The First Law Of Thermodynamics: 2. The Joule–Mayer Controversy

Abstract

Two pioneering scientists are associated with the formulation of the first law of thermo dynamics, James Prescott Joule and Julius Robert Mayer. There are two distinct aspects to their contributions: the actual statement of the equivalence of heat and work, and the experimental justification for that statement. In terms of the former, Mayer and Joule independently made that statement, Mayer a year or so earlier than Joule. In terms of the latter, Joule carried out a scientifically superb range of experiments allowing him to quantify accurately the mechanical equivalent of heat. To begin with, both had very great problems in gaining acceptance from their peers. Joule was ultimately successful, in large measure due to the strong support of Kelvin. Mayer, on the other hand, had the bitter experience of never gaining that acceptance in his lifetime. The situation was exacerbated by the heated controversy initiated by John Tyndall and the biologically oriented X-Club. In strong opposition to the thermodynamic community, they not only maintained the historical precedence of Mayer over Joule but were derogatory to Joule’s contributions. In this chapter, it will be shown that at the time the controversy was unnecessary. Moreover, scientific history, while fully crediting Joule, has been kind to Mayer, in the presentday use of the expression ‘the Mayer–Joule Principle’.