Testing Power and Trust: The Steam Indicator, the ‘Reynolds Controversy’, and the Relations of Engineering Science and Practice in Late Nineteenth-Century Britain

Abstract

The steam-engine indicator has become at once the tool of a trade and the instrument of a science. The operating engineer employs it to perfect the adjustment of valves and to measure power, the physicist to investigate thermodynamic transfers and to trace the cycle of the heat engine. It is to steam engineering at once the commercial scale and the chemical balance.Frederick Rollins Low, 18981INTRODUCTIONThe steam indicator is one of the most important but relatively uncelebrated instruments of nineteenth-century science and manufacturing. I was startled when, one cold early morning in Greenock, just outside Glasgow, I first discovered it represented in a piece of public statuary (Figure 1). The statue in question stands outside what was formerly the Watt Memorial Engineering and Navigation School. The School was opened, and the statue unveiled, by Andrew Carnegie in June 1908 before a crowd of local worthies, representatives of the engineering community, and Clydeside workers (Figure 2). Many if not most of the audience on that occasion, unlike the modern passer-by, would have recognized the device thrust forward in Watt's right hand. They would, however, have attached a range of different meanings to it. We know that Archibald Barr, Professor of Civil Engineering and Mechanics at the University of Glasgow, was present, representing his institution. For Barr the indicator would signify one of the triumphs of modern engineering science - the development of the science of thermodynamics, in which his former colleague William Thomson (Baron Kelvin of Largs), and W J. M. Rankine, a previous occupant of Barr's chair, had played such a significant part. The 'indicator diagram' , that is the trace produced by this instrument when attached to the cylinder of a working steam engine, had become a central conceptual, and pedagogical, tool in the science of thermodynamics. The top-hatted manufacturers and ship-builders, and the flat-capped working engineers, in the crowd would have recognized a device of day-to-day importance and familiarity in the testing, adjustment and modification of the steam engines that powered their factories, their ships, and their locomotives.The indicator was thus as F R. Low described it - both a scientific instrument and a practical piece of technology. Its dual nature produced a tension between, on the one hand, the view that the operation and use of the indicator could be represented and governed scientifically, and on the other hand, the belief that its full meaning and maximum advantage in use were only realized in the hands of a working engineer who brought tacit knowledge and understanding - skill - to its deployment. Writings about the steam indicator in the nineteenth century, especially the numerous manuals produced for working engineers as a guide to its use, frequently referred to the indicator as the steam engineer's 'stethoscope', that is as a tool used in skilled diagnosis. This tension represented in microcosm the more general issue of the relations of laboratory and workshop in industry. Representatives of engineering science based in university laboratories pushed toward scientific control, or claimed superior knowledge, of industrial processes. However, industrialists, industrial engineers, and skilled workmen sometimes resisted or sought to attenuate these moves on the grounds that the scientific approach was too abstract and out of touch with the realities of the industrial world to be allowed too much influence within it.In what follows I first trace the early development of the indicator, its gradual emergence from the secrecy in which it was cloaked initially in the workshops of Boulton, Watt & Co. to be a widely used instrument, produced by a number of manufacturers and the subject of periodic improvement and design changes. These changes had a great deal to do with the evolution of the steam engine itself, its expanding uses, and the problems encountered in those uses. …