ioo POPULAR SCIENCE MONTHLY 



Mayer's failure to secure recognition from the scientific public 

 found its counterpart on a smaller scale with Joule and Helmholtz. 



Joule was the son of a wealthy brewer. In 1830 he saw the first 

 trains which traveled between Liverpool and Manchester. One of the 

 happy circumstances of his boyhood life was his connection with John 

 Dalton and Dalton's laboratory containing effective home apparatus. 

 His association with Dalton gave direction to his constructive genius. 

 Joule's father fixed up a room for a chemical laboratory. Before the 

 boy was of age he began experimentation in chemistry and electricity. 



After laborious tests he succeeded in showing that the heat 

 developed by the union of two chemical elements effected in a bat- 

 tery is the same as that developed by combustion, and that the heat 

 has a definite equivalent in the electromotive force between these 

 elements. 10 He studied the relations between electrical, chemical 

 and mechanical effects and was led to the great discovery of the 

 mechanical equivalent of heat. In a paper read before the British 

 Association in 1843 he gave the number as 460 kilogrammeters. This 

 was only one year after Mayer had published his first paper. Friends 

 who recognized the physicist in the young brewer persuaded him to 

 become a candidate for the professorship of natural philosophy at 

 St. Andrews, Scotland, but his slight personal deformity was an objec- 

 tion in the eyes of one of the electors and he did not receive the 

 appointment. 



The early papers of Joule attracted little attention. His facts 

 were so novel, so apparently heterodox, and the language in which 

 they were conveyed so unfamiliar, that the older physicists permitted 

 them to remain without due consideration. Faraday was then busy 

 with his experimental researches. Graham was studying the diffusion 

 of gases. Wheatstone, Whewell, Herschel, Forbes, Airy were engrossed 

 with problems of their own. Those who were first to applaud Joule a 

 few years later were still pupils. William Thomson and Gabriel 

 Stokes were at Cambridge; Bankine, a youth of 22, was studying engi- 

 neering; Tait was a boy at school; Clerk Maxwell had just acquired 

 the nickname of " Dafty " at Edinburgh Academy. In 1844 a paper 

 of Joule, " On the Changes of Temperature produced by the Baref ac- 

 tion and Condensation of Air," was rejected for publication by the 

 Boyal Society, but was printed in the Philosophical Magazine the year 

 following. 11 



In April, 1847, Joule gave a popular lecture in Manchester, deliv- 

 ering the first full and clear exposition in England of the universal 

 conservation of that principle now called energy. 12 



10 "Memoir of James Preseott Joule," by Osborne Reynolds, 1892, p. 50. 



11 Reynolds, op. cit., p. 78. 



12 Reynolds, op. cit., pp. 104, 105. 



