Shifting Scales. Microstudies in Early Victorian Britain

Home , James Prescott Joule, Thomas Graham (chemist)

H. Otto Sibum1

In 1847 James Joule gave one of his rare public lectures in which he remarked that living force is not destroyed by friction or collision of bodies: “We may conclude, then, with certainty, that these motions of air and water, constituting living force, are not annihilated by friction. We lose sight of them, indeed, for a time; but we find them again reproduced.”2 In this paper I would like to answer the question what was the context of experience which led Joule to this conclusion, one that implicitly presumed a firm knowledge about the microcosm of interacting and transforming natural forces and which leading natural philosophers could not accept. I will show that Joule’s microscopic vision of heat was rooted in his gestural knowledge derived from experience in manipulating heat processes and further developed through instrumental practices and sensuous economies shared by a small collective of researchers at Manchester.3 In the first section I will give a detailed account about practices of collaboration between James Joule and John Benjamin Dancer during the period from 1844 until 1846, a time in which both were engaged in producing a new mercury thermometer which would measure with a degree of accuracy unheard of in that time. In this “extreme sensitive” instrument Joule saw both his high standards of precision measurement and the wish to outwit nature’s capricious behaviour by displaying her latent heat movements materialised. In the following section I will focus on John

1. This paper was presented at the workshop ”Varieties of Scientific Experience” held at the Max Planck Institute for the History of Science, Berlin 1997, at Universities of Princeton , Harvard and Utrecht as well as the Science Museum London. I am grateful to all participants for the stimulating responses. I’am quoting from sources held at the Royal Society, London; Manuscript collection, Cambridge University Library (hereafter CUL); Manchester University Library and Public Library; Joule archive, Library of University of Manchester Institute of Science and Technology (hereafter UMIST); William Thomson archive, Glasgow University Library (hereafter GUL); H. Rowland manuscripts, Johns Hopkins Univer- sity Library (hereafter JHU) and am grateful to have permission to do so. 2. ”James Prescott Joule, ”On Matter, Living Force and Heat.” A lecture at St. Ann’s Church Reading Room; published in the Manchester Courier newspaper, May 5 and 12 (1847); reprinted in The Scien- tific Papers of James Prescott Joule (hereafter SPJ ) vol. 1 (London 1884) 265-276, 269. Amongst a few other traces historians of science have taken this lecture as firm evidence for their claim that Joule is one of the co-discoverers of the energy conservation principle. 3. For further details on the historical embodiement of James Joule’s working knowledge, elsewhere con- ceptualised as gestural knowledge see H.Otto Sibum, “Les Gestes de la Mesure. Joule, les pratique de la brasserie et la science”, Annales Histoire, Sciences Sociales, 4-5 (1998): 745-774, and Sibum, ”Ex- perimental History of Science”, in Museums of Modern Science, ed. Svante Lindqvist (Canton 2000), pp. 49-56.

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Benjamin Dancer’s research practices, which led him to develop microphotography, and also show a common underlying structure with Joule’s working knowledge, specifically a technique which I shall call shifting scales. I will then describe Joule’s research practice and argue that his technique of shifting scales provided not only the means to construct and use a new instrument and experimental arrangements but also to propose a micro- physical theory of heat. In the following section I will compare Joule’s practice with W. Thomson’s approach to the same thermometric issues. The reader will again identify the underlying structure of shifting scales and I will show that in accordance with his working knowledge Thomson proposed an absolute temperature scale but missed out crucial in- sights about the microscopic nature of heat which Joule soundly derived from his se- quence of experimental arrangements. Finally I will show that in encounters with various representatives of different knowledge traditions Joule did not succeed in establishing his microscopic view because Joule’s audience did not share his context of experience. Only gradually through the amalgamation of these two different knowledge traditions, represented through Joule and Thomson, was the dynamical theory of heat established.

‘Nicety of Attention’

“There are probably few sights more pleasing to one who has been brought up in factories than to watch a skilful workman engaged in ex- ecuting a piece of work which requires absolute mastery over the tools that he uses, and demands that they should have the constant guiding of his intelligent mind. Handicraft work of such a kind borders upon the occupation of the artist and to see such work in the course of execution is, as I have said, a source of pleasure.”4

During the years 1844 and 45 the scientific brewer James Joule realised that a collaboration with the virtuoso instrumentalist John Benjamin Dancer could lead to a major achievement in constructing new instruments for scientific research. Since his arrival in 1842 Joule had been one of the regular customers in Manchester’s new instrument maker’s shop at Cross Street (near his own brewing premises) but didn’t feel obliged to mention the gentleman Dancer in his publications which had only been possible through the use of his excellent tangent galvanometer, even ordered by William Thomson shortly after

4. F.J. Bramwell, “On Prime-Movers”, Conferences held in connection with the Special Loan Exhibition of Scientific Apparatus, Vol. 1. Physics and Mechanics, (London 1876): 348-380.

SHIFTING SCALES

the encounter with Joule in Oxford in 1847.5 But from 1844 Joule spent several mornings over longer periods in Dancer’s workshop discussing problems of heat measurement and the design of a new mercury thermometer able to display heat. Both shared an attitude towards experimental practice which the brewer Joule understood as “doing with care”, a literal derivation of the Latin word “accurare”. This was a moral economy of research which demanded “nicety of attention or performance” carrying with it the values of the craft tradition according to which much effort is spent in taking care of the particulars, those minute details which inhabit the material world. To Joule, nicety of attention meant first of all a careful examination of his working objects in order to achieve optimal arrangements to perform in. For his heat measurements Joule determined the specific heats of flint glass used for the construction of thermometers, and the specific heats of brass and copper, materials used for his fluid friction experiments. In a word, he derived knowledge from experiencing every circumstance and material condition relevant for the experimental performance. But such preparatory work could not substitute for the experimenter’s competence performing a proper measurement. This personal or collectively acquired gestural knowledge derived from experience was the sole standard against which artisans and virtuosi instrumentalists like Dancer and Joule judged their workmanship. Recent historical research has shown that the design and especially his performance of experiments had prof- ited extremely from his participation and enculturation in brewing culture. It led him to acquire a specific gestural knowledge in taking heat measures which included the right timing for taking measurements and a proper placement of the thermometer in order to measure the air temperature or the manner of taking the right temperature of the water in the copper vessel. He had incorporated working rhythms of a kind which now governed his experimental practice of properly immersing the thermometer into the water so that it indicates the correct temperature of the water.6 These forms of working knowledge of manipulating objects — the virtuosity in changing arrangements — derived from experience Joule and Dancer recognised in each other’s work.

5. Two tangent galvanometers are held in the Glasgow University Archive, Hunterian Museum. Both were made by Dancer under the direction of Joule in the 1840s. The larger one (J.5.) is a replica of the tangent galvanometer Joule had used and described in his 1843-44 publication “On the Heat Disengaged in Chemical Combinations”, in SPJ, vol. 1, pp. 205-235, communicated to the French Academy in 1846. The second one (J.6.) is a much smaller one in construction and was used by Joule himself. See G. Green and John T. Lloyd, Kelvin’s Instruments and the Kelvin Museum, (Glasgow 1970), p. 53. 6. Indeed, Joule’s whole choreography of the performance of measuring heat was to a large degree an im- print of his brewing practice. See Sibum, “Les Gestes de la Mesure”, op.cit. (note 3); and Sibum, “Work- ing Experiments: A history of Gestural Knowledge”, The Cambridge Review, 116, no. 2325 (1995): 25- 37. No wonder that the set up of the paddle wheel experiment turned out to be a small scale model of the brewers mash tun and previous related experiments like the one to determine the friction of fluids by pressing water through narrow tubes was an adaptation of a well known arrangement in brewing, the refrigerator to cool down the worts by passing cold water through narrow pipes mounted at the bottom of the vats.

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During this collaboration the most sensitive and precise thermometer produced in the country was made. The scientific optician Dancer provided a calibrating device which he himself called the “travelling microscope”, a device which could be moved horizontally by rotating a screw. The distance of travel could be determined from a graduated disc at one end of the screw. But it also served as a means of rotating the screw. The pitch of the screw was 1/20 inch and the circumference of the disc was divided into 200 equal parts, so that the instrument reads to 1/4000 inch. The exceptional manner of graduation and calibration and its impact on Joule’s work can be explained as follows: Firstly, the “travelling microscope” (Figure 1) was extremely helpful for proving the quality of every glass bore. Secondly, the instrument allowed him to make extremely fine graduations onto the surface of the glass. Finally he managed to “calibrate the thermom- Figure 1. Dancer’s‘Travelling Micro- eter by the graduation itself:”7 This was undertaken scope’ built for Joule’s thermometer calibration. (Drawing by A. Mathieu. Photo because if the tube had a perfectly uniform bore it below by courtesy of The Museum of Sci- would only have been necessary to make a millime- ence & Industry, Manchester). tre scale of equal parts between the freezing and boil- ing-points. But usually no bore had these conditions. Joule therefore decided to outwit the material’s capricious behaviour by means of dividing the scale, to make allowance for the variations in the tube’s capacity. He took a glass tube of narrow bore and introduced a one-inch column of mercury and measured the two endpoints of the drop. Then he moved the drop so that one of its ends was at one of the previous points. He took a second measure of the drop’s length. In each position the probable varying length of the column could be ascertained to 1/4000th part of an inch. By means of this process the tube’s surface was marked in sections of different length. Afterwards, these different distances were each graduated into fifty divisions. The divisions of a thermometer built thus did not represent degrees of the ordinary scales of temperature, but of an arbitrary value, differing for each instrument. Joule had made his measurements their own standards because he created a system of values and assigned them to a particular thermometer which no one else pos- sessed. His arbitrary scale had allowed him to increase the sensitivity of measurement but made him the only person able to judge his accuracy. This “extreme sensitive” device act-

7. Letter from Joule to Thomson, 25 May 1879, CUL, MSS Add 7342 J 291.

SHIFTING SCALES ed like Dancer’s microscopes which made visible the latent images of the microcosm. Joule’s thermometer displayed the latent movements of heat which under normal circum- stances would not leave any visual trace. Imagine a second measurer of temperature present in the same room and employing a less sensitive thermometer. He would not detect any change in temperature whilst Joule’s new device would open up a new field of experience. Joule and Dancer had provided the means to shift scales within heat research but as Joule rightly stated with the result that: “I have always found a difficulty in making people believe that fractions of a degree could be measured with any great certainty.”8 An expert culture was not yet set up in which people shared these practices, values and norms about science which Joule wished to establish. For nearly all his publications Joule chose to report his measures in one form of detailed tables of decimals — a well-known practice amongst writers about brewing, to express what was often forty years of experience in determining mashing heats. As a further means of communication within the emerging republic of science Joule and Dancer began to produce collectively their new thermometers, and provided leading scientists like Lyon Playfair and Thomas Graham with them. Joule equally took thermometers from those scientists in order to be able to compare their readings with his new sensitive one.9

Dancer’s Microcosm

Joule summarised this episode by writing that he had “great pleasure in acknowledging here the skill displayed by this gentleman [Dancer] in the construction of the different parts of my apparatus; to it I must, in a great measure, attribute whatever success has attended the experiments detailed in this paper.”10 The paper he is referring to discusses an experiment to determine “the changes of temperature arising from the alteration of the density of gases — an inquiry of great interest in a practical as well as theoretical point of view, owing to its bearing upon the theory of the steam-engine.”11 Finally it was another

8. Letter from Joule to Thomson, 7 November 1848, CUL, MSS Add 7342. 9. Joule to Playfair, May 12, 19 and 26, 1846 (Archive of the Manchester Literary and Philosophical So- ciety ), cited after A. G. Pate, James Prescott Joule 1818-1889. A bibliography of works by and about him, (Manchester 1981), p. 45; see also Joule’s Laboratory Book 1843-58, Lowery No. 5(b), held in the Joule archive at UMIST. 10. James Prescott Joule, “On the Changes of Temperature produced by the Rarefaction and Condensation of Air”, Philosophical Magazine, 26 no. 174 (May 1845): 369-383; reprinted in SPJ, vol.1, pp. 172- 189, 175. 11. ibid, p. 172. As we will see later in this paper it is important to note that this design of the experimental set-up was especially made in order to overcome the problem that “our knowledge of the specific heat of elastic fluids is of such an uncertain character, that we should not be justified in attempting to deduce from them the absolute quantity of heat evolved or absorbed.” (ibid, p.174).

H. OTTO SIBUM version of the determination of the mechanical equivalent of heat as a means to contribute to a new understanding of the nature of heat, to overcome the caloric theory of heat which ascribes materiality to heat. As Joule later testified Dancer has provided him with various apparatuses for electricity, magnetism, meteorology and all “those multifarious instruments which are needed by scientific men.”12 Although Joule wrote this on Dancer’s own request to testify his competency, in most of Joule’s publications, with the exception of the 1845 paper’s footnote, only Dancer’s status as a most competent instrument maker is prominent, neglecting completely his equal social standing as a natural philosopher. In this section I will recon- struct Dancer’s scientific persona and research practices in order to distil a characteristic form of experience which will show similarity in underlying structure with James Joule’s research. In comparison with portraits of Dalton or Joule the first portrait of Dancer, a “likeness of themselves in miniature” (Figure 2) made by the British agent of Daguerre, Beard’s Gallery at Manchester, indicates that he regarded himself as be- Figure 2. ‘J. B. Dancer’, daguerreotype, November ing a natural philosopher of equal rank 1842 (Source: Article by Michael Hallett, “John Ben- and to be an “equally enthusiastic Exper- jamin Dancer 1812-1887: a perspective”, in: History 13 of Photography, July-Sept. (1986), pp. 237-255). imenter in Chemistry.” In all of these portraits we see a device characteristic for their research placed next to the subject. Dancer displayed himself besides a “porous un- glazed jar” which he had used since 1838 as a voltaic battery,14 and hardly identifiable device, probably an “Electrical Current Interrupter” which he invented and which later be-

12. Joule to Dancer, March 5th 1885; reprinted in “John Benjamin Dancer, F.R.A.S. 1812-1887. An Auto- biographical Sketch, with some Letters”, Foreword by W. Browning, Memoirs and Proceedings of the Manchester Literary and Philosophical Society (hereafter MLP), 107 (1964-1965): 115-142, 139. 13. ibid, p. 119. 14. Dalton displayed a vacuum thermometer and some illustrations of atomic models, Joule is seen next to an imaginary arrangement of his experiment on the determination of the mechanical equivalent of heat and with his new thermometer in hand. Dalton’s portrait is an engraving from Joseph Allen from the year 1814 (Courtesy of the Manchester Public Libraries), Joule’s portrait was made in 1863 and has been housed since the fire of 1941 in the Literary and Philosophical Society Manchester (the paddle wheel experiment is a patchwork from his first version and the one from 1850); Dancer’s portrait was taken from the original Daguerreotype by E.H. Duckworth and originally made in the Beard’s Gallery, Man- chester 1842.

SHIFTING SCALES came the key device in Ruhmkorff induction coils but was already being used by Joule in 1842.15 With his jars he was able to separate more conveniently the zinc and copper so- lutions in the Daniell cells and to get rid of the bladders and ox gullets which had been employed previously. His research concentrated on increasing the powers of the battery by crimping the copper plates to double the surface of the metallic surface which was acted on by the sulphate of copper solution. As the superintendants of the first Manchester telegraphic line of Messrs. Cook &Wheatstone connecting Victoria Station Strangeways with Miles Platting, he also developed telegraphic instruments and it is reasonable to argue that this work led to his construction of precision galvanometers.16 This historical background information reveals the faithfulness of this representation and Dancer’s wish to be regarded as an electrician. But soon after his start as superintendant of the telegraphic line and owner of an instrument making workshop in Manchester in 1842, he gave up the former post in order to concentrate fully on the improvement of instruments for research and the establishment of his instrument business. In the same year he became a member of the Manchester Lit- erary and Philosophical Society like the scientific brewer James Joule. Both were at that time forced to earn their livings through producing and selling commercial goods. Where- as Joule had to work eight hours a day in the family brewery and to pursue scientific research in his spare time, Dancer tried to concentrate on research fields of primary public interest in which he could bring together his expertise as instrument maker and his experience as researcher and teacher in natural philosophy. One of the first decisive research technologies he successfully offered his new audience in Manchester was his achromatic microscope, available in a quality and price (£ 7.40) unheard of in those days. Amongst others John Dalton received one and immediately the technology spread throughout the city and abroad.17 Dancer saw this device as a means to democratise scientific research which had been restricted to a small elite. In ac-

15. “John Benjamin Dancer, F.R.A.S. 1812-1887”, op.cit. (note 12), p. 123. 16. In 1847, William Thomson ordered one galvanometer right after his encounter with Joule at the BAAS meeting in Oxford. For the connection between electrical telegraphy and precision measurement see Si- mon Schaffer, “Late Victorian Metrology and its Instrumentation: A Manufactory of Ohms”, in Invisible Connections: Instruments, Institutions, and Science, eds. Susan Cozzens and Robert Budd (Bellingham 1992) 23-56; Bruce Hunt, “The Ohm is were the Art is: British Telegraphic Engineers and the Develop- ment of Electrical Standards”, Osiris, 9 (1994): 48-63. 17. In his autobiographical sketch Dancer states that he provided firstly Dalton with one of his devices. “Dr. J.P. Joule, the late Mr Joseph Sidebotham, and a host of other Scientific Gentlemen, ...were speedily dis- carded. Dr. W. Carpenter purchased some Microscopes for his pupils from Mr. Dancer.” John Benjamin Dancer, F.R.A.S. 1812-1887”, op.cit. (note 12), pp. 132-133. We have to distinguish between the early period of Dancer’s work in Manchester during which he was joined by his partner Abraham. After he left in 1845 Dancer not only altered his trade card but changed the design of his achromatic microscopes. The pioneer instructor John Quekett of the Royal College of surgeons used them and medical students at University College were supplied with the new device. Compare R.H Nuttall, “Microscopes for Man- chester”, Chemistry in Britain (March 1980): 132-135; J.T. Quekett, A Practical Treatise on the Use of the Microscope (London 1848).

H. OTTO SIBUM cord with the family tradition of instrument making and in particular through his fathers interest in improving the public understanding of science he saw this technology as a means to enable amateurs and lay people to take up research on their own and to partici- pate actively in science. Dancer was born in London where his father Josiah and grandfather Michael were well known scientific opticians and instrument makers.18 Josiah was apprenticed to his father and than had gained further experience in the famous York firm, Throughton and Simms, makers of large astronomical telescopes. Besides his craft Josiah was an “accom- plished linguist ‘proficient in Latin, Greek, Hebrew, Arabic and Egyptian’”, a public lecturer in physical science and astronomy and a musician playing the piano and organ.19 Together with Vaughan Yates Josiah was the main founder of the Liverpool Mechanics Institute and assisted in the foundation of the Liverpool Literary and Philosophical Soci- ety, where he lectured more than any other member. He himself supervised the education of his son in mathematics and classics. John Benjamin was taught the French language by a tutor. Traditionally, he became an apprentice to his father in order to learn how to grind lenses and to perform other workshop routines. But he was also an early assistant to his father’s extensive lecturing. This combination of developing artisanal skills in the instrument making world and his tremendous reading of scientific and classical literature together with a remarkably good memory made him an outstanding candidate for the improvement of science. Knowing very well from his fathers lecturing experiences how difficult it was to perform successful experiments in front of an audience whose interest in science had to be awakened Dancer was keen to provide new means for gaining “demonstrable truth in science”. But this aim natural philosophers were striving for stood in a complex relation to their practices and varieties of experience. And it is important to keep in mind: “Neither scientists nor lay people have experience, as it were, by itself: whenever experiments are performed and the results of empirical engagement with the world are reported and as- sessed, this is done within some system in which trust has been reposed and background knowledge taken for granted. When we have experience, we recognise it as experience- of-a-certain-sort only by virtue of a system of trust through which our existing state of

18. His grandfather was apprentice to Mr. Sangate, a favourite pupil of Jesse Ramsden (inventor of the de- viding engine) and the person who taught George III to use the lathe. 19. Henry Garnett, “John Benjamin Dancer; Instrument Maker and Inventor”, MLP 71 (1926-27): 7-20, 8. For further biographical material on Dancer see for example Michael Hallett, “John Benjamin Dancer 1812-1887: A perspective”, History of Photographic Journal 10, no.3 (1986): 237-255; “The Late Mr. J.B. Dancer”, (Obituary) The Manchester Guardian, (November 26, 1887): 98-99; L.L. Ardern, “John Benjamin Dancer”, Occasional papers No.2, Library Association, Reference, Special and Information Section, (London 1960): 1-19, 4.

SHIFTING SCALES knowledge has been built up.”20 In the republic of letters certainly literary technologies played a most important role in making the reader feel to have been an eyewitness of an actual experimental performance.21 But as I have shown elsewhere, in early Victorian England and particularly in the artisanal world, knowledge was most often derived from experience based on practical engagement with material objects, which led to faith in materials as much as to faith in human bearers of knowledge. Their performance of work constituted a different world of sense. Circulation of texts or illustrations were hardly sufficient to communicate this knowledge to the uninitiated. Furthermore during the first half of the nineteenth century the production of knowledge became more and more a private enterprise and the explorer’s complex practices and forms of experience often required sophisticated means to demonstrate their explorations in public. Comments on the first meetings of the BAAS give evidence for this conflict between the increasing specialisa- tion of knowledge production and the demands of communicating gestural knowledge amongst the new global republic of science. Here ever new practical and theoretical technologies were required but often violated the established system of trust because their use didn’t harmonise with the moral economy of the leading practitioners.22 As Simon Schaffer has shown in some detail astronomy and in particular the practice of astronomical drawing was one of these challenging fields of enquiry amongst early Victorian scientists. Although apparently an individual act of observation, the experience at the eyepiece of a telescope was based on the astronomers attention which was “not di- rected instantly to singular images but across prolonged series of pictures, techniques and personnel.”23 John Benjamin Dancer and his father were quite aware of this problem of providing demonstrable truth because as scientific opticians they knew of the limits in astronomical drawing as well as in its complementary field, the practice of micro physics which equally challenged the scientists’ perception and trust in established systems of knowledge. As an experimenter and experienced lecturer Dancer knew that certainty of knowledge relied on established practices and forms of sensuous experience in which the eye was an integral part and not superior to the unified human sensorium. New technologies like the achromatic microscope and Rosse’s telescope mediated latent images to the observers’ eye which immediately raised the issue of authenticity because it presented im-

20. Steven Shapin, A Social History of Truth. Civility and Science in Seventeenth-Century England (Chica- go 1994), p. 21. 21. For literary technologies see Steven Shapin and Simon Schaffer, Leviathan. and the Air-Pump. Hobbes, Boyle, and the Experimental Life (Princeton 1985). 22. For an example see Simon Schaffer, “Self-Evidence”, Critical Inquiry 18 (1992): 327-362. H. Otto Sibum, The Golden Number of the Century. The History of a Scientific Fact. Max Planck Institute for the History of Science, Preprint no. 174. Italian translation to appear in Quaderni Storici (2001). 23. Simon Schaffer, “On Astronomical drawing”, in Picturing Science, Producing Art, eds. Caroline A. Jones, Peter Galison and Amy Slaton (New York 1998) 441-474.

H. OTTO SIBUM ages of a world to which they had no sensuous access. In order to counteract sceptical views John Benjamin Dancer performed in 1841 an astounding experiment in front of an audience of 1,500 in Liverpool in which he linked the production of a microscopic image with new photographic techniques, the most con- vincing technology to guarantee authenticity, he thought. He magnified a flea by a gas microscope to 6 inch length and prepared on stage a photographic image of it on a silver plate. Even for people who already knew a bit about photography and its slow process this performance was in many ways a triumph

“when taking portraits from life by the aid of the Camera, fifteen or twenty minutes was sometimes required to produce the desired result. In 1840 when vapour of Bromine and Chlorine along with Iodine was employed to sensitise the silver surface a few seconds only was required to produce a good picture, in bright weather.”24

It is remarkable that he was able to perform these rather new and complex techniques with such ease in public,25 but Dancer’s competencies in producing precision instruments as well as his research on making Daguerreotypes and Calico types were extremely ad- vanced. However, it took a considerable time before this machinic production of “self- portraits of nature” changed the attitude of scientists from achieving verisimilitude to non- intervention in scientific practice — the core of “mechanical objectivity” which should replace the older ideal of “truth to nature”. The notion of mechanical objectivity as introduced by Lorraine Daston and Peter Galison addresses nicely the frame of problems Dancer faced. His previous research on electrotyping had already persuaded him of the possibility of expanding mechanical reproduction through electricity. Electrotyping was immediately used to produce thousands of identical objects.26 Therefore those machines certainly “provided a new model for the scale and perfection to which standardisation might strive”, but neither the audience nor the scientists themselves were walking on solid ground yet. A good example of the problems involved in establishing large scale production was recently presented by Nieto-Galan in his paper on standardising colours. It was partly the same group of Manchester scientists and industrialists whose artisanal expertise

24.”John Benjamin Dancer, F.R.A.S. 1812-1887”, op.cit. (note 12), p. 124. 25. The first photographs of this kind were produced just one year earlier by Daguerre and Niepce in France. Compare for example Victor Fouque, The Truth concerning the Invention of Photography. Nicèphore Niepce. His Life, Letters and Works (1867) reprinted (New York 1973). 26. Dancer engraved a copper plate with his initials and deposited a plating of copper on it by means of elec- troplating. After stripping off the plating the letters were clearly embossed. Henry Garnett, “John Ben- jamin Dancer; Instrument Maker and Inventor”, MLP 71 (1926/27): 7-20, 11. Lorraine Daston, Peter Galison, The Image of Objectivity, Representations 40 (Fall 1992): 81-127.

SHIFTING SCALES objected against the ideal that mechanical reproduction would faithfully replace the artisanal skills of producing dyestuff prints through machinery.27 If mechanical reproduction did not succeed in substituting artisanal skills, what would it then mean for displaying nature? One of the promising test cases to achieve “truth to nature” certainly would have been the production of a photographic image through a telescope, a scientific project which brought different members of the Manchester Literary and Philosophical Society like James Nasmyth and Joseph Sidebotham (1851) in close contact with Dancer. Sidebotham (Figure 3) was educated at Manchester Grammar school and became interested in mechanical science and natural history. He became an apprentice to the Calico Printers, Nelson & Knowles, and attended classes at the Mechanical Institute. It was Dancer who taught him the use of the microscope for his botanical studies. In 1846 at the age of twenty six he became the junior partner in the Calico Printing firm of Melland, Ap- pleby & Sidebotham.28 Already at the age of twenty two he became interested in astronomy and under the supervision of Dancer and Nasmyth he ground the mirrors for his own telescope.29 Sidebotham’s dyer’s craft gave him the status of the chemist in this collective.30 In calico printing mechanical reproduction of new patterns was a driving motive for the directors of the booming industrial firms, so also for Sidebotham. In 1838 “A calico-printer of Manchester... had between two and three thousand patterns designed, of which only about five hundred were selected for engraving”.31 Every means to economise this process was appreciated. Sidebotham’s various experiments to improve photogenic drawing, “a method of producing silhouette pictures by means of light acting on various chemicals of which silver nitrate was the most important” show that he tried hard to understand the still obstruse ways of “nature’s hand”. In this expanding collective of photographic researchers his expertise was very welcome. And indeed, in their experiments from 1849 on improving the production of an emulsion on glass that would allow a photographic image of high resolution Sidebotham’s experience with cotton textiles helped to find the right mixture for a clear adhesive emulsion. It was the waste cotton that was

27. Other examples are the introduction of the metronome in musical performances and the sliding rule in mensuration practices. 28. For further details see Harry Milligan, “Joseph Sidebotham. A Victorian Amateur Photographer”, The Photographic Journal (March/April 1978): 83-87, 83. 29. With regard to the contemporary research of astronomers like Herschel and the fact that Dancer and Nasmyth communicated with Herschel, Milligan’s assumption that this Manchester collective were driven by the idea to produce a photographic image through a telescope seems reasonable. 30. Also it seems as if Dancer saw himself as the technician as his microphotograph “The Technician” (Fig. 3) indicates. 31. Augusti Nieto-Galan, “The Standardisation of Colours in 19th Century Europe”, paper presented at the Centre de recherche en histoire des sciences et des techniques (May 1997): 24; Nieto-Galan, “Calico Printing and Chemical Knowledge in Lancashire in the Early Nineteenth Century: The Life and the Col- ours of John Mercer”, Annals of Science 54, no. 1 (1997): 1-28.

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Figure 3. J.B. Dancer, ‘The Technician’ [Possibly of Joseph Sidebotham], daguerreotype, ca. 1851, 85mm x 85mm (Greater Manchester Museum of Science and Industry). not suitable for spinning, called cotton linters.32 The scientific optician Dancer seemed to have been the father figure who had acquired the gestural knowledge to grind lenses, to produce photographic images within seconds, and to solve optical problems which occurred throughout the work. He was looking for a very fine medium on glass that would produce a clear photographic image of high resolution. The engineer with keen astronomical interests, James Nasmyth, would have liked to make use of a more sensitive technique to take astronomic pictures. In 1846 they began to work out the project. It was the amalgamation of these different knowledge traditions which led to the foundation of the Man- chester Photographic Society33 and a new sensitive emulsion on glass, a type of collodion

32. For further details about this neglected side of the discovery of the collodion process see Harry Milligan, ”Joseph Sidebotham...”, op.cit. (note 28). 33. It was founded in 1855 and included members like Roscoe, Frankland, Joule, John Graham, John Mer- cer, Joseph Sidebotham et al. compare H. Milligan, “New Light on Dancer” , MLP 115 (1972-73): 1-9, 6.

12 SHIFTING SCALES that was highly suitable for photographic applications, like Dancer’’s microphotography and Nasmyth’s picture of the moon.34 For Dancer the key to the problems of mechanical reproduction visible in the Figure 4. Microscopic slide (above) and image from slide (below). different fields of human production rested in the construction of reliable technologies of shifting scales. Already in 1839, he successfully began to reduce real objects into minute forms. His first working object was a twenty inch long bill which he reduced to one eighth of an inch. The production of this ”microphotograph” as he called it, was a dem- onstration of the power of human skill. But this image was still opaque and could not be viewed easily through the microscope. As he later recalled in his autobiography it was the size of the mercury particles which prevented him from producing much smaller precise Figure 4.1 . John Benjamin Dancer (1812-1887). Imag images. from microscopic slide (Photography by R. Suter. Phot by Courtesy of the McCormick Collection.) With the collodion process Dancer achieved his major breakthrough. In the two illustrations (Figures 4 and 4.1) you see to what extend Dancer was able to make use of this microscopic technique. The upper illustration displays a microscopic object mounted on a slide. The illustration at the bottom gives you the view through a microscope onto that sample. The person you view is Dancer himself, now portrayed as the scientific optician. In the next illustration you see the apparatus with which he was able to produce these microphotographs (Figure 5) and needless

34. The earliest remaining positive collodion taken before 1850, displays a group of “people of whom one, a Mr Brittain, died in February 1850. This photograph is what is known as a positive collodion in which the negative image produced within the camera is made to appear as a positive image by coating a black varnish on the back of the glass. Who took the picture we cannot say, but it is of interest that Mr Brittain was a near neighbour and friend of James Nasmyth....Nasmyth could contribute a picture of the Moon that must have been taken before 1852/53, and both Dancer and Sidebotham were making quite large images on glass at the same time”, Milligan, “Joseph Sidebotham...”, op.cit. (note 28), p. 86.

13 H. OTTO SIBUM

Figure 5. Dancer’s experimental set up to produce microphotographs. Description by Shadbolt (1857): “On the mode of producing extremely minute photographs for microscopic examination”, Journal of the Photo- graphic Society of London, 4, 78-81. a. Camphine (oil) lamp b. Condenser lens c. Condenser lens d. Negative e. Objective carried in substage f. Microscope´s ordinary objective used to check focus

(Contemporary illustration taken from Bracegirdle/ McCormick, op.cit.). to say these images of variouskinds became a best-seller in Victorian culture.35 But what I am interested in here is not his fame as the inventor of microphotography but the influ- ence this had on the development of scientific research, particularly in the 1840s — years of major changes in the physical sciences. First of all I will argue that Dancer’s technique was part of a broader program of producing reliable means to orientate in the new optical space which astronomers and micro physicists had began to open up. Enlarging minute objects so that they became visible to a huge audience as well as projecting images of macroscopic objects into the micro world was thrilling and frightening at one and the same time. Were these representations of real objects faithful at all or just illusions? The microscopic show-man who travelled through the country allowed lay people to see with their own eyes that beyond/within their world of sense there seemed to exist other worlds. Sometimes these worlds were inhabited by monstrous figures like the micro-organisms in Thames water which were depicted in a cartoon as “monster soup” (Figure 6) . For Dancer faith in latent images hinged on trust in the techniques of producing them. But although his ease in shifting scales was persuasive, the consequences it might have for the acquisition of new knowledge were still an issue. Neither in medicine nor in the physical sciences of the 1840s was achromatic microscopy yet fully accepted as a scientific instrument,36 because physicians still relied on sensuous experience which was part of their culture of science. The production of microscopic images continuously ran the risk of contradicting well-established knowledge about the nature of the human body.

35. Brian Bracegirdle, James B. Mc Cormick (eds.), The Microphotographs of J.B. Dancer (Chicago 1993); Marina Benjamin’s paper on the reception of Dancer’s microphotographs in Victorian England, “Sliding Scales: Microphotography and the Victorian Obsession with the Minuscule”, in Cultural Babbage: Technology, Time and Invention, eds. Francis Spufford and Jenny Uglow (London 1996) 99-122. 36. It was medical men like Edwin Quekett who founded the London Microscopical Society in his house in 1839 in order to promote the introduction and improvement of the microscope as a scientific instrument. Stella Butler, “Microscopy and Medicine” in The Social History of the Microscope, eds. Stella Butler, R.H. Nuttall and Olivia Brown (Cambridge 1986) 10-16. For the impact of achromatic lenses on the development of science see Miles Jackson, Spectrum of Belief. Joseph von Fraunhofer and the Craft of Precicion Optics (Cambridge, Mass. 2000).

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Dancer’s experience in producing optical devices of different kinds provided him with the background knowledge, the practices and forms of sensuous experience as well as a moral economy which together constituted a subculture of knowledge in which those images could be trusted.37 They were probably more plausible than the known analogies by which natural philosophers reason to what they might experience Figure 6. Caricature by W. Heath, 1828. “Monster Soup, commonly called Thames Water”. (Photo by on a far reaching scale. In order to control courtesy of the Wellcome Institute Library, London). micro- and macro events far beyond the scale of their immediate experience, Dancer showed that techniques of precision measurement and standardisation were the means to keep control over this optical space. It was his gestural knowledge in manipulating material objects with extreme accuracy that gave him confidence to trace and judge the movements of bodies in these optical spaces. He had applied it quite early in the 1840s to replicate Brownian motion experiments to con- tinue one of his father’s research projects and it should be mentioned here that he posed the hypothesis that movement “may possibly be connected with the absorption and radi- ation of heat.”38 Here we have identified a site of knowledge production in which the remapping of the tactile within a new optical space was practiced. But although scientists and lay people got more and more used to aligning their minds and bodies to images and graphs in the 1840s, it was still difficult for Dancer to make members of the republic of science trust the new optical perception which was based on shifting scales.39 As we have seen, only researchers who had the opportunity to visit his workshop and to experience first hand the quality of his instruments and the integrity of this gentleman collaborated closely with

37. For a use of the term subculture see Peter Galison, Image and Logic. The Material Culture of Micro- physics (Chicago 1997). 38. We do not know when he exactly performed these experiments but he published in 1868 a paper in which he states his thirty years engagement in these experiments and his confidence in his precise technologies. See Dancer, “Remarks on Molecular Activity as shown under the Microscope”, MLP, 7 (1868): 162-164; Stanely Jevons, “On the so-called Molecular Movements of Microscopic Particles”, MLP, 9 (1870): 78-84; see also the not by Daniel Deutsch, “Did Robert Brown observe Brownian Mo- tion: Probably Not” Bulletin of the American Physical Society 16 (1991): 1374, in which he questions the possibility of Robert Brown having been able to see anything like molecular motion on technical grounds. 39. On the changing techniques of the observer see Jonathan Crary, Techniques of the Observer. On Vision and Modernity in the Nineteenth Century. (Cambridge Mass. 1991), pp. 62-63. On the role of the graph- ical method in science and culture see Robert Michael Brain’s dissertation The Graphic Method. In- scription, Visualization, and Measurement in Nineteenth-Century Science and Culture (Los Angeles 1996).

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Dancer. Only later, with the production and dis- tribution of his microphotographs, did these im- pressive specimens of workmanship (Figure 7) lead scientists immediately to acknowledge Dancer’s craft and realised what potentials lay in this technique of shifting scales. David Brewster — who had “calculated that an ency- clopaedia of twenty volumes could, if reduced to the same dimensions, be easily carried in a purse”40 — suggested the use of this technique of reduction to produce a micro-grid which would allow the calibration of distant optical spaces against a fixed standard. Figure 7. Dancer microphotograph “112 Por- traits of Eminent Men”. (Arthur I. E. Barron Collection. Photo by Courtesy ot the McCor- “My Dear Mr. Dancer, In mick Collection). making some additions to the article Micrometer which I drew up many years ago for the Encyclopae- dia Britannica it occurred to me that micrometers, both for telescopes and microscopes, might be made with extreme accuracy by your process for reducing pictures or photographs upon Colloid. Upon examining your Microscopic Photographs of the Queen and Prince Albert I observe that the film of the collodion is so fine that objects are seen through it as distinctly as through glass even with very high powers. Hence a system of lines upon it will actually have the same appearance and properties as if they were suspended in the air. The most perfect Mi- cro metrical Scale both for telescopes and microscope may therefore be obtained by the reduction of single lines or system of lines.”41

A few month later Dancer indeed provided Brewster with such a “photographic micrometer” of which he had no doubt that it would be superior to all other position- and annular- micrometers. Although Dancer was known for having built a micro-meter machine, too, “capable of ruling lines with a diamond if required on glass to the ten-thousandth part of an inch” Brewster wrote that “gratings, as they are called when made for optical experi-

40. Joseph Sidebotham, “On Micro-Photography” Photographic Journal (April 15th, 1859) reprinted in L.L. Ardern, ”John Benjamin Dancer”, op.cit. (note 19), p. 4. 41. Brewster to Dancer, July 30th, 1857, reprinted in Dancer, ”John Benjamin Dancer, F.R.A.S. 1812- 1887”, op.cit. (note 12), p. 137.

16 SHIFTING SCALES ments, may be constructed from large drawings, when they could not possibly be made in any other way, and generally speaking whenever we want minute patterns of great accuracy they may be obtained by your process from large drawings.”42 James Joule applied the photographic micrometer to improve his experimental deter- minations of the earth’s magnetism. A very thin glass pointer was connected to a thread of 50 horizontally fixed metallic needles in such a way that this three inch long pointer was kept in balance. At the other end of the pointer the observer could detect small movements of the pointer through the microscope and calibrate it against the grid. Joule wrote “with divisions corresponding to 1/2000 inch each division indicates 34'' of arc.”43 With microphotography John Benjamin Dancer had provided an important instrument embodying a technique which we might call shifting scales, characteristic for his research. Besides this device he designed and produced another important tool which is today equally understood as having established the emerging visual culture of the 19th century — the stereoscope.44 As we will see the technique of shifting scales appears to be a common underlying structure in Joule’s experimental practice in particular and other sites of industrial production.45

A Frictional Moment

With regard to the developments described above the construction of Joule’s new sensitive mercury thermometer and its timing is telling in many respects. Why did Joule decide in the ﬁrst place to construct a new mercury thermometer despite the fact that air thermometers were taken as the most reliable standards? Why is it that he moved away from his electro-magnetical research in order to focus on heat and mechanical friction and their relation to each other? Why did he start the collaboration with Dancer at that time? This section will provide some answers. Generally speaking Joule hoped that his

42. Brewster to Dancer, September 3rd, 1857, see also letter to an unidentified person referring to Brews- ter’s request. Both letters are cited in “John Benjamin Dancer, F.R.A.S. 1812-1887”, op.cit. (note 12), pp. 137, 120. 43. Joule to William Thomson, March 1st, 1865, GUL., J 177. 44. Besides the works mentioned he collaborated with David Brewster and Charles Wheatstone on the perfection of the stereoscope. It was Dancer who finally designed the optimal camera with the lenses posi- tioned at eye distance. He was also successful in providing technologies of display for use in lectures. See Aldern collection on John Benjamin Dancer in Manchester Public Library manuscript collection. Compare Jonathan Crary’s study, “Techniques of the Observer”, op.cit., (note 39). 45. It is reasonable to link the emergence of techniques of visual communication with a broader cultural change in early Victorian England in which a new sensuous economy gets established. Sight becomes superior to other sensuous perceptions, see Sibum, “Reworking the Mechanical Value of Heat. Instru- ments of Precision and Gestures of Accuracy in Early Victorian England”, Studies in History and Phi- losophy of Science 26, no. 1 (1995): 73-106.

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”extreme sensitive” thermometer would do an equally excellent job of shifting scale, but this time shifting scale of observation into the micro realm of heat research. Most characteristic for early nineteenth century Manchester was certainly expanding machine culture and a widespread enthusiasm for the potential steam engine technology, the related regime of self-acting machinery and the railway system could offer.46 Even authors of natural philosophy books were mediating the promises of the machine age when reflecting on key issues like friction :

”Friction... It has been long known that it costs more force to drag a loaded wagon up one inconsiderable hill, than to send it thirty or forty miles along a level rail-road, but until lately this knowledge has scarcely been acted upon. The general introduction of such means of transport would effect a greater revolution and improvement in the state of society, than perhaps any other single circumstance that can be mentioned. (Without in reality changing the distances of places, it would have the effect of bringing all parts nearer to each other, and would give to the whole kingdom the conveniences of both town and country...) In a word, such a change would arise as if the whole of Britain had been compressed by magic into a circle of a few miles in diameter, yet without any single part losing the least of its magnitude of beauties and the sea would be but a little south of the metropolis, and Edinburgh but a little way north, and the mountains of Wales but a little way to the west.” 47

Indeed, friction became regarded as a key phenomenon prompting fantasies about the power of shifting scales of human experience through new technologies like the railway. But according to profession, respective opinions about friction were quite different. En- gineers as well as users of steam engines worked hard to study friction as a measure of work lost in mechanical processes. Armchair philosophers on the other hand still treated friction in their mechanical philosophy books as a mundane side-effect which should be kept at arms length from theory.

46. Benjamin Love, Manchester as it is. Or, Notices of the Institutions, Manufactures, Commerce, Rail- ways, etc of the Metropolis of Manufactures: interspersed with much Valuable Information Useful for the Resident and Sranger (Manchester 1839), Reprint 1971. 47. Neil Arnott, Elements of Physics, or Natural Philosophy, General and Medical, Explained Independ- ently of Technical Mathematics (London 1828), compare William Whewells account on friction in Wil- liam Whewell, First Principles of Mechanics (Cambridge, 1832).

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Heat was another key issue discussed in science and society. Understood as the prime mover of the ‘ministry of civilisation’ – as early Victorian machine culture was called – it was a more and more pressing phenomenon to understand in all its dimensions. Up to the 1840s most scholars treated heat as an immaterial substance, called caloric. A new regime of Cambridge-trained natural philosophers including William Thomson and others began to adopt French mathematics in which heat became even more obscure. In their mathematical equations heat gained the status of a quantitative term which did not require any explanation as to its nature. Not only engineers and natural philosophers but especially practicing brewers like Joule regarded “heat as nature’s first instrument”. His father’s brewing premise provided the most fertile ground to further investigate issues related to heat. As a young Mancunian Joule participated actively in these different worlds of work. And as the son of the wealthiest Manchester brewer he was in a position to choose freely research topics he thought of as most important. Living in this industrial environment it is not astonishing to see him begin to experiment on the question of self-moving forces in nature and their imitation through self-acting machinery. Although his research on the electro-magnetic engine was in the beginning a test of its economic feasibility, the machine gradually became a tool to investigate conversion processes of natural forces. While experimenting over the years Joule finally realised that

“we have therefore in magneto-electricity an agent capable by simple mechanical means of destroying or generating heat . In a subsequent part of this paper I shall make an attempt to connect heat with mechanical power in absolute numerical relations.”48

His electro-magnetic experiments had shown that the materiality of heat did not hold any longer because it could through mechanical means be destroyed or generated.49 Fur- thermore it showed that there exists an intimate connection between heat and the mechanical force by which it was produced. In a sense the machine had functioned as a displaying technology of effects when shifting between the micro- and the macroworld, between

48. Joule, On the Caloric Effects of Magneto-Electricity, and on the Mechanical Value of Heat”, in SPJ, vol. 1, pp. 123-159, on page 146, Italics by Joule. 49. It is important to mention here that caloric theory was already under attack by different researchers, particularily those who were in favor of the “wave theory of heat” which assumes that heat is the vibration of an etheraeal fluid that fills all space and which transmits vibrational motion from one atom to another. “By this time [1842-1850] the caloric theory was almost dead, and the wave theory of heat had already made it seem natural to treat heat as a form of mechanical energy.” Stephen G. Brush, “The Wave The- ory of Heat. A Forgotten Stage in the Transition from Caloric Theory to Thermodynamics”, The British Journal for the History of Science 5, no. 18 (1970): 143-167, 147. He argues that the most common argument that caloric theory was accepted until it was replaced by thermodynamics is a myth created by William Thomson himself.

19 H. OTTO SIBUM electro-chemical processes and the world of mechanical work. The unintended drift in the course of his early research finally not only provided Joule with an important empirical argument against the already declining theory of caloric, but also tempted him to make an important generalisation, namely that there exists an absolute numerical relationship between heat and mechanical work which was the beginning of Joule’s well known experimental series to determine the mechanical equivalent of heat. Within this period of research, starting in the late 1830s until 1844 he had particularily hoped to be able to en- lighten the dubious concept of latent heat.50 As John Forrester has convincingly shown, from the early 40s Joule wanted to persue a more sophisticated electro-chemical explan- atory framework to be able to unify the “study of electrical, chemical and calorific forces” through quantitative methods.51 Initially crediting electrical force with ontologically primary status, by 1844 Joule had enunciated the doctrine of the primacy of mechanical powers in the workings of nature based on his experiments in which heat is evolved by the passage of water through narrow tubes, and he wrote “I shall lose no time in repeating and extending these experiments, being satisfied that the grand agents of nature are, by the Creator’s fiat, indestructible; and that wherever mechanical force is expended, an exact equivalent of heat is always obtained.”52 This postscript to one of his papers has the mechanical equivalent of heat at its centre, a number which would allow Joule to “conceive that ultimately we shall be able to represent the whole phenomena of chemistry by exact numerical expressions, so as to be enabled to predict the existence and properties of new compounds.”53 This was the moment when Joule saw clearly that current conflicting opinions about the nature of heat and friction could be resolved. At this point, Joule realised that he had gained sufficient empirical evidence to support the argument that on the microscopic level there existed an intimate connection between heat and mechanical force — they were, in fact, convertible. So he could publish an attack on the caloric theory. But in order to be able to establish the mechanical value of heat as an absolute measure, he had to demon-

50. Already in 1841 Joule regarded electrical force as the primary force in nature and tried to come to an electrical definition of latent heat. In a lengthy paper “On the electric origin of the heat of combustion” he stated “we have proof that some of the effects which are usually referred to “latent heat” are in fact nothing more than the recondite operations of resistance to the electric current. In a future paper I hope to extend my inquiry, and also to show the relation of latent heat to electrical intensity”, James Joule, “On the Electric Origin of the Heat of Combustion”, read before the Literary and Philosophical Society of Manchester (November 2, 1841) reprinted in SPJ, vol. 1, pp. 81-102, 96, 107. 51. John Forrester, “Chemistry and the Conservation of Energy: The Work of James Prescott Joule”, Studies in History and Philosophy of Science, 6, no. 4 (1975): 273-313, 280. 52. Postscript to Joule, “On the Caloric Effect of Magneto-Electricity, and on the Mechanical Value of Heat”, read at BAAS meeting at Cork, 21st August, 1843, reprinted in SPJ, vol. 1, pp. 123-159, 157/ 158. 53. ibid, p. 158.

20 SHIFTING SCALES strate that this numerical fact existed independently of materials and procedures employed in his experiments. The vexed subject in this endeavour was still heat, or to be more precise the practices of measuring heat. Without going into detail about the minute steps Joule took to extend the meaning of this number for estimating all natural forces it is reasonable to argue that with his new most sensitive thermometer he hoped to gain further empirical data about the microscopic nature of heat. In 1844, when he began to work with Dancer, he was at his height of establishing a unifying microscopic theory of powers in nature which he based on mechanical force as the primary force in nature and the mechanical equivalent of heat.54 His theoretical and practical studies of latent and specific heats, as well as of gas expansions, seemed to him the most rewarding explorations which would demonstrate not only the superiority of his experimental practice but also that his microscopic view of the nature of heat was based on solid grounds. He wanted to link practical measurements and calculations to concepts, and with his new thermometric practices and his dynamical theory of heat he was convinced he had established the scientific view that heat was a mode of motion. But everything hinged on exact temperature measurements and Joule appeared to be the person who had the experience. “With the practised experience I have since attained I think I could make evident any difference [ in temperature, O.S.] if it existed.”55 Joule was right, reading temperatures on this scale required more than good eyesight. Not only did Joule have to develop his gestural knowledge to perform properly with this device, he also had to know what particular indications of the mercury level meant. Furthermore he had to trust the materials used for constructing the device, the person’s gestural knowledge who made the precision instruments to calibrate the thermometer, and he had to pos- ses a background knowledge about heat in order to judge the functioning of the device. Except for his trust in Dancer’s and his own workmanship, nearly all the practices of heat measurements within the exact sciences were heavily under attack. For example, comparisons of thermometer readings caused serious troubles. Readings of two instruments made by the same maker could show differences in indication of one to one and a half degree Fahrenheit:

“When the Kew Committee commenced its work it was no uncommon thing to find thermometers put forth by the best instrument makers of

54. See the title of the first draft of his 1847 lecture, held at St. Anne’s Church called “Theory of Mechanical Powers”, Joule papers, UMIST, 55. Joule to Thomson, 7 November 1848, letter in which he discussed the experiment from 1845 on the rarefaction and condensation of air with regard to repeat it at a different temperature level. “I am anxious to try my old experiments on the condensation of air again and will endeavour to find whether there is any difference in the results obtained at 32 and those at 50”, CUL, Add 7342 J63.

21 H. OTTO SIBUM

beautiful workmanship and large cost, but which could not be trusted within a degree or a degree and a half Fahrenheit.”56

Clearly in the years before Kew took up the standardisation of thermometers, the common thermometer indications did not match the standards of Joule’s research, whose heat experiments showed minute differences of nearly half a degree Fahrenheit. German glass blowers regarded this lack of quality as an effect of the decline of the craft world whose members now had to do their job only for securing their living and not for improving the art.

“Daß das Thermometer ein Instrument ist, welches die Wärme und Kälte anzeigt, ist Jedermann bekannt. Da aber unter der großen Menge dieser Art Instrumenten sehr wenige gefunden werden, die dasjenige wirklich leisten, wofür man sie ausgibt, dieses bestätigt die Erfahrung. Wollen wir die Ursachen untersuchen, so liegt es vornehmlich daran, daß die Verfertiger in ihrer Kunst sehr verschieden sind, und dann, wenn auch einige darunter sind, die darinnen recht erfahren, so sind sie jedoch gezwungen, davon zu leben, mithin werden eine Menge solcher Instrumente gemacht, die nur um Brot sollen umgesetzt werden; von denen es sodann mit Recht heißet; wie die Arbeit so der Lohn.”57

Furthermore the practice of reducing arbitrary scale readings to an agreed standard of measure — usually the air thermometer — was shaken in its fundaments through disa- greements about the validity of physical laws like that of the different expansions of gases “discovered by Gay Lussac & Dalton.”58 The conflict about accurately measured values indicated a frictional moment in the development of the exact sciences and the physics of heat in particular. The far-reaching dimensions are nicely reflected in controversies about the different practices of determining the mechanical equivalent. Joule’s correspondence about the well known priority dispute with the German physician Julius Robert Mayer is quite enlightening in this respect. From

56. William Thomson, “Protocol National Conference of Electricians”, Baltimore, Sept 10, 1884, JHU, Henry Rowland papers. 57. A.A.G.(anonymous), “Die Glasschmelzkunst bei der Lampe, oder Anweisung ,wie aus Glasröhren und Bruchstücken von weißem und gefärbtem Glase verschiedene zur Chemie, Physik und Technik erforder- liche geräthschaften, auch allerlei Figuren, Wettergläser, Augen für ausgestopfte Tiere und Vögel, Emalien und andere Kleinigkeiten verfertigt werden können. Für Chemiker, Naturforscher, Emailleure und Goldarbeiter, Gewerbsleute, Dilettanten und die gebildete Jugend des reiferen Alters herausgege- ben von einem praktischen Glaskünstler A.A.G.” (Brünn 1824), pp. 37-38. 58. Student notes from William Thomson’s lecture “Experimental Course on Heat”, Lecture XXII, Dec. 4th 1849, GUL, Kelvin papers.

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Joule’s point of view, Mayer’s claim of the existence of the mechanical equivalent of heat was “mere speculation” and only his own work was “research”. In order to understand why Joule and other British scientists could regard Mayer’s work as speculative and “pre- scientific” and to judge the specificity of Joule’s experimental practice with its peculiar moral values it is important to know that he based his whole argument of the existence and the value of the mechanical equivalent of heat on the assumption that a constant expansion coefficient for all gases existed. The concept of the expansion coefficient, however, was one of the major concerns amongst natural philosophers in France, England and Germany up to 1840. By taking for granted the constancy of this coefficient, Mayer neglected completely this research problem which was tackled in the field of thermometry. Although for nearly forty years this number had been regarded as “eine der sichersten Zahlen der Physik” new criticism arose through several researchers (Regnault, Rudberg, Magnus). The final value was then suggested by Regnault but he also concluded that the expansion coefficient was not exactly the same for all gases and therefore the Gay-Lussac law was not generalisable.59 Magnus rightly reminded his readers that this conflict in values would make it difficult to take the expansion of air as the measure of temperature which was practised since the works of Dulong and Petit. This redetermination of the value of the expansion coefficient had several consequences: a practical one, the then used air thermometer as the French standard was questioned again and it fell back onto the same level as the mercury thermometer whose workings according to Regnault “are more or less a complicated function of heat increases.”60 The theoretical implication was also expressed by Regnault that we are still lacking “the means to measure absolute quantity of heat and with regard to this current conditions of our knowledge we have little hope to discover simple laws of those phenomena which depend on these measures.” From this perspective it seems obvious that Poggendorff, the editor of Poggendorff’s Annalen, was hesitant to publish Mayer’s first account on the mechanical equivalent of heat in which he didn’t even mention experiments but just claimed that heat could be transformed into motion, and that thermal or material expansion was its phenomenological evidence.61 It seems that Poggendorff decided to keep the paper until he knew more clearly what the outcome of the controversy about the reliable measure of thermal expansion would be. But finally he refused to publish at all.

59. Victor Regnault, “Untersuchung über die Ausdehnung der Gase”, Poggendorff’s Annalen der Physik und der Chemie 55 (1842): 391-414 and 557-585. 60. Regnault, ”Über den Vergleich des Luftthermometers mit dem Quecksilberthermometer”, in Poggen- dorff’s Annalen der Physik und der Chemie 57, (1842): 199-218, p. 218. 61. Mayer, “Über quantitative und qualitative Bestimmung der Kräfte” sent to editor of Poggendorff’s An- nalen on June 16, 1841, not published; later found in Friedrich Zöllner’s ”Nachlass” published in Julius Robert Mayer, Die Mechanik der Wärme. Sämtliche Schriften, ed. Hans Peter Münzenmayer, (Heil- bronn 1978).

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In Manchester, Joule certainly could not have known of Poggendorff’s hesitations but he was well informed about the French literature — Victor Regnault’s publications — and his own experience in reducing temperature readings on an arbitrary scale to the standard of the air thermometer made him an equally competent person to judge these matters.62 And indeed he critiqued the lack of knowledge about specific heat and the problem of determining reliably absolute quantities of heat. As we have mentioned, during the course of various experiments during the 1840s Joule had finally shifted his interest away from electro-chemical arrangements to set-ups in which mechanical friction of water could be studied. He had identified them as the key arrangements to establish a unified theory of powers in which mechanical force had finally become the ontologically primary force in nature. Concepts like specific and latent heat had to be re-interpreted, and during this series of experiments to determine the effects of the friction of fluids he rejected the macroscopic caloric theory of heat. With his microscopic view based on the technique of shifting scales he regarded friction as the conversion of mechanical force into heat. The use of his new thermometer with its microscopic powers allowed him to detect latent mechanisms of intercourse between natural forces and “again and again latent heat was held up as an exemplar of the links between chemical and physical heat, between chemical and mechanical forces, and between micro- and macro-levels of explanation.”63 He employed the sensitive thermometer firstly in his research “on the changes of temperature produced by the rarefaction and condensation of air” in which he stated “our knowledge of the specific heat of elastic fluids is of such an uncertain character, that we should not be justified in attempting to deduce from them the absolute quantity of heat evolved or absorbed”.64 He wanted to provide a mechanical explanation of this anomalous behaviour observable in the transformation of bodies by establishing a dynamical microscopic description in which the materiality of heat, i.e. caloric, had to be displaced. He even further developed his microscopic view of heat into a complete mechanical model of nature’s microcosmic machine (Figure 8). In an illustration, Joule had sketched his atomic model while preparing for a lecture to be held in Manchester in the year 1847. However, he never made use of this illustration in public demonstrations although he regarded it as being founded on solid empirical grounds. As John Forrester has pointed out, his early experiments on the electro motor from 1843 served as the visualisation of conversion of mechanical force into heat and this image became the ingredient for his rota

62. See Joule’s extensive comparisons of thermometer readings in his Laboratory Book 1843-58, Joule papers, UMIST. 63. John Forrester, ”Chemistry and the Conservation of Energy”, op.cit. (note 51), p. 294. 64. Joule, ”On the Changes of Temperature”, op cit. (note 10), p. 174.

24 SHIFTING SCALES tional theory of heat as depicted in this illustration of rotating circles.65 When Joule had dropped his electrical theory of chemical heat he retained the rotational model in order to be able to make a distinction between latent and sensible heat. The rotation of the atmospheres represented sensible heat which he had identified already in 1845 with vis viva.66 The space between the atoms causing them to attract one another with greater distance, was latent heat.

“Suppose now a number of fine cords to be rolled around each of these atoms and to pass over a wheel. It is evident that the force of the atoms will be diminished in winding up the weight W. This diminution of the velocity of the atoms is what we generally call a diminution of temperatures, which Figure 8. James Joule’s latent machine, we have already shown, occurs drawing of his atomic model of heat, whenever heat is applied to raise a 1847, first draft of St. Ann’s lecture. Pho- 67 to by courtesy of the University of Man- weight.” chester Institute of Science and Technology. While preparing for his lecture in 1847 he envisaged this dynamical theory of heat which broke with the concept of caloric and preferred to regard heat as a mode of motion. The latent relation between force and heat became explicit in his definition of friction as a conversion of mechanical force into heat. When mechanical force became heat at the macro- level the corresponding change at the micro-level was from a macroscopic motion of matter to a microscopic rotational motion of atoms.

65. He took the two main elements for his model on the one hand from Faraday’s insight that each atom is associated with the same absolute quantity of electricity and on the other hand from Humphrey Davy’s hypothesis of rotary motion. Compare Joule, SPJ, vol. 1, pp. 122, 291: “In 1844 he proposed that mo- mentum of electrical atmospheres surrounding the atom constituted caloric, and the velocity of their cir- cumferences determined temperature. The electrical matter that defined chemical character was thus also the seat of motion that constituted heat”; Forrester, ”Chemistry and the Conservation of Energy”, op.cit. (note 51), pp. 294-96. 66. “Assuming that the expansion of elastic fluids on the removal of pressure is owing to the centrifugal force of revolving atmospheres of electricity, we can easily estimate the absolute quantity of heat in matter. For inelastic fluids the pressure will be proportional to the square of the velocity of the revolving atmospheres, and vis viva of the atmospheres will be proportional to the square of their velocity”, James P. Joule, ”On the Existence of an Equivalent between Heat and Ordinary Forms of Mechanical Power”, (1845), SPJ, vol. 1, pp. 202-205, 204. 67. First draft manuscript of Joule’s lecture given at Manchester in St. Ann’s Church, 1847, op.cit., (note 54).

25 H. OTTO SIBUM

Although Joule did not present this illustration to the public it was this local context of experience that Joule implicitly referred to when publicly saying during his lecture that in mechanical friction we ”lose sight” of the macroscopic force for a time but we find it again reproduced.

“Experiment has enabled us to answer these questions in a satisfactory manner; for it has shown, that, wherever living force is apparently destroyed, an equivalent is produced which in process of time may be re- converted into living force. This equivalent is heat. Experiment has shown that wherever living force is apparently destroyed or absorbed, heat is produced. The most frequent way in which living force is converted into heat is by means of friction.”68

By Means of Performance: Towards the New Physics of Work

The period between 1844 and 1850 was certainly a phase of major transformation within the physical sciences and different practices of shifting scales were visible not only in Dancer’s and Joule’s virtuosity in changing experimental arrangements. In the same year that Joule was working with Dancer on improving the material conditions of heat research the Cambridge educated Wrangler and Professor of Natural Philosophy of Glasgow, Wil- liam Thomson, was enjoying Regnaults’ laboratory life in Paris. During a visit he experienced first hand how this master of precision measurement practised thermometry. Although Thomson equally practised a technique of shifting scales his encounter with Regnault in his laboratory led to a completely different contribution to practical thermometry, the creation of an absolute thermometric scale founded on Carnot’s theory of the motive power of heat and calculated from Regnault’s observations.69 With the expression “absolute” he meant a definition of temperature independent from any material substance and that this scale would apply “to the measurement of temperatures the idea of absolute measurement that he had developed for electricity in 1845.”70 By means of employing the engineering concept of the machine he intended to reduce not only the theoretical entity called electricity but now heat equally to practical measure.

68. Joule, ”On Matter, Living Force, and Heat” op.cit. (note 2), p. 269. 69. William Thomson, ”On an Absolute Thermometric Scale founded on Carnot’s Theory of the Motive Power of Heat, and calculated from Regnault’s Observations”, Philosophical Magazine, 33, no. 3 (1848): 313 – 317, reprinted in William Thomson, Mathematical and Physical Papers vol. 1 (Cam- bridge 1882-1911) pp. 100-106. 70. For more details see M. Norton Wise, Crosby Smith, “Measurement, Work and Industry in Lord Kel- vin’s Britain”, Historical Studies in the Physical Sciences 17, part 1 (1986): 147-173, 158/59.

26 SHIFTING SCALES

Although we still need further details about this specific encounter it is possible to in- fer from a close consideration of his education the course Thomson’s research took. If we look at the educational practices of physics teaching during the 1840s we will see that leading British physicists were going to import new techniques of mathematical physics from France. For the natural sciences it was William Thomson who had begun to employ a mathematical technique to transform the analysis of action at a distance into terms suitable for contiguous action. This link of practical calculation and measurements to concepts was based on a method which Norton Wise has identified as the transformation of a microscopic description into a macroscopic description. “Microscopic means having in- visibly fine grained structure, while macroscopic means without structure, even at the level of infinitesimal. Taken physically, molecular theory is microscopic and continuum theory is macroscopic; but in a broader sense, macroscopic does not necessary imply anything about physical reality. A macroscopic description refers to the techniques of either smoothing over or ignoring microscopic structure and then reducing the smoothed result to infinitesimal regions, assuming in the process that the smoothed description remains valid.”71 Without repeating here the details of this important move within British mathematical physics it is sufficient to emphasise that Thomson prepared grounds to treat electricity, magnetism and heat as single entities which did not have to be discussed regarding their physical reality anymore. For him Fourier’s theory of heat was exemplarily in this respect and he took Fourier’s analytical practice as his key technique. At the age of fifteen he had already studied major French works of Lagrange, Poisson and Laplace and therefore was the ideal candidate to develop further mathematical physics along those lines. “From Fourier and the continuity equation Thomson learned something significant about mathematical theory: it need not be complex and it need not rely on a detailed physical picture such as Poisson’s radiated and absorbed caloric. Fourier emphasised that the nature of heat was not at issue in his calculation; heat might be caloric fluid or it might be a communicated motion of some kind. His equations would remain the same.”72 Thom- son’s plan to establish a dynamical theory of heat was founded on this idea of a geomet- rical description of the behaviour of any matter, his engineering concept of an engine and the idea of precision (absolute) measurement. According to this Cambridge education and its emphasis on the “training of the mind”, Thomson had acquired a gestural knowledge which differed greatly from that of men like Joule or Dancer whose knowledge was in the first place derived from manipulating practical technologies.73 Joule’s experiments per-

71. M. Norton Wise, “The Flow Analogy to Electricity and Magnetism, Part I: William Thomson’s Refor- mulation of Action at a Distance”, Archive for the History of Exact Sciences 25, no.1 (1981): 21-70, 23. 72. M. Norton Wise, ”William Thomson’s Mathematical Route to Energy Conservation: A Case Study of the Role of Mathematics in Concept Formation”, Historical Studies in the Physical and Biological Sci- ences , 10 (1979): 49-83, 56.

27 H. OTTO SIBUM formed with accuracy required a sensuous economy which differed from the Cambridge Wrangler’s tact. William Thomson, equally keen in performing with speed and accuracy had learned to modify, create and apply masterly theoretical technologies74 in order to provide faithful descriptions of natural phenomena. However, both were trying to unify the varieties of scientific studies on natural forces through suitable abstractions from the concrete, but each form of gestural knowledge acquired through long continuous practice led them to different standards which guided their reasoning. As we see in Joule’s case, he was much more willing to break with theoretically accepted rules and concepts when his performance of a series of experimental arrangements would demonstrate a reproduc- ible phenomenon.75 Thomson on the other hand would have most likely prefered performing an elegant mathematical proce- dure which would unify disparate fields of research instead of investigating particulars. The latters technique of shifting scales had supported him in imagining the new physics of work in which the nature of heat wasn’t an issue at all, it could be caloric or a mode of motion. However, by doing so and despite his own competences in experimental inquiries he missed out

Figure 9. Original conclusion of Joule´s paper from Joule’s important insight into the dynami- 1850. (Photo by courtesy of the Royal Society Lon- cal nature of heat which the latter had es- don). tablished within his small knowledge collective but wasn’t able to get credit for from the leading natural philosophers of the 1840s.76 Moreover , the response by the Royal Society to Joule’s submitted paper on the determination of the mechanical equivalent of heat (submitted 1849, published 1850) was not fully positive. In the original draft (Figure 9) Joule concluded

73. For the encounter between experimenters and theoreticians see Sibum, “Working Experiments: A history of Gestural Knowledge”, op.cit. (note 6), pp. 25-37, 33-36. 74. For the concept of theoretical technologies see Andrew Warwick, “Cambridge Mathematics and Cav- endish Physics: Cunningham, Campbell, and Einstein’s Relativity, 1905-1911”, Studies in History and Phislosophy of Science 23 (1992): 635-656. 75. Forrester has shown in detail how Joule’s experimental arrangements over the period of 1841 to 1847 have led to extreme conceptual changes about the nature of specific heat and the primacy of forces in nature. Forrester, “Chemistry and the Conservation of Energy”, op.cit (note 51), pp. 293-301. 76. The similarity in underlying structure in both practices might have been one reason why Thomson took up close collaboration with Joule.

28 SHIFTING SCALES

“It will therefrom I think be admitted, and demonstrated by the experiments contained in this paper, - 1st. That the quantity of heat produced by the friction of bodies, whether solid or liquid, is always proportional and equivalent to the quantity of force expended... 2nd. That friction consists in the conversion of force into heat. I consider that 779.692, the equivalent derived from the friction of water, is the most correct, both on account of the number of experiments tried, and the great capacity of the apparatus fro heat. And since even in fluid friction it was impossible entirely to avoid vibrations and the production of a slight sound I prefer to state in round numbers as the result of the research, That the quantity of heat capable of increasing the temperature of a lb of water (weighed in vacuo and taken at between 55 and 60) by one degree Fahr., is equal to the mechanical force represented by the pressure of 772 lbs through the space of one foot.”77

The paper was considered to be published only on condition of altering the conclusion which runs as follows:

“I will therefore conclude by considering it as demonstrated by the experiments contained in this paper, - 1st. That the quantity of heat produced by the friction of bodies, whether solid or liquid, is always proportional to the quantity of force expended. And 2nd. That the quantity of heat capable of increasing the temperature of a pound of water (weighed in vacuo, and taken at between 55 and 60) by 1 Fahr. requires for its evolution the expenditure of a mechanical force represented by the fall of 772 lb. through the space of one foot.”78

Joule had agreed to take out his second conclusion that friction consists of the conversion of mechanical force into heat in order to get it printed after all but he wrote to the Cam- bridge don George Gabriel Stokes:

77. Joule’s original draft of “On the Mechanical Equivalent of Heat” (1850) held at the Royal Society archive, London. PT.37.3. 78. James Joule, “On the Mechanical Equivalent of Heat”, (1850), SPJ, vol. 1, pp. 298-328, on p. 328.

29 H. OTTO SIBUM

“I beg your acceptance of the enclosed paper in which I have endeav- oured to determine the mechanical equivalent of Heat with accuracy. The result at which I conceived I had arrived was that Friction consists in the conversion of Force into Heat; but the Committee of the R.S. having disapproved of such a deduction from the experiments I thought it best to withdraw it, although I think this view will ultimately be found to be the correct one.”79

Joule’s context of experience as outlined above had convinced him that his microscopic theory of heat was right. But the resistance to accept his views in print indicates how local Joule’s knowledge space still was. Since his performance in 1847 at the Oxford BAAS meeting a few but influential natural philosophers like George Stokes, William Thomson and Michael Faraday gradually began to engage with his work. In July 1847 Joule wrote to Stokes:

“I inferred from conversation with you that you are entirely in favour of the mechanical theory of heat. I hope to see labours of yours in the same direction. I have not unfortunately had opportunities of studying mathematics sufficiently to follow the subjects in the mathematical depart- ment .”80

Unfortunately the experimentalist Joule did not fully understand neither Stokes nor Thomson’s mathematical world of physics. But he was prepared to collaborate and take up suggestions about further modes of repeating the experiments on the friction of fluids in order to establish firmly his mechanical theory. Stokes like Faraday probably suggested further modes of replication:

“I am at present engaged in getting up an apparatus made of wrought iron in order to repeat the experiment on friction of fluid with mercury. I am not sure that this form of the expt. was not suggested by yourself or whether it has not presently occurred to myself. If the former is true I should be glad to know. I intend also to repeat the expt. with friction of metal against metal as suggested by Faraday but do not expect to ob- tain more heat at thereby.”81

79. Joule to Stokes, July 3rd, 1850, CUL, Add. 7656 J75. 80. Joule to Stokes, July 10th, 1847, CUL Add. 7656, J 73. 81. Joule to Stokes, July 10th, 1847, CUL Add. 7656, J 73.

30 SHIFTING SCALES

But despite these first fruitful collaborations Joule still had experienced the power of the established community of natural philosophers not willing to accept any speculation about the microscopic nature of heat.82 Joule’s local knowledge that “friction consists in the conversion of force into heat” had emerged at the intersection of different local knowledge traditions at Manchester. But in order that it got scientifically accepted further in- tense collaboration with William Thomson was required who finally regarded Joule’s experiments on the friction of fluids as the key to unlock nature’s hidden machinery and to establish the new physics of work.83

82. For a detailed study of Faraday’s referee report on Joule’s paper see Crosby Smith, ”Faraday as referee of Joule’s Royal Society paper ‘On the mechanical equivalent of heat‘”, ISIS 67 (1976): 444-449. 83. The experiments which led to the well known Joule-Thomson effect have their origins in this encounter of two knowledge traditions. See in particular M. Norton Wise, ”William Thomson’s Mathematical Route to Energy Conservation”, op.cit., pp. 49-83; Crosby Smith and M. Norton Wise, Energy & Em- pire, (Cambridge 1989), pp. 302-316, and Christian Sichau, Der Joule-Thomson Effekt. Der Versuch einer Replikation. Physics Diploma Thesis, University of Oldenburg, 1995.