The theory of glaciers

Abstract

The years from 1840 to 1870 were amongst the most fruitful and turbulent in the history of physics, for they divide the obscurities of the early part of the century from the elegant classical physics of the latter part. The foundation of this rapid development was the principle of conservation of energy, ‘the grand doctrine of our own generation’, as Tait called it (1). The credit for its discovery was generally ascribed to Joule, until in 1862 John Tyndall, at the Royal Institution, sponsored the claim of the German physician J. R. Mayer. This claim led to a famous controversy between Tyndall and the Scottish Professors, Thomson of Glasgow and Tait of Edinburgh, who upheld the claim of Joule (2). The purpose of this article is to trace the origin of this controversy in an earlier one over the structure and flow of glaciers, which divided British physicists for nearly twenty years, and to show why this specialized branch of science was so important to those who were developing the mechanical theory of heat. The complicated story is best unravelled chronologically. It is tempting to start with the twenty-year argument between Count Rumford, the founder of the Royal Institution, and Sir John Leslie of Edinburgh, over their work on radiant heat (3). However, in spite of a coincidence of places, it is unlikely that this had any bearing on the later disputes. A more realistic starting point is 1 April 1831, when Faraday lectured at the Royal Institution on the subject of Musical Rockers (4). (If a hot bar is placed across two thin blocks of metal then it may rock to-and-fro, emitting a musical note.) In his audience was a twenty-one year old student of Leslie’s, James David Forbes (4, 5). When Leslie, who had also been interested in this phenomenon, died the next year, Forbes was elected to his chair (6). He took up the study of musical rockers, but his subsequent paper (7) was wrong on almost every matter of fact.