the vessel were 17 half-seconds, then the flow can be read as 9 pouces 127 lignes, or as 132 Paris pints/min, or as 27 muids 130 pints/hour, or as 658 muids 237 pints/day. (The muid was a measure of 288 pints. Each pouce is divided into 144 square lignes.) A second, shorter, table is constructed for use with a standard vessel of I3V3 pint capacity. Such long and detailed numerical tables were of course common in the proceedings of the Academie, and they relieved the users of a great deal of tedious calculation. However, Couplet's main purpose in writing his Memoire was evidently to report and comment on five tests he had made on flow in pipe-lines in and around Versailles. He comments, justly, that previous experiments had been done on short lengths, and that the basic laws of flow (e.g. discharge proportional to square root of head) did not allow for the effects of friction in long runs of pipe. Some of the pipe-lines laid half a century earlier at Versailles were now disused; Couplet's first test, for example, was on the old iron conduit from the Place Dauphine to the Petites Ecuries. This particular iron pipe was of 4 in diameter and about 300 toises long (exactly: 291 toises 5 pieds 9 pouces). The line was surveyed by Couplet, and he gives a detailed drawing and description (as he does for the other four pipe-lines). He made tests under three separate differences of head between one end of the conduit and the other; the heads were 9 in of water, 21 in and 31 in. For each experiment he recorded the full-pipe discharge, and he drew two conclusions. First, the discharges were not proportional to the square roots of the corresponding heads; the latter are in the ratios 1:1.53:1.86, while the measured discharges were in the ratios 1:1.64:2.22. Second, Mariotte had shown experimentally that a circular hole of 3 lignes diameter under a head of 13 ft would discharge 1 pouce, and Couplet uses this to deduce that a 4 inch diameter pipe under a head of 9 in should discharge 61 * V25 pouces. In fact, Couplet's measured discharge was 2 pouces 63 lignes; as he remarks, this is a very considerable difference, and must be attributed to friction losses in the pipe.

40

Couplet's Engineering Memoirs,

1726—33

Couplet made similar experiments on the other four conduits, the longest of which was 1800 toises, and of 18 in diameter. One result, called bizarre in the Histoire, was observed on conduit number five. After subjecting one end to a head of water, Couplet had to wait ten days before discharge started at the other end. For this he has a completely satisfactory explanation. He first shows that an airlock can prevent discharge, and he fully understands static pressure differences. The mystery of why flow did in fact start after ten days is then solved by reference to leaky pipes or joints, which would allow any air-lock to dissipate. The general conclusion drawn in the Histoire from Couplet's experiments was that the effect of friction would be greater the longer and narrower the pipe, and would also be augmented by bends and elbows, and by larger speeds of flow; however, even the approximate numerical determination of the effects of each of these characteristics is envisaged as a problem of great difficulty. Couplet himself attempts no numerical analysis from which such laws might be deduced; he is content to record the physical descriptions of the conduits and the results of his experiments. He does not even comment on the fact that, while theoretical and measured discharges differ by one or two orders of magnitude, the ratios of discharges are reasonably proportional to square root of head, despite his assertion to the contrary. The experimental evidence presented by Couplet is valuable, and a start could in fact have been made to establish empirical laws for the friction losses in pipes. Indeed, the evidence was used in this way by Dubuat, 2 9 nearly fifty years later. Perhaps it is unfair to expect Couplet to have taken the step, when Daniel Bernoulli's Hydrodynamica was not to be published until 1738; it is, however, disappointing. The Memoire on the haulage of carts and sledges, 1733 Couplet's interest in the haulage problem seems to have been sparked by two circumstances. He noted the passage through Paris of two carved stone blocks, destined for St. Sulpice, which were carried on a sledge pulled by ten or twelve horses in line, and he recalls some model experiments made before the Academie by a M. Duquet on the relative merits of carts and sledges. Duquet had apparently 'shown' that a sledge could be pulled up a slope much more easily than a cart; Couplet attacks the demonstration on the grounds of experimental technique. The arguments hinge on the question of horizontal and inclined forces and Couplet is clearly right in his fuller understanding of force as a vector quantity. Moreover the two sculptures, hauled on a sledge through the streets, had probably gone to the sculptor's studio in two carts each drawn by three horses, from which Couplet deduces (after allowing for some cutting away of stone in the studio) that a load

Jacques Heyman

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Figure 11. From Couplet (1733) which can be pulled by three horses in a cart would require seven or eight horses in a sledge. Couplet then makes some calculations on the force needed to haul a cart over a rough road, and arrives at a general formula. For a cart carrying 4000 lb on wheels of 3 ft. radius, with stones 6 in high to be surmounted, he deduces a pull of some 2600 lb, corresponding to three or four horses. Finally, Couplet notes that the last horse in the line-ahead St. Sulpice train was very tired. In Fig. 11, the pull from the leading horses is horizontal, but the inclination of the final portion AB of the trace (carrying the total pull of up to a dozen horses) can lead to a high vertical load on the last (and only the last) horse. Couplet gives, as usual, a numerical example (for a string of ten horses). There is a rather feeble conclusion on the fracture of the wheels of carts, and indeed the whole Memoire is insubstantial. The calculation of the forces acting on the last horse in a train is interesting, but hardly worth a paper; Couplet's study of carts tires par des chevaux seems more to be tire par les cheveux. Scolie Gautier (op. cit.) listed in 1717 five problems in civil engineering which needed solution, namely 1. the thickness of abutment piers for all kinds of bridges; 2. the dimensions of internal piers as a proportion of the span of the arches; 3. the thickness of the voussoirs between intrados and extrados in the neighbourhood of the keystone; 4. the shape of arches; 5. the dimensions of retaining walls to hold back soil. These challenges of Gautier engaged the attention of many workers in the eighteenth century who were engaged in bridge construction. More widely, problems arose from the building of dykes, harbours and docks, and canals with their locks. Memoirs on the

42

Couplet's Engineering Memoirs,

1726—33

calculation of rate of working, both of men and horses, were not uncommon. At a more fundamental and scientific level, the 'strength of materials' was being developed, and the flow of water was studied. Above all, the Academie was obsessed by the notion of friction; Amontons' basic Memoire3 ° of 1699 had 'caused some astonishment', and papers were published throughout the following century dealing with such problems as the working of various machines and the action of ropes and pulleys. Couplet's five topics fit squarely into this civil engineering framework. His first five Memoires, three on soil thrust and two on arches, take up Gautier's challenge directly and successfully. The memoir on haulage is slight but central, combining ideas of both friction and rate of working. That on flow in pipe-lines gives the first record of experiments in this field, and discusses fluid rather than solid friction, but is disappointing theoretically. The memoir on mansard roofs is also slight, but again seems to be the first record of an attempt at the analysis of forces in a timber frame. In his choice of problems, then, Couplet shows himself to be an engineer; he wishes to record and explain phenomena that he sees, and to develop formulae for design, rather than t o break scientific ground. The tools he uses are those of an engineer; he has a firm grasp of low-grade mathematics (e.g. differential calculus and the resolution of forces in statical problems), and he makes no attempt t o vie mathematically with more learned colleagues. However, at his own level, his grasp of calculus and statics, about that of an entrant to an engineering school of today, is in some sense remarkable; the calculus had been invented only half a century earlier, and the problem of the resolution of forces had been clarified at about the same time. Moreover, like a good scholarship candidate, he is adept at manipulation while at the same time missing some of the finer points, and he has certain idees fixes, such as the magic of 45° as a natural slope for soil or as the weakest point in an arch. His strength seems to lie in his ability t o apply his modest theoretical equipment to problems which were, in one way or another, thrust on his attention. Explicitly, he saw broken-backed roofs and he saw horses struggling to pull sledges. The pipe-lines at Versailles were disused and could be tested. The major problems of soil thrust and arch thrust were, in the elegant phrase of a Nobel Laureate, 3 l up for grabs, and Couplet knows how to use the results of practical observation to direct his theory to formal solutions. Above all, one of the great driving forces in scientific enquiry in the eighteenth century was that of competition; the very fact t h a t Gautier, for example, had published a challenge, or that Duquet had made some doubtful experiments, would be enough to set Couplet, and others, to work. It is for this reason that

Jacques

Heyman

43

memoirs of this time sound boastful to modern ears, and Couplet is by no means alone in making sure that his reader understands that the author is breaking new ground. By contemporary standards, indeed, Couplet almost seems modest, and perhaps the final conclusion must be that he lacked the assurance, even the arrogance, of a first-class scholar. Certainly there is a marked decline after the first five memoirs, and the last three were followed by a silence of ten years up to his death. His father's life in the service of the king, professor of mathematics, treasurer of the AcadGmie, resident in the Observatory, is exposed for all to see in the inscription in a marble table in the Musee de Versailles. The table top shows a map of France, and is dated 1684; it carries the words Presentee AU ROY Par C. Couplet M(aitre) aux Math(ematiques) des pages de sa g(ran)de Escurye com(m)is en so(n) Accad.des Sci loge en son observatoire HAE TIBI ERUNT ARTES 3 2 In a sense, this biography is a complete description of the father. The same biography applies also to the son, but is in no sense complete; the father was content to be a seventeenth-century servant of the established Academy, but the son attempted something more, and he had some modest success. 1700 1701 1726 1727 1728 1729 1730 1731 1732 1733

Couplet's publications Extrait de quelques lettres ecrites de Portugal & du Bresil, Memoires de VAcademie Royale des Sciences, p. 172. Observation de l'eclipse de Lune du 22 fevrier 1701 a Collioure, par Mrs. Cassini, Maraldi, Chazelles, et Couplet, ibid., p. 63. De la poussee des terres contre leurs revestemens, et de la force des revestemens qu'on leur doit opposer, ibid., p. 106. , seconde partie, ibid., p. 139. , troiseme partie, ibid., p. 113. De la poussee des voutes, ibid., p. 79. , seconde partie, ibid., p. 117. Recherches sur la construction des combles de charpente, ibid., p. 69. Recherches sur le mouvement des eaux, ibid., p. 113. Reflexions sur le tirage des charrettes & des traineaux, ibid., p. 49.

Notes 1. Index Biographique des membres et correspondants de VAcademie des Sciences 1666—1954, Paris 1954.

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2. Maindron, E., Vancienne Academie des Sciences: Les Academiciens 1666-1793, Paris 1895. 3. Maindron, E., VAcademie des Sciences, Histoire de VAcademie . . ., Paris 1888. 4. Dortous de Mairan, Eloges des Academiciens de VAcademie Royale des Sciences, morts dans les annees 1741, 1742, & 1743, Paris 1747. 5. Histoire de VAcademie royale des sciences, vol. 1, Paris 1733. 6. Mitford, N., The Sun King, London 1966. 7. Couplet, C-A., Description du niveau, Memoires de VAcademie Royale des Sciences, 1699, p. 127, Paris 1702. 8. La Hire, P. de, Traite de nivellement, Paris 1684. 9. Todhunter, I., A history of the mathematical theories of attraction and the figure of the Earth, 2 vols., London 1873. 10. Memoires de VAcademie Royale des Sciences, 1701, p. 66. 11. Maindron, VAcademie des Sciences, . . . 12. Heyman, J., Coulomb's memoir on statics, Cambridge University Press 1972. 13. Heyman, J., Simple plastic theory applied to soil mechanics, Proc. Symp. on the role of plasticity in soil mechanics, Cambridge 1973. 14. Bullet, P., Varchitecture pratique, Paris 1691. 15. Gautier, H., Dissertation sur Vepaisseur des culees des ponts, . . ., Paris 1717. 16. In Mayniel, K., Traite experimental, analytique et pratique de la poussee des terres et des murs de revetement, . . ., Paris 1808. 17. Coulomb, C. A., Essai sur une application des regies de maximis & minimis a quelques problemes de statique, relatifs a Parchitecture^Memoires de Mathematique & de Physique, presentes a VAcademie Royale des Sciences par divers Savans, . . ., vol. 7, 1773, p,343, Paris 1776. 18. Belidor, B. F. de, La science des ingenieurs . . ., Paris 1729. 19. La Hire, P. de, Traite de Mecanique, Paris 1695. 20. La Hire, P. de, Sur la construction des voutes dans les edifices, Memoires de VAcademie Royale des Sciences, 1712, p. 69. 21. Pitot, H., Examen de la force qu'il faut donner aux cintres dont on se sert dans la construction des grandes voutes des arches des ponts, &c, Memoires de VAcademie Royale des Sciences, 1726, p. 216. 22. Heyman, J., The safety of masonry arches, Int. J. Mech. Sci., vol. 11, 1969, p. 363. 23. Frezier, A. F., La theorie et la pratique de la coupe des pierres . . ., ou traite de stereotomie . . ., 3 vols., Strasbourg and Paris, 1737—39. 24. Danyzy, A. A. H., Methode generate pour determiner la resistance qu'il faut opposer a la poussee des voutes, 27 Feb. 1732, Histoire de la Societe Royale des Sciences etablie a Montpellier, vol. 2, p. 40, Lyon 1778. 25. Gwilt, J., An encyclopaedia of architecture (new Impression), London 1903. 26. Grimal, P., Frontin: Les aqueducs de la ville de Rome, Paris 1944. 27. Herschel, C, The two books on the water supply of the city of Rome of Sextus Julius Frontinus, Water Commissioner of the city of Rome A.D. 97, New York 1913. 28. Mariotte, E., Traite du mouvement des eaux, Paris 1686. 29. Dubuat, P. L. G., Principes d'hydraulique (nouvelle edition), 2 vols., Paris 1786. 30. Amontons, G., De la resistance causee dans les machines, tant par les frottemens des parties qui les composent, que par la roideur des cordes qu'on y employe, & la maniere de calculer l'un et I'autre, Memoires de VAcademie Royale des Sciences, 1699, p. 206. 31. Watson, J. D., The double helix, London 1968. 32. Virgil, Aeneid vi, 851.

A t t i t u d e s a n d

t o t h e

R o m a n

E n g i n e e r i n g

Q u e s t i o n

I n v e r t e d

o f

t h e

S i p h o n

NORMAN A. F . SMITH I. A general introduction Because much has been written on Roman technology and because what has been written bears an air of great authority it is tempting t o suppose that the subject has been thoroughly researched and is well understood. In discussions of many aspects of Roman technology the temptation t o follow an established pattern has proved irresistible. Continual repetition of the same facts and figures and a sustained commitment t o certain ideas and interpretations have consolidated a stereotyped view of history. Not infrequently the original authority for what has become a firmly held and rarely questioned position is disturbingly venerable. Many of the views that are rigidly adhered to were first advanced in the nineteenth century at a time when the study of classics reigned supreme, architectural history was flourishing and, most influential of all, archaeology was uncovering new material at an unprecedented rate. Such was the enthusiasm to make use of archaeological findings that conclusions were prematurely drawn by people who in many cases were n o t well qualified t o assess the work and capabilities of ancient engineers. Even less excusable, on occasions, were the pronouncements of engineers who, inspired t o dabble in ancient history and archaeology for a variety of motives, were prone t o expound some manifestly extravagant views, n o t least in the area of hydraulic technology. Regrettably the fashion is by no means dead even now and the legends continue t o be given an occasional airing. It would be foolish and unjust t o deny the value of a large part of the earlier work done by classicists, architectural historians and archaeologists. As a source of basic information awaiting the scrutiny and appraisal of modern historians of technology theirs is important material. This is especially true of t h e archaeological evidence which in many cases cannot now be examined, so thoroughly have modern developments and re-developments obliterated the traces of Roman engineering over, on and under the ground. On the other hand new archaeological studies continue t o add t o our knowledge; they range from the more

46

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modern applications of underwater archaeology and aerial photography1 to definitive treatments of Roman remains in geographical areas previously only casually explored. 2 Without doubt, however, there is still much to be done, or repeated, if the object is to understand the Romans as engineers rather than as architects, town planners, farmers, soldiers and so on. The translation and annotation of a variety of classical texts has made available a wide range of material which is of importance to historians of engineering and technology. To the established and definitive works of E. A. Thompson 3 on military technology, A. G. Drachmann 4 on Roman (and Greek) mechanical technology and L. A. Moritz5 on grain-milling have recently been added H.Plommer's 6 work on Roman building manuals, O. A. W. Dilke's 7 study of Roman surveying and K. D. White's8 extensive research into Roman agriculture. The body of information accumulated by classicists and archaeologists is impressive and of substantial interest. Nevertheless, a very real question remains. Do we yet have a full appreciation of the nature and purpose of Roman engineering which does justice to the material on which such a study could be based? The answer is no, not by a long way. Historians of engineering have as yet failed to compose anything like a coherent and complete account of Roman engineering. Worse, and in many ways surprising, is their failure to address themselves, with a few exceptions, even to specific areas of Roman technology. There is after all every reason to suppose that the engineering historian, looking in a fresh way at the evidence and asking new and more pertinent questions of it, may arrive at interpretations and conclusions different from those of linguists and archaeologists. 9 The study of ancient engineering generally and Roman engineering in particular is beset with difficulties. Professor M. I. Finley has aptly remarked: l ° Paradoxically, there was both more and less technical progress in the ancient world than the standard picture reveals. There was more, provided we avoid the mistake of hunting solely for great radical inventions and we also look at developments within the limits of the traditional techniques. There was less — far less — if we avoid the reverse mistake and look not merely for the appearance of an invention, but also for the extent of its employment. There is more than a hint here that a major obstacle to comprehending ancient technology is the difficulty of coming to terms with attitudes to technological change and purpose which are unfamiliar to ourselves. Modern technology is characterised, amongst other features, by rapid change and development, by the presence of a profit motive, by an immense reliance on labour

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saving techniques and by the massive production of consumer goods and services. In antiquity these characteristics were, for the most part, conspicuous by their absence. Ancient technology evolved in a different social, economic and cultural climate from our own and it reflects this fact. What today we would classify as civil engineering was immensely important throughout a wide repertoire from irrigation and land reclamation to road- and bridge-building, water-supply works and the construction of docks and harbours. The building and agricultural arts also flourished but, comparatively, the mechanical ones did not. Machines characteristically fell into the province of the military engineer; they played only an ancillary r61e in the civilian techniques of building, irrigation (for water-raising), mining and to a small extent farming. The case of water-power is instructive. Vitruvius' description 11 of the vertical water-wheel is so lucid and unambiguous that there is no way of denying the Romans' familiarity with at least the idea of water-power at an early date, about 25 B.C. Three and more centuries later evidence for a handful of working installations has been unearthed by archaeology. 1 2 Modern writers have favoured two interpretations of these facts. Convinced that once the water-wheel was known it must have been widely and enthusiastically adopted, some historians turn a blind eye to the slightness of the written and archaeological evidence. At the other extreme the infrequent use of water-power is accepted but surprise is expressed at Roman society's failure to capitalise on what ought to have been a revolutionary new idea (as the Middle Ages did). In reality we must face the fact that although the Romans knew how to use water-power they chose not to, at least not to any extent and then only at a late date. The real question is why not, and the answer, ultimately, is that we do not know. 1 3 What is clear, however, is that an attitude to mechanical power prevailed which was fundamentally different from that adopted in later periods, and the fact is important. Generalisations about the nature of technology — its purpose, the way it progresses and the influences which bear upon it (especially science) — are commonplace. Such generalizations are almost always too sweeping and too simple; as a result they are misleading and often nothing less than erroneous. Two important points have to be borne in mind. Technology's role and man's expectations of it have not been the same in different periods; and the fundamental natures of various technologies are intrinsically different. To what extent these considerations help to account for the relative importance of different branches of technology in antiquity it is difficult to say. Basic needs — irrigation, transport, water-supply, mining and so on — were met partly because they were inescapable but partly

48

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also because what was required in these cases was more obvious. The building and agricultural arts embodied, to a large extent, essentially simple technical propositions (and components which were static). They also required massive organization and abundant labour for their execution on a grand scale and time, in other words the accumulation of experience, for their technological development. By comparison the mechanical arts involve concepts which are most difficult to grasp and their application requires labour which is skilful rather than plentiful. Quite what promotes and cultivates mechanical ingenuity — the capacity, in short, to visualize combinations and couplings of moving parts which will perform a rather precise function — is a most fundamental question. Some peoples have demonstrated mechanical ingenuity, medieval European and Chinese for instance; others have not. The Roman Empire's failure to mechanize is perhaps attributable to a measure of mechanical 'blindness' in addition to all the other factors which have been proposed. To quote Professor Finley again: There was more, provided we avoid the mistake of hunting solely for great radical inventions and we also look at developments within the limits of the traditional techniques. This notion is borne out convincingly by Roman civil engineering. There is virtually no aspect of Roman structural and hydraulic engineering which had not been practised, to some extent, by earlier societies. And in fact Roman engineering generally drew heavily on the accomplishments of captive peoples: the Carthaginians (mining, ship-building and harbour construction); the Etruscans (irrigation, land drainage and reclamation, and arcuate construction); the Greeks (a host of techniques amongst which surveying, hydraulic cement, water-supply, harbour works and ship-building were particularly significant); the Egyptians (irrigation and canal-building); and the Nabataeans (desert irrigation using dams). Even though the Romans contributed nothing that was fundamentally new to the civil engineering repertoire they did nevertheless apply this repertoire on an unprecedentedly grand scale and achieve an impressive result. Moreover, Roman engineering emphasized three significant developments which had never been prominent before: a widespread application of the semicircular arch, the extensive use of concrete and the concept of public works. In these important respects the Roman civil engineer was the peer of his predecessors. The catalogue of Roman civil engineering attainments is impressively long. Regrettably many histories of the topic are little

Norman A F. Smith

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more than a chronological ordering of that catalogue. The number of engineering historians who have addressed themselves to a critical assessment of techniques, methods, organization, personnel, costs and so on is conspicuously small. Perhaps the means to probe such issues do not exist, at least not sufficiently to reach substantial conclusions or a complete insight. But until the effort is made and the questions are asked of the evidence there is no knowing what might be revealed. At present we know virtually nothing about Roman engineers. How many can be named? Far fewer than must have been involved in so many projects. Who carried out the work? Evidently it was very frequently corps of military personnel 14 in which case it would be most interesting to know how many men were involved, to what extent they specialized, how they were organized, where and when they were employed and what techniques they used. Professor Dilke's work 1 5 on Roman surveying is disappointingly uninformative about the problems of setting out large construction jobs and levelling and aligning routes for roads and aqueducts, not agrimensorial work strictly speaking but unquestionably closely related. Especially interesting is the nature of the improvements and progress achieved by Roman civil engineers. It is evident that structural evolution, a process which is typical of civil engineering's development in other periods, did occur; it is manifest in aqueduct bridge-building, in dam-construction and in road bridges. Changing shapes and increasing size are probably related to improved methods and new materials, notably concrete. But the nature of the relationship is anything but clear. The need (and ambition) to build on a larger scale perhaps prompted the development of concrete construction; alternatively, the development of concrete and a growing awareness of its strength and capabilities could have been the basis for confident steps towards bigger structures and structural units, a culmination being the amazing roof of the Pantheon. There is another important issue, and a central one: Roman technical writings, or rather the lack of them. In relation to the immense amount of engineering work carried out the surviving texts — Vitruvius, Frontinus, and a handful of later works 1 6 — are exceedingly few and not especially relevant. It might be argued of course that another era of great building, the Middle Ages, has not bequeathed to us a very large literature either. But there is a difference. Medieval notebooks and drawings are strictly relevant. There is no escaping the purpose and practicality of Villard de Honnecourt's 'Sketchbook' or Mathias Roriczer's On the Ordination of Pinnacles.1 7 That surviving drawings of cathedral facades and ground plans really were the ones used is evident from comparison with the existing structures.

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What can be said of the status or indeed the purpose of Vitruvius' De Architectural In the first place it must be remembered that De Architectura is a unique survival and for that reason alone a considerable importance is attached to it. But whether or not the 'Ten Books' comprise either an accurate or a full picture of Roman building is another matter. Some deficiencies in Vitruvius as a source are self-evident. The date of his treatise, c. 25 B.C., is early in relation to the bulk of important Roman engineering. Vitruvius leaned so heavily on Greek writers and material that his work is concerned as much with Greek technology as Roman. There are many aspects of Roman civil engineering which we know were skilfully and frequently practised which find no place in De Architectura at all. What was the status of the 'Ten Books' in the Roman period? The truth is that we know of no substantial evidence that Vitruvius' book was valued as a building manual by his contemporaries and successors. He was quoted by Pliny the Elder and there is a fleeting reference to him in Frontinus (in connection with the sizes of water pipes). Further, H. Plommer has shown the extent to which the later Roman tracts on building by Cetius Faventinus (4th century) and Palladius (5th century) were based on Vitruvius. Nevertheless, in relation to the bulk of Roman civil engineering as it was practised in the first and second centuries Vitruvius was probably of limited use. As Sir Reginald Blomfield once remarked: 'Of the true vitality and creative power that was latent in Roman architecture I doubt if any glimpse is to be caught in Vitruvius' treatise'. It is an intriguing thought that the status and importance of Vitruvius was very likely far greater during the Renaissance than ever it had been under the Romans. This same exaggerated importance attaching to a sole survival has worked its deceptive influence in modern times. Frontinus' De Aquis Urbis Romae presents problems of a different sort. Unlike Vitruvius, Frontinus was a man of good family and education; he was at one time (A.D. 74—78) the governor of Britain; and he wrote on various aspects of land surveying together with a treatise on warfare. 18 His study of Rome's aqueduct system was based on some seven years experience as the city's water commissioner during which time he worked resolutely to bring some order and efficiency to the operation of a public utility which had been woefully neglected and chronically mismanaged for years. There is an immediacy and sense of personal involvement in De Aquis which is necessarily absent in De Architectura. The two works differ too in that whereas Vitruvius is wide ranging and ostensibly technical, Frontinus is focused sharply on one specific issue and is not primarily a technical work. Frontinus was above all a civil servant, not an engineer. As a source for engineering history De Aquis

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needs to be used carefully and more critically than has usually been the case. 19 In essence the state of affairs is thus. Archaeological evidence from all over Europe, North Africa and the Middle East demonstrates the unprecedentedly huge scale on which civil engineering flourished in the hands of Roman engineers. At the same time, however, we know disproportionately little about the practice of Roman civil engineering — the way it was organized, financed, constructed, maintained and surveyed; how it improved and developed; who were the engineers and their work forces. Two important surviving treatises (plus a handful of lesser, and later, ones) are of limited value in throwing light on these matters. Public water-supply was the most significant aspect of Roman civil engineering. Nothing like its scale had been achieved before, nor was to be again until the nineteenth century. A crucial problem facing European and American cities a century or so ago was the need to supply water on the Roman scale; and, as a public utility, in the Roman manner as well. Essentially it was a wholesale resurrection of Roman engineering which solved the nineteenth century problem. Thus it is no coincidence that one hundred years ago civil engineers cultivated an interest in Roman archaeology and history. What follows in the second part of this paper is a new look at one particular aspect of Roman water-supply technology — the inverted siphon. II. Roman inverted siphons 'Inverted siphon* is, in some ways, an unfortunate term for what is in fact a pressurised pipe-line carrying water across a valley or depression. However, the term is firmly established in the technical vocabulary and this is no occasion for trying to eject it. Roman inverted siphons will bear investigation for three reasons. In the first place the subject is of some technological interest in itself and raises significant questions about the materials and hydraulic skill employed. Secondly it is a topic which has rarely been considered (and not at all recently) and even when it has, a number of misconceptions and inaccuracies have been expressed so convincingly that they have gained general currency. And thirdly the siphon issue affords an opportunity to make one or two general points of significance in a broader context. Historians of technology have rarely noticed, and never emphasized, a significant feature of water-supply in antiquity which is that, with two exceptions, all the essential technological ingredients and variations had been identified, and utilized, before Roman engineers came on the scene. As early as 700 B.C. Assyrian engineers had laid out a

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Roman Engineering and the Inverted

Siphon

water-supply system of notable technical completeness at Nineveh, 2 0 and Greek engineers regularly supplied drinking water over long distances and arranged its distribution. 21 The two omissions in the pre-Roman repertoire were, firstly, the use of large impounding reservoirs at the sources of aqueducts 2 2 and, secondly, the application of hydraulic concrete for both structural and hydraulic purposes. The preoccupation among engineering historians with Roman water-supply is understandable in view of the novel scale on which the Romans worked, the imposing remains and the survival of Frontinus' unique manuscript. But bearing in mind that the Romans learned much of their engineering from the Greeks, that they regularly (and perhaps frequently) employed Greek engineers, and that Vitruvius relied extensively on Greek sources it is important to notice that a number of Greek aqueducts featured siphons. Among examples which have been identified are those at Pergamum, Patara, Mylasa, Methymna, Catania, Selinus and Syracuse. Lead was evidently a material used to fabricate the pipes and wood, earthenware and stone have been suggested as well. From many and various opinions expressed by modern writers, a brief selection will indicate what a variety of confused and contradictory views comprise the current position. It was R. J. Forbes who wrote: 2 3 Siphons and bold tunelling are typical for the water-supply systems built by the Greek tyrants and the Hellenistic kings from Sicily and southern Italy to Asia Minor. In Roman times the siphon was used only in some few cases, probably because of leakages and the relatively poor materials available for high pressure. F. Klemm has taken a different view with emphasis on a non-technical argument: 24 Engineering in the Roman Empire was principally State engineering, which accomplished much with the traditional technical means, especially in organizing the making of streets, bridges, aqueducts, war machines and lofty buildings. There were in the Empire more than 186,000 miles of good roads. Ten aqueducts provided Rome daily with some 220 million gallons of water (Plate 1). And the dome of the Pantheon, built in Rome in the second century of our era had a span of over 142 feet 6 inches. Though the Romans usually constructed gravitational water supplies which necessitated extremely costly aqueducts, yet it must by no means be concluded that they were ignorant of the fundamental principle of communicating pipes for the supply of water by pressure as constructed by the Greeks

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before them. Perhaps indeed the difficulties of firm control of a water supply system worked by pressure may have partly determined the choice of gravitation. But it was undoubtedly also a question of different styles of building technique. The Roman wished his technical works to express the political power of the Empire. Here was a reason for the gravity supply system, borne on high through the countryside on mighty arches, whereas the pressure system merely adheres closely to the natural contour of the land. Similarly the arrangement of Roman State buildings was on an axial and symmetrical plan which was an expression of the Idea of Power. This was alien to the thought of classical Greece, who erected her buildings in freedom and without constraint. In a lengthy and confused discussion Sir Thomas Ashby, whose central point is that Roman engineers were fearful of high pressure and always anxious to avoid it, contributed these views: 2 5 Just as some ridges, however, demanded a tunnel [for an open-channel] and precluded circumvention, so certain valleys, too long to skirt and too deep to bridge, had to be crossed by a siphon. The principle that water thus conveyed rose to its own level was well known, and striking examples of its employment e x i s t . . . . It should be noted that Vitruvius specifies that the lowest point in a siphon should run level for some distance, and should have vents to reduce pressure. Thus, every attempt was made to avoid the natural creation of a pressure-supply, with which these siphons have been confused. The siphons were very expensive to build, since the pipes were small ones of lead, arranged in series to reduce pressure;. . . It might be asked why the Romans did not take advantage of their excellent skill in cement manufacture to construct the conduits for a siphon in this material, and so to arrive at the theory of a pressure-supply; for the crushing resistance of their hydraulic cement exceeds the figure now accepted as the safe standard. Some of the points referred to by Ashby we shall look at in more detail shortly but here and now one piece of nonsense can be disposed of. The strength of pressurized pipe-lines has nothing to do with 'crushing resistance'; the strength of an internally pressurized tube is dependant in fact on the material's tensile strength. Finally, the most recent view. In 1974 H.R.H. The Duke of Edinburgh observed that: 2 6 The ancient Romans succeeded in building magnificent unsupported domes like the Pantheon in Rome and those

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superb aqueducts like the Pont du Gard in France. But those very aqueducts would not have been necessary if the engineers had realized that water in a pipe will always come back to its original level. The above extracts are at odds with the evidence and with each other. And above all if Greek engineering, with which the Romans were so familiar, could make successful use of siphons why not Roman engineering? The fact is that inverted siphons were a component of Roman water-supply technology and they were regularly adopted and rationally utilized. The high water-pressures induced were contained by pipes whose wallstrength was adequate; there is no evidence that leakage was such a serious problem as to be a disincentive; and evidently the use of inverted siphons was not avoided simply because tall aqueduct bridges looked more spectacular. Already known Roman siphons outnumber the Greek examples. There may well be more. From an archaeological point of view it is important to bear in mind that whereas an aqueduct bridge may survive, if only in fragments, a pipe-line, especially of lead, is very vulnerable, an easy and attractive target for subsequent demolition. In time little trace of it will remain. 2 7 A list of the more important Roman siphons which have been located is as follows: Country

Place

France

Lyon Rodez Aries Almunecar Cadiz Rome Angitia Alatri Termini Imerese Lincoln Aspendos

Spain Italy

Britain Turkey

No. of siphons 9 1 1 1 1 1 1 1 1 1 1

Not 28 29 30 31 32 33 34 35 36 37 38

By far the most substantial remains are to be found at Aspendos and among the set of nine siphons at Lyon. The most thoroughly documented specimens are those at Lyon. 3 9 As for written evidence there is only one source and that is Vitruvius. 40 Here we begin to get into difficulties. Vitruvius on siphons is puzzling, obscure and inaccurate although here and there, as will emerge, he is plausible and straightforward. Unfortunately modern writers, with rare exceptions, have swallowed Vitruvius more or less whole on the subject of siphons and as a result they have offered some strange interpretations of how

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Figure 1. The elements of the inverted siphon. Roman siphons worked, and even stranger ideas in some cases for their construction. Figure 1 shows the essential features of an inverted siphon carrying water across a valley from a header tank to a receiving tank. The difference in water-level between the tanks, h feet, is the head lost in giving the water velocity and overcoming frictional resistance in the pipe. The head H feet is a measure of the static pressure in the siphon at any point. The maximum pressure will almost certainly be at the first bend provided that the deepest portion of the pipe-line is substantially horizontal. In conjunction with Figure 1 we can examine the relevant portions of Vitruvius' account and analyze their contents in order to see how the Vitruvian material has been misunderstood and in what ways it has so successfully misdirected previous enquiries. Everything is taken from Chapter 6, Book VIII of De Architecture. To begin with Vitruvius writes: 4 * If the distance round such depressions is not great, the water may be carried round circuitously; but if the valleys are extensive, the course [of the siphon] will be directed down their slope. On reaching the bottom, a low substructure is built so that the level there may continue as long as possible. This will form the 'venter', termed KOILIA by the Greeks. This piece is clear and corresponds satisfactorily with Figure 1. Notice that Vitruvius gives the Greek word for the venter, the lowest section of the siphon which was carried often, but not invariably, on a bridge. Vitruvius continues by stating: Then, on reaching the hill on the opposite side, the length of the venter makes the water slow in swelling up to rise to the top of the hill.

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Roman Engineering and the Inverted

Siphon

This makes very little sense. If it is an effort by Vitruvius to describe the hydraulics of the situation, and the mechanism which makes the water climb to the receiving tank, it is less than adequate or comprehensible. Previous commentators rarely question or analyze this sentence and existing translations are as various as they are numerous; none make much sense. The next sentence is acceptable. Vitruvius says: But if there is no such venter made in the valleys, nor any substructure built on a level, but merely an elbow, the water will break out, and burst the joints of the pipes. Sharp bends in pressurized pipe-lines are indeed undesirable. In reality the archaeological evidence suggests that V-shaped siphons were never built, and in fact never had to be. Precisely how the sloping portions of a siphon joined the venter and the extent to which the bend was reinforced is not certain. However, at another point in his account, when discussing the use of earthenware pipes, as opposed to those of lead, Vitruvius says: Their joints must be coated with quicklime mixed with oil, and at the angles of the level of the venter a piece of red tufa stone, with a hole bored through it, must be placed right at the elbow, so that the last length of pipe used in the descent is jointed into the stone, and also the first length of the level of the venter. Presumably this procedure was as applicable to lead pipes as to earthenware ones. Certainly there is no need to go so far as did the French engineer Belgrand who, in 1875, became so worried about elbows that he dispensed with them altogether, and credited the Romans with siphons laid in a continuous curve entirely free of any sharp bends. 4 2 Nothing suggests that this was ever done; the archaeological evidence is for the shape shown in Figure 1 and Vitruvius is not at odds with it. Precisely what Vitruvius says next, or is trying to say, remains extremely obscure. The oldest extant versions of Vitruvius' manuscript — from the eighth, tenth and eleventh centuries — and many later versions based on these, are not in agreement and no one rendering makes any better sense than the others. Modem versions vary; for instance Morgan reads: And in the venter water cushions must be constructed to relieve the air pressure. Granger puts it like this: 4 3 Further, stand-pipes are to be made in the bend [Granger really means venter] by which the force of the air may be released.

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Others suggest neither water-cushions nor stand-pipes but 'airvalves'. On the other hand one point is clear. Vitruvius is proposing some sort of device to relieve air pressure in the siphon. In fact he is advising on a non-existent problem. In a siphon carrying water under pressure the problem of air-locking cannot arise simply because the pressure is high. There is no air pressure to relieve when the siphon is in flow. The conviction that Vitruvius must be writing sense at this point, and offering practical and useful advice, has led a sequence of modem writers to some odd conclusions so unscientific and impractical as to be extraordinary. Regrettably there is one body of opinion that can find in this part of Vitruvius an idea for reducing not the air pressure in the siphon tube, but the water pressure. This is impossible. The pressure in the venter is determined solely by the head above it and it cannot be relieved by valves, stand-pipes, water-cushions — whatever they are — or anything else. Of all the recent interpretations which have been given some practical form, the prize for incompetence must go to the eminent French architectural historian Auguste Choisy. His extraordinary layout is shown in Figure 2 . 4 4 Quite apart from failing to mention what the Romans used for sky hooks, the arrangement achieves nothing. Choisy is merely substituting two siphons for one, he is adding to the flow length, and achieving not one iota of pressure reduction or anything else. And in any case these idiotic elaborations do not even match the Vitruvian text. Nineteenth century translators and annotators of Vitruvius, whose work laid the basis for twentieth century interpretations and whose ideas are embedded in these later works, were guilty of two defects in their approach. In the first place they had, more often than not, pre-conceived ideas as to how a Roman siphon ought to work, Vitruvius himself being less than explicit, and once they had finalized a design in their own minds and according to their own experience, they then succeeded in twisting and shaping Vitruvius' words to fit their own conclusions.

Figure 2. The Vitruvian siphon according to Choisy.

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Roman Engineering and the Inverted

Siphon

And secondly it is implicit in nineteenth century, and later, writers that Vitruvius is ultimately a reliable source. Any failure to comprehend him is ajudged to be a failure of modern translation and intelligence. This attitude overlooks two possibilities. Conceivably the extant versions of Vitruvius' manuscript are not, in fact, a faithful rendition of the original 45 which necessarily raises obstacles to understanding not likely to be overcome easily, or with any degree of certainty. On the other hand, even if they are faithful renderings, it is possible that Vitruvius did not fully understand his material himself. And if Vitruvius did not know what he was talking about then it is hardly surprising that we cannot find out. How much of an experienced and practised engineer Vitruvius was is difficult to say. He claims very little personal involvement in engineering work, and later on the only mention of Vitruvius by Frontinus is in connection with plumbing and pipe sizes. Nor is Vitruvius to be judged as a particularly well educated man if the concensus view of his written Latin is a fair one. Indeed it is so bad that there used to be a vogue for attributing him to the third, or an even later, century. 4 6 And what of his ability to read Greek, Greek sources being so frequently quoted in the 'Ten Books'? It is conceivable that Vitruvius' imperfect reading of some Greek work on siphons had caused him to confuse the inverted siphon with the true siphon, that is to say a pipeline which at some point carries the liquid flow above the hydraulic gradient. In this situation air-locking can be a problem because the pressure is less than atmospheric; it is a very serious issue in modern aqueducts and was already identified in some early Renaissance works. 4 7 Vitruvius' apparent concern over air pressure in his siphons might be accounted for by a misreading of one of his Greek sources or by a lack of familiarity with the realities of conventional practice or both. However, if one reads on to a later statement in Chapter 6 of Book VIII much appears to be clarified. In dealing with siphon tubes made of earthenware Vitruvius says: The level of the pipes being thus adjusted, they will not be sprung out of place by the force generated at the descent and at the rising. For a strong current of air is generated in an aqueduct which bursts its way even through stones unless the water is let in slowly and sparingly from the source at first. The use of a valve, or valves, to facilitate the release of air when a siphon was started up from dry, potentially a very damaging operation, is not only plausible, but desirable. It is interesting too that those venters on the Lyon siphons which are sufficiently complete to allow measurement are not quite horizontal. They

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slope upwards in the direction of flow and this could be construed as an air release device also. Air valves for the above purpose would serve in another capacity as well. Vitruvius says: It is also not ineffectual to build reservoirs at intervals of 24,000 feet, so that if a break occurs anywhere it will not completely ruin the whole work . . . such reservoirs should not be built at a descent, nor in the plane of a venter, nor at risings, nor anywhere in valleys, but only where there is an unbroken level. However, in the interests of repairs and maintenance some means to drain a siphon tube would be needed. The essentially straight forward position we have arrived at then is this. A Roman siphon comprised a run of parallel lead tubes connecting a header tank and a receiving tank each at the end of the conventional open channel. Valves in the venter were used to release air when the flow was started up, or they could be opened to drain the siphon when necessary; otherwise they were permanently closed. This specification will not explain all of Vitruvius but nowhere is it seriously at odds with him, and it does conform to the extant archaeological evidence. Let us now look more closely at some of this evidence. And in view of what is to follow a small digression is in order. There is a need to be exceedingly cautious when applying modern analytical techniques to ancient, and for that matter not so ancient, technical problems, situations, machines and so on. There is potentially a great danger that the outcome will be no more than a rather futile proof of the obvious. For example, the application of modern stress and stability analyses to historic and surviving dams will often show that these structures are stable and not over-stressed. And sure enough they are still standing. And even if they were not, or even if they were when they should not be — by no means an unusual result 4 8 — one is not really any further forward. Nothing is learned of the ideas, attitudes and concepts in the minds of the original builders or the design methods they used. A recourse to elaborate modern analysis to demonstrate much that is irrelevant and nothing that is particularly relevant, is rather pointless. On the other hand the process is sometimes of value. If one calculates the specific speeds of early Fourneyron turbines, it is found that the values are so low as to indicate that it is not correct to regard those otherwise important machines as pressure turbines. And indeed this can be confirmed by a close inspection of the machines' settings. To some extent then, a modern treatment is useful as a basis for rejecting the conventional view that Fourneyron brought the fully developed modern pressure turbine

Aqueduct Date

Siphon

Length (feet)

Depth (feet)

Fall (feet)

Mont (TOr Augustus

Cotte-Chally d'Ecully Tupinier Tourillons Grange-Blanche St. Genis Soucieu Beaunant St. Irenee

1,640 6,560 4,260 15,740 9,200 2,920 3,950 8,560 1,993

110-120 210 82 375 290 270 304 405 155

6V2 65V2 16V2 115 59 19V2 29 30V2 5V4

Craponne

Augustus

Brevenne Gier

Claudius Hadrian

Pipe diameter (external) inches ? ? ? ? ? 10 10 10? 10

Number of pipes ? ? ? ? ? 9 9 ±10? 7 or 8?

Siphons at Lyon (compiled from C. G. de Montauzan and A. Grenier, see Note 28, and B. Buffet and R. Evrard, L'Eau Potable a Travers les Ages, Liege 1950, pp. 80—85)

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into existence single-handed and overnight, so to speak. It is undoubtedly not so simple. In the field of medieval cathedral construction some interesting work has been done recently by means of photo-elastic stress analysis and some valid conclusions have been drawn. 4 9 Modern analysis then must be used judiciously and the results evaluated cautiously. Useful conclusions need to be carefully separated from worthless ones and, in addition, basic assumptions and the accuracy of the values of known, or supposedly known, parameters must be assessed carefully. There are decided limitations upon the use of modern hydraulic theory to investigate Roman siphons. Nevertheless, it will prove at least interesting to try it in the case of a few of the Lyon siphons, the only ones for which we have sufficient information (see table opposite) even to make a start. The best preserved remains (see Figures 3 and 4) are of the four siphons of the Gier aqueduct, the last of the quartet of aqueducts to be built, probably in the reign of Hadrian. The aqueduct drew its supply from the river Gier near modern St. Chamond and ran a winding course of 75 kms to Lyon. The second of the four piped crossings, the so-called Soucieu siphon, had the following specification: 5 ° External pipe diameter Number of pipes Length of siphon Fall Maximum depth

10 9 3,950 29 304

inches (0.26 mts) feet (1204 mts) feet (8.844 mts) feet (92.822 mts)

Previous enquirers have been obsessed with the problem of siphon strength, some going so far as to deny (as we have seen) that Roman engineers ever used them because the pressures would have been uncontainable. The preoccupation with trying to find in Vitruvius the means to reduce water-pressure is probably associated with this attitude. In fact strength is not a problem, at least not necessarily. The tensile strength of lead is about 2,000 pounds per square inch and when Belgrand tested 5 * some replica Roman pipes in the 1870s they failed at stresses in the range 2 , 1 0 0 - 2 , 2 0 0 pounds per square inch, equivalent to internal pressures of 18 atmospheres which is something in excess of 600 feet of water. Let us assume for the sake of being cautious a stress factor of 2, i.e. an ultimate stress of 1,000 pounds per square inch, and an operating head of 400 feet of water, adequate for any of the Lyon siphons. For these conditions a 10 inch pipe would contain the pressure if its wall thickness was % inch. In other words the internal diameter would be 8V2 inches. Without doubt this represents a very hefty pipe, bigger by far than any of the standard

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Roman Engineering and the Inverted


SIPHON RAMP

•

Figure 3. Plan of the header tank on the Soucieu siphon (dimensions in metres). pipe sizes quoted by Vitruvius or Frontinus. However such pipes must have been made and an extraordinary commitment to large scale soldering was accepted. Such pipe sizes also represent a very considerable weight of lead. One can show that the Soucieu siphon must have weighed, in total, of the order of 1,700 tons and Montauzan's estimate that the nine Lyon siphons between them weighed in at between 10,000 and 15,000 tons is not far-fetched. If the Romans were disinclined to build siphons then the difficulties of mining, processing, transporting, fabricating and laying these prodigious weights of lead are the best reasons of all.

Figure 4. Header tank and siphon ramp on the Beaunant siphon.

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Many engineers have attempted to calculate the quantities of water which Roman aqueducts supplied to towns. More often than not this is a hopeless task because of various imponderables not the least of which is the fact that the depths of the covered conduits were determined to allow the movement of workmen rather than the flow of water. And leakage, as Frontinus complains, was frequently very serious. However, compared with an open-channel, a siphon is rather precisely specified and an opportunity exists to carry out a more objective estimate. The standard pipe resistance formula is h = where h L V d f

4 f. L.V 2 2gd

= fall = length = pipe velocity = internal diameter = pipe friction coefficient

Applying this formula to one of the Soucieu tubes — and without reproducing the intricacies of the calculation — one can show that the pipe friction coefficient is 0.0038 at a pipe Reynolds number of 2.7 x 10 5 which signifies, not surprisingly, turbulent flow. The pipe velocity is 4.69 ft/second and the flow of the whole siphon works out at 16.7 cubic feet per second. Now it is reasonable to suppose that the other three siphons carried the same flow and we can test therefore the performance of the St. Genis siphon, the first of the four siphon crossings on the Gier aqueduct. It used the same size tubes, the same number of tubes and was 2,920 feet long. The pipe friction formula gives a value of h for the St. Genis siphon of 21V2 feet in order to provide a sufficient flow capacity. In fact the measured fall across the St. Genis siphon is 1 9 ^ feet. The degree of agreement is encouraging and suggests that a standard layout of pipe sizes and number of pipes was used in conjunction with a fixed ratio between length and fall. The L/h factor is 150 for the St. Genis siphon and 137 for Soucieu. Unfortunately this proposition will not work. The L/h ratio is 281 in the case of the Beaunant siphon, the third on the Gier aqueduct, and higher still, 380, for the St. Irenee siphon which is the fourth and last. In other words the four siphons on the Gier aqueduct were not hydraulically similar and in particular if the Beaunant and St. Irenee siphons discharged the same quantities as those of St. Genis and Soucieu they must have been fitted with more pipes or bigger pipes or both. Conceivably the problem is made even more complicated by another factor.

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Roman Engineering and the Inverted

Siphon

Over 200 years ago it was first noticed that the venter bridges on the Lyon system were significantly wider than the sloping ramps which carried the siphon tubes down and up the valley sides. Some writers have taken this to indicate that in the depths of the siphon more tubes or bigger tubes were used as compared with the higher levels. It has been supposed that at the lower levels each tube was branched into a pair for the purpose of developing greater pipe strength (the old spectre), one 10 inch tube of % inch wall thickness being divided, for instance, into a pair of 6 inch tubes of V2 inch wall thickness. Quite what sort of an improvement this represents and whether or not it would have been worth the effort is difficult to say. In any case a simpler interpretation suggests itself. Access to the ramps for maintenance was relatively simple, everything being more or less at ground level. Across the venter bridges however the case for additional width to accommodate workmen, materials and transport is a strong one. Perhaps no further explanation is needed. As emphasized already, historians have been hitherto much concerned with the question whether or not Roman siphons could have been made sufficiently strong. By comparison hydraulic problems have not been given sufficient consideration and the issue of overriding importance has hardly been broached at all. It is of course the difficult question of how Roman engineers matched the flow of an open channel to the flow capacity of a multi-piped siphon. Flow calculations of the type used above were not developed until the nineteenth century and if Frontinus is a reliable witness (which in this matter may very well not be the case) the Romans had not even deduced that quantity of flow is a function not only of cross-sectional area but of velocity as well. 5 2 However, experience and experiment would reveal, presumably, that a given length of aqueduct required a much greater fall per unit length by siphon than by open channel, the frictional resistance being so much higher in the case of a siphon. Given the knowledge that a siphon needed to fall about 1 foot for every 100 feet of its length, we can conjecture that the configuration of a siphon was finalized by judicious trial and error and adjustment, and by simply ensuring that there were sufficient tubes to cope. Using a multi-tube system this approach is substantially possible. It is of interest in this context that the header tank on the St. Genis siphon was originally fitted with ten tube inlets. One of these has been blanked off which may suggest that the siphon in its original form was over-designed. On the other hand in some header tanks, the presence of a high-level side-spillway makes it very clear what happened to an excessive inflow from the open channel. It was simply tipped over the side, a wasteful but effective expedient.

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It was Germain de Montauzan's view 5 3 that the Romans fixed the size of siphons by referring to tables which related such parameters as velocity, fall, length, pipe diameter and so on. Such tables were compiled, so Montauzon supposed, from the observed performance of existing pipe-lines. This idea is not really tenable. It ascribes to the Roman engineer an appreciation of experimental analysis and a capacity to extract useful results from such an approach for which there is no evidence whatsoever. And in any case the number of siphons built was probably not sufficient to make the method viable in the first place. So far the essence of the construction and operation of the typical Roman siphon has been outlined and while many of the details are obscure the basic proposition is clear. The calculation carried out for the Soucieu siphon at Lyon gave a flow of 16.7 cubic feet per second. It would be foolish to claim a high order of precision for this figure but in suggesting the order of magnitude of the siphon's capacity it is clearly satisfactory. If anything the quantity calculated is too large which means that the effect of pipe-friction has been underestimated. The next problem is to consider the role of siphons in relation to the alternative, that is to say an aqueduct bridge carrying water in an open channel along the hydraulic gradient. Aqueduct bridges were, after all, the conventional and by far the most frequently adopted solution if it was not possible, or expedient, to build an aqueduct at or below ground level. Sometimes, across the Roman Campagna for instance, aqueduct bridges were miles in length. Under what conditions then did Roman water-supply engineers choose to construct a siphon? The highest Roman bridges, for roads and aqueducts, are listed below. PontduGard Alcantara Narni Cherchel Segovia Merida

(France) (Spain) (Italy) (Algeria) (Spain) (Spain)

160 155 120 115 100 85

feet feet feet feet feet feet

Only two examples surpass 150 feet and only three more reach three figures. For the siphons, however, at least in those cases for which figures are available, the depths reached are greater (with a few exceptions): 5 4 St. Irenee Ecully St. Genis Grange-Blanche Soucieu

(Lyon) (Lyon) (Lyon) (Lyon) (Lyon)

155 210 270 290 304

feet feet feet feet feet

66

Roman Engineering and the Inverted Tourillons Beaunant Rodez Alatri

(Lyon) (Lyon) (France) (Italy)

375 405 300 340

Siphon

feet feet feet feet

Comparing the two tables the conclusion is inescapable: depth of crossing was the criterion. Something over 150 feet was evidently regarded as the limit for a bridge. Beyond that figure the task of constructing a bridge of masonry and/or brick and concrete was judged to become increasingly impossible as the height rose. Even if the required quantities of construction material could have been made available, the provision of falsework, scaffolding and mechanical lifting equipment would have been prohibitive. And beyond that there was the question of the superimposed weight on the foundations of the bridge's piers at heights approaching, or above, 300 feet. Problems of sheer weight might well have been a powerful disincentive in themselves. 55 It would be interesting if the depth (or height, depending how one looks at it) criterion could be tested in some context and in fact one opportunity exists. The case in point is possibly significant in view of a development at present under way. Toledo was not a major city in Roman times but it did possess a water-supply system of some interest. 56 Not the least significant feature of the Roman aqueduct at Toledo — its date is the 2nd century A.D. — was the Alcantarilla dam which impounded water at the channel's head. 5 7 The aqueduct itself is not particularly notable and its length, 24 miles, was not exceptional. The source of Toledo's water was to the south of the city and therefore, in its final stage of delivery, the aqueduct had to cross the Tagus Gorge, a formidable obstacle. The remains of the conventional open-channel bringing water from the Alcantarilla dam have been located across the gorge from Toledo and their elevation shows that the depth of crossing involved was of the order of 100 metres. In the 1930s a Spanish engineer, Alphonso Rey Pastor, encouraged by remnants of a bridge's foundations which had been located on the sides of the Tagus Gorge, proposed a rather splendid reconstruction of the one-time Roman aqueduct bridge. It is shown in Figure 5. For his model Rey Pastor took the Pont du Gard although for reasons of geography and chronology the Alcantara bridge would have been more suitable. 5 9 Pastor's three-tier bridge is massive by any standards, and not just those of the Roman period if the 19th century example at Roquefavour is anything to go by. 6 ° The Toledo bridge, if bridge there was, was twice as high as the next highest, the Pont du Gard or the Alcantara bridge. The difference is too great for Pastor's

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Figure 5. The Toledo aqueduct bridge according to Alphonso Rey Pastor: view looking upstream. reconstruction to be convincing. The highest, the longest or the biggest specimens of civil engineering works are usually just a little in excess of their closest rival. For the highest Roman bridge to have been no less than twice as high as any other takes some believing. Then there is the question of the bridge's fate. Where is it? What has happened to the huge quantity of material it must have contained? 6 1 Why have only the merest fragments survived until modern times (and indeed until some centuries ago to judge from old prints and engravings of Toledo)? The Pont du Gard and the bridges at Alcantara, Narni, Segovia, Merida, Metz and a host of other places have all survived, substantially complete in many cases. The extant fragments of the Toledo bridge are probably very revealing. The four lumps of unquestionably Roman masonry correspond only to the lowest tier of the bridge, of the order of 50 metres in height and a very high piece of construction according to Roman standards by itself. Indeed 50 metres is directly comparable with Alcantara and the Pont du Gard and at the limit of what Roman engineers regarded as viable. The inference is obvious. Only one tier of Rey Pastor's bridge in reality ever existed and it was the venter bridge of a siphon some 50 metres (164 feet) deep. Indeed but for the problem of building bridge piers in a very torrential river at a difficult site, the venter bridge might have been even lower. 6 2 Plans are advanced in Toledo to modify the Tagus regime, to rebuild Juanelo Turriano's 'Artificio' and its machinery and to house within the building a museum, and to resurrect on the sides of the Tagus gorge some substantial pieces of a 100 metre high aqueduct bridge of reproduction Roman masonry. In fact replica Roman lead pipe would appear to be much more appropriate. Five conclusions 1. The Romans' use of siphons was calculated and rational. Bridges were not favoured because they were more impressive or

68

Roman Engineering and the Inverted

Siphon

because they presented opportunities for ostentatious displays of structural expertise and grandeur. So far as was possible Roman engineers went to some lengths, quite literally, to dodge valleys. Up to depths of 150 feet or so aqueducts were carried on bridges. Beyond that siphons were resorted to; it was not necessary very often. 2. Vitruvius' discussion of siphons is very obscure, parts are probably inaccurate, and there is no reason to suppose that our failure to make sense of much of what he says is a failure of modern intelligence. Nor are we necessarily deprived of essential understanding by ignoring or rejecting Vitruvian material. Vitruvius was not necessarily the last word on Roman engineering and very likely, here and there, he is not even the first word. In the absence of a single text against which De Architectura can be compared we simply do not know how good or reliable a source Vitruvius is. Conceivably he is rather inferior and presents a less than full or typical picture of contemporary practice. 3. A technological study of a part of engineering history which has been most frequently presented by classicists, archaeologists and architectural historians suggests a shift of emphasis and the need to reject certain false notions. Siphon strength is not such an important issue as hydraulic behaviour; how Roman engineers produced the desired performance in siphons of differing specification is a mystery. 4. The use of modern analysis to evaluate ancient (and not so ancient) technical problems is of very limited application because of the nature and number of the assumptions which have to be made. The chances of reaching an unhistorical, irrelevant, untypical, inaccurate or silly conclusion are high. 5. Anything like a full understanding of any part of ancient engineering requires a certain level of archaeological and/or written evidence. If the evidence does not reach the requisite threshold of reliable facts, figures and other details then there are distinct limits to the firm conclusions which can be drawn. This is true of the siphon issue and it is undoubtedly true of other aspects of ancient technology. However let it not be thought that the study of ancient technology is either impossible or worthless. There may be obstacles but the field is far too interesting and, if the history of technology is to be seen in its full perspective, too important to be overlooked. Notes 1. See for example J. W. Shaw: * Greek and Roman harbourworks' in A history of seafaring based on underwater archaeology, edited by G. F. Bass, London 1972, pp. 87-112. 2. For North African dams and irrigation for instance there is C. Vita-Finzi: * Roman dams in Tripolitania' in Antiquity, Vol. XXXV, 1961, pp. 14—20 and plates II—IV and also C. Vita-Finzi and O. Brogan: * Roman

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dams on the Wadi Megenin' in Libya Antiqua, Vol. n, 1965, pp. 65—71 and plates XXI—XXVII. For water-supply in Spain the standard work is now C. F. Casado, Acueductos Romanos en Espana, Madrid 1972. 3. Thompson, E. A. A Roman reformer and inventor (being a new text of the treatise De Rebus Bellicis), Oxford 1952. 4. Drachmann, A. G. The mechanical technology of Greek and Roman antiquity, Copenhagen 1963. 5. Moritz, L. A. Grain-mills and flour in classical antiquity, Oxford 1958. 6. Plommer, H. Vitruvius and later Roman building manuals, Cambridge 1973. 7. Dilke, O. A. W. The Roman land surveyors. An introduction to the Agrimensores, Newton Abbot 1971. 8. White, K. D. Roman farming, Thames and Hudson 1970. 9. An excellent example of the sort of thing which can be done, although in this case the subject is ancient Egyptian technology rather than Roman, is K. Mendelssohn, The riddle of the pyramids, Thames and Hudson 1974. 10. Finley, M. I. * Technical innovation and economic progress in the Ancient World' in The Economic History Review, 2nd Series, Vol. XVIII, No. 1, August 1965, p. 29. 11. Two modern translations of Vitruvius are: De Architectura, trans, by F. Granger, Loeb Classical Library, 2 Vols., London 1962; and Vitruvius. The ten books on architecture, trans, by M. H. Morgan, Dover Publications, New York 1960. The description of the water-wheel is in Chapter V of Book X. 12. For these installations and further references to them see R. J. Forbes, Studies in ancient technology, Vol. II, Leiden 1955, pp. 90—93. The Roman water-mill at Barbegal is described by C. L. Sagui: 'La Meunerie de BarbegaP in Isis, Vol. 38, Parts 3 and 4, February 1948, pp. 225—31. 13. On this point see M. L Finley, Note 10, pp. 35—7. 14. In connection with the construction of an aqueduct tunnel in A.D. 152 at Saldae in Algeria, the engineer, Nonius Datus, refers specifically to gangs of * Alpine troops' and a * detachment of marine infantry'; see L. Sprague de Camp, The ancient engineers, London 1963, p. 195. 15. As Note 7. 16. For Vitruvius see Note 11 and also H. Plommer, Note 6. A modern edition of Frontinus is The stratagems and aqueducts of Ancient Rome, Loeb Classical Library, London 1961. There is also C. Herschel, Frontinus and the water supply of the City of Rome, Boston 1899. 17. See J. Gimpel, The cathedral builders, London 1961, pp. 107—45. 18. For Frontinus on surveying see O. A. W. Dilke, Note 7. Frontinus on warfare is as Note 16. 19. It is generally accepted, for instance, that Roman engineers were unable to calculate water flows in open channels because they were under the impression that quantity depended only on cross-sectional area of flow and not on velocity. In fact the only authority for this conclusion is Frontinus and it is decidedly problematical whether he can be trusted on a technical matter such as this. Would it not be extraordinary if Roman engineers, who saw so much water flowing down so many channels, should never have deduced that velocity of flow governed quantity just as much as crosssectional area? For the origins of the current belief in Frontinus' authority see C. Herschel, Note 16, Chapter V. 20. For this scheme and references to it see R. J. Forbes, Studies in ancient technology, Vol. 1, Leiden 1955, pp. 155—9. 21. See for example A. Burns: * Ancient Greek water supply and city planning: a study of Syracuse and Acragas' in Technology and Culture, Vol. 15, No. 3, pp. 389—412. 22. For a more detailed treatment of Roman dams see N. Smith, A history of dams, London 1971, Chapter 2.

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Siphon

23. As Note 20, p. 161. 24. Klemm, F. A history of Western technology, London 1959, p. 48. 25. Ashby, Sir T. The aqueducts of Rome, Oxford 1935, pp. 34—7. 26. H.R.H. The Prince Philip, Duke of Edinburgh: Research and prediction' in Notes and Records of the Royal Society of London, Vol. 29, No. 1, October 1974, p. 18. 27. This point is especially significant in relation to the problem of the aqueduct at Toledo. 28. The standard work on the Roman aqueducts at Lyon is C. G. de Montauzan, Les aqueducs antiques de Lyon, Paris 1908. A more modern but briefer treatment is A. Grenier, Manuel d'archeologie Gallo-Romaine, Vol. 4, Part 1, 'Aqueducs', Paris 1960. 29. Grenier, Note 28, p. 153 says that the Rodez siphon crossed the valley of the Aveyron in lead tubes at a maximum depth of about 100 metres. 30. The Aries siphon is especially interesting because it was laid, apparently, across the bed of the Rhone. Remnants of the lead siphon tubes which have been dredged up are stamped with their makers' names. 31. See Casado, Note 2. 32. ibid. 33. A branch of the Aqua Claudia was carried by a siphon to the Palatine. See Marion E. Blake, Roman construction in Italy from Tiberius through the Flavians, Washington, 1959, p. 123; also E. M. Winslow, A libation to the gods, London 1963, pp. 81—3. 34. See Marion Blake, Note 33, p. 82. 35. The Alatri siphon is supposed to have been constructed in 134 B.C., see C. G. de Montauzan, Note 28, pp. 194—7. 36. This siphon, near Palermo, is mentioned by G. Giovannoni: 'Building and engineering' in The legacy of Rome, Oxford 1957. p. 467. As yet no further details have been located. 37. The source of Lincoln's water-supply, a spring called Roaring Meg, was lower by 70 feet than the delivery point. It seems most unlikely that the required uphill flow could have been pumped by a machine of the Ctesibian type. It is much more reasonable to suppose that the water was lifted 70 feet at its source, by a chain-of-pots for example, and then 'siphoned* to the town. In her unpublished Ph.D. thesis entitled Municipal and military water supply and drainage in Roman Britain, Inst, of Archaeology, Univ. of London, 1970, pp. 46—51, Julie Hanson presents the archaeological evidence thoroughly but her understanding of the technology is less than adequate. In particular her rejection of the idea of a siphon is technically unsound. See also F. H. Thompson: 'The Roman aqueduct at Lincoln' in The Archaeological Journal, Vol. CXI, July 1955, pp. 106 ff. 38. This was evidently a big siphon which has left substantial remains of its venter bridge. As yet very little information has been forthcoming; see K. D. Matthews: 'Roman Aqueducts: Technical Aspects of their Construction' in Expedition, The Bulletin of the University Museum of the University of Pennsylvania, Vol. 13, No. 1, Fall, 1970, pp. 2—16. 39. See Note 28. 40. C. G. De Montauzan, Note 28, pp. 178—92 and H. Plommer, Note 6, pp. 25—30 offer commentaries on the Vitruvian siphon material. Another effort is P. Grimal: 'Vitruve et la technique des aqueducs' in Revue de Philologie, Vol. XIX, 1945, pp. 162—74. 41. Morgan's translation, see Note 11, has been used throughout unless otherwise stated. 42. M. Belgrand, Les aqueducs Romains, Paris 1875, p. 80. 43. F. Granger, see Note 11, Vol. 2, p. 185. 44. A. Choisy, Histoire de VArchitecture, 2 Vols., Paris 1899, Vol. 1, p. 582.

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45. And in fact examples are not hard to find. Some of the manuscripts suggest a slope for open channels (see Bk. VIII, Ch. 6, para. 1) of 6 inches (semipede) per 100 feet; others give V4 inch (sicilico) per 100 feet. One of these must be a mistranslation. Another example is the choice between colliquiaria and collivaria in Bk. VIII, Ch. 6, para. 6; see H. Plommer, Note 6, p. 28. 46. Stahl, W. H. Roman Science, Madison 1962, p. 92. 47. See for example F. di Giorgio Martini, Trattati di Architettura Ingegneria e Arte Militari, 2 vols., Milan 1967, Vol. 1, pp. 160—70. 48. See for example the calculations done on some early Mexican dams by J. Hinds: * 200-year-old masonry dams in use in Mexico' in Engineering News-Record, 1 September 1932, p. 252. 49. R. Mark: 'The structural analysis of Gothic cathedrals' in Scientific American, November 1972, pp. 90—9. 50. Taken from C. G. de Montauzan, Note 28, pp. 197—9 and 217. 51. M. Belgrand, as Note 42, p. 71. 52. See Note 19. 53. C. G. de Montauzan, Note 28, p. 217. 54. Some of the Lyon siphons do not reach great depths, Tupinier about 80 feet and Cotte-Chally probably less than 120 feet. However, on aqueducts where siphons had to be built in any case it would have been expedient to take care of lesser depressions with a shallow siphon. 55. And it is interesting to note that the highest aqueduct bridge ever built, the Roquefavour bridge near Marseilles, reaches just 270 feet and that was erected in 1846. 56. J. P. Martin-Cleto, El Abastecimiento Romano de Aguas a Toledo, Toledo, 1970. 57. As Note 56, pp. 4—5 and also N. A. F. Smith, The heritage of Spanish dams, Madrid 1970. 58. The reconstruction is illustrated in J. A. Garcia-Diego: 'Restoration of Technological Monuments in Spain' in Technology and Culture, Vol. 13, No. 3, p. 427. 59. The Pont du Gard is in France and was built sometime in the reign of Augustus, conventionally 19 B.C. The Alcantara bridge spans the Tagus about 150 miles west of Toledo and is Trajanic, about A.D. 105. Therefore Alcantara is a more appropriate model for a second century bridge in Toledo. 60. See Note 55. 61. On this point and in relation to the conclusion about to be reached see Note 27. 62. Remember that Roman engineers only constructed full-centred semi-circular arches and hence heights were fixed at half the dimension of the span.

T h e

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R. A. BUCHANAN Man has succeeded in gaining progressive control over his material environment by a combination of his faculties for speculative thought and for practical action, exercised respectively by his mind and his hands. He is fortunate in possessing both a more highly developed brain than any other terrestrial species, which makes him inquisitive and capable of conceptual thought, and also a more dextrous hand, with its prehensile thumb which allows him to grasp and shape objects with a high degree of accurate control. By combining these faculties of mind and hand, Man has been able t o fashion tools, t o explore inter-relationships, and to make two blades of grass grow where only one grew before. Even though archaeological and anthropological evidence is very varied and capable of several interpretations, it does permit the generalization t h a t primitive societies acquired skills cumulatively over a long period of time, and that these skills were used both to increase material productivity and to express in burial rituals and other cultural practices the speculations of their members, about human life and purpose. But while it might be convenient t o interpret these twin achievements of hand and brain as the archetypes of technology and science, it would be a profound historiographical mistake t o use the terms in such a way if it is meant t o imply a clear distinction between them in such simple societies. If any archetype is required, a more expressive and satisfactory image is that of the Promethean fire, stolen from Heaven by Man's quest for knowledge and power, and bringing with it the punishment for having too much knowledge of this sort. When Professor Landes used the Promethean myth t o provide a title for his excellent text on technological change and industrial development in modern Europe, he stated his purpose quite explicitly.* Together with other stories from Western mythology such as the Biblical account of the Fall of Adam and Eve, the story of Prometheus expresses the hopes and fears which derive from Man's quest for knowledge. It also provides a model for a linear, progressivistic, view of history, for although the acquisition of knowledge is frequently painful it is cumulative and encourages the hope that ultimately it will give complete power over the world in which Man finds himself. Thus Zeus punished Prometheus and all mankind for the theft of the divine fire: b u t he did

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not take back the fire. In Landes' scenario, the unbinding of Prometheus represents the universal acceptance of science and technology in the modern world as the basis for the optimistic expectation that material satisfaction is now within the reach of the whole population: This world, which has never before been ready to accept universally any of the universal faiths offered for its salvation, is apparently prepared to embrace the religion of science and technology without reservation. 2 But how was the unbinding achieved? How has mankind been persuaded to accept so whole-heartedly the faith in material progress? It is clear that, despite the antiquity of the Prometheus myth, the enthusiastic adoption of progressive development as a dominant interpretive axiom is an event of fairly recent history. Throughout the Ancient World of the Mediterranean civilizations and for a long time thereafter, it was the pain and anguish consequent upon the supposed theft of Prometheus and his mythological peers which was most emphasized. The potentialities for material improvement implicit in scientific and technological discoveries and inventions were not understood: Prometheus remained firmly bound. Some time in early Western Civilization, however, the change began. Slowly at first, but then with increasing conviction and confidence, the unbinding began, and by the middle of the nineteenth century the process of conversion was virtually complete, with the entire civilized world accepting the assumptions and implications of a progressivistic world view. Historians have, naturally enough, been fascinated by this transformation, and they have tried to account for it in a variety of ways. Broadly speaking, they have tended to choose explanations ranging between those presenting a science-led intellectual revolution as the primary driving force and those placing most explanatory weight upon the hard-headed pragmatic acumen of craftsmen and businessmen seeking their own profit. Professor Landes is one of those historians who has emphasized the role of the empirical craftsman and inventor in initiating the complex processes of industrialization, although he readily acknowledges the important part played by scientific research in these processes, especially after the middle of the nineteenth century. 3 In adopting this moderate position he is in good company. Posing the question: 'Who Unbound Prometheus?' Professor Mathias has subsequently reviewed the discussion amongst historians about the relationship between science and technology in the British Industrial Revolution, and he has placed Landes along with such distinguished scholars as Lord Ashby, J. D. Bernal, A. Rupert Hall, and A. P. Usher in the category of those who have minimized the role of science in industrialization before the nineteenth century. 4

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On the other hand, Mathias assembles an equally impressive group of historians who have stressed the positive linkages between science and industrial innovation, even in the eighteenth century and earlier. This group includes T. S. Ashton, A. E. Musson, W. W. Rostow, and E. Robinson. 5 Whether any of the scholars so named would be completely happy about being categorized in this way is a matter for conjecture, but Mathias is surely right in recognizing different emphases in the explanations offered for British industrialization, which was the central feature of the transformation or 'unbinding' with which all are concerned. Professor Musson, editing a collection of essays in which that of Mathias appears,6 adopts what might be described as a 'convergence' position in a perceptive introductory review of the relationships between science, technology, and economic growth in the eighteenth century: In the end, then, one has to recognize the existence of a multiplicity of interacting factors — economic, social, political, and psychological, as well as scientific and technical — among which there is not much possibility of indicating preponderance. 7 Mathias also settles for convergence. After considering some of the difficulties of the argument for science as the 'engine of growth', and illustrating them with accounts of the development of steam power and of agricultural improvement, he sums up: We may conclude that together both science and technology give evidence of a society increasingly curious, increasingly questing, increasingly on the move, on the make, having a go, increasingly seeking to experiment, wanting to improve. 8 He acknowledges a certain banality in concluding of industrial society 'that the advances in science and technical change should both be seen as characteristics of that society, not one being simply consequential upon the other'. 9 The question posed in the title of his essay is thus left without a specific answer. While accepting the general lines of the 'convergence' argument, with its emphasis on a societal and multi-causal explanation of the relationship between science, technology, and industrialization, it should be observed that there is one fundamental point on which the treatment of Mathias, Musson, and most of the other participants in the discussion, is not entirely adequate. This is a point of definition. It is too readily assumed on all sides that the terms 'science' and 'technology' can be used retrospectively in senses with which we are familiar in everyday use today. Admittedly, there is not as much clarity as one would like even about the contemporary connotation of these words, as recent

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discussion concerning the social relations of science has demonstrated. 10 Attempts to sharpen the definition with derivative terms such as 'pure science' and 'applied science' have tended only to convert imprecision into confusion. However, it can be agreed that there is a distinction between science and technology in present-day practice, coinciding in general with fairly discrete professional groups. But to use these words as precise designations of particular movements and experiences before the middle of the nineteenth century is to invite misunderstanding. Until that time, 'science' passed more normally under the name of 'natural philosophy', which as a search for knowledge in general and the systematic study of the natural order in particular included aspects such as theology, philosophy, and history, which would not now be commonly classified as sciences. As is well known, the personal noun 'scientist' describing the practitioner of science was invented by Whewell as recently as 1 8 4 0 . ! ! And if the use of 'science' was vague before the nineteenth century, the early use of 'technology' — as distinct from 'technique' and 'technical' — is even more shadowy. It seems at first to have had a grammatical connotation, and according to the Oxford English Dictionary acquired the sense of 'a discourse or treatise on an art or arts: the scientific study of the practical or industrial arts' in the seventeenth century. 1 2 From this it is apparent that any contradistinction with 'science' is a more recent gloss on the meaning. The problem of trying to apply a modem distinction out of historical context has already been indicated in relation to primitive societies. It is now necessary to pursue this historical review in order to establish the emergence of a meaningful distinction between science and technology and to relate this to the dramatic processes which have transformed Western Civilization in the last four hundred years. With the consolidation of the first 'civilized' societies in the Middle East some five millenia ago, it would be extremely hazardous to suggest a clear distinction between scientific and technological activities. To be sure the perfection of techniques of literacy and numeracy, which are frequently taken as the indications of civilization, permitted a much more systematic study of Man's immediate environment than anything that had previously been possible, and the result was the development of careful measuring and recording which laid the foundations of the first great speculative attempts to give a comprehensive account of the nature and structure of the universe. But it should be recalled that the first series of systematic measurements of which we have records were made for highly practical purposes: they were land measurements to control the distribution of elaborate irrigation systems, and star charts to record the movements of the heavenly bodies for the construction of calendars and the convenience of astrologers. It should also be

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recalled that these skills were part of another phenomenon of early civilizations — the growth of large social organizations with clearly delineated functional groups usually related to military conquest or the imposition of slave status, but in any event establishing a social distinction between the speculative and practical qualities of mankind. The importance of these qualities has already been stressed, and their subordination to distinctions of political and social status was to have far-reaching effects. Henceforth, for some three thousand years, an artificially contrived social barrier separated the speculative function in civilized society, represented by philosophy, religion, and political thought, from the highly practical activities of craftsmen, traders, navigators, and slaves. No such barrier can ever be complete, and the great civil engineering achievements of Graeco-Roman Civilization show that there were some outstanding results from the inter-play of theory and practice. But the generalization remains tenable because the separation of a dominant literary, speculative, minority of the population from the illiterate subject majority was a social pattern characteristic of the Ancient World. The ethos of such a society regarded manual work as menial and abstract speculation as the privilege of the leisured ruling classes. Again, however, it is desirable to emphasize the point that the distinction is not one between science and technology as we know them today, but between two basic human faculties representing the powers of Man's mind and hand respectively. We are dealing, in ancient civilizations, with a form of social organization in which nothing recognizable as modern science and technology could exist, despite the convenience, irresistible to historians of science and technology, of seeking predecessors of these modern phenomena amongst the varied activities and abundant achievements of such societies. If it is allowed that Man is the species with the thinking hand, then while the hand without the thought is aimless, so the thought without the hand is barren. The speculative sterility of so much that is presented as ancient 'science', and the puzzling failure of classical 'technology' to pursue its successes, may thus both be related to the context of social organizations within which they operated. The first significant breach in this classical ethos came with the adoption of the incarnational aspects of Christian theology, and in particular with the monastic fusion of theory and practice expressed most succinctly in the Benedictine identification of work and prayer. The rise of a new Christian civilization in Western Europe, in a society lacking both a strong tradition of philosophical speculation and the institution of slavery, provided fertile ground for a reconciliation of theory and practice, of speculation and action. This did not happen suddenly: there was much learning that the emergent civilization of eleventh century

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Europe had to recover and assimilate, and it had to acquire techniques for refining and testing this learning. Nor did it happen completely: the classical ethos has survived, even if in an attenuated form, with its denigration of the menial skills buttressed by aristocratic power and social prejudice, and is visible in several European institutions including the English public school. But given the comparative social flexibility and the political multiplicity of Western Europe, with its concern for industrial and mercantile enterprises, its military rivalries and expansive tendencies, the Christian ethos was able subtly to transform the European world view. The result was a change of revolutionary significance, for it gave a new direction to human endeavours and enriched them with potentialities which they had not previously possessed. In religion and philosophy, including 'natural philosophy', the old authorities were challenged and in their place was substituted a critical and pragmatic view about authority in all its forms. The traditional backwards-looking or cyclical view of life was replaced by a linear sense of time and a belief in progress. And in the advance towards ever greater achievements it became axiomatic that Man could and would win an Empire over Nature, as Francis Bacon graphically expressed it, by harnessing the knowledge of Natural Philosophy and the new skills which could be derived from this. From at least the early seventeenth century this view was being coherently and forcefully expressed. It has never been unanimously accepted, as in successive generations there have been reservations and criticisms of the new world view, but it has steadily increased its domination until, as Professor Landes has observed, it can be claimed without exaggeration that it has become the most prevalent and most widely accepted world view ever to be expounded. From this point of view, the 'Scientific Revolution' of modern historiography assumes a slightly unrealistic appearance. It would be pedantic to quibble about the use of the term for much the same sort of reasons as economic historians have implicitly agreed to live with the term 'Industrial Revolution'. Both are useful short-hand descriptions of important historical phenomena, and thus acquire descriptive and pedagogic value. But both comprise complex inter-relationships which may be distorted or misrepresented unless they are used with great care. In scholarly usage, the term 'Scientific Revolution' has received such care.1 3 In common parlance, however, it has come to be identified with the whole range of changes which made up the transformation to the modern progressivistic world view already outlined, and this is more than the term 'science' can meaningfully bear. According to this popular interpretation, 'Science' slumbered during the gloomy stagnation of the Middle Ages (after its early successes in the Ancient World), to undergo a dramatic revival in the sixteenth and

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seventeenth centuries which caused the overthrow of accepted authorities, triggered off the spate of technological innovation which led to the Industrial Revolution, and came to occupy its rightful place as the guide and inspiration of all human actions in the nineteenth century. It is hardly necessary to rebut the details of such a popularized interpretation, but it is desirable t o recognize it as an oversimplification and one which has distorted our understanding of the relationship between science and technology. In order to account for this distortion it is appropriate to return to the distinction developed in this paper between the speculative and the practical functions of human life. The Christian civilization of Medieval Europe had gone far towards reintegrating these in a working partnership after centuries of social separation. Of course, the conservatism of established social groups and of institutional religion provided powerful restraints on this development, but the increased respect accorded to craftsmen, merchants, bankers, navigators — the rising 'entrepreneurial' classes — ensured that new thinking about the human condition was directed with mounting potency to practical problems, so that new techniques in manufacturing industry, book-keeping, ship construction and navigation, became widely known. The invention of the printing press encouraged the spread of new knowledge and new techniques, whether it be novel and heretical religion or information about methods of mining or about organizing the state. This was the social and intellectual background not only to the Scientific Revolution but also to the rise of the new nation states, to the expansion of European influence through the voyages of exploration, to the cultural Renaissance and the Protestant Reformation. It seems likely that as a comparative late-comer to historiographic recognition, the Scientific Revolution has been made to bear an innovative responsibility which earlier generations of scholars accredited to Protestantism or Nationalism 14 But this should not be expected of it, for behind all these developments lay a more profound reorientation subsuming them and inspiring them all. This was the Promethean Revolution — the first continuing union of theory and practice in any great world civilization. It was in Western Europe in the late Middle Ages that Prometheus was metaphorically unbound, when the practical potentialities of speculative thought were first welcomed and systematically explored. Everything that is characteristically modern in our society has stemmed from this event. In referring to the massive shift of the Western world view as an 'event' it is not meant to suggest a sudden once-for-all occurrence. An intellectual earthquake of this magnitude does not happen overnight, and there are some aspects of Western life

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which have even today survived virtually untouched by it, although they are increasingly hard to find as even so robust a bastion of conservatism as the Catholic Church is manifestly being deeply influenced by it in our own time. But it has happened: it began to happen in Medieval Europe: and since then it has had revolutionary consequences for social life, political organization, religious attitudes, and artistic activity, to mention only some of the more significant areas of impact of the new world view. Seen in this perspective, the relationship between science and technology appears more intimate than when we attempt to apply contemporary terminology retrospectively. On this analysis, both science and technology in the modern sense were b o m out of the fusion of speculative thought and practical action: both are products of the Thinking Hand, of the Promethean Revolution. Certainly, the scientific tradition derived new strength from speculative insights such as the overthrow of Aristotelian physics, but it also drew its most distinctive novel qualities from the conscious application of these insights to practical problems of mechanics, ballistics, and material production. At the same time, the practical tradition lent heavily on the cumulative acquisition of technical skills by craftsmen, but it also gave a fresh twist to this inherited 'know-how' by a deliberate attempt to encourage systematic innovation. The point is that, at the time when science and technology begin to become recognizably modern, they were virtually indistinguishable. They were practised by the same sorts of men with almost identical objectives. In some cases they were united in the same personality, as in that of James Watt. In Britain, they were all products of the new society — merchants, Quaker businessmen, nonconformist ministers, Latitudinarian churchmen, puritan craftsmen, Whigs and Tories, captains of East Indiamen, civil servants, military and naval officers, and aristocrats and academics with practical preoccupations. Of none of them would it have been possible to have said that they were 'scientists' or 'technologists' in the modern professional sense. Some of them were more practical and others more speculative, but of all of them it could be said that they were practical-minded speculators, involved, in Professor Mathias' words, in 'having a go' at improvement, in discovering the hidden mysteries of the universe arid applying them to the service of man. Baconian science, the Royal Society, the provincial philosophical institutions, all pointed in this direction. So did the struggle to produce iron from coal fuels, to make the steam engine work, and to increase agricultural productivity. Even when the theory was mistaken or completely wrong, if it 'got results' in a specific situation it could be applied with vigour, as with Jethro Tull's views of agricultural fertilizers or the phlogistic theory in chemistry. The implication of this argument is that there ought to be

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many two-way linkages between scientific theory and technological practice because both sprang from the same source, and careful examination of particular locations or themes reveals many such connections. Musson and Robinson show a remarkable network of interconnections in the Manchester area in the eighteenth century. 1 5 The recent study by Professor Cardwell on the history of thermodynamics has established the same sort of pattern. 16 The argument over whether or not Thomas Newcomen could have known about the scientific research of Denis Papin becomes thus one of little significance (although it would be satisfying to know the answer): the important facts about Newcomen are that he was a skilled craftsman, that he was literate, and that he was a nonconformist, all of which attributes made him one of the 'new men' who were the bearers of the new practical knowledge. 1 7 He belonged to this group as surely as Isaac Newton, who devised the clockwork model for the universe while retaining a mystical religious faith himself, or John Locke, who applied this mechanistic model to political systems with tremendous success, or Joseph Priestly, the unitarian clergyman whose church was burnt by the mob because he sympathized too openly with the French revolutionaries. The British leadership of this movement was, in scientific and technological terms, largely fortuitous. It stemmed from socio-political conditions rather than anything intrinsic to science and technology, and the movement was a Western European phenomenon which spread rapidly to the colonies in the eighteenth century. But the socio-political conditions were significant because they were such as encouraged the new men whose skill and enterprise found uses for the new knowledge and transmitted the techniques by personal example. The essence of these conditions was a measure of social mobility, permitting rewards for enterprise, and a spread of literacy, encouraging the transmission of knowledge and skills. Britain after the Glorious Revolution of 1688 was well placed to provide these conditions, but it also provided the lessons which could be readily learnt by other countries in the nineteenth century. So in place of the familiar Scientific Revolution it is helpful to recognize a Promethean Revolution inspiring the emergence of the modern world view, and in place of an anxious search for causal inter-relationships between science and technology in the process of industrialization it is more meaningful to examine the widespread attitude of assertive speculation from which both science and technology have stemmed. In conclusion, it is useful to carry the argument of this paper one stage further and ask what happened to break up the symbiosis of theory and practice in the nineteenth century, creating the distinction between science and technology with which we are now so familiar? The answer, in a

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word, is professionalization. In the eighteenth century it had been possible for a group such as the Lunar Society in Birmingham to make serious enquiries into a very wide range of theoretical problems. 18 But even while science became ever more dependent on sophisticated technological tools from telescopes to microscopes to spectroscopes to electronic computers, and technology came to rely increasingly on mathematical ability and scientific knowledge, so the ability to practise more than a fragment of either science or technology diminished. The mid-nineteenth century saw the last of the great polymaths like Charles Babbage and I. K. Brunei, both of whom moved easily amongst theoretical speculators and practical engineers. After them, however, a scientist stuck to his last and an engineer remained an engineer. Specialization went further than this, so that the natural sciences became the fields of different experts, and engineers chose between civil, mechanical, electrical, and a host of other subdivisions. Moreover, specialization was confirmed by institutionalization, as each professional group acquired its own representative body. The process by which this professionalization has taken place has been inevitable, inexorable, and irreversible in the sort of highly complex society which Western Civilization has created. Nevertheless, familiarity with this intricate set of professional relationships should not lead historians to give it credit for a longer ancestry than it can meaningfully claim. Science and technology may be the most formative influences in our society. But they are only two brands from the Promethean fire which was kindled in Western Europe in the Middle Ages and transformed the world view of subsequent generations. There was, moreover, little need to distinguish between them at a time when all resources of theory and practice were devoted to harnessing the powers of Nature for the benefit of Man. Only the enormity of the task has compelled our society to undertake the professionalization — and thus the distinction — of science and technology, and this process only became apparent in the mid-nineteenth century. To seek to impose the distinction on the record before then is thus to fall into the historiographical fallacy of anachronism. Notes 1. David S. Landes: The Unbound Prometheus, Cambridge, 1969, pp. 554—5. 2. Ibid., p. 554. 3. Ibid., pp. 104, 113-14, and 323. 4. Peter Mathias (ed): Science and society 1600—1900, Cambridge, 1972. Mathias' own contribution to this symposium is Chapter 3: 'Who unbound Prometheus? Science and technical change, 1600—1800', pp. 54—80. This essay also appears in the collection edited by A. E. Musson, see note 6, below. The references here are to A. R. Hall: The historical relations of science and technology, London, 1963; J. D. Bernal: Science in History, London, 1954;

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E. Ashby: Technology and the academics, London, 1958; and A. P. Usher: A history of mechanical inventions, Cambridge, Mass., 2nd ed., 1954. 5. Ibid., pp. 55—6. The references are to T. S. Ashton: The Industrial Revolution, London, 1948; W. W. Rostow: The stages of economic growth, Cambridge, 1960; and various essays by A. E. Musson and Eric Robinson (see note 15, below). 6. A. E. Musson (ed): Science, technology and economic growth in the eighteenth century, Methuen, London, 1972. 7. Ibid., p. 68. 8. Mathias, op. cit., p. 80. 9. Ibid. 10. See, for example, the summary of the debate in M. Adelman, 'Toward a Sociology of Technology?' Technology and Society, Vol. 8, No. 4. August, 1974, Bath University Press, pp. 123—127. 11. William Whewell, mathematician, 1794—1866, in Philosophy of the inductive sciences, 1840, Vol. I, p. 113. 12. The earliest citations mentioned in the O.E.D. are Buck in 1615 and Venner in 1628, the latter being in a treatise on 'The Baths of Bathe', p. 9. 13. See, for instance, H. Butterfield: The origins of modern science, 1300—1800, Bell, London, 1949; A. Rupert Hall: The scientific revolution, 1500—1800, Longmans, London, 1954; and Thomas S. Kuhn: The structure of scientific revolutions, Chicago, 1962. Kuhn is concerned more with a conceptual analysis than either Butterfield or Hall, but he attaches the same importance to the idea. 14. This is suggested by Butterfield's assertion (op. cit., p. vii) that 'it (the scientific revolution) outshines everything since the rise of Christianity and reduces the Renaissance and Reformation to the rank of mere episodes, mere internal displacements, within the system of medieval Christendom'. 15. A. E. Musson and Eric Robinson: Science and technology in the Industrial Revolution, Manchester, 1969. The point is developed in several of the essays in this important collection. In a review of this book for Technology and Culture January 1971, pp. 95—6), I rather naively supposed that this inter-relationship did not need emphasis, but I have since had cause to recognize that my criticism was misguided as the resistance to this fact is stronger than I had imagined. 16. Donald S. Cardwell: From Watt to Clausius — the rise of thermodynamics in the early industrial age. Heinemann, London, 1971. 17. See the forthcoming work, G. Watkins and R. A. Buchanan: The Industrial archaeology of the steam engine, Allen Lane, London, where we attempt to put this discussion into perspective. 18. The standard work on the Lunar Society is R. E. Schofield: The Lunar Society of Birmingham, London, 1963.

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MAURICE DAUMAS A note by the translator The following paper first appeared some six years ago in the Revue d'Histoire des Sciences, vol. 22, and in Cahier no. 7 of the Documents pour Fhistoire des Techniques. I have translated it* partly because I fear that the general concepts of our foreign friends and colleagues concerning the discipline of history of technology are n o t as well known as they might be t o English readers, partly because I believe that what M. Daumas writes is still relevant and important, and indeed chiefly because his paper serves as a timely assertion of the view that the true history of technology is a history of technical things. This history is primarily concerned with craftsmanship, tools, processes, machines, farms, buildings, vehicles, ships and furnaces; it is only secondarily concerned with social and economic organization, cultural patterns, and the rise and fall of civilizations. Save in its greater generality history of technology seems t o me t o resemble (say) political history, economic history, the history of art or that of science in not being merely a subservient branch of cultural and social history. Naturally we may suppose (if we wish) that it is possible t o construct a 'super-history' of mankind in which the political, artistic or technical aspects of the history of each people (or society) figure only as small components, though most expert practitioners in any branch of history are dubious of the validity of such a 'super-history'. What is certain is that the study of these distinct branches of history is n o t t o be validated only by the claim that they contribute to a 'super-history'. Quite on the contrary: the historian of politics, art, technology . . . formulates his own questions about the past and attempts t o obtain answers to them; he, and he alone, has the expert knowledge, the command of sources, and the critical experience t o do this for his own area of specialization. (Of course it does n o t follow that he will do this well, unfortunately.) The 'superhistorian' is unable thus to work from the crude (but only authentic) materials of history; he, framing his own questions and in turn seeking answers to them, must rely on the resources that specialist historians present t o him. I do n o t know whether there *I am grateful to my friend M. Henri Orteu for revising my translation.

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are those who claim that (say) diplomatic history must be set in its total social and cultural context. This would require a history of the relations between Germany, France and Britain in the eighteen months (say) before the outbreak of war in 1939 to embrace a study of relative military forces, the distribution of races in central Europe, the development of anti-semitism, political ideas, the class war in France and Britain and so forth— in short the advantage of specialization, that it makes knowledge possible, would be lost. One is back with the writing of 'universal history' which, for all its attractions, has never avoided the dilemma of superficiality on the one hand or exclusiveness on the other. Certainly there are commentators who argue that the study of the past has no merit for its own sake, as a vicarious experience, as a form of literature, or as a satisfaction of curiosity. Rather, they allege, history is meritorious — or at least modern history is meritorious — in so far as it borrows its theoretical structure from other disciplines, and satisfies their requirements. Thus, 'in principle, no historian has cause to fear such a challenge [the challenge that he should have "something to offer" to philosophers and sociologists] if the discipline he represents has a firm basis in the social sciences and rests on a solid theoretical footing'. 1 In other words, so long as Clio is a lowly and obedient servant, her masters will tolerate her existence. This is no place for a general criticism of such a conception of history, which would surely have astonished historians of even the very recent past. What I wish to claim here is simply that history of technology is a subject whose subdivisions possess coherence and definition and which as a whole is concerned with so important a constituent in the totality of human experience that it demands independent study within its own terms; its fundamental focus is upon the logic whereby human will has won control over nature. To claim this is not to deny a two-way relationship between any society at any epoch and its technology; certainly the non-technical characteristics of society create technical problems, and inversely solving a problem, or failing to solve it, may deeply influence the general history of a society. Just as the difficulties experienced in one area of technology create problems for another (see Mr. Hollister-Short's paper below), or scientific discovery classically presents the opportunity for technological exploitation (Dr. Dawson's paper), so lack of response in society may retard the full deployment of technological possibilities ('The Strange Case of Aluminium'). M. Daumas quotes from the great French historian Lucien Febvre a formulation of the tripartite objects of the history of technology: 1. to create a technical history of techniques; 2. to evaluate the rfcle of science in advancing technology, and vice versa that of technology in advancing science;

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3. to place technology in its human context. It seems to me absolutely right to place the technical history first, as the distinguishing feature and prime responsibility of the historian of technology. The second objective relates largely (not entirely) to the last few centuries; and in pursuing it the historian of technology enters the territory of the historian of science. In trying to achieve his third objective the historian of technology again enters other territory, that of the economic and social historian, and may compete, if he attempts to generalize, with the cultural historian. M. Daumas himself goes on in his paper to discuss the historiography of objective (1), and (to a less extent) of objective (2). The question now to be examined is: Is this the right emphasis? Some recent commentators do not think so. They praise books which take Tgreat pains to sever whatever ties they had to a tradition that had been dominated by narrow technological interests'; they welcome an 'interest focused more on the inter-relationship of technology, economics, and society'. 2 Another, more emphatically, declares that 'the most important concern, the central issue in the history of technology of any age and any culture or geographical area' is the study of 'the social results of technology'. His demand is perhaps moderated slightly later into one for 'a social history of technology, an external history if you please, that will complement, not replace, the specialist and monographic works'. 3 Yet a third historiographer castigates the reduction of the history of technology 'to the history of techniques and the things produced by techniques'; in particular, he regards the two major histories of technology produced in Britain and France as grossly defective in this respect. The writer wishes to devote more attention to technological ideas, a change which should 'have the effect of integrating the history of technology more closely to other branches of intellectual and social history'. 4 If such proposals mean anything precise, it is that the prosecution of the technical history of technology as envisioned by Febvre, discussed by M. Daumas and practised (to the best of their powers) by many writers who have considered themselves historians of technology, should now be largely abandoned in favour of a Mumfordian study of inter-relations between technology and society. Presumably further research into the modem history of power-sources, 5 or of textile technology in Britain in the nineteenth century, is held to be unnecessary, or else those who persist in such investigations, the 'sentimental engineers', are unworthy of the name of historian of technology. Somewhat strangely, the admirable work of Lynn White is chosen as a model work by those who desire to renounce the 'history of techniques',

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even though a large part of Dr. White's book is concerned with the origin, definition, chronology, and transmission of techniques. True, Dr. White is also much concerned with the relations between technical change in the Middle Ages and the changing nature of medieval society; he has announced his interest by entitling his book Medieval Technology and Social Change. That his interest is not limited to establishing (say) the chronology of the windmill in Europe is thus made plain. But he would be the last to deny that a paper throwing fresh light on that chronology would be a valid contribution to the history of technology; and (unless one would accuse him of tautology) it is obvious that he distinguishes between the concept of social change and the concept of medieval technology. A most useful book could be written on Steam Power and Social Change in the Eighteenth Century. But the author who embarks on it would be well to be sure that — by analogy with Lynn White's excellent example — he has thoroughly investigated the steam-engine, its origins, development, applications, diffusion, capabilities and so forth (the dreary technical history of techniques) before embarking on an assessment of its significance in a wider frame of history. If he does not, he may make the mistake of supposing 'the first practically employed steam engine' was set to work 'seven years [after] Watt's first patent in 1769'. 6 It was precisely because that kind of historical knowledge — and even theory — seemed significant that the history of technology began to be written. One final, different point about M. Daumas' paper should be briefly made. Its last pages are devoted to the possibility of developing formal, possibly symbolic analyses applicable to the historiography of technology, upon whose basis a sort of historical calculus might conceivably be raised, should a way of operating according to given rules on the chosen symbols be devised. The object, of course, would be to eliminate the subjective element from the history of technology as far as possible; 7 to avoid the 'rhetoric' of which Fr. Russo has written (that is, the ordinary prose of historians) by substituting for it a method according to which (for example) the relation of a subsidiary technique (for instance, the use of iron oxide in place of a sand floor) to a principle technique (puddling iron) might be precisely defined. Thus vague words like 'invention', 'development', 'application' might be banished. I myself do not clearly see why the history of technology would benefit more considerably from such a symbolic calculus (if it could be devised) than any other branch of history (perhaps it could even be extended to diplomatic negotiations) and certainly, like M. Daumas himself, I cannot imagine how to make it practicable. M. Daumas appears to believe that further progress towards rigour by (may one say?) 'computerising' the history of technology would be worthwhile, and the action possesses a certain tantalizing attraction. But its potential useful-

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ness I leave t o those more acquainted with logical symbolism than I am. A. RUPERT HALL Notes 1. Reinhard Rurup, 'Historians and Modern Technology', Technology and Culture, 15, 1974, p. 166. 2. Ibid., 179. 3. Eugene S. Ferguson in ibid., 15, 1974, pp. 17, 26. 4. Edwin T. Lay ton, Jr. in ibid., pp. 31, 41. 5. A point insisted on by Dr. Multhauf in his article in Technology and Culture, 15, 1974. 6. Ibid., p. 185. 7. For a somewhat comparable suggestion see Joseph T. Clark, 'the Science of History and the History of Science' in Duane H. D. Roller (ed.) Perspectives in the History of Science and Technology (Norman, Oklahoma, 1971). The History of Technology: its A i m s , its Limits, its M e t h o d s It is a truism t o declare that the history of technology is in its infancy and explores, still without a method, an ill defined area. In its present state of diversity it ranges from anecdotal biography t o economic history pure and simple, embracing the episodic history of inventions and their fate, and the technical description of machines and processes. Thus it fails to form a coherent discipline, of uniform character. Since Lucien Febvre and Marc Bloch published a special issue of Annates d'histoire economique et sociale under the title 'Technology, history and life' 1 the various aspects of the history of technology have been the subject of many studies, b u t is it possible t o say that this history has a clearly defined object, or limits, or methods? In 1935 Lucien Febvre asked the following question: 'What is the aim of the history of technology?' He assigned t o it the three following tasks. Firstly, t o establish a technical history of techniques: 'Necessarily the work of technical people, t o avoid the risk of serious mistakes, of unavoidable confusions, of misunderstanding completely the general conditions of an industry'. Secondly, to evaluate 'the role of science in technical invention and the place of technical invention in the body of scientific fact'. Thirdly and lastly, to place technological activity within the context of other human activities. It is the combination of these three chapters, wrote Lucien Febvre, that constitutes the history of technology, and he went into details about the conditions under which each might be written, and a synthesis formed. For example, concerning the first of them he went on: 'But the work of technical people restricting themselves neither t o their own age nor t o their own speciality'. And he demonstrated forcibly, in relation t o the construction of

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the synthesis, that a history like that of techology 'requires the convergent zeal of technical people inquisitive about their technique and its past, who may be artisans, chemists, engineers, etc.; of scientists familiar with the history of their science (until teams of historians of science soundly prepared and equipped for their difficult task shall come into existence); lastly of historians properly speaking, historians of civilization with a synthetic outlook; all having to collaborate together lest they should find their work deficient in adequacy and scope'. And he added: 'But what is collaboration?' We might ask the same question afresh today. Although now thirty-five years old, the descriptive model of the history of technology set up by Lucien Febvre retains its value intact. And each of us, according to his competency, has set himself to do the spade work for a part of the chapter that interested him. Monographs, biographies, specialized researches have multiplied. But it seems rare for each kind of specialist to make the effort to leave his own speciality, his age, and (sometimes) his own country. The technical history of technology has suffered from the technicality and often the nationality of those who wrote it. Each topic is taken by itself and rarely linked with the other areas of technology upon which it was dependent or with the age in which it was developed. 'Each age has its own technology, and this technology carries the stamp of its age.' This fundamental dictum of Lucien Febvre has been generally overlooked by those technical people who would be historians. The influence of nationality has been such that the parallel histories of an age like the seventeenth century or a technical activity like the construction of roads and bridges in the eighteenth and nineteenth centuries, or of the appearance of the automobile, the cinema, and radio may be totally different according to the country in which they are written. Richness of documentary material insufficient sifting of information, the phenomenon of the convergence of creative efforts in technology when a subject is everywhere 'in the air' to some extent at the same time — many reasons for these 'incidental difficulties' may be invoked, excluding chauvinistic malice from which each investigator is, by definition, protected. It is nevertheless the case that every technical expert who becomes a historian is, at first, merely an autodidact in his own branch of history, and reveals a certain naivety in his knowledge of historical facts and their interpretation. But how can the history of technology do without the collaboration of technical people in order to establish indisputable facts? For indeed, the most urgent problem, perhaps, is still the establishment of a technical history of technology agreed by everyone. We are as yet far from this goal. Firstly, because as I

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have just said the history of technology written by technical experts is not infallible. Secondly, because the whole range of the history of technology in its totality is far from having been systematically surveyed — as the range of political history, or military history, or the histories of art and religion have been. The task has been approached late, but this delay at the start does not explain everything. The difficulties are more numerous: the chief of these stem either from the abundance of source-materials or from their inadequacy. This abundance is overwhelming as soon as one goes beyond the middle of the nineteenth century and starts to deal with the contemporary epoch: there is a multiplication of original sources such as patents in all the countries open to industrialization, of manuscripts and of archives both personal and industrial; a proliferation of journals and technical literature. Besides, one must take into account that printed sources have often suffered at their author's hands a distortion, whether unintentional or enforced, when measured against strict historical truth. This is explained by the fact that the great firms which have industrialized the manufacture of certain products have not permitted complete publication and most of them (having become powerful economic forces) have used their influence to mould the a posteriori narrative of the facts relating to them. The over-abundance of sources is a difficulty which is also met with when inquiring into the history of technology in certain ancient civilizations. The countless Mesopotamian clay tablets that are known have never been systematically combed through with this end in view, the same is true of the documentary material on the [ancient] civilization of Egypt, on the civilizations of South-east Asia, or on the pre-colombian civilizations of Central and South America. In these areas the archaelogists' task is still vast, and so long as the major part of it has not been treated we shall be reduced to mere conjectures about basic problems of the foci of initiation and the transmission of what was achieved upon the surface of the globe. Between these two extreme periods it is not so much the abundance of the sources that constitutes a problem as their occasional poverty. The history of the harness of horses for riding or pulling affords a characteristic example of this, and a number of others could be quoted referring to other periods. An atmosphere of uncertainty surrounds the circumstances in which optical instruments first appeared and in which the mechanical clock originated; in which coal was employed industrially between the seventeenth century and the last quarter of the eighteenth; and of the exact origins of the steam-engine and of the creation of Newcomen's machine — these doubtless will never be wholly clarified.

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The second chapter of the history of technology as identified by Lucien Febvre is that of the relationship between science and technology, that is, between the history of techniques and that of science. It ought to be the subject of extensive remarks which cannot be developed here. This is not only an historical problem but a contemporary one that becomes more and more pressing. The positions [adopted by scholars] are extreme. Bertrand Gille discerns in the evolutions of the [historical] process a 'leapfrogging' of intermediate stages which betrays itself in the vanishing first of invention and then of innovation as separate activities, the scientific phase merging directly with the industrial phase. 2 But on the contrary three American authors write: 'The theory that technological innovation arises directly out of, and only out of, advance in pure science does not provide a full and faithful story of modern invention. As in the past three centuries, there is still a to-and-fro stimulus between the two; each has a momentum and a potential of its own.' 3 Perhaps what is in question is a sharper definition in the terminology employed by writers dealing with the contemporary period. I shall return to this subject a little later in this article when I examine the influence of economic history and the modern development of the social sciences on the history of technology. During the last thirty years historians of science have made a valuable contribution to the history of recent technology. This relates to the techniques whose development (or evolution) is directly dependent upon their scientific content. But one must affirm that the historiography of science has been of little use to the history of technology so far as earlier periods are concerned, that is up to the middle of the nineteenth century, if it has not actually been damaging. It has instead given credit to the widespread notion, which is false, that the progress of technology has always throughout the centuries been directed by that of science. Historians of science, too, have neglected the advice of Lucien Febvre: 'collaborate'; and also the answer which he gave to his own question: 'what is collaboration?' — 'collaboration, surely, around the problem to be investigated which each collaborator must, no doubt, study on his own account —but with the obligation afterwards to match the results he has obtained and the ideas he has conceived against the results and ideas gained by his colleagues in the grand task under the same conditions'. 4 This want of collaboration, despite good intentions, has accordingly resulted in a continuing lack of precision if not a lack of knowledge with respect to this fundamental problem of the relations of science and technology. In consequence also the technical history of technology is unfamiliar to historians of science and the technical expert who studies the history of his speciality receives no positive aid from them. One example may serve among many to make the importance of these gaps clear: I

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mean the relationship between [pure] mathematics, theoretical mechanics and nascent thermodynamics on the one side and the progress of applied mechanics and the first gropings towards heat-engines on the other, in the period between the end of the seventeenth century and the middle of the nineteenth. A study of this subject begun two years ago in Pierre Costabel's seminar has revealed its richness and also the extent to which it has been overlooked up to the present. Until similar collective researches have been adequately developed, the history of technology will suffer from a certain way of thinking which is common to the scientist and the technical man alike. Weighing these words science and technology against one another in a rather scholastic manner each historian strives either to assimilate one to the other or on the contrary to oppose them in pretty muddled antitheses. Perhaps there may exist a method of mutual comprehension from which fruitful consequences would ensure this might be to take into consideration a novel area of creative activity in which science and techniques are so closely linked that it is difficult to decide what belongs to one, what to the other. The word technologie might serve to distinguish this domain which became more and more significant as the last century drew to a close and the present one unfolded. The study of the relationship science/scientific technology/technology might replace that of the direct relationship science/technology. 5 One difficulty remains. In French the word technologie [scientific technology] has no absolute meaning. The work of Georges Canguilhem and his pupils during the last few years upon the beginnings and development of technologie give grounds for hope that this ambiguity is about to disappear.6 It will nevertheless remain true that the equivalent English word, technology, embraces both the French words technique and technologie. As regards the third chapter opened by Lucien Febvre and Marc Bloch, two points may be made. Firstly their summons has been heard, and secondly the present state of general history has transformed the conditions under which this third chapter might be written. During the past thirty-five years the historians of civilization have been giving proofs of their goodwill. The example furnished by Marc Bloch has been followed with a praiseworthy zeal, and we are now informed about everything concerning the water-mills which worked virtually everywhere through several centuries except (perhaps) about what was, generally speaking, the exact nature of these mills: did they have the wheel horizontal or vertical, and in the latter event were they undershot or overshot or breast-wheels, or else indeed impulse-wheels, and how was the transmission from the water-wheel to the stones or saw arranged? For the fact is that we have exact representations at a very late date, in the time of the first printed treatises and woodcuts.

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Before the sixteenth century a few sketches in the manuscripts of engineers suggest a certain line of development although several of them, like Villard de Honnecourt's drawing of a water-driven saw, are obviously full of errors. Only at the end of the fifteenth century are the drawings of Fransesco di Giorgio Martini precise enough to yield us unambiguous information on the arrangement of mechanisms. 7 Although it has been possible to recognize the growing economic importance of water-power during the first fifteen centuries of our era, the technical facts are still not well understood. Thus the problems involved in the perfection of the classical water-engine are generally unknown to cultural historians. When the latter speak of the water-wheel in the eighteenth century, which was (they say) known since the time of Vitruvius, they treat it as an inadequate power-source, already obsolete. From that notion to underestimating the economic importance of water-power throughout the nineteenth century, to ignoring the effective efforts to perfect it made during that century, efforts in which mathematical reasoning played a far more important rdle than it did in the transformation of the atmospheric steam-engine into a rotative motor, and to viewing the invention of the Fourneyron turbine and the Pelton wheel in quite a false light, is but a short step that is too often and too lightly taken: in all innocence, of course. Our inadequate knowledge of the technical history of technology may in part excuse misrepresentations of the kind which one too often encounters when the general historian turns to the history of technology. But how can one explain the fact that manifest errors, corrected over and over again, are still propagated by the most conscientious and indeed renowned historians? How many times have we seen Denys Papin descend the Weser in a steam-boat, Jouffroy d'Abbans employ a double-acting engine in his boat, or Cugnot's truck crash into a wall? How many times has the creative genius of Leonardo da Vinci been given responsibility for all the inventions of the sixteenth century, and others? How many times has Beau de Rochas 'invented' the four-stroke motor? It is astonishing to find graver mistakes in chronology which are not without significance for the arguments of the authors who make them. J. U. Nef, failing to check his sources, makes Watt's patents expire in 1785 at the same time as those of Arkwright and considers this date to be a critical one; 8 everyone knows that on the contrary the renewal of Watt's patents in 1775, for twenty-five years, sterilized the evolution of the steam-engine until the end of the Napoleonic wars. The following passage from Mumford is, moreover, characteristic of this writer's way of taking liberties with history: 'If the twelfth century witnessed the introduction of the mariner's compass, the thirteenth brought the installation of

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the permanent rudder, used instead of the oar for steering, and the sixteenth introduced the use of the clock to determine longitude and the use of the quadrant to determine latitude — while the paddle-wheel, which was not to become important until the nineteenth century, was invented possibly as early as the sixth century, and was designed definitely in 1410, if not put into use until later.' 9 It is with such carelessness in the use of words and with such flippancy with respect to the history of technology that the author means to reply to the questions that he himself raises in his opening lines: 'During the last thousand years the material basis and the cultural forms of Western Civilization have been profoundly modified by the development of the machine. How did this come about? Where did it take place? What were the chief motives that encouraged this radical transformation of the environment and the routine of life: what were the ends in view: what were the means and methods: what unexpected values have arisen in the process? 1 ° It is a melancholy thought that far from sinking under ridicule this hotch-potch of commonplaces, unchecked assertions ('the mechanical arts advanced as the humane arts weakened and receded') 1 * and historical errors has passed for an original work. The French translation has gone through two editions. 1 2 Thus it is that a vast and unprepared public has for the first and perhaps the only time made contact with a certain kind of history of technology, that which seeks to overrule the facts and give an interpretation of the past and present of our civilization. To be sure not all cultural historians have fallen into such painful errors. Nevertheless it remains true that the collaboration between them and historians of technology extolled by Lucien Febvre has not yet been established in a satisfactory manner. And already other disciplines have taken shape in the last thirty-five years which raise new problems; I mean economic history, economics and its history to which it is fitting to add social history and the sciences of man in general. Differing as these do in content and method, their relations with the history of technology are just as close as those of the history of science (let us say of the exact sciences to avoid all ambiguity) and cultural history with the history of technology. Yet these relationships are a little different, at least as regards those disciplines which are concerned with facts and economic theory in the past or in the present epoch. Economic history authoritatively takes the history of technology within its compass. Accepting the latter naturally in its present state, in its rapid advance it imposes its own methods and major interpretative themes. Among these themes there is one at least which might well act as a sterilizing constraint on the history of technology: that of industrial revolutions.

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Until the middle of the twentieth century this concept appeared to be an excellent interpretation of the phenomena which, at one period, upset the process of industrialization in our civilization. Even in its classical formulation the industrial revolution did not succeed in discovering a well-defined chronological niche. Mantoux places it in the last forty years of the eighteenth century, following in this the economists and sociologists of the nineteenth, John Stuart Mill, Engels and Marx among them; the first edition of Mantoux's book appeared in 1906. T. S. Ashton and other more recent authors afterwards removed the close of the industrial revolution to 1830 or even later; in formulating new ideas about social evolution in England. Ashton assigns more importance to the first decades of the nineteenth century than to the last decades of the preceding century. As early as 1943 J. U. Nef criticized this classic conception of the industrial revolution; 1 3 he has returned to this thesis several times in developing the idea of a 'first industrial revolution' occurring between 1560 and 1660, one marked by the decline of the economic power of Spain and the confirmation of that of England. 14 In the first of the references cited, Nef writes: 'If it were necessary to keep the expression "industrial revolution" to designate the eighteenth century, how could one distinguish this period from the following one during which industrial progress became so swift in its course, so mechanical in its nature, so world-wide in its extent?' Other historians likewise have asked the same question. Some have replied to it by bringing forward the notion of a second industrial revolution between 1850 and 1880. This period corresponds both to a movement of economic expansion (which in France, for example, was promoted by the creation of the great credit banks, and a reformation in certain fundamental technologies, in particular those concerned with the manufacture of steel, the production of energy and the processes of industrial chemistry). But then Nef's 1 5 question remains, and some reply to it by supposing that this second revolution has not yet reached its end and that we are now living through a phase of it. In a preface to a posthumously published work by H. Pasdermadjian, in which the author adopts this point of view more or less and asks if we are not at the beginning of a third revolution, that of nuclear energy, electronics, and cybernetics, Andre Siegfried writes: 'In truth, it was always the case of the same industrial revolution (the first) continuing its course, but of a different phase, that of organization, following upon the specifically mechanical phase.' 16 This idea, formulated in passing by Andre Siegfried, has been developed by other authors, particularly by Max Pietsch who sees no solution of continuity from the eighteenth century to our own

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day 'from the invention of the steam-engine to automation and atomic fission'.17 This is likewise, it seems, N e f s 1 5 idea, as we have said. The idea is still clearer when one considers the works which have tried to give substance to the notion of industrial revolution as a national phenomenon. Applied to the evolution of the economy and of industrial techniques in the United States it becomes inadequate. The factors which contributed to making the United States the second most productive country in the world after great Britain (and far enough behind her) from the middle of the nineteenth century onwards are of quite a different kind from those which occasioned the famous English industrial revolution. As for France, if the industrial revolution is supposed (as it is by Arthur L. Dunham) to have taken place during the Restoration and the July Monarchy, 18 this immediately encroaches upon the second revolution which is presumed, broadly speaking, to coincide with the Second Empire. Thus there is no breach of continuity and it is impossible to see why one revolution should be distinguished from the other. Hence, as we project ourselves further into our own twentieth century, and as the evolution of which we are ourselves witnesses helps us to examine with fresh eyes the evolution of last century which so astonished those who then witnessed it, the concept of industrial revolution assumes an increasingly misty outline. This concept is the more tiresome in the history of technology because it focuses all attention on certain themes which only acquire a unitary significance when studied from an economic point of view. Railways and the steam-engine, iron and steel production and the textile manufacture are the chief of these themes. For the historian of technology they ought to be further divided into several sub-topics, a certain number of which are common to the principal themes: such are the copper and tin-smith's trade, plumbing, the making of metal conduits and mechanical construction, particularly the construction and use of machine tools, fundamental industries upon which all the process of development of the great industrial innovations of the century, such as railways or the employment of ferrous metals, rests. Doubtless one would see that the evolution of each one of these fundamental industries, which are so much neglected, also conditioned the appearance and progress of other areas of industrial activity which have been of no little significance for the general course of nineteenth century industrialization, for example, the great heavy inorganic and organic chemical industries and the coal-gas industry. Finally, by the same method of analysis the technical factors determining the appearance of electrotechnology and of precision mechanics might be defined, with the construction of electric telegraphs, then sewing-machines, internal combustion engines, typewriters, etc.

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Methods

Everything that the history of technology might gain if it freed itself from the restrictive concept of industrial revolution thus becomes obvious. There remains the influence of present-day economics upon the history of technology. What has gone before shows that this influence is not new. But in the course of the last forty years and particularly since the last war it has grown more weighty. Everyone knows that economics is evolving rapidly and (in what concerns us) the theories of economic dynamics may be reckoned among the fleetest of the moment. Naturally this dynamics is supported by the examination of phenomena both close to and distant [from us] in time and evolution; thus we have placed before us an abundant literature in which one can see only the reflection of technical facts through economic facts and theories. This body of writing which employs, often t o good effect, certain examples of the process of technological creativity properly speaking, does not describe this process; it does n o t see it, and only allows it to be perceived through economic or socioeconomic effects. So far as its own objectives are concerned economics attains its goal, but a greater and greater reliance upon an underlying technological evolution gives the illusion that there is thus composed a history of technology which could be written in no other way and which is sufficient in itself. At the extreme comes an actual denial of the pure technical fact as an entity in its own right, often because it is n o t adequately understood. 'Of course there can be no question of conferring upon technology an autonomy according to which it must progress along ineluctable and predetermined lines. Its evolution can only be completely understood with respect t o wants, which are recorded in history, and technical goals by which wants are mediated'. 1 9 This sentence of J. L. Maunoury is very revealing of an attitude which places history of technology in an inferior position in relation t o economic history. It would be a mistake t o think that prestige alone is at issue here. In the contemporary literature Maunoury's work is one which can stimulate reflection and most effective ways of thinking in the mind of the historian of technology, enabling him to quit the closed world within which he is t o o easily confined. But it is also one which raises the question of the personal objective and the proper limits of the history of technology. It may be inquired: would n o t the historian of technology derive the most advantage from a reversal of Maunoury's fundamental formula? Why should wants always be recorded in history ahead of means? Have not means in some measure given rise t o wants? Surely no technical innovation has diffused and given birth to progeny 2 0 unless it has satisfied wants. But were these wants pre-existent?

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This may be demonstrated without any ambiguity in some historical cases of great importance such as the nexus mining — steam-engine — iron industry in the eighteenth and nineteenth centuries. But the situation is reversed in a great many other instances, such as the electric telegraph and electrometallurgy. May it not be supposed that the discovery of electromagnetism and its immediate application to the transmission of signals have given rise to a desire for speedier communications? In the second case the Hall-Heroult process for the production of aluminium gave rise to a desire to use the light metals industrially. One might say as much, for the contemporary period, of radiocommunication, nuclear energy, rocket motors. In all these areas technology has run ahead of wants. If it had not furnished the materials or the processes, the economy would have done without them. The contrary opinion is strongly influenced by an illusion denounced by Jewkes, Sawers and Stillerman: 'it is argued that technology is now so versatile, there are so many different technical routes to the solution of a given problem, that once a general need has made itself evident it can be confidently assumed that this need will be met, that in one way or another an answer in the form of an appropriate invention will emerge'. 21 Actually it is not wants which have stimulated and do stimulate technological creativity, but the prospect of profits. If this prospect is revealed as a consequence of the creation of new technological means, the entrepreneurs of the kind defined by Schumpeter cause the need to appear. In another form and a different context Gilbert Simondon has expressed an idea that serves to corroborate the preceding: 'At the industrial level the [technical] objective has gained its coherence, and it is the system of wants which is less coherent than the system of the objective; wants mould themselves upon the'industrial technical objective which thus acquires the power to shape a culture'. 2 2 In this context it must be emphasized that economic analysis by itself is not enough to explain the evolution of technology. Think of all those great inventions which related to no immediate economic goals but rather to political or military desiderata at the moment when they were conceived and at the moment when they were exploited; those which have been cited above are the best examples. The influence of military operations upon the development of technology has been, ever since the second half of the nineteenth century, extremely important in Europe and the United States. Naturally the economic objectives of either civil or international wars can be invoked in order to justify the primacy of economic wants over technical means, but that would be to adopt a roundabout route while overlooking the complexities of the phenomenon. However that may be, bearing in mind that there is no

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question of denying that the evolution of technology can only be understood if it is placed in its own general historical context, one may well reckon that the primary task before the historian of technology is precisely to reveal the internal logic 2 3 of the evolution of technology. This evolution does in fact proceed by an internal logic which is quite alien to the logic of the history of socio-economic development. This may be demonstrated for almost all the periods and episodes of technical creativity. The close relationship between mining, the steam-engine, and the manufacture of coke-iron is a classical example of this. It is confirmed by the study of both horizontal and vertical affiliations. For example: from the distillation of coal [to make coke] to the fabrication of coal-gas, from this to the preparation of artificial dyestuffs and the practical realization of the internal combustion engine there exists a clear logical chain. The same thing is found again when one examines the influence of the steam-engine upon the morphology of the first gas-engines and the electro-magnetic motors of Froment. Investigation into this internal logic of technical evolution alone can free the technical history of technology from its episodic character, which still stamps it so strongly. This alone can put it into the position of making an effective contribution to the general history of our civilization, more particularly to its economic history. Li order to overcome its own deficiencies and to relieve itself of too-heavy pressure from neighbouring disciplines, the history of technology must further elaborate the methods of investigation and analysis enabling it to pursue its objectives effectively. Here we say little about the collation of information and the means of documentation. It is quite certain that the history of technology cannot claim to attain concepts unless it adopts effective means of sifting through all the original sources with which it is abundantly furnished; to this end it will be necessary to make use of data processing techniques as applied to documents. This is a problem of equipment and money on which I do not dwell. Other methodological problems must be resolved which will require the use of mechanized documentation. This is a problem of vocabulary closely linked to a problem of concepts. This is a perpetual subject of inquiry which must be pursued at the same time as documentary research and for which, it seems, there is at present no well defined policy. The problem of vocabulary is forced upon us by that of the modern economic sciences and for the reasons which I have described above. Indeed, in so far as the history of technology borrows its vocabulary from economics, it is right that the words

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used should have the same meaning for all. We are far from that state of affairs. There have been long controversies over the words discovery and invention; begun long since, they are not yet exhausted. One of the most recent opinions on this subject is that of Maunoury; 24 analyzing scientific and technical events, he expresses surprise at the gradual abandonment of the word discovery while invention continues to be used: 'Logically, we ought to give up the word "invention", or distinguish "scientific invention" from "technical invention".' The terms pure research, replaced nowadays by fundamental research, and applied research, for which nowadays industrial research is substituted, are likewise words of imprecise definition. But confusion is no less embarrassing in the use of the words invention and innovation. It may be said that Schumpeter cleared up this issue at the beginning of this century; nevertheless it remains the case that the word invention is used to designate the most dissimilar technical events: did Newcomen or Watt invent the steam-engine or should it rather be held with more justification that the different types of steam-engine are the fruit of a convergent series of inventions? What does the word invention mean when it is applied to the water-wheel, Fourneyron's turbine, railways, aviation, or the atomic pile? Very few authors are sensitive to such subtleties. As for the word innovation, it has evolved with such rapidity in the modern economic literature that one might almost say that each author gives it his personal meaning. Each attempt at a precise definition leads to a debate. 'How can one talk of the "invention" of radio, or television, or the motor-car, for example? These should be spoken of as examples of "innovation", for their discrete elements did not appear on the market separately. To speak of them as "inventions" leads to dangerous simplifications of the process.' 2 5 One may well agree with Maunoury that the word innovation should be employed in these instances, yet one cannot help thinking that the discrete elements did appear separately on the market; in the case of the car, for example, there was first the differential, then vulcanized rubber, then the i/c engine, then the carburettor, etc. Maunoury himself notes that there is a tendency to renounce the word innovation, substituting for it such expressions as 'technical change', or 'technological change'. 26 It is true that this is happening rather in the economic than the technological context, but if the history of technology seizes hold of innovation at the moment when economists abandon it, some fresh difficulties arise. Bertrand Gille has begun to attack this problem by trying to differentiate between several types of innovation: compensatory,

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marginal, structural, global. 2 7 But one perceives at once all the difficulties in the way of a complete understanding between authors when one finds that he lists the hot-blast in iron-furnaces as an innovation (a marginal innovation), rightly in my view, while Maunoury's work states: 'Any technical change whatever, springing from scientific and technological origins, but introduced in response to an alteration in the relative prices of the constituents, is not an "innovation".' 28 However that may be, Gille's essay is highly significant and, if extended further, will contribute effectively to the methods of analysis in the history of technology. However, as it is desirable that similar perspectives should penetrate more deeply into the history of technology, it would be convenient for invention and innovation to form the basis of a common language. In the same style of analytical method the famous binomial, research-and-development, which is a fundamental basis of contemporary economic dynamics, should provide a priceless means of investigation in order to determine the general traits of the evolution of technology. If this were to be applied to the labours of Watt between 1763 and 1775, for example, in an attempt to work out the input-output ratio of the operation in order to estimate its real economic value, one would have a portrait of a technical episode in the eighteenth century comparable with that of a technical episode in our own time. The same studies of research-and-development devoted to the work of Lenoir, Otto, Gramme and Siemens, or a host of other instances, would yield prolific information on the technological process of industrialization during the nineteenth century. But it would still be necessary to define this terminology within an historical perspective and to fix it in relation to invention and innovation in order not to relapse into a tedious ambiguity. Clearly also it would be necessary to avoid confusing the development of a product (in the modern sense of the term) with the development of an activity or of the branch of an industry. We shall find later that this precaution is not without value. Other terms should also receive a more exact definition, among them the expression 'technological progress'. This is, of course, an extremely difficult notion to define and in treating the history of contemporary technology it would be judicious to substitute for it, systematically, the expression 'technological evolution'. We are now aware that technologies vanish from our industrialized world. So it has been with the piston steam-engine. With this machine a phase of technological evolution was concluded; how may we express [the idea] that the succeeding phase represents progress with respect to the previous one? The word progress has no absolute value and if we seek to link with it a quantitative notation, what infallible criteria could be used?

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The exactitude of a common vocabulary does not form a mere problem in semantics, it must help the historian to define his position in relation to the subject of his studies. Two relatively recent investigations begin to outline the course of a methodology which is almost completely lacking in the history of technology. Without claiming to resolve this problem in a few pages, both contribute positive elements which it is desirable to take up and develop. Noting the necessity for 'precise and structural analyses founded upon objectively defined principles and conceptions', Father F. Russo writes: 'The present ways of doing things, when each person examines problems in his own manner, whereby the most ordinary terms (invention, discovery, technique, process) have uncertain meanings varying from one writer to another, and wherein the treatment is still almost universally in a "rhetorical" form, allow of no response to these demands.' 2 9 With the object of eliminating 'rhetoric', the author proposes a series of lattices designed to render uniform the analysis of techniques and their history. He begins first by giving a few basic definitions and distinguishing three levels of analysis concerned respectively with elementary techniques, technical entities and industrial complexes. Obviously a linkage of increasing complexity relates each level to the next. The middle level, that of the technical entity, seems the most important to him, that which provides opportunity for the most objective analysis and to which the lattices described later can be applied. Further the analytical lattices must be used under the stated conditions, that 'the invention itself has been clearly defined' and that one assumes 'a well-determined time'. When these conditions are fulfilled, Father Russo distinguishes within the technical entity its basic idea and the processes which have enabled it to be brought into practice. Though he fails to indicate how the first term, the basic idea, could be analyzed it is obvious how one lattice or another could be used for that purpose. In fact the author applies his analytical system directly to processes which he classes into two groups: indispensable components and the components which only effect the improvement of the invention; each one of these is represented by a corresponding symbol: Essential basic idea New process Existing process linked with Pn Component of improvement

= = = =

C Pn Px Pa

The introduction of this lattice is facilitated by an example, that of the Bessemer converter.

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The analytical lattice of the technical entity is followed by lattices for the analysis of the other aspects of creativity and development: characterization of results, represented by the symbol R with letter indices; thus Re = cost, Rq = quality, Re = field. The qualitative results are numerous, thus Rqr = regularity of manufacture, Rqf = reliability, etc. application of a technique: under this heading the author gives no symbolic notation. relationships between technologies and between science and technology. The symbol used is again R with index letters: Ru = utilization of a technique A, already in existence, by a technology B; but also with signs, R'u = creation of a technology A in order to practice the technique B, etc. characteristic of innovation, represented by the symbol V. VI = place of production, Va = capacity, etc. scientific and technological creativity working through time. Under this heading, the symbol T designates a period, t = moments; Ts = interest taken in a subject, To = a period of orientation. Here the symbolic expression also contains a certain complexity when one wishes to enter into details, e.g., Tf = diffusion of a discovery, Tfl = limited diffusion, Tuf = universal diffusion. The foregoing enables one to understand the lattices proposed by F. Russo. His essay is modestly presented as an appendix to the highly developed studies contained in the Cahier in which it appears. Although very brief it is very dense and suggests many ideas. We shall return to it after presenting the essay which B. Gille has devoted to the same problem, 3 0 and to which we have made frequent reference above. 'The sketch presented here', writes the author, 'can have no pretentions. It is meant simply to offer suggestions. It is essentially a question of delimiting the problem, of constructing hypotheses for investigation'. The problem to be delimited is that of the notion of technological progress and Gille in turn actually sketches the foundations of a methodology for the history of technology by taking account of four fundamental ideas: technological progress, invention, innovation, economic progress (or growth). The terms themselves appear at first sight pretty clear, and as not requiring any gloss to make their meaning understood without ambiguity. What is in question is the linkage between any two or three of them, taking it for granted that 'the central linkage, the relationship between invention and innovation, forms a permanent relationship'. The first difficulty raised by Gille in discussing the two-by-two relationships between the terms is that belonging to the definition

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of invention. Let us agree that this difficulty is troublesome for one clearly defined period (relatively short in the history of the world, but how important in that of contemporary technology!), that is, roughly, the period of two centuries separating c. 1750 from c. 1950. As for the contemporary period, Gille believes that invention, as a distinct phenomenon, has vanished. This belief is arguable in so far as there is no exact agreement about the modem meaning of the word invention, as I have shown above. It rather seems that we must not be too hasty in striking invention from the list of living realities. 31 We must return to this point later. Continuing his analysis of the 'leap frogging of intermediaries' 3 2 Gille states that innovation itself disappears as a distinct phenomenon and that only the relationships between economic growth and scientific progress exist, the former directing the latter. We have already seen that this notion is opposed to that of some other authors. Before making these assertions and in studying the relationship between the terms two-by-two Gille has established a distinction between several forms of innovation, quoted above. 3 3 He has besides insisted on the fact that the relationships are not necessarily comparable and invariable. 'The relationships between phenomena vary with time and, within the same period, according to the field of activity. The definition of a general technical level, of a global technical system, does not necessarily imply that there are identical relationships, in all fields, between the phenomena invoked.' In the last part of his study Gille examines the 'degree of three-fold relationship', relationships which come into being from the opening of the eighteenth century, either between the three first terms (technological progress, invention and innovation) or the three last (invention, innovation and economic growth); we have already noted that he affirms the disappearance of the two intermediate terms in the contemporary epoch. Although very different in their approach and their presentation the two essays summarized here display consistent features in their attempt to devise a methodology for the history of technology. It is in this that they are of interest. In fact it is apparent that the general framework that each presents overlaps in a satisfactory way [with that of the other] and that they could be made to coincide perfectly at the cost of slight adjustments to each, although it is not certain that it is of benefit to historical analysis to enclose oneself within a rigid framework. Gille, commenting on the paper by Russo, has clearly shown all the vague fringe-areas that may remain from such a framework of principle. 3 He applies the method of analysis to a particular case (the replacement of the cold by the hot-blast in iron furnaces), the technique of blowing hot air being a subsidiary technique in the blast-furnace considered as a technological entity.

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His analytical lattice for the subsidiary technique may be summarized as follows: 1. Original basic idea: origin of the idea; condition of its realization; integration into the technological entity. 2. Testing and perfecting: Gille limits himself to stressing the importance of this part of the research. 3. Innovation: nature and relative importance of the problem; circumstances of the spread of the technique; motivations; doubts and difficulties about the implementation of the technique, either of a technical or financial nature. 4. Developments (improvements, adaptions, economic consequences . . . ) . 5. Disappearance. It is evident that at 4 the word development is not employed in its modern sense, meaning the development of a product or technique (as in R and D) but in the sense of the future course of a [successful] technique. It will be gathered that in this essay Gille does not try to use the symbolism proposed by Fr. Russo. Examining attentively the example discussed by Gille, the hot-blast, one finds that it is indeed difficult to find symbolic notation in Russo's lattices corresponding to each of the analytical factors. Certainly a large number of these notations could be employed: C, Pn, Px under the heading 1, Re, Rq, Re under the heading 2, V modified by its various indices under the heading 3, T and t under the heading 4. But then the usefulness of the symbols may be questioned. The formation of a symbolic notation implies the intention of expressing the phenomena or the facts that have been investigated by formulae which are relatable one to another. Fr. Russo expresses the idea exactly when he condemns the use of 'rhetoric' in the historical analysis of techniques. Unfortunately he has not yet delineated any way of using these symbols. Does it suffice to juxtapose them in order to yield an analytical result and to compare with one another the various arrangements thus obtained? Will it be possible in some cases to express relations between several symbolic terms? This may very well be imagined for the analysis of the relationships between technologies and between science and technology: such notations as Ru, R'u etc. or else the symbols T, t for the analysis of scientific and technological creativity extending through time. It seems essential that the historical analysis of technology should not terminate in a merely static expression. Certainly Fr. Russo has laid down the condition that the clearly defined invention must be treated at a 'well defined instant'. It is

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indispensable to prepare static analyses in order to know the facts thoroughly, but in order to link facts to one another and to comprehend the evolution of techniques in all their generality it is impossible to neglect analysis of a dynamic character which alone can account for it. Moreover this is implied by the frames of reference proposed by Fr. Russo (relationships between techniques, creativity in time) as well as by B. Gille (invention, development, disappearance). One appreciates the difficulties of the undertaking immediately. Without speaking of the problem of knowing by what signs the symbolic notations should eventually be linked, it is obvious that their expressive capability is already limited by the complexity they present as soon as one tries to penetrate to the details of analysis. Confusion may occur through the use of symbols of similar form, for example R with certain indices for results and R with other indices for relationships; the multiplication of letter indices when it is necessary to express the different ways in which the time intervenes can again increase the confusion. It should be noticed further that the attempts at application given as examples by the two authors bear on relatively simple topics. What will happen to the symbolic notation and its employment when it may be a question of analyzing more complex phenomena like the history of telecommunication by electrical, and later electronic, means? Or the history of aviation from the Wright brothers to Concorde? This does not mean that the history of technology must renounce the hope of discovering a constant mode of expression for the results of its analyses. But it can only hope to attain it if, at any rate in the early stages, it limits its ambitions. In this respect it seems that both B. Gille and Fr. Russo seek prematurely to encompass a subject that is too vast. Russo's first schema, that which distinguishes three levels of analysis (elementary technology, technological entities, and industrial complexes —'see p. 103)is clear and satisfying. The danger of confusion arises from the multiplication of lattices before the schema has been exploited in so general a way that homogenous and comparable knowledge has been definitely established. In the same fashion Gille's four notions lose their perfect clarity when, facing up to the contemporary epoch, he contemplates the disappearance of the intermediate terms and leaves scientific progress confronting economic growth. Further it is necessary to define the concept of economic growth without ambiguity. Is it not clear that pressure for scientific progress does not, in vast areas of contemporary technology, spring from [the wish for] economic growth, simply understood? The desire of certain major states to ensure their economic hegemony cannot be assimilated to economic growth; it distorts the interplay between this last and scientific progress by interjecting political and military factors which throw an enormously heavy load upon

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technological progress in the true sense, as I have remarked already. The space saga is one of the most perfect examples of this distortion in the interplay of the classic factors, which the suppression of Gille's intermediate terms cannot explain. 3 5 It may further be asked whether the sacrifice of invention, and even of innovation, in the contemporary epoch is justified. In reality invention is still manifest everywhere, and at every moment. As the individual solely responsible for a particular creative act, the inventor seems to have disappeared towards the end of the nineteenth century or the beginning of the twentieth, but it is not so with invention to the extent that this reveals a certain mental process [working] towards a material creation. Gille has noted the difficulty of defining invention, quoting Etienne Lenoir, one of the first to make a gas-engine. The whole episode of the history of internal combustion engines would permit an analysis to be made of the evolution of invention from the classical to the contemporary period. From Lenoir's manner of procedure to that of Diesel, via Otto and Daimler, we might see how relationships between scientific knowledge and invention change, as well as the role of the individual in invention. In my opinion it would be more worthwhile to investigate how invention manifests itself in our own age, and how it has contributed to creativity at the three levels: of elementary technology, of technological entities and of industrial complexes, rather than expunge it from the scheme of analysis. This is, in fact, to expunge a large part of the creative process in the region where science and technology are more and more dependent upon one another, without (however) mingling together in the manner often asserted; that is, as a result, to diminish the history of technology to the advantage of economic history and even general history. In other words, it is to return to the 'rhetoric' condemned by Fr. Russo. And we have the defects of narrative too often before our eyes not to wish to seek for an alternative. 'In the domaine of history', J. U. Nef writes, 'the relations of cause to effect are infinitely too complex to be expressed in a mathematical formula.' 36 Despite this hitherto very reasonable pessimism, endeavours such as those of Fr. Russo should be pursued. I have myself expressed the idea that a symbolic notation for the history of technology and its relations with contextual events will become an indispensable tool. 3 7 This notation, of which the time factor would be an element, might lead to an expression for the equilibrium of the technological level at a particular epoch as a function of the internal tensions operating within this area. The problem would be to evaluate the tension-creating factors which have determined a technological episode in relation to the determining events. The expression of these factors might be in the form of the relation F£ = K/T, in which T would be the

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time-interval separating the determining event B from the determined event A . 3 8 One sees at once that the factor (F) would be greater as the response time (T) is less, which would be a good representation of the phenomena of tension within the scientifictechnical-economic complex. One might be able to try to evaluate, in other language than the rhetorical, whether the effects of tension do increase notably in the so-called periods of industrial revolution or if they only display a constant increase, as I believe. The determined event is either an invention, in the classical meaning of the word, or an innovation, or the end of a phase of development (in the R & D sense), that is to say the start of industrialization properly speaking. The determining events may be of a technical nature, or scientific or economic. Their nature does not, moreover, have to be defined in any particular way. For example the discovery of atmospheric pressure by Torricelli and Otto von Guerike is an event determining Savery's 'miner's friend'; that and the airpump are determining events of the Newcomen steam-engine — but these are not the only ones. Other coefficients than that of time must play a role in evaluating the factors of tension. For the present they are included within the factor K. Indeed it is necessary to take into consideration the bearing of a determining event upon that which is determined. For example, having regard to the condensing steam-engine, Kx for the Newcomen engine will be far greater than Kx for Black's calorimetric investigations. To take another example: in the industrialization of hypochlorite bleaches Kx for the discovery of chlorine by Scheele will no doubt be given the same value as K2 for the development of the cotton industry. No doubt the difficulty would be in evaluating the coefficient T, but perhaps this might be got over by choosing the appearance of the spinning-mule as the determining event. Later it will be necessary to bring in the degree of linkage and to try to express in this way whether the event begins a new line of descent, prolongs one or concludes it. To return again to the descendants of the steam-engine, K2 would in that context express the morphological link between it and the first gas-engines. This coefficient would then be a driving coefficient which would enable the crude expression 1/T or Kx /T to be refined. Finally, if it is desired to take account of the fact that every act of creation in the general evolution of technology only assumes its full significance in a socio-economic context and in technically receptive circumstances, it is indispensably necessary to think of a coefficient of receptivity that would be a qualitative factor. It would express the relation between the practical potentialities of the new creation and the wants of the context to which it belongs. The coefficient K 3 would be higher for the Watt rotative engine than for his simple steam-pump; the K3 of this

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latter would be much higher than the K 3 of the Newcomen engine. In a different set of ideas, the K 3 of Pascal's arithmetic machine would be very low, whereas that of the machine of Thomas of Colmar would be a little higher, and if one went on to evaluate that of computers it would have a high numerical value. Of course a technical event does not spring from a single determining event. Thus one would be led on to form a lattice of factors of tension for each event F g F c F n , etc.; no doubt the value of these factors individually considered, or as a whole by taking a mean between them, the density of the whole, would render visible the physiognomy of a chronological section through the general evolution. It is not unreasonable to think that the density of the factors of tension for an event or for a group of events taken together at a time under consideration would supply a numerical expression for the technological level of that period. Through comparison of the density of several chronological sections one might perhaps arrive at a graphical representation of technological change. I am conscious of all that remains indefinite in the above suggestions and of their arbitrariness. Like those previously summarized, they form no more than a modest essay, without pretentions directed towards the elaboration of a methodology for the history of technology. We are still groping in the dark and must try every avenue that offers itself, ready to abandon it if it proves a cul-de-sac. It should not be concealed that all the suggestions which have been reviewed here can only be subjected to exploration, if it be their fate to get so far, when well-equipped and numerous teams of historians can grapple with them. Of necessity and not merely for the sake of fashion the history of technology must adapt to its use the barely nascent methods of 'cliometrics', this presupposes a certain technicality in its methods of documentation, of anlaysis and interpretation. Notes 1. Annates d'histoire economique et sociale, no. 36, 30 November 1935. 2. Bertrand Gille, 'Note sur le progres technique', Revue d'histoire de la Siderurgie, 7, 1966, p. 3. 3. J. Jewkes, D. Sawers, R. Stillerman, The sources of invention (2nd. eda, London 1962), p. 224. 4. It is significant that the French journal publishing our work, brought into existence by historians of science at a time when the history of technology was virtually non-existent in France, still bears the title of Revue d'histoire des sciences et de leurs applications. 5. I have expanded this proposition in 'Rapport entre les sciences et techniques: etude generate du point de vue de l'histoire des sciences et des techniques', Revue de synthkse, no. 25, 1962; et 'Les relations entre le progres des sciences etcelui des techniques', Organon, no. 1, 1964.

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6. Thales, annee 1966. Travaux des seminaires de PInstitut d'Histoire des Sciences des annes universitaires 1963—64 et 1964—65. 7. B. Gille, The Renaissance engineers, London, 1966. 8. J. U. Nef, * Regard nouveau sur la revolution industrielle', in La route de la guerre totale, Paris, 1949, p. 28. 9. Lewis Mumford, Technics and Civilization, 1962, pp. 120—21. First pub. in England 1934. One could extract passages of this sort from every page of the book. 10. Ibid, p. 3. 11. Ibid, p. 112. 12. In English, Lewis Mumford's book has been even more popular and highly regarded. It had passed through eight impressions by 1962 (T). 13. J. U. Nef, 'The Industrial Revolution reconsidered', in Journal of Economic History, 1943. 14. See the work cited in note 8 above; also La naissance de la civilisation industrielle et le monde contemporain, (Paris, 1954). He seems to have tried out his idea in a short chapter of the first work, considering the period of the 16th and 17th centuries as a sort of proto-revolution and still writing of the 'industrial revolution properly speaking*. Then he affirmed it in the second work. 15. Through a slip of the pen, the French text here prints the name of (Abbot Payson) Usher. M. Daumas has confirmed in a letter that the name should be Nef. 16. H. Pasdermadjian, La deuxieme revolution industrielle, Paris 1959, p. xi. 17. Max Pietsch, La revolution industrielle, Paris 1963 (published in German, 1961). 18. That is, between 1815 and 1848 (T). 19. Jean-Louis Mannoury, La genese des innovations. La creation technique dans Vactivite de la firme. Paris, 1968. 20. The word is borrowed by Mannoury from G. Simondon, Du mode dyexistence des objects techniques (Paris, 1958) and very happily employed in the study of the evolution of heat engines from the eighteenth century to the present day. 21. Op. cit. (note 3), p. 228. 22. Op. cit. (note 20), p. 24. 23. Maunoury speaks of the internal logic of the evolution of a line of descent (op. cit., note 19, p. 58). The same idea should be extended to the evolution of the whole body of technology. 24. Ibid, p. 218. 25. Ibid, p. 222. 26. Ibid, p. 229. 27. B. Gille, op. cit. (note 2), p. 3. 28. Maunoury, op. cit. (note 19), p. 230. 29. Frangois Russo, 'L'analyse des techniaues et de leur evolution*, in Siderurgie et croissance economique en France et en Grande-Bretagne (1735—1913), Cahiers de PInstitut de Science economique appliquee, 5, no. 158, 1965, pp. 232-7. 30. B. Gille, op. cit. (note 2), pp. 185—95. 31. I have defended this notion in 'Plaidoyer pour Phistoire des inventions', Problemy Kultury, Warsaw, 1963. 32. See above, p. 92. 33. Above, p. 101—2. 34. B. Gille, review of the book cited in note 29, in Revue d'histoire de la siderurgie, 7, 1966, pp. 45—53. 35. The R&D budget of the USA for fiscal 1968—69, of the order of 130.109 francs, is divided thus: 50 per cent for national defence, 25 per cent

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Methods

for space, 12 per cent for atomic physics, 13 per cent for other industrial sectors, health, education, etc. (Le Monde, 5th February 1969). 36. J. U. Nef, op. cit. (note 14), p. 78. 37. M. Daumas, * Rapports sciences et techniques: etude generate du point de vue de l'histoire', Revue de Synthese, no. 25, 1962; 'Le mythe de la revolution technique', Revue d'Histoire des Sciences, 16, 1963,pp. 291—302. 38. The terminology proposed here is of course very provisional; one could employ such expressions as 'inducing phenomenon' and 'induced phenomenon'. Various forms may be tried out and their use alone will enable one to keep or discard them.

E l e c t r o m a g n e t i c E a r l y

I d e a s ,

T e l e g r a p h y :

P r o p o s a l s ,

a n d

A p p a r a t u s KEITH DAWSON The first suggestion for an electromagnetic telegraph is most probably due to Ampere who, after his famous analysis of 'Electro-dynamics' following Oersted's discovery, 1 announced his results to the Royal Academy of Sciences in Paris on 18 and 25 September 1820. This was followed by a memoire summarizing the findings and presented to the Academy on 2 October 1820 which concluded with two sentences containing suggestions for electromagnetic telegraphy. 2 Ampere, aware of a successful experiment carried out by Laplace, proposed a telegraph based on the use of as many conductors and magnetized needles as there are letters in the alphabet. By connecting the ends of the conductors to a distant battery so as to obtain needle deflections, signals might be transmitted if each needle carried a letter of the alphabet. A further refinement might be the arrangement of this transmission by means of a keyboard at the battery end. Ampere took no steps to promote his own idea b u t his suggested telegraphic system of keyboard transmitter, intermediate conductors, and transitory signal indicators set the pattern for some of the earlier attempts t o produce electromagnetic signalling devices. Some of these were almost exact interpretations of Ampere's generalized specification and included the cumbersome (and expensive) means of transmission involving many conductors. Ritchie, for example, in a lecture on electromagnetism on 12 February 1830 at the Royal Institution exhibited a telegraph operating through a necessarily short distance. The descriptions of his methods and apparatus in the Quarterly Journal and the Philosophical Magazine show that, apart from using galvanometers as indicators, he was following Ampere's suggestions entirely. 3 Even as late as 1837 when more sophisticated attitudes and considerations of design had already been applied to the development of the telegraph William Alexander demonstrated his model at the Edinburgh Society of Arts. It consisted of a chest about five feet long, three feet wide, three feet deep at one end and one foot deep at the other, containing thirty copper wires extending end to end. At the one end the wires were connected to a set of keys 'precisely similar to those of a pianoforte' and at the other they

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terminated in a common return wire. Thirty horizontal magnets, each 'poised within a flat ring of copper wire', carried small squares of black paper on one end which uncovered letters of the alphabet and signs when the magnets were deflected. The only apparent changes here from Ampere's suggestion would seem to be the idea of the common return wire, the circulation of the wire around the rings or its attachment to flat copper rings and the transfer of letters from the needles to a base board, the needles then carrying covers to hide the letters until required when signalling. However the Mechanic's Magazine commented: Such a machine reveals a new power, whose stupendous effects upon society no effort of the most vigorous imagination can anticipate. 4 and, in a previous article, gave a fairly comprehensive costing for a scheme to lay such a telegraph between Edinburgh and London with a possible extension to Glasgow. 5 Both these examples (effectively demonstration models) varied little then from Ampere's original ideas with the possible exception of increasing the effect of a single conductor on each needle by the inclusion, in Richie's case, of a coil or delicate galvanometer (making use of discoveries following Ampere's announcement) and the single return wire in Alexander's device. As the original suggestion had been limited to single letters and sign indications by each needle or magnet (and this had been followed entirely) then, in addition to a return wire, as many conductors were required as there were signs and letters. Alexander's choice in this respect was of twenty-six letters and four signs, so requiring thirty-one wires. Even this rather unwieldy number was considered an improvement (and gained favourable comment) on the fifty-two lines implied in Ampere's proposal. Further, Alexander's connections to the individual signalling mechanisms were of the simplest uni-directional type. The return wire was connected to one plate of the supply (the 'Galvanic trough') and from the other plate a lead was taken to a long narrow basin filled with mercury with which it made electrical connection. The out-going leads, fixed to the keys of the keyboard which was arranged above the basin, then dipped into the mercury when the keys were depressed so completing the required circuit. The current direction therefore would always be the same, dependent on the connection of the supply and in fact there would be no reason for considering a variation in direction if the requirement at the indicator end was limited merely to the display of a sign by uncovering it. However, by this time it had been realized that current reversal at the transmission end by more complex keyboards or switching devices could increase the signalling potential of the electro-

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magnetic indicators and so economize on the number of line wires required for transmission, since in this way each needle could assume at least three positions, normal and deflected either way. Already Wheatstone was developing his permutating keyboard in England, and in Italy Luigi Magrini was announcing his twentyfour part transmitter capable of current reversal. Both were to maintain Ampere's idea of alphabetic indication so that an observer could read letters or signs directly (as indeed Wheatstone was to do later in some of his more sophisticated devices) while neither adopted the all too simple expedient of merely using the possible two-way deflection of the magnet only; an approach which would simply reduce the number of indicators and, in consequence, the number of line wires by about 50 per cent. By combining the deflections in either direction of any one indicator with those of another in a different position Wheatstone definitely, and Magrini possibly, were able to indicate letters on charts, the two magnetic needles acting as pointers. In this way Wheatstone was able to produce in 1837 his five-needle device capable of indicating twenty letters by the deflections of the needles using two at a time, while for Magrini it is claimed that three needles produced the same number of letters by varying the degree of deflection of any two of these needles in either direction. These methods had the effect of reducing the line wires to five in Wheatstone's case and to six for Magrini (see Figure 1). By this time also the electromagnetic multiplier capable of giving quite positive deflections to the magnetic needle (and rather incorrectly associated with Ampere's proposals in accounts of Ritchie's demonstration) was well established and in use for galvanic measurements and demonstrations as well as for telegraphic devices. Its origin is attributed to J. S. C. Schweigger of Halle who was one among many who repeated Oersted's Experiments and expanded on them. In a paper read to fellow scientists and subsequently reported in the Journal fur Chemie und Physik Schweigger described his methods and findings and in that section of the paper recorded in Vol. XXXI of 1821 under the heading 'Fortsetzung dieser Vorlesung in der Versammlung in der Gesellschaft zu Halle am 4 Nov. 1820', 6 pointed to the deflections obtained by inserting a compass needle in either half of a loop of wax-covered wire twisted in the shape of a figure-of-eight. In a subsequent article, 'Noch Einige Worte iiber diese neuen Electromagnetischen Phanomene', 7 he made further reference to his experiments using an elongated loop held firm by two vertical wooden struts. At this stage Schweigger did not refer to this experimental apparatus as a multiplier and in fact the term does not seem to appear in print until it was used in an editorial footnote to a letter from Oersted in Vol. XXXIII of the Journal

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Figure 1. Left Wheatstone's vertical hatchment dial indicating 'S7. Right Magrini's table-top indicator showing 'S\

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fur Chemie und Physik. Here the editor remarks that Poggendorff has made a series of experiments with Schweigger's electromagnetic multiplier and notes that Poggendorff describes the instrument as a 'Condensator'. The reference to Poggendorff's alternative description indicates a possible claim on his behalf to have developed the multiplier independently as he describes the use of a similar device, and experiments with from one to 1300 windings in his paper, Thysisch-Chemische Untersuchungen zur nahern Kenntnis des magnetismus der Voltaischen Saule'. 8 However, it may be accepted that the multiplier had evolved through scientific investigation inspired by Oersted's discovery towards the end of 1821 and would be well known in 1822 in the form of a coil of wire surrounding a suspended magnet. It can also be assumed that attempts to make the device more sensitive for scientific purposes would soon include Ampere's method of using an astatic pair of needles which he describes in 1821 in Annales de Chemie et de Physique.9 Having noted that Oersted obtained deflections of less than a right angle in his investigations due to the effect of the earth's magnetic field, Ampere proposes the astatic method, 'pour soustraire une aiguille aimantee a Taction de la terre', and further illustrates that double the deflecting force (compared with th3 effect on a single needle) is obtained from a number of parallel conductors when one needle in the astatic arrangement is placed just under them and the other just above. This addition to the simple multiplier was no doubt an advantage in making the scientific version of the instrument more sensitive but must have been a mixed blessing when it was introduced into telegraphy. An initial, quick response to the signalling current would be attractive, but this must have been followed by a relatively long restoration period to or near the rest position for, if the same needle were required for a subsequent signal or part of a signal, the effect would be to slow the process or at least render the signalling uneven. The design of telegraph receivers, possibly even early signalling methods, would have to adapt to this effect. In this respect it is noticeable that in Wheatstone's five-needle device mentioned above he arranges the astatic pairs vertically, having the lower ends somewhat heavier than the upper, so that gravity exerts a much more effective restoring torque than could be obtained with the earlier silk suspensions of astatic needles arranged horizontally. These, then, were the earlier versions of telegraphic equipment which were not merely practical interpretations of Ampere's suggestion. By combining more versatile transmitting mechanisms with a limited number of multipliers, so placed that they could indicate letters by means of needle-deflection patterns, these

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devices economized on line wires as far as was possible for such direct-reading transitory systems. Meanwhile, however, other ideas on the electrical telegraph had been realized in Germany. The earliest, although not electromagnetic, had been completed in Munich in answer to a political request and seems, together with its originator, to have been in part the inspiration of a subsequent electro-magnetic apparatus. Other electromagnetic devices had also emerged, possibly as side issues from scientific investigations into terrestrial magnetism. The value of the Chappe mechanical telegraph had been demonstrated in the Napoleonic wars. Its use in informing Napoleon of the invasion of Bavaria by Austria was noted by the Bavarian minister Montgelas who was associated with the admini-

Figure 2. Soemmerring's Telegraph — general view (1809).

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stration of the Royal Academy of Sciences in Munich. He requested that Dr. Samuel Thomas Soemmerring, a member of the Academy from 1805 to 1820, should investigate the possibility of some form of telegraphic development taking place at the Academy, no doubt thinking in terms of mechanical and optical devices. Soemmerring decided to examine the problem himself and by 6 August 1 8 0 9 / ° within about one month of hearing the Minister's wishes (on 5 July 1809) considered that he had completed a satisfactory device. His description of the completed apparatus appears in the Denkshriften der Koniglichen Akademie der Wissenschaften zu Miinchen in 1809, * * together with clear drawings of its details and assembly. These show that Soemmerring had decided to use the electrolytic effect of a current for his telegraph, an innovation which reflected his interest in electro-chemistry. This interest was probably very active in 1809 as Hamel records that Soemmerring delivered a lecture, in 1808, to the Royal Academy in Munich on Humphry Davy's recent electro-chemical discoveries. For telegraphy, however, Soemmerring used the earlier discovery of the electrolytic decomposition of water that had been made by his fellow physiologist, Antony Carlisle, along with W. Nicholson, in 1800. It can be seen from the illustrations (Figs. 2 and 3) that, by connecting the ends of a voltaic pile using differently shaped key-plugs (Figs. 6 and 7 in Fig. 3) inserted in two of the drilled terminals (Fig. 5) of a thirty-five way transmitter (Figs. 9, 10 and 11), he was able to produce hydrogen and oxygen emission at two corresponding pointed gold electrodes (Figs. 3 and 4) in a thirty-five electrode water voltameter (Figs. 1, 2 and 8). All the electrodes at this receiver were lettered or numbered to correspond with the terminals at the transmitter so that an observer could note the two symbols where gas was produced and record them, giving precedence to the one indicated by the greater emission of hydrogen at the negative electrode. In this way messages could be transmitted and received but, here again, a direct-reading transitory indicator required thirty-five line wires with little opportunity of reduction unless the numbers were omitted (Soemmerring did in fact eventually make a reduction to twenty-seven line wires). Further, this number would be doubled if two-way operation between two stations were considered, the only alternative being a very cumbersome reconnecting process from transmitter to receiver and vice versa if the one compound transmission cable were to be used. However, despite some considerable publicity in scientific journals, demonstrations to scientists, diplomats and military figures, and the circulation of models to other cities and countries, this telegraph was not used in practice and now rests in the Deutsches Museum in Munich.

Figure 3. Soemmerring's Telegraph — details (1809).

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Its inspirational value, though, was probably quite considerable in demonstrating the possibility of producing electrical effects at a distance, in exposing the associated circuit difficulties and their solutions, and generally in producing a stock of knowledge which in the right circumstances could help in the production of the electromagnetic telegraph. That Soemmerring himself did not use his own knowledge and experience can possibly be attributed to the disappointments he suffered through failing to achieve the serious consideration he no doubt thought his invention merited. Notably, after its presentation to the National Institute in Paris in December 1809 an examining committee including Biot, Carnot, Charles and Monge failed, after eighteen months, to submit any report and as late as 1819 a suggestion (unsolicited by Soemmering but eagerly accepted) that it should be taken to England for possible examination by Humphry Davy did not materialize due to the dilatoriness of the British diplomat involved. Soemmerring did not learn of this latter failure until 1820, one year after the original suggestion. This was the year of Oersted's announcement, Ampere's analysis, the development of the multiplier and, coincidentally, Soemmerring's retirement to Frankfort in his own sixth-sixth year. If the electromagnetic discoveries had arrived too late to be adapted to telegraphy by a rather thwarted, though experienced, inventor they were well timed for a relatively young man of thirty-four who had had the advantages of living in Munich since 1803 (two years before Soemmerring was appointed a member of the Royal Academy of Sciences), of meeting Soemmerring and his acquaintances regularly over a period of thirteen years and, of some importance in the present context, of helping Soemmerring considerably with his experiments on the telegraph from 1810 onwards. This was the Russian Baron Pawel Lwowitsch Schilling von Canstadt. Schilling came from a combined military and diplomatic background. His father died in Russian military service and his mother's re-marriage was to a Russian diplomat. At the age of nine be became a cadet in his father's regiment and by sixteen was a lieutenant on the General Staff. In 1803, however, his stepfather moved to Munich as Ambassador and Schilling joined his family there to become a translator with the foreign affairs staff at the Embassy. His acquaintance with Soemmerring commenced with a visit (for medical reasons) in 1805 and the subsequent friendship between the two was to last until Soemmerring died in Frankfort in 1830. During the period 1810 to 1820 Schilling was to bring many visitors to see Soemmerring's telegraph. He assisted with demonstrations and experiments and as a result was led to pursue investigations of his own. He seems, interestingly enough, to have

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been preoccupied with the means of transmission and with conduction problems in general.1 2 At his suggestion, in 1811, he and Soemmerring tried the effect of breaking the two operative conductors of the telegraph and inserting the ends into tubs of water, so verifying that conduction continued. They followed this with further tests in a canal by the river Isar and then in the river itself. In 1812 he manufactured a cable and tested its insulation by carrying out conduction tests in moist earth and water. Hamel considers that these tests were prompted by the impending Franco-Russian war and that the purpose of such a cable would be for telegraphy, on the one hand, or for the remote exploding of gunpowder, on the other. The case for the latter seems stronger, and more in keeping with the prevalent atmosphere, as Soemmerring received reports that Schilling, recalled to St. Petersburg, had exploded mines galvanically across the Neva by means of a submerged cable. Hamel states that Schilling told him that after the entry of the Russian troops into Paris he caused astonishment on several occasions by using his cable to ignite gunpowder across the Seine. This was in 1814 and shows that following Schilling's apprenticeship under Soemmerring he had not only acquired an interest in telegraphy but had involved himself practically in transmission problems, conductor protection and insulation. He would have become practised in the use of voltaic supplies and have gained a qualitative appreciation of their ability to produce effective currents in long conductors. (It is claimed that Soemmerring operated his telegraph through line distances of 724 feet in early tests and subsequently through 1,000 and 2,000 feet.) But any application to telegraphy at this stage was necessarily limited to such ideas as Soemmerring's electro-chemical device. However, telegraphy was always in the background in the continuing friendship of the two, as also was scientific discussion and meetings. Schilling was to meet Schweigger when the latter visited Soemmerring in 1815, and when Schilling interested himself in another recent development in communication, namely lithography, Soemmerring and he made a dual purpose expedition to obtain good lithographic stones for the one and organic fossils for the other. Consequently by 1820 Schilling probably possessed a fair degree of technical and scientific knowledge. He had mixed with scientists and interested himself in scientific work. His closest domestic connections were in cities having centres of learning; the Royal Academy of Sciences in Munich and the Imperial Academie of Sciences of St. Petersburg. Through these he could no doubt gain access to scientific papers from other academies, universities and institutions, and he was an officially recognized translator. All this has led to the assumption that very soon after the discoveries

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announced in 1820 Schilling rapidly commenced work on his electromagnetic telegraph which, in its simplest form, consisted of a slightly modified Schweigger multiplier connected to two wires and operated by a small voltaic cell. Muncke implies this in his article on the telegraph in Gehler's Physikalisches Wdrterbuch where he says that it was soon after Oersted's announcement and the subsequent construction of the multiplier that Schilling had the idea of using the effects for telegraphy. 1 3 Hamel also, in his desire to gain pre-eminence for Schilling in the development of the telegraph, says in the context of 1820 that Schilling made the first electromagnetic telegraph. 14 However, neither author gives a specific date of construction, which is to some extent surprising as both had met Schilling; Muncke, on the occasion of the first public display in Europe of Schilling's telegraph in 1835 in Bonn, and Hamel on an occasion when Schilling recounted his remote explosion activities on the Seine. In fact despite Schilling's scientific interests and knowledge of scientific society he was not a scientist himself and, as a result, not accustomed to recording and publishing his work. Consequently, some confusion has arisen concerning the date of Schilling's telegraph, largely caused by Hamel who allowed two versions of his paper to the St. Petersburg Academy to be printed; the one, 'die Enstehung der Galvanischen und Electromagnetischen Telegraphie', appears in the Bulletin de VAcademie des Sciences de St. Petersburg in 1860, and the other, in English, appeared first as two articles in the Journal of the Society of Arts in 1 8 5 9 . 1 5 The two articles were subsequently printed as a separate pamphlet in London under the heading: Historical Account of the Introduction of the Galvanic and Electro-magnetic Telegraph. The two versions, German and English, are almost identical in order, presentation and use of language, but with slight additions in the English version relating to the date of Schilling's apparatus. For example, the English pamphlet states: Baron Schilling's telegraph was an object of great curiosity at St. Petersburg; it was frequently exhibited by him to individuals and to parties. Already the Emperor Alexander I had been pleased to notice it in its earlier stage, and, when it was reduced to great simplicity. His Majesty the Emperor Nicholas honoured Baron Schilling, in the beginning of April 1830, with a visit at his lodgings in Afrossimow's house in the Konooshennaja, to see experiments performed with it through a great length of conducting wires. 1 6 whereas the corresponding paragraph in the St. Petersburg Bulletin reads:

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Schilling's telegraph was an object of admiration in St. Petersburg. He had, very often, to show it working to curious individuals and occasionally even whole parties. Later even his Majesty the Emperor Nicholas deigned to have experiments with the telegraph demonstrated to himself in Schilling's house. 1 7 The reference to Alexander I, in the English version, is highly significant as this would indicate that Schilling's telegraph had been made before 1825, the year of Alexander's death. (Its omission from the paper to the Academy might be equally significant.) The English record appears t o have led to the assumption on the part of subsequent historians of technology that the date 1825 may be quoted for Schilling's device (e.g. Sellars, 1 8 Fahie, 1 9 and even Neuburger 2 0 in Germany). Further, having created for the English reader the impression that Schilling's electromagnetic interests and activities had started in the early 1820s Hamel attempts some degree of corroboration by describing a journey to the Orient made by Schilling in 1830 as follows: In May of the last mentioned year, 1830, Baron Schilling undertook a journey to China. He had a strong propensity for studying the language, and everything relating to China. His most ardent desire was to be able to visit Pekin, b u t he was obliged to confine his travels to the borders of the Empire. He collected a great many precious Chinese, Tibetan, Mongolian and other writings which are now preserved in the Imperial Academy of Sciences at St. Petersburg. He had a small electro-magnetic telegraphical apparatus with him, and the astonishment which the experiments performed with it excited, assisted him not a little to obtain many of the most interesting works, which he would not have got by simply paying for them. 2 * However in the St. Petersburg Bulletin this becomes: In May 1830 Baron Schilling undertook a journey in Mongolia to the border of China. He had a passion for the study of the Chinese language and it is admirable how many Chinese, Tibetan and Mongolian writings he has collected during his voyage. They may now be found as is well known in the Asiatic Museum of our Academy. 2 2 The omission of the final sentence quoted in the English version is again significant. Finally it can be noted that Hamel, towards the end of his paper, records that 1833 or 1832 is the date usually quoted for Schilling's telegraph and that current opinion in Moscow favours 1 8 3 2 . 2 3

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It would seem therefore that 1832—3 might be the most likely date for Schilling to have been occupied with the early version of his telegraph (after his return from the East) and that that version of Hamel's paper given to the knowledgeable scholars of the Imperial Academy is the more reliable, rather than that presented to the British public. Hamel was probably using the English version as a counter to Morse of America whose own apparatus, claims of priority and methods of establishing those claims, Hamel considered puerile, derisory and contemptible. Although Hamel includes a description of Schilling's apparatus in his paper, an earlier account (and therefore nearer to the probable date of construction) is given by Muncke in Gehler's Physikalisches Worterbuch in 1 8 3 8 . 2 4 As noted above Muncke, Professor of Natural Philosophy at Heidelberg, met Schilling when he was chairman of the section before which Schilling exhibited his telegraph at the meeting of German scientists at Bonn in September 1835. He was so interested in Schilling's telegraph that subsequently he made and demonstrated models of it at Heidelberg. Characteristically, for someone who had discussed the device with Schilling, he commenced his description with the main problem of transmission (das Hauptproblem). He notes that Schilling convinced himself that the electric current would not weaken in travelling long distances, by means of experiments made on his own estate through wires of several 'versts' in length (1 verst = 1,067 metres). This sounds very much like Schilling's earlier work with Soemmerring, or his experiments leading to the production of the underwater cable. Next, Muncke considers the method for generating the current and makes reference to the apparatus shown in Fig. 4. He also mentions that he made use of the same method himself for his models. A relatively heavy base AB carried a vertical wooden bar gg divided by a saw cut so that it would clamp two plates, copper and zinc, K and Z. These were separated by a moistened membrane. Consequently, for the Bonn demonstration at least, Schilling was using a supply of the order of 0 . 5 - 1 . 0 volt. Muncke then turns his attention to the receiver, having previously implied in his article that this was of the multiplier type. He points out that the suspension of untwisted silk thread was attached, at its upper end, to an appropriate bearer and, at the lower end, to a small wooden bar or brass wire, )3j3, ]3'j3' to which the magnet needle NS, N 1 S 1 was firmly fixed. A paper or card disc A, A 1 , about 1.5" to 2.0" diameter, was then held by friction to the small bar so that its edge was towards the observer in the rest position, any deflection displaying one or other side. The sides could be distinguished from one another by vertical and horizontal bars or any other signs.

Figure 4. Schilling's Telegraph - details (1838).

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For the greater detail of the multiplier he refers to Fig. 11 of his illustration (see Fig. 4) which shows that the multiplier was placed in a box, its ends terminating in small wooden beakers of mercury, P, into which the line wires could also connect. Finally (from the point of view of the description of the apparatus) Muncke concludes with a rather vague sentence which states that to prevent any excessive deflection of the magnetic needle a small 'strut' (really, a vane) must be fixed somewhere in the system. The use of the term 'somewhere' to describe the position of the damping 'strut' is rather surprising as it is shown in the normal and most suitable position for the apparatus in Muncke's Fig. 11 (Fig. 4). Consequently, as Muncke does not describe this part of the mechanism in detail, reference may be made to Hamel's description which, although limited solely to the receiver, does expand on this point. Hamel notes that Schilling fitted a paper disc, differently coloured or marked on its two sides, at the middle of the magnet axle which, at its lower end, carried a small platinum 'rudder' dipping into quicksilver to prevent oscillations of the needle. 2 5 The full description of the receiver now becomes clear. The moving part of the indicator consists of a single needle (at this stage) mounted on a vertical wood or brass axle which is suspended from an untwisted silk thread so that it may hang within a coil. A vane of platinum is attached to the axle, below the needle and coil, and moves in a container of mercury to damp any oscillation of the needle system. As the needle is deflected from its normal rest position to one side only so one or other side of the card disc, with its appropriate marking, is displayed to the observer. Successive deflections can be used therefore to transmit messages by means of a code. Muncke concludes by pointing out that his illustration is arranged for observing signals 'from the first station' and that one can signal back from the second station by removing the line wires from the multiplier, connecting them to the plates of a supply and, if the reverse operation has been carried out at the first station, transmit signals back to a like apparatus. This is well illustrated in Cooke's drawing, Cooke having seen Muncke's demonstrations of his models of Schilling's telegraph in Heidelberg in 1836 (Fig. 5). Incidentally, Cooke's drawing agrees substantially with Muncke's as far as the receiver is concerned and completely so in the case of the voltaic supply. Cooke also confirms that Muncke's versions of Schilling's apparatus were fitted with the platinum-mercury damping device (otherwise only confirmed by Hamel nearly a quarter of a century later) by noting in the table to his drawing that the Fig. 7 refers to: Steadying piece: dipping into a steadying cup of mercury to support the needle and check oscillation. 2 6

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Figure 5. Cooke's drawing of Muncke's apparatus (1857).

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This then was the apparatus described by Muncke. It gives the impression of being a prototype or, more likely, a simplified version of a more sophisticated device, possibly one of Muncke's models used by him to demonstrate principles in his lectures, and subsequently forming the basis of his description of Schilling's work. This would then explain the third drawing of the receiver (and alarm) which both carry certification that they are taken from the originals of 1832 held in the Royal Academy of St. Petersburg (Fig. 6). The signatory of the certificates (dated St. Petersburg 11 May 1873) is the Director of the Royal Russian Telegraphs. Here the receiver assumes the appearance of a scientific instrument. The circular wooden box containing the multiplier coil consists of a number of well fitted parts turned on the lathe. An astatic needle system has been introduced and the problem of levelling has been recognized and catered for by the use of levelling screws placed at 120 degree intervals around the periphery of the base. It can be noted that the circular tell-tale disc is coloured black on one side and white of the other. The drawing represents the final stage in the development of Schilling's receiver and has been universally used for the manufacture of the facsimile copies of the 'single' device found in museums. The mention of a single device introduces a further controversy concerning Schilling's telegraphs. As well as the apparatus described above, telegraphs using five and six multipliers placed side by side are attributed to him; these could therefore display as many deflections of the five or six discs. What would, in the case of the single indicator, be a series of consecutive deflections to transmit a symbol would, for the multi-indicator device, be a simultaneous display of all or some of the indicator discs. The question is, however, did Schilling commence with the multiindicator device and simplify it to a single indicator, or did he commence with the single indicator and later increase the number used to form the multi-indicator devices? The different attitudes to this are illustrated by Hamel and Muncke (who may even have started the controversy). Following his description of the indicator mechanism Hamel says that for some time Schilling used five indicators next to one another to obtain a complete alphabet and the numbers and that gradually he simplified the arrangement to give all his signals with one device only. 2 7 On the other hand, Muncke reports that Schilling commenced signalling with a single needle, but that he was well aware that it would be an improvement to use several needles next to one another, with as many conductors, for which a single return wire would suffice.28 Consequently, later writers have either followed Hamel's idea of simplification (Sabine, 2 9 Neuburger, 3 ° Hubbard, 3 * Marland3 2 ) or

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Figure 6. Schilling's Telegraph - details (1873).

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opted for an increase in the number of indicators as described by Muncke, (Fahie, 3 3 Guerout 3 4 ) . However, the available historical evidence and certain technological aspects of Schilling's work appear to favour a development from the single indicator to multi-indicator devices. Rather surprisingly, in view of his comment above and his additions to the English version of his paper quoted earlier, Hamel himself gives some indication of this. In his paper to the Academy he criticizes Gauss for expressing surprise, in 1837, that since Oersted's discovery a fair number of years have elapsed before anyone seems to have thought of its use for telegraphy. This comment, which represents a rather grand disregard by Gauss of earlier efforts and suggestions, is made in the Resultate aus den Beobachtungen des Magnetischen Vereins for the year 1837 3 5 and seems to have inspired Hamel to further efforts. He presented a postscript to his original paper to the Academy on 18 May 1860, the main part of which is devoted to denying the possibility that Gauss could have been unaware of Schilling's work. As evidence he quotes a letter from Gauss to Schilling written on 11 September 1835 (twelve days before the demonstration of the telegraph in Bonn) in which Gauss refers to Weber's departure for Bonn, expresses satisfaction at his renewal of acquaintanceship with Schilling and the consequent opportunity of discussing scientific matters, and proceeds with a lengthy paragraph on the possibilities of developing the electromagnetic telegraph. He mentions the probability of transmitting at a rate of eight or ten letters per minute and, with respect to the transmission, says that he has estimated that only 1.6 millimetre copper wire would be required for a line between Leipsig and Dresden, even less with greater electric power and a multiplier. He then says that if one could expend the larger costs for a multiple cable 'according to your idea of seven lines' (nach Ihrer Idee von sieben strangen) then Schilling's method will be able to attain greater speed and require less special intelligence on the part of the operator. 36 Now, Hamel certainly seems to have proved his point concerning Gauss's knowledge of Schilling's work, but in so doing has disclosed the information that in 1835 in discussion with Gauss, Schilling had the 'idea' of a 7-line multiple cable which gained approval from Gauss (provided the expenditure could be borne) in that it would give greater signalling speed and independence of the observer's intelligence. It may be noted at this stage that a 7-line cable would serve a 5-indicator receiver, plus an alarm, the six devices then using a common return wire. Muncke had already noted that Schilling was aware of the use of a single return wire (see above) where he also

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states that Schilling knew that several needle devices next to one another would be an improvement on a single needle (used initially) to obtain numerous combinations of ciphers. He explains this by saying that Schilling favoured the idea of simply telegraphing numbers which would relate to words in a cipherdictionary. He then suggests that five needles, each supplied with two numbers (one on either side of the disc) would be a suitable arrangement for Schilling's system. This, he considers, would give a more than sufficient total of number combinations for use with the cipher-dictionary. 3 7 Consequently Muncke, writing within three years of his meeting with Schilling, chooses the 5-needle device for his article, one which could transmit more of the numbers (preferred as signals by Schilling) than would be required for the decoding book and, incidentally, one which would require a 7-wire cable. However, it must also be noted that Muncke, having selected the 5-needle version for his description, then only briefy describes the transmission of signals from the production of an electric current in one station, when either one or up to five needles will move simultaneously in the second, thus giving the requisite number for decoding, before describing in detail the single needle arrangement. His one reference back to the 5-needle device occurs when, having described the distinguishing technique for the different sides of the disc of vertical and horizontal bars (p. 125 above), he states that for five discs the chosen arrangement is allowed of 0 + 5, 1 + 6, 2 + 7, 3 + 8, 4 + 9. As this method does n o t appear to have been used in the multi-indicator telegraphs it could mean that at the time of Muncke's meeting with Schilling in 1835 the 7-wire cable was strictly an idea, whose potential, although recognized for use with the established single devices to form a multiindicator receiver, had yet to be realized. Furthermore, the transmitter would need to be developed beyond the stage of manual connection of wire ends to cell or battery plates, this being the only method described by Muncke. Possibly, however, the most convincing argument for a progression from the single indicator to the multi-indicator telegraph is the technological one hinted at by Gauss when he says that signalling would be quicker by use of a cable of seven wires. If signalling by means of a single indicator is considered, using the most refined version of the apparatus illustrated in the Bulletin of the Royal Academy of St. Petersburg, then the unfavourable characteristic mentioned on page 117 (the long restoration period) would be only one element in the overall disadvantage of extreme slowness in the action of the device. The restoring torque or (more correctly) the controlling torque against which the mechanism moved would be that due to the earth's magnetic field (the suspension having been made as

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torsionless as possible) and this would be greatly reduced by the astatic arrangement of the magnetic needles. Consequently, with no damping, the needles would oscillate violently about their fully deflected position. The damping device arranged by Schilling to prevent the oscillation was such as to provide a relatively massive torque, much too large for the effects it had to control, due to his choice of materials. The selection of a system where mercury surrounds a platinum paddle is surprising, to say the least, when less costly and more readily available substances might have been chosen. The choice of mercury as the damping fluid was probably made because of its customary use as an electrical connector (page 127), (if it was used for one purpose why n o t for another?) The selection of platinum would no doubt follow as other materials, only fractionally as dense, would almost certainly float or partially float in the mercury, so disturbing the suspension. Another factor would be that the substance chosen for the paddle would need t o be one which did n o t form an amalgam with mercury. However, irrespective of the reasons for this choice of materials to counteract oscillation, the needle system must in the end have been extremely over-damped. (It could be noted here that in modern electrical instruments where mechanical damping is used a very light aluminium vane moving in an enclosed space suffices, the damping fluid here being air. The controlling torque for such instruments, however, is generally supplied by hairsprings and is consequently much stronger than the earth's magnetic field. This means that the oscillations which require damping are less violent than those which would have occurred in Schilling's instrument.) Consequently, if the operation of the single indicator t o display a signal consisting of several deflections of the needle system is considered, one may suppose that a first deflection of reasonable speed would be followed by a very long period of waiting for the system to return sufficiently near to its zero position to allow the next deflection. The astatically weakened restoring effect on the needle system would require some fair length of time to rotate the platinum paddle back through the mass of mercury. A conservative estimate for one deflection and return might be fifteen seconds. This would indicate that several deflections t o give a particular cipher could take up t o a minute or more, which falls well short of Gauss's expectation of a rate of eight to ten letters per minute. In fact, signalling with a single indicator must have been dismally slow so that Gauss's comments concerning a rate of signalling and his prediction that Schilling's compound cable would increase speed indicate that these pioneers were already preoccupied with transmission time and the means of reducing it. With a 5-indicator device, however, up to five deflections for a

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cipher requiring this number could be shown in very little greater time than that of one deflection on the single indicator, given a suitable transmission mechanism. It is a matter for conjecture as to why Hamel and, subsequently, others say that Schilling's apparatus was * simplified' to a single indicator, and it may be assumed that they, thinking in more modern terms, found the idea of economy in the use of line wires attractive in the progression towards the telegraphic ideal of one wire only. However, for a man whose previous telegraphic experience had been with Soemmerring, using twenty-seven to thirty-five wires for one-way communication, the thought of fourteen or sixteen lines for two-way transmission could not have been particularly daunting nor does t h e need for financial economy seem to have been pressing in the design of the damping mechanism of Schilling's receivers. It seems, therefore, that the evidence concerning the development of Schilling's receivers supports the interpretation of Auguste Guerout, the nineteenth century French writer on telegraphic history. In 1883 Guerout reported that Schilling's telegraph had been described sometimes as having five or six needles. It appeared probable to Guerout that Schilling had tried different arrangements and that he had first made a single needle telegraph, then had been led to combine several such together in order to transmit a number of signs simultaneously. ('Ce qui parait probable, c'est que Schilling avait essaye diverses dispositions et qu'il avait d'abord construit un telegraphe a une seule aiguille, puis avait ete ensuite amene a en combiner plusieurs ensemble afin de pouvoir transmettre a la fois un certain nombre de signes,') 3 8 Before Schilling could use several indicators effectively, however, he would have to develop the transmitter and this was probably initially based on the commutator. Both his single version and a 6-indicator telegraph were displayed by the Russian Government at the International Electrical Exhibition of 1881 in Paris (Fig. 7), together with a rather confused and confusing descriptive notice. Referring to the 6-indicator device, the notice states that a keyboard transmitter (displayed) was used with it and, after describing the process, states that the apparatus has six commutators. A description of the construction of the commutators follows and the information is then given t h a t Schilling, having first used the commutators, quickly realized their inconvenience and replaced them by a keyboard. 3 9 This latter information seems most probable as, in the first instance, Schilling was doubtless aware of the commutator, due t o his friendship and dealings with Gauss. In 1833 the latter, in a letter to the astronomer Olbers in Bremen, described his recent galvanic experiments in Gottingen and mentioned that he had

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Figure 7. Schilling's six-indicator telegraph (1883). thought o u t a simple device for the instant reversal of current which he called a commutator. 4 ° Consequently, the simple commutator (which Gauss was to develop considerably in his own later devices) had been designed nearly two years before the discussions with Schilling on the electromagnetic telegraph. Further, the reference to the inconvenience of the commutators on the Russian notice might possibly relate to a restriction which their use would impose on Schilling's signalling methods. Figure 8 shows the circuit of a multiple indicator receiver with a commutator transmitter. Any attempt to obtain deflections of the needle systems of two of the indicators in opposite directions results in the short-circuiting of the cell or battery supply. This means that such an indicator must always have displayed either all-white or all-black combinations of disc sides for a signal (the Russian notice describes the discs as black on one side and white on the other — Muncke's earlier suggestion of symbols n o t having been realized, possibly due to this very complication). It is likely that Schilling changed his signalling code as a result of this effect and that the choice of five single indicators to form a multiple indicator was also initially dictated by it. Guerout states that with the single indicator Schilling used a code to obtain twenty-six letters, four signs and the ten numbers, and t h a t the maximum number of deviations required in any one case was five. (In fact to obtain these forty signals, sixteen would require four deviations and ten would require five, a point which might be noted in connection with the comments on signal time made above.) Now, any signal consisting of mixed black and white

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showings on the single indicator (e.g. black followed by white followed by black again) could n o t be transferred as a static display (black-white-black) t o a multiple indicator using a commutator transmitter. Consequently a new code would be required to cater for displays in one or other colour only which gave at least the forty signals previously obtained with the single indicator. The number of displays obtainable without mixing colours on (say) a two indicator receiver is six (as well as black-black and white-white, disc edge-white; white-disc edge; disc edge-black and black-disc edge are also available). This value, (2 3 — 2) is one form of a general expression for the number of single colour displays available, when using commutators, from n indicators in the form; 2n+1 - 2 . Consequently, to obtain forty signals: 2n+i

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For n = 4 (i.e. four indicators) the number of signals available is only thirty, whereas, with five indicators, sixty-two signals may be obtained and this quantity would be available, therefore, for use with Schilling's five indicator receiver. Some indication of a change in signalling method can also be gleaned from those descriptions (in general terms) which comment on the use of Schilling's devices. Muncke notes in 1838, in the context of the multi-indicator telegraph, that Schilling favoured the idea of simply telegraphing numbers which could relate to words in a code-book (see above). The Russian notice points out, with reference to the six indicator device, that before it can be used for signalling an alphabet or dictionary of phrases must be composed relating to the different positions which the discs may take. The two comments appear to indicate that Schilling's early desire to telegraph numbers and refer to a code-book had been ultimately realised. Two further comments on telegraphing letters of the alphabet and a restricted quantity of numbers come from Hamel and Guerout. Guerout specifically limits his comments on alphabetical, sign and number signalling to the single receiver while Hamel records that Schilling used five devices next to one another to exhibit a complete alphabet and the numbers. Now if it can be assumed that Hamel, having reversed the development order of the telegraph, is really describing the use of the single indicator (and further that the use of the term alphabet in the Russian notice might refer also to this) it could be inferred that a change had occurred in the signalling code with the arrival of the multiindicator receiver. Consequently, with a 5-indicator device and a commutator transmitter with suitably marked boards (as described in the

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Russian notice) to prevent short-circuiting the supply, Schilling would have sixty-two signals available for use in telegraphing. The development to the 6-indicator receiver no doubt followed in order to more than double this number by the addition of the sixth indicator, so giving 126 signals (2 7 — 2), an addition which would involve only one more wire in the cable. It can be assumed that with this number of indicators and the alarm, the manipulation of the commutators for transmission would become rather cumbersome and that some refinement or change in design of the transmitter would emerge. This appeared in the form of a keyboard transmitter which was described in the Russian notice at the Paris Exhibition. Guerout who had examined the apparatus at the exhibition analyses the description and describes the circuit and its operation very concisely and logically. He points o u t that the system requires only eight wires, seven out-going and a return wire, formed into one cable. Each wire makes connection with two keys at the transmitter, one white and one black. When a white key is depressed it makes contact with the positive (say) of the battery while the depression of a black key connects the wire to the negative. If one wishes, therefore, t o display the white side of the first disc of the indicator it is necessary to depress the first white key together with the black key of the return wire. To display the black side of the same disc the first black key and the white return-wire key are depressed. As the alarm acts in one direction only one of its two keys is superfluous. 4 * The keyboard transmitter was quite a compact device of about 16"—18" long and 8"—10" tall, and the circuit according t o Guerout's description is shown in Fig. 9. It has the intriguing characteristic that, with a suitable supply and circuit constants, it could show mixed signals of black and white discs as 'black key' circuits could act as returns for 'white key' circuits so giving a signal capacity of 728 signals ( 3 7 — 1). However, this was probably never either intended or used. In fact, Schilling's telegraphs were never installed for practical use, despite the favourable finds of an investigating committee in St. Petersburg who examined his apparatus under the most difficult transmission conditions, notably, when the cable was submerged in a canal near the Russian Admiralty. The committee's report inspired the Emperor Nicholas in May 1837 to instruct Schilling to prepare a scheme, complete with costing, for an undersea telegraphic link between Kronstadt and St. Petersburg in the waters of the Gulf of Finland. Before Schilling was able to develop this project, however, he died in August 1837 at St. Petersburg and the plan was never realized. Nevertheless it may be said that Schilling's contributions t o electromagnetic telegraphy were quite remarkable. As a non-

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scientist he seems to have had a ready grasp of necessary scientific principles and a quick appreciation of the action and potential of apparatus. His lack of overall technological expertise is perhaps demonstrated by a poor choice of materials in his damping mechanisms but the general principles of his method are currently used to prevent oscillation in some modern instruments. It would be difficult, on the other hand, to direct any criticism from the technological point of view at his approach to line transmission. His performances with underwater cables, ultimately subjected to and gaining approbation from state investigation, must be regarded as impressive. Finally it can be said that he so combined ideas, devices, mechanisms and instruments, that by virtue of his acquired knowledge and experience he was almost certainly the first to produce a working electromagnetic telegraph. However, by the time of its official acceptance and approval in 1837 other devices were appearing in America, Germany and England, which were to enter into practical service. Notes 1. Journal de Physique, de Chemie, D'Histoire Naturelle et des Arts, Tome XCI (Juillet 1820), pp. 72—6; Annals of Philosophy (Thomson), Vol. XVI (Oct. 1820), pp. 273—6; Journal fur Chemie und Physik (Schweigger), Vol. XXIX (1820), pp. 275—81; Annales de Chemie et de Physique, Vol. XIV (1820), pp. 417—25. See also Isis, Vol. 10 (1928), pp. 437-44; Journal of Society of Telegraph Engineers, Vol. V (1876), pp. 459—69; Robert C. Stauffer, 'Speculation and Experiment in the Background of Oersted's Discovery of Electromagnetism,' Isis, Vol. 48 (1957), pp. 33—50. 2. Annales de Chemie et de Physique, Vol. XV (1820), p. 73. 3. Quarterly Journal of Science, Literature and Art (Royal Institution), Vol. XXIX (March 1830), p. 185; The Philosophical Magazine, 2nd series, Vol. VII (1830), p. 212. 4. Mechanics' Magazine, Vol. XXVIII (25th Nov. 1837), p. 123. 5. Mechanics'Magazine, Vol. XXVII (12th Aug. 1837), pp. 318-19. 6. Journal fur Chemie und Physik, Vol. XXXI (1821), pp. 7—17, and Taf. 1. 7. Ibid., pp, 35-41. 8. Isis, Oder Encyclopadische Zeitung (Von Oken), Zweiter Band, heft VIII (1821), pp. 687-710. 9. Annales de Chemie et de Physique, Vol. XVIII (1821), p. 320. 10. J. Hamel, 'Die Entstehung der galvanischen und electromagnetischen Telegraphie,' (Lu le 23 decembre 1859), Bulletin de VAcademie Imperiale des Sciences de St. Petersburg, Vol. II (1860), p. 103. 11. Denkshriften der Koniglichen Akademie der Wissenschaften zu Munchen, Vol, II (1809), pp. 401-14, Tab. IV and V. 12. J. Hamel, Op. cit., pp. 108, 110, 111. 13. Physikalisches Worterbuch (Gehler), Vol. IX (1838), p. 111. 14. J. Hamel, Op. cit, p. 118. 15. Journal of the Society of Arts,Vol. VII (22 July 1859 and 29 July 1859). 16. J. Hamel, Historical account of the introduction of the galvanic and electro-magnetic telegraph, p. 41.

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17. J. Hamel, 'Die Entstehung der galvanischen und electromagnetischen Telegraphie,' (Lu le 23 decembre 1859), Bulletin de VAcademie Imperiale des Sciences de St Petersburg, Vol. II (1860), p. 119. 18. H. G. Sellars, 'Short History of the Electric Telegraph,' Post Office Green Paper, London, No. 5 (1934). 19. J. J. Fahie, A history of electric telegraphy to the year 1837, London, 1884. 20. A. Neuburger, 'Telegraphie und Telephonie,' Der Siegeslauf der Technik (Ed. Max Geitel), Stuttgart, 1890. 21. J. Hamel, Historical account of the introduction of the galvanic and electro-magnetic telegraph, pp. 42—3. 22. J. Hamel, 'die Entstehung der galvanischen und electromagnetischen Telegraphie,' p. 119. 23. Ibid., p. 131. 24. Physikalisches Worterbuch (Gehler), Vol. ix (1838), pp. 111—115. 25. J. Hamel, 'Die Entstehung der galvanischen und electromagnetischen Telegraphie,' p. 119. 26. W. F. Cooke, The electric telegraph; was it invented by Professor Wheatstone? London, 1857, Drawing 1, Part A., p. 217. 27. J. Hamel, 'Die Entstehung der galvanischen und electromagnetischen Telegraphie,' p. 119. 28. Physikalisches Worterbuch (Gehler), Vol. IX (1838), pp. 111—12. 29. R. Sabine, The history and progress of the electric telegraph, London, 1869. 30. A. Neuburger, Op. cit. 31. G. Hubbard, Cooke and Wheatstone and the invention of the electric telegraph, London, Routledge & Kegan Paul, 1965. 32. A. Marland, Early electrical communication, London, AbelardSchumann, 1964. 33. J. J. Fahie, Op. Cit. , , 34. A. Guerout, 'L'Historique de la Telegraphie Electrique,' La Lumiere Electrique, 1883 (series of articles). 35. Gauss & Weber, Resultate aus den Beobachtungen des Magnetischen Vereins im Jahre 1837, G "1838, pp. 14—15,. 36. J. Hamel, 'Die Entstehung der galvanischen und Electromagnetischen Telegraphie,' p. 300. 37. Physikalisches Worterbuch (Gehler), Vol. IX (1838), p. 112. 38. A. Guerout, Op. cit. (Troisieme Article), pp. 335—6. 39. A. Guerout, Op. cit., pp. 337—8. 40. E. Feyerabend, Der Telegraph von Gauss und Weber im Werden der Electrischen Telegraphie. Berlin, 1933, p. 158. 41. A. Guerout, Op. cit., p. 338.

T h e

S t r a n g e

C a s e

o f

A l u m i n i u m

MARIE BOAS HALL It is customary to imagine that the chief problem in the development of the chemical industry was the application of scientific discovery to large-scale production. The classic case is the expansion of the chemical industry in the service of the newly revolutionized textile manufacture, where eighteenth century science provided the chemical knowledge which nineteenth century industrial ingenuity turned into the alkali and bleach industries. Here industry (and society) created a demand, and chemically trained and inventive men like Muspratt and Tennant produced the materials required. Or, in the twentieth century, there is the war-time demand for nitrogen, or rubber, and successful processes for nitrogen fixation (Haber) or synthetic rubber emerge to rescue the economies of the belligerents and to survive into peace-time conditions. But though notable examples of this exist, a very different situation was even more common, in which production preceded demand, and difficulties were encountered in creating such a demand. To a certain extent the chemical industry always had the problem of creating a demand, for 'synthetic' materials always seemed inferior to natural ones. Eighteenth century experience of the use of chemicals in bleaching (e.g. lime and dilute sulphuric acid) showed that cloth was thereby weakened, even more severely than by exposure to the atmosphere for several months. Leblanc 'black ash' alkali was not as strong or pure as natural barilla or kelp ash, and had t o be 'sold' t o the textile producer or soap maker by persuasion and cheapening. Artificial dyes did not always seem as good as the organic dyes they replaced, and the nineteenth century experience of celluloid, like the more recent experience of pvc, have shown t h a t plastics cannot be crudely introduced without care and preparation. Even rubber found its true market somewhat slowly, although there the chief problem was technical, as methods of processing required complex development. Strangest and most complex of all is the history of the commercial production of aluminium, third most abundant of the elements, yet one of the last metals to be widely utilized. For although aluminium objects were t o be seen in t h e Paris Exhibition of 1855, and although aluminium was then (and later) hailed as the metal of the future, its widespread utilization was delayed for over fifty years by a complex variety of factors, of which price was probably the least important. In recent editions of

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the Encyclopedia Britannica it could be denominated one 'of the common metals', yet as late as 1910 it was still not certainly established in commerce. The chemical problems associated with the production of aluminium have inevitably had something to do with this. Although the chemical history is simple, it is perhaps not really very well known, and is worth recording here. Aluminium salts have a tremendously long history of commercial exploitation, and the late Charles Singer called the production of alum (a naturally occurring double salt of potassium and aluminium sulphate, or, sometimes ammonium and aluminium sulphate) 'the oldest chemical industry', for alum was widely used as a mordant in dyeing from very ancient times. 1 Even older, strictly speaking, is the use of aluminium in pottery — for clay is mainly aluminium silicate. The oxide, alumina, occurs in many exploitable forms, including gems (ruby, topaz, sapphire) and abrasives (corundum or emery). Yet the metal was not prepared until the nineteenth century, for the oxide cannot be smelted in the ordinary way, since the aluminium and oxygen are too tightly bound. Humphry Davy tried to electrolyze alumina as he had other 'earths' and may have isolated some very impure samples of what he variously called 'alumum' or 'aluminum'. 2 In 1825 Oersted mixed a potassium-mercury amalgam and anhydrous aluminium chloride; on distillation a small quantity of impure material was obtained. Two years later Friedrich Wohler tried the action of more or less pure potassium upon anhydrous aluminium chloride, obtaining some few traces of grey powder. Not until 1845 did he succeed in obtaining a few globules of grey metal, and this was by no means pure aluminium. The first to obtain true, reasonably pure, metallic aluminium was H. St. Claire Deville, Professor of Chemistry at the Ecole Normale in Paris, who was engaged in fundamental research into metallic oxides. 3 Trying to prepare AlO, he first tried to prepare the metal in powdery form in order to combine it with aluminium chloride (A1C13) to give A1C12, from which he might hope to get AlO. But his reaction took an unexpected turn: he duly prepared aluminium metal, as he thought, by reduction of aluminium chloride by potassium, and then passed over it a vapour of more aluminium chloride. The result was not the oxide, but a mass of salt (actually an aluminium-potassium double salt, Al 2 Cl6 2KC1) in which were small globules of a grey metal. This proved to be ductile, malleable, of low density, not readily oxidized on melting, resistant to nitric acid, although readily soluble in hydrochloric acid and potassium hydroxide. Deville reported this discovery to the Academie des Sciences on 6 February 1854, describing this experiment as of importance both for the light it shed on the chemical properties of aluminium, and for the possibility it offered of preparing the metal in a pure

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state. 4 He declared his intention of trying to develop a commercially viable process. The imagination of the Academie's members was caught by this, and 2,000 francs were allotted to assist Deville in his research. (Although Deville's work was clearly original, and it is probable that he did not know of even Wohler's work, yet a claim for priority was entered by C. B. A. Chenot, an engineer who in 1847 had prepared a metallic alloy of aluminium; although the method was published by him in 1849, when he advocated the commercial importance of this discovery, he seems to have proceeded no further, and in any case was not interested in the pure metal.) 5 Now the striking fact in all this is the way in which the idea of being able to prepare aluminium metal on a commercial scale captured the imagination of French scientists. There is no very obvious reason, yet the fact remains that it was so. Not only Deville, but the sober members of the Academie saw in the new metal exciting possibilities, even though they had no very precise idea of what these possibilities were. And this remains a central fact of the history of the development of aluminium: in spite of technical difficulties and disappointments it was a metal in which many people had faith and to whose technical production and exploitation they were prepared to devote their lives and fortunes, hoping to awaken in others the enthusiasm they so clearly felt themselves. For aluminium was a metal which fascinated people, and one which they felt rather than knew to be of future use, as appears over and over again for the next fifty years and more. Deville's researches were directed towards avoiding the use of potassium, which was expensive and dangerous, besides not giving a very good yield. His first efforts involved the electrolytic decomposition of aluminium chloride; on 20 March 1854 he was able to send to the Academie des Sciences a leaf of the metal produced in this way, having had the assistance of a number of distinguished chemists, notably Thenard, who had been impressed by Deville's first report to the Academie. In May he sent Liebig a five or six gram lump, while the method was publicly explained in lectures at both the Sorbonne (by Balard) and the Ecole Poly technique (by Fremy). 6 But this was still a small scale operation, too expensive in terms of the batteries required to be commercially feasible. Consequently Deville returned to purely chemical methods, but varied his approach by using metallic sodium. This, incidentally, led him to investigate the production of sodium, most effectively. He used the method which was to be developed after 1857 at Nanterre on a large scale, namely the reduction of sodium carbonate (the soda ash of commerce) with carbon and chalk. But his chief interest continued to be the production of aluminium. He produced a fair amount by the electrolytic

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method; after Bunsen had independently discovered this method Deville asserted his claim to priority, and patriotically struck a medal which he presented to Napoleon III. The Emperor, noting its lightness, and dreaming of glory for the French armies, thought aluminium might provide light-weight but strong helmets and armour for his cuirassiers. He consequently offered to finance Deville's efforts, and by the beginning of 1855 Deville was able to undertake large-scale experiments, chiefly at a chemical works at Javel (centre of the bleach trade), with two young assistants, Charles and Alexandre Tissier.7 On 18 June 1855, Deville presented to the Academie des Sciences several large bars of the new metal, which struck everyone as very beautiful, and Deville paid tribute to the Emperor's generosity in making it possible for him to undertake four months of research 'without the preoccupation of expense'. He somewhat naively claimed, 'I hope to have placed the aluminium industry on a firm basis.' 8 Some of these bars were displayed in the form of ingots in the Palais de l'lndustrie at the Paris Exposition of 1855; there were also manufactured objects: a rattle for the Prince Imperial, made at the command of the Ministre d'Etat, and various bibelots and jewels. Much interest was aroused in the new light, bright metal, advertised as 'silver from clay' and it seemed to many that all that was wanting was large scale production and a consequent lowering of the price to permit its widespread use — for imagination ran riot on potential uses for this light, strong, non-corroding metal. The immediate result of the success of the exhibition at the Paris Exposition in attracting public interest was an attempt to set up a company to undertake commercial production. In the summer of 1855 a manufacturer of Rouen, M. Chanu, with two others, founded a company to exploit the new methods, with the Tissier brothers in charge. There were, as the Tissiers confessed, difficulties in both production and utilization — the latter in large part stemming from the price, 1,000 francs per kilo (about £40 at the then rate of exchange). M. Chanu had obviously not anticipated the incomplete state of the industry, and the amount of capital required, and the works ceased operation in February 1856, the first of many aluminium works to close during the nineteenth century. The Tissiers succeeded in obtaining support from a William Martin who set them up in a works at Amfreville-la-mi-Voie (now a suburb of Rouen), where efforts were made to find a use for the metal successfully produced (at about 300 francs a kilo) from the reduction of cryolite by sodium; by 1859 they were producing about 960 kilos a year, but again the works soon closed for want of a market. 9 Meanwhile Deville had continued to work on the industrial problem. The original ingots were produced by what he called a 'procede detestable' — cumbersome, inefficient, dangerous, and

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self-defeating. 10 In this procedure, vaporized aluminium chloride was passed to a cylinder containing about seventy kilograms of red hot iron nails, to purify the starting material. (The iron absorbed all other chlorides and any hydrochloric acid, and converted any sulphur compounds into ferric sulphate.) When the purified vapour was passed through a long tube at 300° C, all the ferric chloride was deposited on the tube. The pure aluminium chloride was then allowed to pass into a cast iron cylinder containing three cast iron boats, each holding a pound of sodium metal. Heat was applied until the reaction began, after which it generated its own heat. The initial reaction gave aluminium and salt, but this combined with the excess aluminium chloride to give an aluminium-sodium double salt, which in turn with heat decomposed to the metal again. However, the reaction was so unsatisfactory that only 'globules' of aluminium, contaminated with aluminium chloride, were finally produced. Clearly some other method was required if aluminium was in fact to become a commercial metal. At the Paris suburb of Glaciere, in the chemical works of Rosseau Freres, the method chosen was to reduce aluminiumsodium chloride with sodium using cryolite as a flux. The cryolite had to be purified, first by hand, then with slaked lime to remove calcium fluoride; the alumina was then precipitated out with carbon dioxide. The double chloride was made from ammonia alum—(NH 4 )2S04A1 2 (S04)3 2 4 H 2 0 — which was calcined in iron pots at bright red heat, mixed with pitch and charcoal dust. Salt was then added, and into the hot mixture was passed chlorine gas, well dried over calcium chloride. Any gases produced were driven off by heat. (Hence the objections of the neighbours, which soon led to the removal of the works to Nanterre.) Here 300—500 kilograms of sodium were made on a continuous scale per month. The proportions used at first were 400 grams of aluminiumsodium chloride, 200 grams of salt, 200 grams of fluorspar (to assist in dissolving the alumina) and 75—80 grams of sodium, but soon a larger scale became possible, with 10 parts double-salt, 5 parts fluorspar and 2 parts sodium. In 1872 the cost of manufacturing a kilogram of aluminium was reckoned to be 69 francs and 25 centimes, and it was sold at 130 francs a kilogram. The break-down was as shown on p. 148.* l In the first year at Nanterre (1859) approximately 600 kg of aluminium were made from 2,000 kg of sodium and 10,000 kg of the aluminium-sodium chloride; by 1872 about 1,800 kg were annually being manufactured by Deville's process. In the same year 750 kg (1650 lbs) were manufactured in England, by Bell Brothers 1 2 of Newcastle-on-Tyne, who had begun manufacture in 1860. None was manufactured in the United States, and only a trickle imported. Two years later the English firm ceased work; as

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Cost per kilogram in 1872 Cost in francs Sodium: 3.44 kg at 11.32 francs/kg Aluminium-sodium chloride: 10.4 kg at 2.48 fr/kg Cryolite: 3.87 kg at 0.61 fr/kg Coal: 29.17 kg at .014 fr/kg

38.90 24.90 2.36 .41

Total cost of ingredients per kg Wages Overhead

66.57 1.80 .88 Total

69.25

a contemporary encyclopedia put it, 'Mr. J. Lothian Bell, of Newcastle-on-Tyne, manufactured aluminium on the large scale for several years, but has of late relinquished the undertaking on account of the limited market for the metal.' 1 3 It is ironical that in 1879 a German chemist (Clemens Winckler) could say, writing for an industrial audience in an article picked up by Scientific American, that while the international Paris Exhibition of 1855 had merely displayed this 'wonderful metal', and that of 1867 demonstrated its possibilities, 'we see at the Paris Exhibition of 1878 the maturity of the industry.' 14 This can only be regarded as yet another example of the incredible and wild optimism which aluminium had engendered in industrial chemists since Deville's first work in 1854, and which it was, unjustifiably as one might think, to continue to engender until optimism became truth. 1 5 In spite of all difficulties, the world-wide use of aluminium slowly increased: whereas only two pounds appear to have been imported into the United States in 1873, 250 pounds were imported in 1878, and about 500 pounds annually during the 1880s. x 6 In 1883 manufacture began in the United States on a small scale, by a German-American chemist of Philadelphia named William Frishmuth, after over fifteen years of experimentation, although, characteristically, in 1886 there was, apparently, no aluminium produced in the United States. In France, the annual production slowly rose from about 1,800 kilograms (about 4,000 lbs) in 1883 to 2,400 kilograms (over 5,000 lbs) in 1884. What was this small but appreciable production of 'silver from clay', as it was called in 1855, employed to make? It is difficult to determine, for written accounts seldom distinguished with precision between the potential and the actual. Certainly, after the rattle for the baby Prince Imperial, aluminium was used to provide some ornamental light-weight armour for the Emperor and his guard. A complete table service was made for Court use, which aroused great admiration because the knives, forks and spoons were so light in weight. In emulation some small number of sets (it

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seems impossible to determine exactly how many) were made to be sold in New York by the fashionable jewellery firm of Tiffanys. Jewellers seized upon aluminium as a novel and still fairly expensive metal, and jewels and 'objects' were made of it. Aluminium tags were used to compensate clock pendulums. A certain Loiseau made a sextant in Paris with an aluminium frame (before 1860), which encouraged a belief that the metal might be more widely used in making instruments for marine use, where the two properties of lightness and resistance to corrosion by salt seemed to make aluminium an effective material. But little seems to have been done in this line, although aluminium opera glasses were made in some quantity 1 7 (I myself inherited a pair, which may well have been made before 1880). The most astonishing use of aluminium was as a substitute for bronze: as early as 1859 a statue of Diana in the antique mode was cast as an outdoor ornament, in the belief that it would withstand the elements well; that this judgement was correct is amply demonstrated by the more famous statue (cast in 1893, but still in Deville-process aluminium) 18 of Eros in Piccadilly Circus, which has happily withstood nearly eighty years of modern urban pollution. But although plenty of possible applications were suggested by aluminium enthusiasts, very few articles of common use were being manufactured. Deville in 1859 had already seen aluminium used for coffee-pots and egg-cookers, replacing silver because of its resistance to corrosion, but little was done in this line before 1880. He saw a future in saucepans, perhaps in surgery and in marine engineering. 19 But he was saddened to find that his metal was not being adopted into industry as quickly as his enthusiasm wished. True, Deville was writing in 1859, only four years after the first public display of the new metal, but what he observed remained very much true for the next twenty-five years. He wrote 2 ° Les objets de luxe et d'ornamentation sont assez variables dans leur forme et dans leur nature, mais tout ce qui se rapport aux necessites de la vie et sert aux besoins de chaque jour ne se modifie au contraire qu'avec une extreme lenteur. J'ai tout espoir qu'un jour la place de l'aluminium se fera dans nos habitudes et dans nos besoins. And so it remained with the rather small supply of aluminium produced in its first quarter-century of industrial life. Production rose but slowly, even while enthusiasm remained high. One of the most curious features about the industrial history of aluminium metal, indeed, is the manner in which successive generations of industrial chemists sought to improve existing methods and produce aluminium on a larger and (therefore) cheaper scale, apparently convinced that all that stood in the way of aluminium's

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widespread acceptance was price. Thus English production, which had ceased when Bell closed his works in 1874, revived in 1882 when James Webster organized the Aluminium Crown Metal Company near Birmingham. 2 * It was based upon patents obtained by Webster for an improvement in the manufacture of alumina by which a salt containing 84 per cent of alumina was obtained, as compared with the 65 per cent obtained by the usual methods. This naturally considerably cheapened the alumina, especially as potassium sulphate, sulphur, and iron salts were recovered as usable by-products, and also improved the yield of metal, for the purity of the alumina used was a critical factor. The process consisted in calcining potash alum and treating it with weak hydrochloric acid; the resultant mass was mixed with charcoal powder and lampblack, and then heated in a current of steam and air. The result was ground, heated with water to dissolve the potassium sulphate and then washed and dried. The plant throve and produced enough aluminium to preclude importation from France. It is no wonder that it was Webster's company to which a young American, H. Y. Castner, turned after he had secured a patent in 1886 for the improved manufacture of sodium. Basically his invention consisted in converting a simple laboratory process — the reduction of caustic soda (NaOH) or soda ash ( N a 2 C 0 3 ) with carbon at high temperatures — to a large scale, commercially viable process. This involved the use of cast iron pots, and, more important, of coke (initially made from pitch) weighted with iron filings; the weight was necessary to ensure a thorough mixture of the reaction products. This method reduced the cost of sodium to one quarter or less of its previous price. Castner had always had the production of aluminium as his ultimate goal and, after convincing Webster and his associates of the worth of his process, he joined forces with them to form the Aluminium Company Ltd., incorporated in June 1887 to exploit the patents of Webster and Castner. It was in production at Oldbury, near Birmingham, within a year, with an annual capacity of 100,000 lbs of aluminium — probably twice the total amount of aluminium produced up to that date. 2 2 It was, not surprisingly, the largest aluminium plant in the world, a position it still retained in 1890, even though the Deville process, on which it relied, was on the eve of being totally superseded by the dramatically new process invented in 1886 by Charles H. Hall in the United States, and P. L. C. Heroult which, although the inventor was French, was first utilized in Switzerland. This was only natural, for Switzerland had already more hydroelectricity than other countries, with an immense potential, and the new process was dependent on cheap electricity first and foremost, and on chemical methods only secondarily. Both Heroult and Hall discovered how to electrolyse alumina, using

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molten cryolite as the electrolyte. The two processes differed slightly: Hall's was a purely electrolytic process in which alumina was suspended or dissolved in a bath of fused salts, whereas in Heroult's process the electrolysis is of molten alumina rendered fluid by the use of an electric arc, with a hard carbon anode and a layer of molten metal (copper or iron) as the cathode. Hence Heroult's process was most suitable for the manufacture of alloys, while Hall's was used for the pure metal. But now at last, some seventy years after Davy's unsuccessful attempts to isolate 'alumum', his process was found to be viable. The secret, such as it was, lay in the use of cryolite (it is worth recording that many attempts had been made to utilize this aluminium-rich material earlier) and, even more important, of pure alumina. Indeed, the new process would have been doomed to failure without the possibility of a large supply of purer alumina than that used in earlier processes. As for the cryolite, almost entirely derived from the Greenland deposits, not a vast quantity was required since the electrolyte was re-usable. The real crux was the availability of pure alumina. This was derived by a number of processes, of which the most important in Europe was the Bayer method for abstraction from bauxite, in which France in particular was so rich. The method, described by Dr. K. J. Bayer, its inventor, in Stahl und Eisen for February 1889 was in summary as follows: 2 3 Bauxite is fused with sodium carbonate or sulphate, and the solution obtained by washing, containing sodium aluminate, is not decomposed by carbonic acid as formerly, but by the addition of aluminium hydrate with constant stirring. The decomposition of the solution goes on until the quantity of alumina remaining in solution is to the sodium pentoxide as 1 to 6. This precipitation takes place in the cold, and the pulverulent [powdery] aluminium oxide separated out is easily soluble in acids. The alkaline solution remaining is concentrated by evaporation, taken up by ground bauxite, dried, calcined, and melted, and thus goes through the process again. The use of this caustic soda solution containing alumina is thus much more profitable than using soda, because by using the latter only 75% of the bauxite used is utilized, whereas by the former all the alumina dissolved by the solution is obtained again. This process lends itself to continuous production, and, after the precipitate has been washed, dried and calcined (to drive off combined water) produces a coarse grained but freely flowing powder, very easy to handle, and of the required purity for the next stage. This process was devised for ores containing only the monohydrate. When the trihydrate is present, an extra step is required. After the first treatment with cold caustic solution, a

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second extraction is required at about 168° C temperature, and at a pressure of 12 atmospheres. Crystallization, usually by seeding with pure alumina, then follows, taking several days for completion. With the new methods, prices dropped dramatically, and the potential centres of production were entirely altered. The price in England in 1887 was sixteen shillings a pound; two years later the electrolytic process had reduced the cost to four shillings a pound. 2 4 In France, according to Minet (himself the inventor of several new processes) the electrolytic method had cheapened aluminium from 99 francs per kilo to 5 francs per kilo (electricity was cheaper in France than in England). 25 In the United States costs dropped from between ten and twelve dollars per pound to about two. 2 6 A rash of books appeared in praise of the new metal, with detailed accounts of its chemistry, its history, and its potential utility. The most notable thing here is that its utility remained potential. In spite of immense cheapening of the metal, and immense increase in potential production, actual production rose rather slowly. By 1900 in England only about 5,000 tons per annum were being produced; the world production was only about twice that figure. 27 I have already remarked that the statue of Eros in Piccadilly Circus was made of Deville-process aluminium — no doubt stocks were relatively large. It is very noticeable that whereas there was a keen interest in the potentialities of the metal, and detailed textbooks like those of Richards and Minet went rapidly into second editions, the uses they cite for aluminium are still more nearly potential than actual, and actual uses cited are generally of a 'once o f f nature. Thus Richards could happily cite such past uses as for table services, lamp relectors, decorations, mountings for optical equipment, works of art, inlay on furniture, military lace — all uses in which its resemblance to silver, slightly cheaper but still high price, lack of tarnishing, and lightness in weight commended it as a substitute for silver. Still in the future were its potential uses in surgery (for tracheotomies and suture wire, and in surgical appliances) and for dentistry (it was suggested for dental plates, being light of weight and capable of alloying in such a way as to avoid unpleasant electrolytic action). It had been, he remarked, suggested for use in torpedo-boat engines, where light weight was an advantage; and if ever heavier-than-air flight were to become a reality, he thought aluminium would clearly suggest itself for both engines and structure. It had been suggested for use in coinage, but its lack of intrinsic value was against this. (In fact, in 1856 a book had appeared by H. M. Ward [Henry Montucci] entitled VAluminium considere comme matiere monetaire (Paris, 1856) in which the author had suggested its use for small coins only, where its intrinsic value was irrelevant, and where its lightness, as

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compared with the usual copper coins, would be of great advantage.) Finally he remarked 'When aluminium becomes cheaper it will without doubt be used for culinary articles of many kinds, replacing copper and tin vessels.' Now it is possible that this remark survived unchanged from the first edition of 1886, four years before, but evidently any very dramatic fall in the price of the metal had, as yet, met with no great rush to manufacture aluminium articles. 28 And the situation was not very different in 1896, when Adolphe Minet wrote about potential uses, even though he insisted that the price was then only one-fifth of what it had been prior to the discovery of electrochemical methods. 2 9 Again, the best uses were rather special cases. The German army used aluminium for mess tins, to lighten the nineteenth-century infantryman's inordinately heavy pack, and Minet urged that the French army should quickly follow suit. He cited several very enterprising American firms: the Louis Refrigerator and Wooden Gutter Company was reported to manufacture a bicycle appropriately called 'Lu-mi-nium', and other firms there and elsewhere had used aluminium for the rims of bicycle wheels, for mud guards and for chain guards. The Griswold Manufacturing Company of Erie, Pennsylvania and the Wagner Manufacturing Company of Sidney, Ohio made tea kettles — presumably an example of the use of aluminium as a substitute for silver, which already had a long history. The Bangs Oil Cup Company, very appropriately, made an aluminium oil-can. And the John Holland Gold Pen Company of Cincinnati made an aluminium fountain pen case, and a comb. Metcalf and Ferguson of Pittsburgh were tooled up to manufacture aluminium goods —but so far were not in production. C. Sidney, Shepard and Company were making aluminium wire, and had just taken up cooking utensils. William Rochmer of New York made trunks; the Waverley Stamping Company utensils of aluminium plated with steel; George E. Maicks of New York artificial limbs. Elsewhere, Reginald Brougham of London made an aluminium ball for lacrosse, and Reymond and Gottlob made spectacle cases. There were plans for aluminium horseshoes, aluminium was in use in naval construction, for brush handles, and for lithographic plates, and should certainly be used in aeroplanes, now that Maxim and Langley had demonstrated the possibilities of heavier-than-air flight. Minet himself had manufactured visiting cards to sell at five francs a hundred since 1892. He suggested that little aluminium pieces might be used in school as merit marks, and he sagely pointed out, 'tous ces bon points, au bout de plusieurs annees, representeraient encore une petite somme qu'aucun ecolier ne dedaignerait'. There were enumerable potential military uses — for cooking pots, mess tins, instruments — and finally, as bullets for riot control; these would only carry a short

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distance, thereby saving innocent bystanders from accidental injury, and would inflict minor woulds only, but would be effective enough to provide control. Evidently even in 1896 aluminium was a metal which was far from having gained universal acceptance. In 1910 the Encyclopedia Britannica (11th edition) was still not quite sure about it. Aluminium was extensively used for purifying other metals; the Admiralty had used it in the British Navy (presumably for the currently fashionable torpedo-boats), 'European' armies used it for soldiers' equipment; it had some use in domestic utensils and lithography; and, because it was now cheaper than copper, it was used for non-insulated wire. Not until the 13th edition (1926) did the Encyclopedia Britannica show any enthusiasm, although even then pure aluminium was used only for car bodies, cooking utensils and electrical wire; for castings were nearly always of a zinc or copper or zinc-copper alloy, in which capacity it entered into the automobile business. By this time too duralumin (95 per cent aluminium, 3V2 per cent copper, 1V& per cent magnesium and manganese) had been developed for use in aeroplane construction. Aluminium had at last become a useful metal, but it took more than half a century to become so. Why was there this delay? It is of course impossible to be didactic, but certain answers do present themselves. One obvious answer lies in the technical difficulties. Looking back, it is clear that really only quite small quantities of aluminium were in fact ever available at any given time, until late in its history, and consequently production on a largish scale, like that by Bell of Newcastle, found no immediate market. And after the novelty had worn off, aluminium did not have enough intrinsic beauty to replace silver, in spite of its resistance to tarnishing, especially in an age when servants were available. True, aluminium did not require polishing — but it did not have the high shine imparted to silver, and there is no indication that methods sometimes used now to give a reasonably strong shine were in fact practiced then. Further, Deville aluminium was by no means as pure as electrolytic aluminium, and it was some time before it was recognized that defects found in older samples were not necessarily to be expected in samples made by the newer methods. Another difficulty was that aluminium was not as resistant to attack by various agents as had been at first thought. Thus Mendeleeff commented, after the introduction of electrolytic aluminium, 31 Experiments on a large scale have proved that metallic aluminium, although possessed of great lightness, strength and durability, is not so generally suitable for technical purposes as was at first thought. And he goes on to point out that although early workers were

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quite correct in believing that it was resistant to acids (in fact, acids react to give a coating of alumina, not further attacked), it was highly susceptible to attack by alkalies, alkaline substances, and moist salt, while the effect of contact with mercury was rapid and disastrous oxidation. Hence 'In a pure state aluminium is only employed for such objects as require the hardness of metals with comparative lightness, such as telescopes and various physical apparatus and small articles.' 3 2 On the other hand, as Mendeleeff also pointed out, a trace of aluminium in bronze or steel rendered the alloy decidedly superior, and in fact a great deal of aluminium made by the electrolytic process was employed in such alloys. The resistance to acids was, of course, what made it suitable for domestic use, and the production of cooking utensils increased rapidly after the price fell and (an important point) after increased production encouraged the development of better methods of working. For pure aluminium had proved by no means easy to cast and work, unlike aluminium bronze, and there is no doubt that this was a factor in the slow introduction of aluminium into common use. In the end, however, one must conclude by saying that the production of aluminium preceded its demand, that it was possible in the nineteenth century to supply far more of the metal than was required. Only as it became cheap and relatively available did it enter into alloys, when its utility was most clearly seen. Only a generation of metallurgists, metal founders, and producers which was familiar with the idea of aluminium could begin to think of overcoming the inherent difficulties in its working to utilize its immense potentialities. And indeed more than one generation was required. For the first stage involved the employment of heavy castings — whether in cookery or in the automobile industry, and this lasted forty to fifty years. Only after the Second World War did aluminium, often in the form of alloys, fulfill the promise it seemed to offer to its original proponents of nearly a century earlier, of ideally combining lightness with resistance to corrosion, to provide the host of domestic articles, from chairs and window frames to crutches, with which we are all now familiar. One can only ruefully echo Deville, 'Rien n'est plus difficile que de faire admettre dans les usages de la vie et de faire entrer dans les habitudes des hommes une matiere nouvelle, quelle que puisse etre son utilite.' 3 3 Notes 1. Charles Singer, The earliest chemical industry (London, 1948). 2. Third Bakerian Lecture; see The collected works of Sir Humphry Davy, Bart., ed. John Davy (London, 1840), V, 116. 3. The early history of aluminium was briefly summarized by Deville in De Valuminium (Paris, 1859), and more fully by Joseph W. Richards, Aluminium, 2nd ed. (London, 1890), pp. 17—19. The definitive modern work is L. Ferrand, Histoire de la science et des techniques de Valuminium et

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ses developpements industriels: I Le passe (to 1945); II Le present (n.p. 1960). 4. This report, which Deville referred to as 'mon premier Memoire publie au commencement de 1855', was published in Annales de Chimie et de Physique, XLIII, 1855, p. 5. 5. Claude-Bernard-Adrien Chenot (1803—55), after graduating from the Ecole des Mines became 'maftre de forges,' first at Chatillon-sur-Seine, and then at a number of other establishments. He experimented widely on new technological processes. He was the discoverer of a number of minor new metallurgical materials, and a fairly prolific author. However, the majority of his books are judged to be the work of a crackpot, according to his biographer in the Dictionaire de Biographie Francaise. 6. See Richards, pp. 20—21. 7. They were later to annoy Deville by patenting the methods of sodium production developed under his aegis, and by the publication of their Recherches sur aluminium (Paris, 1858), a slight and inaccurate account. For the best historical summary, see Richards, chapter I, upon which much of the following account is based, supplemented by Deville's own description. 8. Richards, p. 22, cited from a paper read to the Academie des Sciences in June 1855. 9. Tissier freres, Recherches sur aluminium; and Richards, pp. 23—4. 10. De I'aluminium, p. 88. Here Deville gives a detailed account of the processes used and their difficulties. 11. Figures assembled from statistics in Richards, passim. 12. See Richards, p. 27, and Carl Von Buch, Aluminium and its alloys (London, 1883), pp. 7—8. 13. Chemistry, theoretical, practical, and analytical, as applied to the arts and manufactures By Writers of Eminence. I, 178—80. 14. Quoted in Richard, p. 27 from Scientific American Supplement for 6 September 1879; the original article was published in Industrie Blatter, 1879. 15. In fact, A. Wurtz in his Dictionnaire de chimie pure et appliquee of 1869 did not feel it worth his while to mention any uses for the metal, although he was aware of the existence of Deville's factories. 16. Richards, p. 45. 17. See especially Deville, ch. VIII, pp. 140—53, Richards, pp. 367—76, and Carl Von Buch, Aluminium and its alloys (London, 1883), p. 9. 18. Leslie Atchison, A history of metals (London, 1960), II, 541—4. 19. Pp. 145-9. 20. P. 140. 21. See Von Buch, pp. 11—12 and Richards, p. 30. 22. Richards, pp. 31—2, 174—7. In 1895 the Castner-Kellner Alkali Company took over Castner's inventions, getting into full production in 1897; see The Castner-Kellner Alkali Company, Fifty years of progress, 1895—1945. 23. P. 112, summarized in translation by Richards, pp. 114—15. 24. Encyclopaedia Britannica, 11th ed. s.v. * Aluminium,' II, 769. 25. Adolphe Minet, VAluminium. 2e partie, p. 33 (Paris, 1896). The first volume (LAluminium. Fabrication. Emplois) has a small aluminium plate affixed to the front board of the binding. Minet was a great enthusiast. 26. Richards, p. 44. 27. According to the Larousse Encyclopedique. By 1928 the world production was about 200,000 metric tons; c. 80,000 produced in the United States, and c. 16,000 each in England and France. (Larousse du XX siecle). In 1935 according to Colliers Encyclopedia, world production was down and the U.S. produced only 54,000 tons, Canada and France each producing a little over 20,000 tons each. English production was very small by comparison. In 1954 the U.S. produced c. 1,500,000 tons, France 130,000 tons and the U.K.

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35,000; world production was some 3,000,000 tons, with Canada and the U.S.S.R. both important producers. (Encyclopedia Britannica, 1961.) 28. Richards, pp. 367—376, esp. p. 369. 29. Minet, pp. 34—56. 30. Encyclopedia Britannica, 11th edition, s.v. * Aluminium.' The author was E. J. Ristori, a highly reputable metallurgist. 31. D. Mendeleeff, The principles of chemistry, 2nd English ed., from 6th Russian edition (London, 1897), II, 85. 32. P. 88. 33. P. 140. Cf. his conclusion (p. 175), ^'introduction d'un nouveau metal dans les habitudes de la vie est une operation d'une difficulte extreme.'

L e a d s

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S e v e n t e e n t h

T e c h n o l o g y

G. HOLLISTER-SHORT During the second half of the seventeenth century English craftsmen and mechanicians were rapidly acquiring a highly enviable reputation in Europe for the remarkable refinement and mechanical ingenuity of their manufactures. A French visitor t o London in 1685, commenting on the material adornments of living he had observed in use among the English, noted that dans les maisons nouvellement baties, j ' a i remarque une chose fort commode. Ce sont de grands chassis de verre avec des coulisses q u ' o n leve sans qu'il soit besoin de cocher pour les arreter. II y a un contrepoids qu'on ne voit point, aussi pesant que le chassis qui le contretient en quelque lieu q u ' o n le laisse, et sans craindre qu'il ne tombe sur la tete de ceux qui regarde par la fenetre, ce qui m'a paru fort commode et agreable. Les Anglais sont fort adroits: ils o n t des portes qui s'ouvrent des deux cotes, et se renfermer toutes seules sans passer jamais le lieu ou elles doivent se fermer. Vous connaissez la delicatesse de leurs clefs et serrures * The words commode and adroit p u t the emphasis very justly on precisely those qualities that were becoming conspicuous in English manufacturers. If one wished t o procure exquisite watches of great reliability that would also sound the hours then it was t o London t h a t one came. During the last quarter of the seventeenth century watch-makers such as Thomas Tompion and Daniel Quare raised English watchmaking to a pre-eminent position in Europe. In 1675 Tompion used a balance spring in a watch made for Charles II; in 1687 Quare first constructed a watch with a repeating mechanism. Nor were contemporary English observers slow to notice what was happening although it is reassuring to find them repeating more or less precisely the story of excellence in the areas marked o u t above by M. de Sainte-Marie. Edward Chamberlayne in 1704 wrote t h a t the English 'are thought to be wanting in industry excepting mechanicks wherein they are, of all nations, the greatest i m p r o v e r s . . . .There being few curiosities of art brought over from beyond sea b u t are here improved to a greater height. Here are the best clocks, watches, locks, barometers, thermometers . . . watches so curious . . . ordinarily of £50 or £60 a watch, and yet these prove profitable merchandise when we send

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them into foreign countries, so valuable and inimitable is the work . . .'. 2 Although work in steel and iron of all kinds and the making of scientific instruments were in the front rank of English manufactures other sectors were not far behind. Moses Stringer could write in 1699 of 'the extraordinary late improvement and nicety in all sorts of brass wares, great and small, in and about London, Birmingham and divers other parts of England', 3 and Charles Davenant, writing only slightly later, while admitting French technical superiority, drew attention to the great improvement in English silk and paper manufacture so that 'there will not be after the war [of the Spanish succession] the same want of or call for French importations as formerly'. 4 It would be easy, but profoundly mistaken, to assume that such improvement and zeal to improve were characteristic of English industry as a whole, for outside the vastly important field for a trading nation of what would now be called 'consumer durables' the picture is utterly different. Indeed, so far as such things are susceptible of being expressed quantitatively, England was at the end of the seventeenth century somewhere between one hundred and one hundred and fifty years behind the progressive areas of Europe in much of the mechanical equipment serving such basic industries as mining and metallurgy. This might appear an astonishing state of affairs given English precocity in the use of mineral fuel in a wide range of operations. Could this and the equally well-marked lead that was to appear in the exploitation of steam power in the eighteenth century co-exist with such a degree of backwardness? It is no difficult matter, as will shortly appear, to show that this backwardness existed, was inveterate, and showed little sign of yielding even at the end of the seventeenth century. One might take first Robert Plot's account of a journey, undertaken about 1680, to Ecton Hill copper mine. 'All was out of order before I came thither', he says, 'and the famous wooden bellows that had no leather about them carried away to Snelston in Derbyshire whither I went to see them'. Here however he found them buried under a pile of timbers in an outhouse and almost impossible to get at. It was only by dint of much dusty poking and note-taking that he was eventually able to carry away an idea of them. Later, with the help of a model kept in the repository of the Royal Society, he was able to prepare the drawing of them printed in his work. 5 Here was a 'curiosity of art' that had not been copied, let alone improved, and yet Ecton Hill, worked by Germans, had been in effect a centre of advanced technology (in English terms) in a number of respects, notably gun-powder blasting. It might very well have served as a model for English entrepreneurs had any such been seeking one. But was Plot speaking only of Staffordshire? It seems difficult to believe after all that the economy of using wood in place of expensive and

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quickly worn out leather would fail to commend itself to English industrialists. It was precisely this spirit of rationality as David Landes has expressed it, this readiness to adopt new methods which lay at the root of English success in creating a new kind of industrial society, in a word, a widely diffused acculturation to change. Despite this one has Joachim Becher's statement that leatherless bellows although well known in Germany in mines and smelters, and even available there in double-acting form, were still quite unknown in England: Ich habe in Teutschland bey den Bergwercken und Schmeltz-Hutten holzerne Blassbalge gesehen/ welche gar ohn alles Leder starck blasen/. . . man kan auch solcher gestalt doppelte Blassbalge machen. Diese invention ist artlich und nutzlich/und in Engelland noch nie bekannt/ . . .'.6 The advantages offered by wooden bellows were very considerable. According to Pierre Grignon writing in 1775 such bellows lasted between sixty-five and eighty years and besides being 60 per cent cheaper to set up cost only 20 per cent of the upkeep required for those made of leather. Nor was the technique a new one in the 1680s. It is reasonably safe to assume that wooden bellows were coming into general use in Germany towards the end of the sixteenth century. Grignon believed that they had been adopted in the eastern parts of France such as Franche-Comte rather before 1700. 7 Nowhere however was English backwardness more marked than in mine-pumping, perhaps the one area where one would most expect to find a spirit keen for improvement and alert to foreign methods. 8 More importantly most of the English mines that were of any economic significance were coal mines. Although mines of metals could and did support rich and varied societies in large regions of Europe which, without such mines, would have remained primeval forest the English situation was quite different in kind. Coal-mining likewise sustained large and prosperous communities in areas such as the Lothians, Durham and Tyneside but beyond this the English economy as a whole was in large degree underpinned by the industry and dependent on it. The importance of coal in the development of the economy during the period 1560—1660 was growing at an unprecedented rate as Nef has shown and the conjunction of growing demand and insufficient pumping equipment was, to say the least, unfortunate. 9 By the late seventeenth century consumption of coal was running at a rate of about two million tons per annum and the point had long been passed at which it would have been possible, in default of supplies of coal, to have made good such quantities in terms of their timber and charcoal equivalent. Already in 1700 it would have required the setting aside of something like five million acres (or 8,000 square miles) of good quality land for forest to have supplied an equivalent amount of fuel. 1 °

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I have insisted on these figures and on the calculations in the footnote which accompanies them in order to show how uniquely England depended on mining. No such calculations would be needed for Brunswick, Saxony or Hungary or indeed for any of the regions of intensive mining activity in Europe although an exception might conceivably be made in the case of Liege. Only England, in other words, had departed substantially from the self-sustaining rhythms of an eotechnic economy and was therefore unique in having shifted its industrial base to mining. Nor was it, as noted above, a position from which the country could retire in the event of the failure of its mining industry to sustain production. Efficient mine drainage was therefore a matter of national rather than regional significance. If this was the case, and there seeems no reason to doubt it, it is scarcely credible, in view of the difficulties the industry was facing, that no sustained effort was made to discover what methods were in use in Europe or to draft in foreign experts. 1 1 All available evidence relating to actual practice in the pits suggests that nothing was done. There was indeed one initiative, that of the Royal Society in 1673, when it was learnt that Sir Joseph Williamson was to travel to Aachen. Henry Oldenburg was directed to draft enquiries to which it was hoped Sir Joseph would promote replies when he left England. 1 2 Among them was No. 4 in case he should visit Liege and have the opportunity to greet Canon Sluse, Oldenburg's correspondent there. He was to enquire about the depth of the pits there and the engines used to drain them. Sluse's reply, dated 8 February 1674 (NS) was read to the members on 19 February. He pointed out gently that the soles of the shafts in the coalfields (so he had been informed) had been sunk to one hundred fathoms and more 'ad centum et ultra orgyiarum profunditatem deprimi', something perhaps at which they might well marvel, 'quod fortasse mirum tibi videatur', since they seemed to think that depths of 150 ells were considerable. As to the query by what arts the pits were freed from water he was frankly either uninformed or careless. He referred them to book six of Agricola and to the buckets and pumps displayed there 'vel situlis hauriunt, vel antliis, quales apud Agricolam in libris de Re Metall. videri licet'. 1 3 What seems extraordinary is that nobody should have thought of approaching either Walter Pope or Edward Browne both of whom, unlike Rene de Sluse, had actually descended into mines and had seen at first hand the machines in use. Both for instance had had papers printed in the Philosophical Transactions on Idrija where the deepest sump was one hundred and forty fathoms (130 lachtern) below adit. Browne, of course, had in addition first hand knowledge of Liege itself. 14 Deep mining, that is to say work carried on at more than about one hundred feet below adit, seems rarely to have been

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attempted in England, and what the German chronicler of the Harz mines, Hardanus Hake, wrote in 1583 that 'The old timers could not drive their soles deeper than eleven lachter (about 70 feet) below the headstock of the winding gear in the adit', 'der Alte Mann unter dem Stollen von der Hengebank bis auf die Sohle nicht tiefer als 11 Lachter gewesen' seems to have been largely true still of late seventeenth century English mining practice. 15 Even in the eighteenth century English mines were still very shallow by Continental standards. As late as 1769 the anonymous author of A Treatise upon Coal Mines cites no pit deeper than 350 feet while the average of all those listed is only a little over 200. * 6 In 1744 Desaguliers could talk of fifty yards as 'a great depth' in his discussion of mine pumping and its problems. At Liege, as has been noted, 600 feet and more was the vertical depth of some of the shafts in 1674 and even when one has allowed for the hilly nature of the terrain about Liege which permitted the most effective and extensive use of adits, the discrepancy requires some explanation. What was the secret of the Liegeois? The answer is really quite simple. By the 1570s the exhaustion of easily won upper coal and the consequent deepening of shafts had led predictably to flooded workings. The critical stage had been reached where deep working below adit could only be pursued if adequate pumping equipment were available. It was not. The situation was so bad that one of the first acts of Prince-Bishop Ernst von Bayern (1581—1612) was to draw up in December 1581 and have publicly proclaimed to the sound of trumpets on 20th January 1582 from the 'perron' — a sort of public platform — in the market place of Liege what came to be known as the Edit de Conquete. Anyone who could unwater the drowned out pits would be allowed to reap his reward and work them unmolested. 1 7 Fortunately for Liege it lay within the German language area, and just as itinerant engineers had brought stangenkunst technology to Saxony in the 1550s and to the Harz in the 1560s, so it seems probable that in the later 1580s or 1590s Liege got its first machines, although what seems to have been an attempt in 1586 to set up pumping engines worked by adit rods (streckengestdnge) seems not to have been successful.* By the *A brief account of the stangenkunst may be found in R. Multhauf, 'Mine Pumping in Agricola's time & later', Paper 7, Contributions from the Museum of History and Technology, Smithsonian Institution, Washington, 1959. The rod-engine (stangenkunst) consisted in its simplest form of reciprocating vertical rods working tiers of pumps placed in the shaft. When the power source lay some distance from the shaft reciprocating horizontal field-rods (feld-gestange) or adit-rods (streckengestdnge) transmitted power to the vertical rods in the shaft. The vertical type may be dated to the 1540s, the horizontal to the 1580s, or possibly somewhat earlier. The latter had, at first, only single rods but by c. 1600 these were being replaced by a much more reliable double type.

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beginning of the seventeenth century, however, the problem had certainly been solved. 1 8 There is no question but that, given a sufficiency of moving water, the rod engine provided the definitive solution to problems of flooding. 1 9 This technology in its mature form probably never reached England or at least was only ever an exotic, a fact which undoubtedly contributed materially to the success of the new and extremely expensive steam engine technology after 1712. But before that time the crisis in English mining, which virtually every historian of the early industrial revolution period in England has accepted as having been serious, was real enough. The specific reasons for the crisis have never been properly examined. It is certain, however, that if English mine engineers were, before 1712, attempting to address the problem of deep mining with the pumping techniques of 1500 of even 1550, they were bound to encounter insuperable problems. Hake's description applied. As against this the general assumption, most clearly formulated by Nef, is that England was in these matters not a world apart but one fully cognisant of Continental techniques. European machines could not solve the English crisis, however, because English mines were deeper than those on the Continent and therefore posed problems of a different order of magnitude. 2 ° The exact opposite of this is nearer the truth. England was a world apart and in making the ciritical transition to deep mining found in Newcomen's engine its own peculiar solution to the problems posed by that transition. In a sense the pattern of palaeotechnic development forced on England in the sixteenth century by reason of its lack of forests and the absence of critical climatic conditions (winter precipitation in the form of snow and a spring melt) necessary for float/flume operations* was here strongly reinforced by a simple failure of the transmission of technical ideas. 2 * England already had a distinctive fuel technology and now it developed in addition a distinct form of prime mover. The reasons why stangenkunst technology never made its way in England, so far as they can be determined, are not without interest: these however I shall reserve for the final section of this essay. The first task is to establish that it had in fact failed to travel or at least that if it had travelled it had signally failed to establish itself. *In order to exploit the forest reserves of mountain regions inaccessible to wheeled transport intricate networks of floatways (holztrifty holzschwemme) were devised so as to discharge their loads of floating wood at the smelters, salt-pans and so forth which had to be supplied with fuel. Such flumes, empty during the winter, filled rapidly during the spring thaw and it was then that stacks of already cut billets (triftholz, bitches perdus) would be tossed in, to be swiftly borne away on the current. At the far end of their run they would pile up against a great rake (rechen) of strong timber placed slantwise across the torrent.

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The state of the art of mine pumping as it stood in England in 1659—1660 is fortunately clearly fixed in one of the best books ever to appear in English on the subject. This was R. D'Acres' The Art of Water Drawing.22 It is not, unlike Poda's and Delius' excellent text books of the later eighteenth century, a manual of standard practice but a critical appraisal of technology in an extraordinarily unsettled state: that his critique should reveal this is of course illuminating in itself. 'D'Acres'' identity has not been definitely established but if, as Rhys Jenkins supposed, the name was a pseudonym for Robert Thornton (1618—1679) of Brockhall Hall near Daventry, situated at no great distance from the Warwickshire coalfield, then D'Acres would indeed have been well placed, as he himself says, 'to have known some experiments and those of no small expence, that have been lately tryed . . .'. His preface clearly implies considerable familiarity with the actual conduct of mining, his avowed object being, as he says, to use it to expose 'the delusions and fallacies of water-machines'. Thus he would set 'sea marks to keep those that come after from ship-wrack', a work of charity so obvious that he wonders it should not have been attempted before. To set up as an anti-projector and bubble-buster would seem an unlikely, not to say ludicrous, undertaking for someone not familiar with practice and every page of his work makes it clear that he had had, as he would have said, both 'practice and experience . . . a firm and solid reason'. Descriptions of the ordinarily used machines were omitted as superfluous for in D'Acres' view there was no better way than to go and look at them if one wished to learn how they worked. His purpose is, on the contrary, to mark out the area of uncertainty — the not usual and common — where a candid assessment of the performance of new machines and devices and of their scope for improvement might at once help to concentrate future effort on the most eligible machines and limit the damage able to be done to unknowing men by imposters. Even the simplest sort of stangenkunst, without field rods, working directly over the shaft is nowhere described. 23 Did it, therefore, not exist? The argument from silence would certainly be stronger if one could pass beyond it somewhat and point to what appeared to be a situation resulting directly from the inferred absence. D'Acres' work does in fact supply liberal quantities of evidence of this sort. So: if the stangenkunst were really unknown to the English then the problem that it had solved elsewhere would still be urgent and pressing in England. It is in this light, I think, that one should view those methods that were in use to effect long distance transmissions of power in the vertical sense. The first system described by D'Acres involved the use of long masts or baulks of timber, their ends set in 'a stop of iron or brasse full of oyl', each deriving

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its motion through right-angled gear wheels at its top and delivering its torque through another set at its lower end. These were not slight affairs either for where a baulk needed to be longer than sixty feet it would be reinforced with collars of brass (presumably to secure the scarfing joints) while anti-friction rollers ensured that the assembly was kept moving in a straight line, 'roulers of iron, thereby to be stayed with the least hindrance'. But the longer they were made the thicker they had to be 'lest in their shoggings they give a trembling palsie motion . . . ' 2 4 . Arrangements such as these were however out of the question where the shaft was oblique and here 'of late use' were 'certain loose chains, which work in grove wheels, after the manner of jack-spit chains . . .'. They worked well for a short space but were attended with very considerable inconveniences. Both the vertical axle method and the chain method were doing work, and that not to anything like the depth, or with anything like the ease, that would in Germany have been performed by the master rods of a stangenkunst. Such rods were as easily adapted to kinks in the shaft as horizontal field rods were to above-ground changes in level or direction. It is scarcely credible that such unsatisfactory methods as D'Acres describes would have been persisted with if rod-engine techniques had been available. D'Acres having examined the problem of transmission where prime movers were far removed from the 'working tool' in the vertical sense, next turns to horizontal situations involving such long separations. In terms of stangenkunst technology, of course, this was familiar ground and runs of field-rods of a mile or more in length had been achieved in Germany some time before ever D'Acres was born, probably even as early as the 1590s. It is apparent from D'Acres' work that nothing of this was known in England although the picture is not one of total inactivity. Indeed, one has a curious feeling of deja-vu: that the situation D'Acres displays may be not unlike a repeat performance of the situation that had obtained in Germany a century earlier. There too engineers had doubtless cast about in search of the best system of horizontal transmission before the success of the elaborated field-rod technique foreclosed all other options. 'There are', says D'Acres, 'many other wayes coming into practice, for moving water gins, a 'great way distance off from the place of the mover'. The first method he describes is a rope-drive able to work 'admirable well two hundred yards remote' but which would be of better service service in D'Acres' opinion if the drive could be rendered reciprocating instead of rotary. But it is another method of securing horizontal transmission involving the use of 'wooden poles joynted one into the other' that seemed to some of the engineers with whom he was acquainted most to deserve research and development work being done upon it. The

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whole passage reveals to an extraordinary degree the isolation in which English engineering had been developing. 'This work [horizontal transmission] may without ropes be effected with wooden poles joynted one into the other to reach a quarter of a mile in length, provided then, that the weight of these poles be taken off by some external means, happily by disposing the weight of the poles in divers places, to rest upon narrow moving centres . . .'. 2 5 What is being described here is the most elementary of all forms of geschleppe, that is to say the simple flat rod moving on anti-friction rollers. Nothing is said about the pumping end of the line or how the rod was connected to the pump it worked but it seems reasonable to suppose that a T bob with sector and chain raised a suction lift-pump against gravity. Not, however, a tier of pumps, but rather something along the lines of Amos Barnes' bob gin at Heaton. But D'Acres has more to say: 'This instrumental mover by poles deserves (as by some is conceived) as much experimental perfection as any the world hath yet (in this nature) laboured with. For hereby the strength and service of rivers . . . too remote from the place where we need them, and which cannot be brought nearer by reason of the ascending ground, may become most commodious to the mineralists . . . ' . This experimental perfection had been previously attempted: 'There hath been some years since an experimental assay made to take off the weight of these poles, by hanging them in several places, like bells or weights at the end of chains; but it being the first experiment of this nature and (nihil simul inventum est et perfectum) nothing . . . is at once and together invented and perfected, first invent next amend, and lastly perfect, it happening in such unlucky times, the prime and chief designer and workman being since dead, in regard of these military discouraging times'. 2 6 A little later when D'Acres turns to discuss the various devices in use for converting rotary into straight line motion one learns that the experimental engine with hanging rods had not been worked through a crank but by means of cams or 'tawmps or stops of wood or iron standing forth of the moving axeltrees'. This means of setting the rods in motion is the same as that used in a machine drawn by Vavrinec Kricka in c. 1560 although in Kricka's machine the rods merely rested on an anti-friction roller. 2 7 It is impossible to say of how long a standing these tentatives were in England but if the experimental hanging rods were, as it seems safe to suppose, the work of the decade 1642—51 (from Edgehill to Worcester) bearing in mind D'Acres' phrase 'such unlucky times' then presumably the flat-rod system had been in use for some time previously. Nor is it any easier to divine the origin of these ideas since single rods of the type described were most likely coming into use in Europe in the 1560s but were certainly being superseded by the 1580s or 1590s. Is one dealing with a product

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of stimulus diffusion or perhaps with some partial assimilation of ideas brought into Cumberland by Daniel Hochsletter in 1568? It is certain from this context at least that little was known of the German achievement, and the engines described might well have been a response to imprecise noisings and reports relating to such machines: how would an engineer translate into hardware (were he so moved) Edwarde Browne's report of the rod-engines at Liege opaquely hinted at by the words 'strong woodwork moving backwards and forwards'? 2 8 As for the possibility of transmission from Cumberland, that is something to which I shall return later. It would however be wrong to leave D'Acres without some comment on the experimental hanging rods. This idea is a curious anticipation of a system shown in a drawing of one of Polhem's machines made by Augustin Ehrensvard in 1729. There is besides this other evidence of Swedish dissatisfaction with orthodox techniques. 2 9 In an English context, however, such ideas have a somewhat different significance, as yet one more indication of the vacuum in which the anonymous designer was working. At no time do such notions appear to have played any part in the development of rod-engine systems on the Continent in the seventeenth century. Indeed the whole weight of experience seems rather to have deflected Continental development away from single rod linkages of whatever kind since, unlike double rod systems, they were not suited to respond to the unequal loadings thrown upon them in the operation of large assemblies of pumps. One feels obliged to add that even if these design studies in England had proceeded to a successful conclusion it is difficult to see what large purpose they (or the flat rods) would have served since unless they were to be hitched to a vertical tier or repetition of pumps they would have been of very limited value. And at no time is there any trace of such tiers in use, at least not before the eighteenth century. It is not without significance, I suspect, that in the earliest known drawing of this kind of machine (Amos Barnes' sketch of 1733, referred to above, of a device at the Low Engine pit shaft at Heaton Colliery, near Newcastle) the pumps, of which there are two, are worked in echelon off individual pump rods and not off a master rod. It may be worth recalling here that when Agricola described his sipho septimus ('seventh pump') it was described as having two, but more usually three, pumps working off what was essentially a single rod. At Fresnes in the same year 1733 when George Saunders completed setting up the first Newcomen engine in French Hainaut it is clear (from Belidor's engravings) that the master-pump rod system, an element of the stangenkunst complex, was used and not the much less elegant 'English system' such as one sees in the pages of Desaguliers. 3 " In other words at Fresnes only the technique of the prime mover was being borrowed by Desandrouin's engineers and when it came to

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the shaft part of the business they had already a well-tried and familiar system to which to hitch it. In 1668, eight years after the appearance of the second edition of D'Acres' work, Edward Browne set out on his second 'grand tour' but instead of following the well-trodden path through France and Italy he followed a very unorthodox itinerary. In the normal way accounts of ordinary grand tours offer few surprises; it is sometimes difficult to suppress a yawn as one comes upon yet another recital of the grotto del cane or yet another rendering of some proverbial praise for the sausages of Bologna or the courtesans of Venice. By contrast it would be a difficult matter to find dullness anywhere in Browne's narratives.3 * Indeed, when his journey takes him ultimately to the military frontier of Austria in the Balkans and later to Idrija and the fortress of Palma Nova in Friuli, one is given a unique glimpse of what was in a very real sense ultima Europa. Browne's interests too were more catholic than was normal, especially his absorption in mineralogy, mining and mine engineering. As for the last it is clear from a number of his remarks that in many places the hydraulic engines he saw in use were quite outside his experience (and one presumes that of most Englishmen). One thing especially is very striking about what he has to say on the subject of mine pumping: whether he is talking about Liege, Saxony or Hungary it is quite clear that the evacuation of water from the deepest workings was ordinarily no problem. To be quite precise it was a problem in one place only, Schemnitz. There, in the worst of all possible mining situations, the difficulty caused by an almost complete absence of moving water above ground was compounded by very strong underground springs which posed a continuous threat to the working of the mines. 3 2 On his return home Browne passed through Aachen and spent some time visiting the zinc pits at La Calamine, five miles south-west of the city. 'Of the works about the mine' he wrote, 'the most remarkable are these: an overshot wheel in the earth, which moves the pumps to pump out the water; and this is not placed in the mine, but to one side of it, and a passage cut out of the mine to the bottom of it, by which the mine is drained'. 33 This description is perhaps not sufficiently explicit to make it clear what was involved. The wheel, fed by water from some higher level, was evidently placed some way along an adit specially dug for the service of the mine. From the wheel horizontal adit-rods streckengest'dnge, stretched to the shaft where their motion was redirected downwards, through master rods to serve the tiers of pumps which lifted water from sump bottom to the adit. The exhaust water flowing under gravity eventually joined the spent water from the wheel itself. As he travelled on further westwards into the principality of Liege Browne again encount-

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ered the stangenkunst with field rods. Most likely the ones he saw served pits to the east of Liege itself at Herve (Erf) or Herstal. Liege was, of course, famous all over Europe for its deep and rich coal mines. 'Their pumps and engines to draw out the water are very considerable at these mines; in some places moved by wheels at above a furlong's distance to which they are continued by strong woodwork, which moves backwards and forwards continually'. 34 It is clear that he has no name, any more than had D'Acres, for these field-rods, or indeed for the rod-engines themselves. As witnesses, however, both D'Acres and Browne are of limited value: the former because he had narrowly defined objectives and the latter because he may, after all, have had only a very limited acquaintance with English mining. No hint is dropped in any of Browne's works, whether by way of parallel or allusion, that he had visited any of the great coalfields of England or was familiar with the machinery used in them. Fortunately from this time onwards a considerable body of evidence is available which bears precisely on the question: what kind of machines were in use in English mines to keep them drained? The writers who together answer this question very comprehensively fail only to include Cornwall, an unfortunate omission since there is good reason to suppose that several initiatives of great interest took place there in the period in question (c. 1670—1710). These will be reviewed later in the present discussion. Stephen Primatt's The City and County Purchaser and Builder published in London in 1667, is the earliest of a group of works in the period 1667—1708 concerned with routine practice in the mines. Primatt's purpose was to write an outline guide to alert the outsider to at least those basic questions a prudent prospective purchaser of real estate would wish to have answered before proceeding to treat. Coal mines might naturally enough figure among estates up for sale, in which case one is to consider 'what engines they use to draw their water . . . \ 3 5 The answer for collieries whether on the Tyne or the Wear is clear: 'In most collieries in the north they make use of chain pumps and do force the same either by horsewheels, treadwheels or by water wheels; and this they find the surest way for the drawing their water, although the charge of such . . . is very great . . .'. As for the lead mines of Derbyshire, the picture is much the same but 'that which is most used among them is a sough, they lying for the most part in hills'. 3 6 The rag-and-chain pump is here the principal pumping engine as it had been in the Erzgebirge described by Agricola. Yet that description had ceased to be valid within ten or twenty years of his death. The re-equipment of the mines of Freiberg was begun by Martin Planer scarcely a year after the publication of De Re Metallica. Unless Primatt was hopelessly misinformed the picture he draws of England's principal mining area shows it still

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untouched by these changes after one hundred years. For a number of reasons it is unlikely that Primatt was wrong. When William Leybourne produced an enlarged second edition of the book in 1680 the information relating to drainage was in no way modified. In the pages of George Sinclair one finds a full length portrayal of the state of English engineering which amply substantiates Primatt's generalizations. 37 After remarking on evidence that seemed to him to suggest that the art of mining underground was of no very remote antiquity, there being visible in many parts 'coals wasted in their cropps only' he goes on to consider the kinds of engines in use where adit drainage would not suffice. There are, he notes, ordinary buckets, horse-works and water-works, the last two consisting in either case of 'a chain with plates and a pump' (by which he seems to mean the pipe through which the chain passed) or 'a chain and buckets' all which are very common, especially those we have in Scotland, they being capable to draw 'but a very small draught, making only use of one sink for that effect'. 3 8 But Sinclair had been 'abroad' and viewed the greater works of the 'Bishoprick' of Durham and in particular had seen and been impressed by the machinery in use at Sir Thomas Liddel's mine at Ravensworth on Tyne. His delight caused him to afford it a very full and clear description. I have previously suggested a parallel between late seventeenth century English pumping practice and that of Agricola's Saxony. Perhaps the comparison should now be advanced a few years since the Ravensworth engines put one in mind of nothing so much as some of Ramelli's mechanical confections, No. XLII perhaps or No. LII, but easily beating both in point of numbers of gears involved. Sinclair is careful to draw attention to the great depth from which the water was drawn; in this case above forty fathoms. Although this hardly compares with the two hundred lachter39 lifts being achieved at this time in Saxony, and it is surely fair to set extreme case beside extreme case, it nevertheless sounds a respectable enough depth and had not Sinclair gone on to describe how it was achieved one would certainly carry away a quite false picture of modest hydraulic competence at least among the northern English. As it is 'water is drawn about forty fathoms in perpendicular but not all in one sink'. Instead the lift was split up into three lifts, of twelve, fourteen and twelve fathoms respectively. The first lift was effected by a machine employing two vertical axles. The first of these was driven through right-angled gearing by an overshot water wheel. This axle, of the sort that D'Acres had described, was about eight or ten fathoms long and through another set of gears at its base turned another such shaft set below it 'and so down till it come to the wheel which turns the axle trees by which the chain is drawn'. 4 0 This rag and chain pump raised water twelve fathoms. The exhaust flowed along a gallery to a second sump (or sink as

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Sinclair terms it) where an engine similar to the first but having only one shaft raised it a further fourteen fathoms. A third machine drawing this water twelve fathoms from a third sump exhausted it into the adit along which flowed the 'day water' which had driven the three wheels of the complex. There was no question here obviously of want of water, or of difficult or oblique shafts, 'the axle tree goes right down in the sink', simply lack of an adequate technology. Indeed, the handling of water in relays in the style of Ravensworth brings to mind the possibility that in such matters the English had put themselves to school with quite the wrong masters and drawn on Dutch practice. If the use of mills in tandem was derived from the molengang idea which Simon Stevin had patented in 1589, then it was, of course, a totally inappropriate technology to borrow. 4 * However well suited it was to the problem of clearing the dead water of polders in a series of shallow lifts it was clearly a technology which did not translate well into mining conditions. The idea of using broken lifts in a mine was absurd when normal practice required the placing of the sump precisely in the place where it would best serve the future development of the work. Still, polder technique was doubtless better than no technique at all and prompts the reflection that the diffusion of stangenkunst technology westwards had met, so to speak, a cordon sanitaire in the Netherlands, beyond which it could not pass. The frontier areas of that tradition were therefore too remote from the English for it to pass easily to them. The Dutch did not need it except in such mines as existed in the secluded eastern parts of the country such as Limburg, while the French, for whatever reasons, were as ignorant of it as the English despite their more favourable position. 4 2 The linguistic divide between French and German speech running from Wallonia across the Vosges t o Franche-Comte was effectively the limit of rodengine technology at this time. Certainly, many of D'Acres' remarks are more readily understandable once the fact of English isolation is predicated. For the 1680s one has a further description of Tyneside from the recollections of Chief Justice Francis North while on the northern circuit. North was curious to visit the coal mines and eventually saw those at Lumley Park 'the greatest in The North', belonging to Sir Ralph Delavel. In discussion Delavel is said by North to have remarked that 'chain pumps were the best engines for they drew constant and even' but that one could have but two stories of them. The description which follows is unfortunately far from clear so that it may or may not be a variation of the Ravensworth model that was being described. 4 3 Much the same picture is drawn for Staffordshire at about this time by Robert Plot, 'It may not be amiss' he says, 'to add a word or two concerning the methods they use in laying their coals dry, when

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anything troubled with water, which because they are not so frequently or so much, as in some other countreys, they are not forced upon such variety of expensive engines. The ordinary ways are by sough or by gin . . . when they have no fall [i.e. no adit] they draw it up by gin . . . which is twofold, either by chain, or by barrels; the chain is made with leather suckers . . . the gin by barrels; whereof always one goes up as the other goes d o w n e ' . 4 4 Finally in 1708, almost on the eve of Newcomen's success at Dudley Castle, a booklet appeared entitled 'The Compleat Collier; or the whole art of sinking Coal Mines' by J. C. Nothing had changed since the days of Plot and Primatt. Water was still a menace of course: 'indeed were it not for water, a colliery in these parts [Tyneside] might be termed a golden mine to purpose . . .'. As for the means of voiding it, . . . if the pit be sunk more than thirty fathom then we use the horse engine which . . . serves also . . . to draw up the wrought coals. Which engine, t h o ' it be but of a plain fashion, yet it is found by experience to be more serviceable and expeditious, t o draw both water and coal than any other engine we have seen in these parts yet, notwithstanding we have had many pretenders in many kinds and methods; though we will be glad any ingenious artist could show us a more effectual way, for expedition and service, then we now use hereabouts. In some places we draw water by water, with water wheels or long axel trees. . . . If it would be made apparent, that as we have it noised abroad, there is this or that invention found out to draw out all great old waists or drowned collieries, of what depth soever, I dare assure such artists may have such encouragement as would keep them their coach and six, for we cannot do it by our engines and there are several good collieries which lye unwrought and drowned for want of such noble engines or methods as are talked of or pretended to....45 One could repeat for eighteenth century France the same sad tale of unwrought riches, at Pontpean and Poullaouen for instance, and find at Almaden in Spain an even more desperate backwardness. Montesquieu was wrong in thinking that 'il n'y a que les Turcs qui ne profitent point des lumieres de la societe humaine'. 4 6 All the English (and the French, Spanish and Turks) needed were a few German mine directors, or at least men trained in the German tradition, t o p u t their lost pits securely and profitably back into operation. Newcomen's engine was, it will be conceded, sorely needed, in default of such expertise. The rate of engine construction tells its own story to some extent but recent research has revealed in sharp detail the ferocious sharks which quickly infested the seas of the new technology. 4 7 The success of the Newcomen

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engine unleashed a desperate clamour from coal-owners each anxious to be served ahead of rivals which, given the shortage of skilled erectors and materials, could not possibly be satisfied. It was in these circumstances that glib middlemen like Stonier Parrott and George Sparrow began to play off one client against another in order to secure preferential rights, and slices of real estate against promises to bring in their precious know-how. The prime cost of the engine, the substantial running costs, to say nothing of the royalties payable to the proprietors of the patent were as nothing if the alternative to paying up was to go out of business. It was however to a large degree a phoney crisis. There are nevertheless certain features in the English mining situation at this time which deserve to be mentioned, especially since they might be thought to modify somewhat the bleak picture of backwardness this survey has revealed. It is interesting, for instance, to reflect on what the early state of pumping arrangements at Griff colliery reveals when contrasted with standard German practice. The Griff arrangements are those presented by Desaguliers in his Course of Experimental Philosophy, based on reports supplied to him by Henry Beighton. 4 8 They may refer to the engine erected in 1714. The total lift of 150 feet was modest enough by Continental standards and involved only a tier of three pumps but for Desaguliers this was to bring up water from 'a great depth'. The pipes were of wood, fixed together in Agricolan fashion forming a lift unit raising a column of water 7% inches in diameter fifty feet. Each of the three pipes in the unit had a distinctive name: first the sucking tree, its end submerged in the sump, then the pump barrel, and finally the upper tree of delivery. The second lift took its water from the exhaust of the first, the third from the second. This was, of course, orthodox stangenkunst technique even if the pumps were set in motion by a new prime mover. A further parallel may be seem in the three-part pipe-arrangement which matches perfectly the descriptions one finds in contemporary German mining lexicons. 4 9 Once again the question of some partial assimilation of German practice arises, for where else did the pump tier idea exist? And how long had such arrangements been in use before one first gets this glimpse? All one can say is that even here the parallel is not remarkably close. The system lacks the master rods (hauptstangen) of the normal rod engine and uses a mode of forking the rods that has about it an unmistakable one-off cobbled-up appearance. The same air of improvisation clings to the forking arrangements at Heaton Colliery as sketched by Amos Barnes in 1 7 3 3 . 5 0 Nevertheless like those examples in D'Acres' work one seems to have here further evidence of a partially assimilated technique. I have referred elsewhere to the geschleppe type pump shown in Barnes' drawing. Even there each pump has

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its own pump rod. The machine is called a bob gm, a name which occurs in an inventory of engines drawn up at Griff Colliery in 1711. Engines driving flat rods were in use in the Derbyshire lead mines at about this period. Later than any of these examples are the hydraulic bob engines driven by giant wheels which worked at the Bullen Garden mine, Camborne. William Pryce who described them in 1778 says nothing about how long they had stood there or who had built them. Another engine of this kind at the Cooke Kitchen mine, its wheel forty-eight feet in diameter, drew water from eighty fathoms below adit in four lifts and according to Pryce would have worked down a further forty fathoms if more water had been available to fill the buckets. The column of water lifted was nine inches. Elsewhere Pryce states that John Coster had inaugurated such large wheels (and presumably the tiers of pumps that went with them) in the early years of the eighteenth century: About four score years back, small wheels of twelve or fifteen feet diameter were thought the best machinery for draining the mines, and if one or two were insufficient, more were often applied to that purpose, all worked by the same stream of water. I have heard of seven in one mine worked over each other. . . . However soon after the above date [sic] Mr. John Costar of Bristol came into this country and taught the natives an improvement in this machinery, by demolishing these petit engines, and substituting one large wheel of between thirty to forty feet diameter in their stead.. . . 5 1 Once again one is confronted by enigmatic evidence. Here are engines almost up to stangenkunst levels of performance, using tiers of pumps and yet completely original in their power transmission system. Were they earlier or later than the first Newcomen engines? This is an important question since they might well seem to copy the beam and sector arrangements of those engines. On the other hand it is easy also to find affinities with the pumping engine of 1608 at La Samaritaine, on the Pont Neuf, Paris. One can amid these questions be perfectly certain of one thing: the type was not widely diffused. It is simply inconceivable that where sufficient moving water existed one would ever have encountered vertical axle-trees if such an excellent alternative to them had been available. Men such as Delavel and Liddel were not, after all, slow to take up the completely novel fire engine technology and were well endowed with that pre-requisite of technological innovation, the mentalite de profit, the capitalist spirit. But earlier in Cornwall than Coster was Joachim Becher. He worked for some months in Cornwall in 1681—2 and it is entirely possible that during that time he himself may have had a hand in introducing stangenkunst technology into the area (if indeed elements of it were not already there). Erik

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Odhelius, a member of the Bergkollegium at Falun, who visited the mines of Cornwall some eight years later in the course of a metallurgical tour of Europe in the years 1690—2, noted in his travel journal that 'the position of the mines extremely seldom allows hydraulic engines to be used, although shortly before his death Dr. Becher is said to have set one up at a place in Cornwall that was extremely effective': 'ehuruwahl Dr. Becher Berattades kort for sin dod en sadan hafwa pa ett stalle i Cornwall med sardeles nytta inrattat'. 5 2 If Odhelius' information was correct it is likely that one has here the date of the first rod-engine in Cornwall. But not perhaps the first in England. D'Acres' remarks on rod-engine work, given their due weight, point to the precarious suvival of stangenkunst technology or rather some isolated elements belonging to it, in the inventories of English engineering practice from some much earlier period. It is clear in fact that those elements belong to the earliest period of field-rod development simpler even than the suspended single-rod design appearing in Jean Errard's book of machines of 1584. There is only one place to look in seeking the origins of such an underdeveloped technology in Elizabethan England and that is in the events which brought German miners from Gastein and Schwatz to Cumberland in 1568. Their role and that of the Augsburg finance house of Haug & Co. in seeking to develop the copper ores of that region have been closely studied and it seems reasonably certain that in order to drive the workings below adit at the Goldscope (Gottesgab) mine at Newlands Daniel Hochstetter set up a rod-engine to drain the sump. Already in May 1568 the terms of the patent to be granted to him for draining mines had been drafted. The account book for 1569 furthermore contains a number of entries which taken together strongly suggest that the fabrication and assembly of the components necessary for the construction of such a machine was carried through from April to September of that year. On 25 April the axle of the water-wheel was carted to the site along with what may have been a toothed gear; on 23 May the carpenter was paid for the construction of water troughs; and so on 13 September were the carters for the cost of the carriage of four great augers to bore the wooden pipes. And that is all: the account book for 1570 does n o t survive. 5 3 Whatever the form of the machine set up by Hochstetter there can surely be little doubt about the nature of the machine at the site described by George Bowes and Francis Nedham in their report of 1602. They talk of a newly erected water-engine which is perfectly understandable for the wheels of rod-engines did n o t usually last longer than about fifteen years and Hochstetter's original would then have been in situ for at least twice as long, if indeed it still existed. Bowes' and Nedham's engine might well

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have been the third set up on the spot. The report mentioned first the leat, 1,200 yards long, which brought water into the mine to serve the engine. As for this, they say We viewed the . . . water engine newly erected in Gods Gift (Gottesgab) and the course of the stream that stirs the double wheel . . . which engine serves as well to draw up the ores and deadworks when need requires, as to draw the water out of the bottom of the mine through many pumps, which is performed very effectually and doth lay the mine so dry that when we were in the bottom we did stand where the nethermost pickmen did work, without any annoyance of water. 5 4 Hochstetter's machine, like the one described here (if there were indeed two) may well have served a double purpose also if a rather cryptic reference to a 'senstochk' (?zahnstock) in the accounts for April 1569 is to be understood as 'tooth-piece'. A number of drawings made about 1560 in Prague show such combined hoisting and pumping machines and the artist/engineer Vavrinec Kricka (in whose note-books they occur) would seem in a good many respects a comparable figure with Hochstetter. I shall discuss elsewhere the place that Kricka's engines seem to occupy in the evolution of stangenkunst design; the Newlands 'machine' built some time between 1570 and 1602 fits very well into my scheme. Doubtless in small-scale operations, and the 'Gift of God' was certainly no very flourishing affair, it would have been grossly uneconomical to set up two machines, a stangenkunst for pumping and a kehrrad (or double wheel) for hoisting, although generally this was standard equipment, as was the case, for instance, at Idrija in 1596. But two wheels would never have been tolerated for long if either had been left standing idle for considerable periods: the accounting techniques of the period extended to infinitely finer points of cost effectiveness than this. In the light of all this the history of the stangenkunst in England would appear to be both more complicated and more interesting than one involving a simple failure of transmission. It appears much more likely that the failure of these techniques to take root in England was connected with the early demise of the one mining area into which they had been imported. Cumberland was, after all, a great disappointment and even the richest mine ever found there appears to have better deserved the name of 'leerestasch' (empty purse) than 'Gottesgab' (God's gift) corrupted by a quaint irony into 'Goldscope', the very thing that, except in the sense of a drain, it was not. Haug & Co. had lost perhaps as much as £19,000 before they called it a day. Unsupported hypothesising is never very profitable, but one has only to imagine Cumberland copper mining as a perennial operation having a long and successful life to see how naturally in such circumstances

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stangenkunst technology would then have been successfully domesticated in England. 5 5 The first experts were naturally enough Germans with the local English serving above ground as an unskilled labour force carting wood and fuel to the site, rather in the way Slovaks performed all the ancillary services called into existence and sustained by the purely German mining communities of the 'Ungarische bergstadte'. 5 6 But a division of labour along ethnic lines would scarcely have persisted long in England. As the original Germans intermarried or retired or died so would the German complexion of the mining force have begun t o give way t o a mixed situation in which even the sons of these men spoke English. Within a generation perhaps even a few native Englishmen would be familiar enough with the technology to be able to transplant it to other mining areas of England as the need arose. How else indeed were techniques ever transferred? This was exactly the manner in which the first European experts in steam engine construction acquired their mastery and took over from their English teachers as death or old age removed these from the scene. Manifestly this never happened in England because the conditions necessary for it to happen did not exist: that is, a continuous profitable mining operation. This the meagre lodes of Cumberland could not sustain. The workings there were more than halfway to the owl-haunted condition dear to the Gothic imagination when they were trodden by the naturalist, Thomas Robinson in 1709, an evolutionary forerunner of the full-blown nature-poets of the end of the century. Notes 1. (i) Un voyageur Fran pais a Londres en 1685, ed. G. Roth, Paris 1968: The MS. in the Bibliotheque Municipale de Cherbourg consists of three letters written probably by C. A. de Sainte-Marie to M. d'Englequeville, Marquis d'Auvers. The quotation is taken from a letter dated 8th May 1685. The earliest known references to sash windows may be dated to 1673. (ii) R. Plot, The natural history of Staffordshire, Oxford 1686, gives a number of examples of the sort of exquisite craftsmanship that took Sainte-Marie's eye. See p. 376 for a description of recording devices fitted to locks to show how often they had been opened, and p. 384 for a machine to perform elaborate turning for the production of * wreath-work', made by John Ensor of Tamworth. 2. E. Chamberlayne, Anglia Notitia, or the present state of England, London 1704, pp. 49—50. On p. 51 there is mention of a 'very agreeable consort . . . performed by clock-work'. Then there were 'the late great improvements in making glass' and a list containing over twenty further items. The same sort of picture is drawn by T. Smith, Art's improvement, London 1703. 3. M. Stringer, A brief essay on the copper and brass manufactures of England, London 1699, p. 9. 4. C. Davenant, An account of the trade between Great Britain, France, Holland . . . etc., London 1715, p. 54. I have not been able to discover an earlier edition although the reference to 'after the war* points to a date of

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composition between 1702 and 1713. It is interesting that, as far as all the arts yet mentioned are concerned, J. Roquet's, The present state of the arts in England, London 1753, confirms the picture of half a century earlier and indeed adds new items such as the stamped or imprinted porcelain manufacture carried on near Chelsea. 5. R. Plot, op. cit., plate X. But see also p. 164 and his remark about 'the vast advantage which they [the iron-workers] have from the new invention of slitting mills for cutting their bars into rods'. According, however, to H. Schubert, History of the British iron and steel industry, London 1957, p. 304, Richard Foley had set up such a mill at Hydehouse-on-Stour, Worcestershire, some time about 1625. In view of the well-known fact that a slitting-mill was in use at the Saugus ironworks in Massachusetts in the seventeenth century and that the works was out of operation by 1670 (E. N. Hartley, Ironworks on the Saugus Norman, Oklahoma, 1957), it might seem that Schubert's chronology was more accurate than Plot's. But whether one takes either example it is clear that by comparison with Continental standards the idea had been taken over rather tardily. Jean Errard pictures such a mill in 1584 and mentions that it was the invention of Charles Desrue, 'the first to make the demonstration and experiment'. In Bar-le-Duc or Nancy perhaps, but not in Nuremberg. Eobanus Hessus in the 'Officini Ferraria', a section of his Urbs Noriberga illustrata carmine heroico of 1532, talks of a'magna rota ingentem vi fluminis acta' and its wheels and gears 'quibus atri lamina ferri scinditur . . .'. 6. J. Becher, Ndrrische Weissheit und Weise Narrheit, Frankfurt 1682, p. 113, No. 42. The section goes on to mention wooden pistons which similarly do away with the need for leather. Plot's drawing shows incidentally that the bellows used at Ecton Hill was double acting, a type more usual in small forges such as those of enamel workers, where the work required a continuous flame. A history of bellows and blowers would be a study well worth undertaking, which would, in the case of wooden bellows, certainly lead back to fifteenth century Italy. What is certain is that here as elsewhere England's development proceeded separately from the rest of Europe. The use of piston blowers in English smelters, beginning as far as one can judge in the 1740s, would be not the least interesting part of the story. 7. P. Grignon, Memoire sur les Soufflets de forges a fer in Memoires de physique sur Vart de fabriquer le fer, d'en fondre . . ., Paris 1775. This admirable memoir on bellows reveals no knowledge of piston-blowers. According to Grignon leather bellows well looked after might last fifty years although quite how this is to be reconciled with H. Calvor's statement in Acta Historico-Chronologico-Mechanica circa Metallurgiam in Hercynia Superiori . . ., Brunswick 1763, p. 162 that they only lasted six or seven years I do not know. Who is right or are both wrong? 8. Since the economically significant coalfields had long been in the hands of wealthy capitalists, men in no way committed to traditional methods except insofar as these were useful, it seems strange that more energy was not displayed in seeking foreign help. Plainly men with a mentalite de profit were a necessary but not a sufficient reason for technical advance or innovation. 9. J. U. Nef, The rise of the British coal industry, London 1932, Vol. 1, p. 123. 'The first three-quarters of the nineteenth century have usually been regarded as incomparably the period of most rapid expansion in British coal mining. But, measured by the rate of increase in the use of coal, the period 1550—1700 may, without qualification, be compared to it'. But see Tables IX and X, pp. 123—4. 10. G. Huffel, Economie forestiere, Paris 1910, p. 10. Huffel takes one ton of coal to yield 7 million calories. One stere of wood (i.e. one cubic metre) yields 1.7 million calories. Four steres are very nearly equal therefore

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to one ton of coal. Four steres are the annual production of one hectare of good forest. English coal consumption in 1700, running at something like two million tons per annum, represented the calorific equivalent of two million hectares (or nearly five million acres). 11. At least one can say that if such efforts were made they have left remarkably little trace. Perhaps, however, a too great (and mistaken) reliance was placed on Dutch engineers. It would be possible to argue, of course, that the very wealth of England's coal endowment acted as a deterrent to setting up new equipment for deeper extraction. As long as one could pillage the surface layers and move on this was doubtless the way things were done, and could only be done. But the grubbing would be shallow grubbing indeed if the water problem were to be avoided. The almost universal use in England of the rag and chain pump and the bucket hoist was doubtless as costly a way of raising water here as it was in Germany and would no doubt have yielded enormous savings if such gear had been replaced by stangenkiinste. Martin Planer's re-equipment of the Freiberg mines after 1557 cut pumping costs by 90 to 95 per cent. 12. A. R. Hall and M. B. Hall, The correspondence of Henry Oldenburg, Vol. IX, London 1973, pp. 625—31, Nos. 2219 and 2219a. The translation of ulnarum in query No. 4, p. 627, 'in earum profunditatem sitnea ea 150 ulnarum, ut fertur' as fathoms cannot, I think, be correct. But see note 13 below. 13. Rene de Sluse's reply is printed in T. Birch, The history of the Royal Society of London, London 1757, Vol. Ill, pp. 125—7. It seems certain that the parties to this correspondence were talking somewhat at cross purposes as far as the question of the depths of the pits at Liege was concerned. Ulna (Fr. aune) was anciently in Liege a measure equal to 25.836 ins. and indeed this was, with trifling variations, what the measure (under its various names) equalled in most parts of Europe. For Sluse '150 ulnarum' undoubtedly meant 300 feet and his remarks make sense only if this is understood to be so: hence his care to equate 'orgyia' with 'toise'. The Liege toise was in fact less than an English fathom by 2V2 ins., or decimally 5.8 feet, unless, that is, the berglachter or toise de houillerie (mining fathom) of 6.6 feet (2.042 m) is the measure intended. But Sluse reckoned without the English (or London) ell, 45 ins., a rogue measure that was nearly twice as great as the normal (Continental) ell. Hence arose the confusion for Oldenburg was not asking whether the pits of Liege were 300 feet deep but wished Sluse to confirm that they had reached 600 feet, which of course they had. Altogether the futility of the exchange seems to me to be well characterized by this misunderstanding. 14. He had not yet published his Account of several travels through a great part of Germany, London 1677, in which he described the field-rod engines of Liege. 15. The evidence to be reviewed in this essay yields numerous instances of some thing like this being the effective limit still in seventeenthcentury England. A lift of about 80 feet was 'a great height' for D'Acres writing in 1660. Although Agricola talks of rag-and-chain pumps working down to 240 feet it seems clear that these were exceptionally large machines. Hake presumably meant to refer to the earlier part of the sixteenth century. 16. William Sharp (?), A treatise upon coal mines, London 1769, p. 52. 17. See G. de Louvrex, Recueil contenant les edits et reglements faits pour le pais de Liege et comte de Looz par les eveques et princes, Liege 1750, Vol. 2, pp. 203—4, for the text of the 'edit du Prince Ernest de Baviere touchant la maniere de conquerir les mineraux extans dans le fond d'autrui'. 18. Although the situation is somewhat obscure a privilege granted to David Remade of Limburg on 27 February 1601 makes it clear that he had succeeded in draining the long abandoned lead mines at Prayon. It may well have been the case that at this time shortage of capital rather than of

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technical skill was the problem. In 1585 when Georg-Johann, Comte de Velden, proposed to drain the flooded coal mines he referred to machines (single field-rod engines presumably) unknown to the Liegeois, which he had employed on his own estates. He certainly intended to attack the problem comprehensively, but after 18th July 1586 —on which day Leonard le Redoute (master carpenter) of Liege and Johann Godschalk (engineer ?) a German, reported to the burgermasters that they had concluded terms with Count Velden and begun work — all is silence. 19. One might cite a number of instances in France in which, when steam engines proved too expensive, rod-engines were installed in their place: for the French it was merely a choice between which of two foreign techniques was the more economic. They were, after all, * committed' to neither. 20. J. U. Nef, op. cit., p. 242. "Try as they would, the British found it impossible, with the pumping devices which had served the copper and silver mines of Bohemia, Hungary, the Tyrol or the Harz, to force a column of water high enough to drain the deeper pits'. But it is clear that Nef is assuming what he has to prove. Citations from Agricola are not enough. In view of what has been said both earlier in this chapter and elsewhere one might well fail to agree with Nef when he states (p. 256) that 'it was precisely in the district around Liege where the coal mines had been most intensively exploited, that the most notable strides in inventive effort and technical skill were made during the 17 th and 18th centuries'. 21. The importance of such long range transport systems in overcoming localized fuel shortages brought on by the needs of smelters, brine works and urban centres has been completely ignored in English writing on the history of technology, with the exception of the brief account to be found in the English translation of J. G. Beckmann's History of inventions. 22. Two editions were produced in 1659 and 1660 but without change in the text. It was reprinted as Extra Publication No. 2 (1930) by the Newcomen Society. 23. In fact at the end of his work D'Acres does list, in summary form, the known engines of common use. The stangenkunst, or anything recognizable as such, does not appear among them. 24. D'Acres, op. cit., p. 15. 25. Ibid., p. 16. 26. Ibid., p. 17. 27. F. Pisek (ed), Mathesis Bohemica, Prague 1947, fig. 44. 28. E. Browne, An account of several travels through a great part of Germany, London 1677, p. 171. 29. A. Ehrensvard, Les machines de Monsr. Polhem, 1729, f. 61. The MS. is in the possession of the Tekniska Museet, Stockholm. This is not the only evidence of an experimental temper at work among Swedish engineers. Gabriel Jars at Falun in 1767 noted horizontally mounted systems of field rod transmission lines which appear from the evidence offered by Ehrensvard to be equally the result of Polhem's inspiration. But both, it should be noted, were deliberate departures from a standard technique which had been fully mastered in the second half of the seventeenth century. All techniques possibly benefit from being seen with fresh eyes outside their classic ground. They may, equally, be degraded. 30. J. T. Desaguliers, A course of experimental philosophy, London 1744, Vol. 2, plate 34, fig. 9. This shows the forking of the pump rods at Griff Colliery, Warwickshire. 31. I refer particularly to his A brief account of some travels in Hungary, Austria . . ., London 1673. 32. The shortage of ground (surface) water was such that even the modest quantities of water required for the use of the steam engines set up by Isaac Potter after 1732 proved difficult to procure.

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33. An account of several travels through a great part of Germany, London 1677, p. 163. 34. Ibid., p. 171. 35. Op. cit., p. 28. 36. Ibid., p. 33. 37. George Sinclair, The hydro-staticks . . . together with some miscellany observations, Edinburgh 1672. 38. Op. cit., p. 298. 39. See Christian Meltzer, Bergklaufftige Beschreibung der Churfurstlichen Sachsischen Freyen . . . . Bergk-Stadt Schneebergk, Schneeberg 1684, p. 99, where the extreme lifts achievable by means of rag-and-chain pumps, bucket hoists and stangenkunste are compared. 40. G. Sinclair, op. cit., p. 299. It seems that similar machines were in use in 1684 in Sir Roger Mostyn's coal mine in Flintshire. Thomas Dineley speaks of two water sheels with * wheels and pinions' that he saw there. 41. The principal works of Simon Stevin, Vol. 5, Engineering, ed R. J. Forbes, Amsterdam 1966, p. 14. See No. 1 of a portmanteau patent granted by the States General on 28th Nov. 1589. This seems to me the most obvious source for these sorts of machines; that there were others appears from Francis North's remarks of about 1680. The idea of linked sequences of machines goes back much further than Stevin*s patent and seems likely to belong to the early part of the sixteenth century. 42. This is evident from contemporary French comment on the Marly machine which invariably characterizes it as a marvellous special creation and quite ignores its pedigree. This latter is stated very precisely by Martin Lister in his A journey to Paris in the year 1698, London 1699, p. 213. The 'invention (is) the same with what is practised in the deep coal pits about Leeds in Lower Germany. To see the pipes lying bare is to imagine a deep coal mine turned wrong side outward'. 43. R. North, The life of Francis North, Lord Keeper of the Great Seal, London 1742, p. 135. Francis North's visit to the coal pits was made during the period when he was a chief justice (1675—1683). 44. R. Plot, op. cit., p. 148. 45. J. C, op. cit., pp. 28—9. 46. A. de Montesquieu (ed), Voyages de C. de Secondat, Marquis de Montesquieu, Bordeaux 1896, Vol. 2, p. 262. The diffusion of engineering know-how was far from being as general as Montesquieu ('a present, tout se communique') assumed. 47. See M. B. Rowlands, 'Stonier Parrott and the Newcomen Engine', Transactions of the Newcomen Society, Vol. XLI, 1968—9, p. 49, for a most illuminating study of this situation. Parrott knew well how to bait the hook, if I may change the metaphor. Parrott's reward for helping at Ravensworth would have been something like £300 per annum and a one-fifth share in Park Colliery. 48. J. T. Desaguliers, op. cit., p. 478. 49. As for instance C. Berward, Interpres phraseologiae metallurgicae, 1673, or J. Hiibner, Curieuses und reales. . . Lexicon, 1713. 50. Amos Barnes, View book, 1733. The MS. is in the library of the North of England Institute of Mining and Mechanical Engineers, Newcastle. At Idrija in 1596 each of the tiers contained 26 pumps, each tier worked off a single principal shaft rod. 51. W. Pryce, Mineralogia Cornubiensis, London 1778, pp. 307—8 . . . John Coster, father and son, took out a patent in 1714, No. 397, 27th May, for an engine for drawing water out of deep mines. This was an ingenious device for making use of small flows of water insufficient to turn a wheel and was really an inverted rag and chain pump. The small arm of water flowing into the pipe forced down the rags successively, the torque on the bottom axle

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serving to put in motion a sprocket wheel to draw up the rags through the pipe of a lower machine in the normal way. This seems to be an important device in the sense that pistons being put into motion by water pressure, as they were here, plainly prefigure (as do floating pistons) the water pressure engines of the period immediately following this time. 52. Erik Odhelius, 'Berattelse om utlandska bergverken 1690—2', p. 462, MS. H.602, Uppsala Universitetsbibliotek, Uppsala (reports on foreign mine engineering). 53. W. G. Collingwood, Elizabethan Keswick. Extracts from the original account books 1564—1577 of the German miners, in the archives of Augsburg', Cumberland and Westmorland Antiquarian and Archaeological Society Transactions, Tract Series No. X, Kendal 1912. 54. The report is quoted at length in M. B. Donald, Elizabethan copper, London 1955, pp. 166—7. 55. M. Daumas, 'L'acquisition des techniques par les pays non initiateurs', Documents pour Vhistoire des techniques, Cahier 8, 1970, puts the point rather well in talking of the Slovakian and Saxon mining regions as each having, *une population de mineurs experimentes qui se renouvelait de generation en generation sur des bassins minieres concentres*. 56. P. Deifontaines, 'La Vie Forestiere en Slovaquie' Travaux publies par Vlnstitut d'Etudes Slaves, Vol. XIII, 1932, p. 47 'A cote des mineurs, s'etablirent des bucherons et charbonniers de bois ce furent le plus souvent des Slovaques ou Ruthnes qui se specialiserent dans ce travail pour le compte des Allemands. Un peuplement slave penetra ainsi dans la zone des colonies saxonnes'. At Tajov a specialism was developed by Slovak cobblers in making boots for the German miners.

T h e

C o n t r i b u t o r s

Dr. R. A. BUCHANAN is Reader at the University of Bath and founder and Director of its Centre for the History of Technology. He has published two books on British industrial archaeology. D. S. L. CARDWELL is Professor of the History of Science and Technology at the University of Manchester Institute for Science and Technology. The present paper relates to his book From Watt to Clausius: The rise of thermodynamics in the early industrial age (1971). M. MAURICE DAUMAS is Director of the Conservatoire Nationale des Arts et Metiers, Paris. Besides his studies on Lavoisier and well-known history of scientific instruments he has edited (and largely contributed to) the Histoire generate des techniques. KEITH DAWSON is Vice-Principal of the North London College of Further Education and received his Ph.D. from the Univeristy of London in 1973 for a thesis on The early history of electro-magnetic telegraph instruments. A. RUPERT HALL is Professor of the History of Science and Technology at Imperial College, London. He has written on both the history of science and the history of technology. MARIE BOAS HALL is Reader in the History of Science and Technology at Imperial College, London. While most of her publications have been devoted to the history of science, she has long lectured on the history of chemical industry. JACQUES HEYMAN is Professor of Engineering at the University of Cambridge. He is author of Coulomb's memoir on statics (1972). RICHARD L. HILLS, who worked for a year at Imperial College, is Reader in Professor CardwelTs Department at UMIST and Director of the North-Western Museum of Science and Industry. He is author of Power in the Industrial Revolution and other works. G. HOLLISTER-SHORT is Principal Lecturer in History at Shoreditch College, University of London Institute of Education. He is completing a thesis on 'Some aspects of invention and diffusion in European engineering, 1450—1750'.

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NORMAN A. F. SMITH is Lecturer in the History of Science and Technology at Imperial College, London. He has published A history of dams (1971) and has in press Man and water.