During the course of the nineteenth century Watt's chemical work and its importance to his improvements of the steam engine were effectively obscured. There was a significant disjunction between public characterizations of Watt in the late eighteenth and very early nineteenth centuries and those extant by the early twentieth. As Watt's early reputation developed and grew, contemporary sources frequently identified him as a chemist and recognized the relevance of his chemical work to the steam engine improvements. By the early twentieth century, however, Watt's chemistry had passed from view. This is readily seen in the events and publications that celebrated the one-hundredth anniversary of his death in 1919 and the two hundredth anniversary of his birth in 1936. So, by some process, during the course of the nineteenth century the recognition of the chemical basis of Watt's steam engine improvements, especially of the first phase of them involving the separate condenser, evaporated. What was that process?

A central element in this process was the ‘water controversy’ concerning whether Watt, Cavendish or Lavoisier should be recognized as the discoverer of the compound nature of water. I have examined this controversy, and the forces that drove it, in considerable detail elsewhere. In this chapter I focus on the way in which the controversy, together with Watt's ‘self-fashioning’ in the later years of his life, radically transformed Watt's chemical reputation and in particular determined the extent to which he was recognized as a chemist at all.

Watt engaged in considerable recasting of his achievement in the years between about 1800 and his death in 1819. During the very early nineteenth century important investigations were being conducted which began to question the material theory of heat, and, even more acutely, the role of heat as a chemical substance. These were key ideas upon which Watt had built his original understanding of steam and of the steam engine. More particularly, from around 1790, a number of investigators, including Agustin de Bétancourt, Gaspard de Prony and John Dalton, conducted and published steam experiments, which in terms of methods, results and interpretation presented challenges to Watt's own.

There are two ways in which the centrality of the chemistry of heat, water and steam to Watt's steam engine improvements can be discerned. One, which will be pursued later in this chapter, is to reconstruct in a technical sense – building on what we now know about Watt's chemistry – the conceptual world in which, and through which, Watt's thinking about the steam engine took place. A second is to gain an appreciation of what we might call the ‘ecology of steam’. By this I mean the broader chemical cosmology, embracing meteorology and geology, of which steam and the steam engine were a part, for Watt and his contemporaries. I start with the wider chemical picture.

The Ecology of Steam: Meteorology, Geology and The Botanic Garden

Newcomen engines are known as ‘atmospheric’ engines. This is because the drive on the piston is provided by the atmosphere working against the partial vacuum created in the cylinder by the condensation of the steam. But there was, and is, a deeper sense in which steam engines were atmospheric engines even when Watt put the steam itself to work in driving the piston. The engines were seen as trading on processes that were ubiquitous in the natural world and responsible for other atmospheric and geological phenomena. Meteorological and geological understandings were thus important to the science of heat and steam that underpinned the steam engine. Those who thought about steam and the steam engine sought, and found, coherences between phenomena in the realm of engines, meteorology and geology. Indeed, I suggest that a steam engine was sometimes thought of as a kind of local corralling of the wild forces of nature. In the twentieth century nuclear physicists sometimes spoke about the act of deploying nuclear forces to provide energy via nuclear reactors as ‘twisting the tail of the dragon’. I believe that the same sense of domesticating a wild phenomenon attended eighteenth-century steam engine technology. The steam engine in the eighteenth-century landscape was, not just aesthetically, but also ecologically, part of what went on around it.

The chemists of the nineteenth century did not embrace Watt as one of their number, but the case was very different with its engineers. In fact not only did the engineers ‘pull’ Watt into their company but the chemists, and other elite scientists, as we saw, ‘pushed’ him in that direction. Watt was, according to the likes of James David Forbes, an indifferent chemist but a ‘profound’ engineer. He was characterized as a ‘philosophical engineer’ because of his understanding, command and use of physical law.

My argument in this chapter is that Watt was made into an ‘engineer’ in the nineteenth century – perhaps it would be better to say ‘engineers’ since he was constructed as multiple manifestations of the type during that period. The implication of this process of construction is that Watt was not an engineer in the late eighteenth century, during his own lifetime. To divest Watt of the status of engineer may seem perverse and I do not mean this literally. His contemporaries often referred to Watt, and he designated himself, as an engineer. Indeed, ‘James Watt, Engineer’ was the extended identifier that he used in his published papers in the Philosophical Transactions of the Royal Society of London. His collaborative publication on pneumatic medicine with Thomas Beddoes used the same phrase on the title page. But it is only apparently perverse to problematize this self-identification because the term ‘engineer’ underwent a remarkable evolution from the mid-eighteenth century to the end of the nineteenth. In understanding Watt's self-designation as ‘engineer’ we need to understand, I suggest, what that term meant in his own time. Having done that we can then comprehend something of the way that Watt habitually presented himself to the world, and how he sought to negotiate the ambiguous status that ‘engineer’ then brought with it. For Watt was no ordinary engineer, and he and his friends wanted to make that clear.

James Watt was certainly a ‘man o’ pairts’, but he was also a coherent whole. For too long our historical understanding of him has emphasized the many parts, seeing the whole only dimly, if at all. By pursuing the links between his practical and theoretical work I have tried to set this to rights. Watt was an engineer. He was certainly an expert, as J. D. Forbes put it in his discussions of these questions, at contrivance. Forbes admired Watt's invention of the parallel motion as showing Watt's genius for contrivance, but he argued that this in itself would never have been the basis for ‘reputation’. Watt's reputation derived from his quality as a philosophic engineer. I have argued that what gave his engineering its philosophic quality or dimension was largely chemical in character. Watt was a chemist, whose chemistry of heat provided the philosophical dimension to his engineering. That philosophical dimension was very different from the equivalent dimension of what became known in the mid-nineteenth century as ‘engineering science’. In engineering science heat was understood as a form of energy, convertible into other forms according to the fundamental laws of thermodynamics. All this was foreign to the intellectual world that Watt inhabited. However, because Watt was adopted as an icon and founding father of their field, the engineering scientists of the nineteenth century were not averse to smoothing over some of the differences between his world and theirs. Watt the chemist and engineer became Watt the mechanical engineer.

In my early chapters I showed how popular representation of Watt, which became a minor industry itself in the nineteenth century, presented the mechanical Watt. This was a natural and easy thing to do given the association of Watt in the popular mind with contrivance. The products of that genius for contrivance, or so it seemed, were everywhere in Victorian Britain, the engines, the linkage and control mechanisms to convert the power of those engines into useful work, the indicators designed to monitor, measure and adjust their performance.

Introduction

Later nineteenth-century histories of the steam engine were most often written by practising engineers and scientists. They exhibited the common tendency of practitioners to write ‘Whig’ history, that is, to interpret past historical actors and actions in modern terms. This genre of literature, then, assimilated Watt to the modern traditions and conceptions of thermodynamics. In its turn this later nineteenth-century literature has left its mark on modern historical writings.

I am concerned in this chapter with two processes of assimilation of Watt to thermodynamics. The first involves conceptual assimilation of Watt to mid-nineteenth-century understandings of ‘energy’. A typical example of conceptual assimilation is an essay by Keith J. Laidler, which presents Watt and his engine as practical progenitors of that science. Certainly the steam engine was an important resource for those developing thermodynamic understandings. But to picture Watt and his engine ‘pushing’ in that direction is problematic. Even sophisticated and nuanced treatments of the issue fall into a similar trap. The eminent historian of technology, Donald Cardwell, implicitly placed the work of Black and Watt on heat into a tradition of the ‘physics’ of heat, a line leading to the ‘Rise of Thermodynamics’. I have already argued that the excellent and detailed account of the origins of Watt's key invention by Richard L. Hills is also on dangerous territory when deploying the concept of the ‘perfect engine’ in telling that history. Although the term does come from Watt's own accounts of how he arrived at his invention, and therefore must in some sense be reliable, what the term meant to Watt is all too easily lost sight of and elided into later visualizations of ideal heat engines that every modern student learns about as the basis of thermodynamics. The second process of assimilation involved the steam indicator, a device that, because of its mid-nineteenth-century involvement with thermodynamic theory, was often taken as some kind of natural bridge between that theory and Watt, who invented the instrument. As I will show, the rather mysterious, chequered and just plain misunderstood, history of this device encouraged a ‘telescoping’ of its later and early history.

By way of introduction I need to do two things. The first is to provide a historical outline of the life of James Watt, a general overview that will assist in situating my specific, and rather specialized, argument about the centrality of chemistry to his life and work. The second is to explain the structure and the strategy of my study, as well as some of the basic assumptions that underlie it.

The ‘Great Steamer’ – A Life Outlined

James Watt, who the geologist Roderick Murchison referred to in 1839, with a peculiar mixture of deference, affection and condescension, as ‘the Great Steamer’, had been born just over a hundred years earlier, in 1736, to a moderately prosperous merchant family in Greenock, a small town on the lower reaches of the River Clyde, near Glasgow in Scotland. Watt's paternal grandfather was a ‘professor’ of mathematics, teaching that subject and navigation in a community dominated increasingly in the mid-eighteenth century by maritime trade. Watt's father was a ships’ chandler and general merchant. While Watt's elder brother John entered the family business – he was lost at sea on a merchant venture – the family was prosperous enough to invest in an informal apprenticeship for Watt to the London-based instrument maker John Morgan. The young Watt's time in London was undoubtedly difficult. He worked exceedingly hard and suffered problems with his health. But the experience opened up for him a world of instruments, skills and trade that profoundly shaped his later career.

The next step in that career was Watt's establishment as an instrument-maker at the University of Glasgow, within the confines of the College. Though Watt certainly did make and repair instruments for the professorate of the College he also engaged in a more general trade in musical instruments and fancy toys. In the early days he was also an agent for his father's business and plied the general hardware trade. By all accounts, as a child Watt had been studious and thoughtful, though his education at the local grammar school had been badly interrupted by health problems.

I argued in Chapter 2 that the realities of Watt's chemical work and understandings were obscured in the nineteenth century by his own narratives of his invention, and by the ‘water controversy’. In the latter, elite scientists, such as members of the Cambridge group and the leadership of the Chemical Society, sided with Cavendish and condemned Watt's chemistry as archaic, more of a stain on his reputation than a valuable addition to it. Watt's supporters, on the other hand, made their claim for their hero in a way that artificially and incidentally modernized the nature of his chemical claims and arguments (as well as Cavendish's). It remains a difficult task to understand Watt's chemistry on its own terms, but in this chapter I will make an attempt. I am guided by a conviction that it is a mistake to separate in an a priori fashion, as authors usually do, Watt's philosophical (or theoretical) chemistry and his practical chemistry. That mistake is probably predicated also on the belief that Watt failed as a chemical theorist (that is in his public venture into the chemistry of water and airs), while still doing interesting things as an ingenious ‘cookbook chemist’ with glazes, varnishes, inks, bleaching agents, medically promising airs and, of course, steam.

The bifurcated approach to Watt's chemistry is misleading on two counts. First, a number of Watt's practical ventures did draw upon his theoretical ideas. Second, there is a good case for seeing Watt's chemical ideas as in turn evolving as a result of his practical engagements. We will see in detail in this chapter and the next that Watt's experiments on steam, undertaken in part to inform his attack on the practical problem of steam engine improvement led him to develop a chemistry of heat that went beyond that of his mentor Joseph Black. Watt was thoroughly convinced that there was a connection between the chemistry of steam and the chemistry of airs. In fact ice, water, steam, mist, water vapour, common air and other airs were all subject to the chemistry of heat and their practical and theoretical study was interrelated as a result.