A sketch for a history of early thermodynamics

Accounts of the origins of the first and second laws of thermodynamics follow a fairly standard pattern. The caloric theory of heat, we are told, assumed that heat was a fluid endowed with a number of properties, among them indestructibility. The cannon‐boring experiments of Rumford (1798) and the ice‐rubbing experiment of Davy (1799) destroyed the basis of the caloric theory because they showed that heat could be created by the expenditure of work. A full half‐century elapsed, however, before Joule repeated and extended Rumford’s experiments and measured the conversion factor J accurately with his paddle wheels. In the meantime (in 1824) Carnot formulated the second law of thermodynamics and drew many valid conclusions about the efficiency of heat engines though his ideas were based on the caloric theory. Kelvin came across Carnot’s work, as rewritten by Clapeyron; he became convinced of its truth and because it was based on the caloric theory he found it difficult to accept Joule’s results. However, by 1850 both Kelvin and Clausius had formulated the first and second laws as we know them now. In retrospect, the caloric theory of heat seemed to have been slightly ridiculous.