HISTORY OF THE CONSERVATION OF ENERGY 99 



In 1858 a few voices were heard in Germany in praise of Mayer, 

 but the one who did most to bring him historical justice was John 

 Tvndall, who in 1862 lectured before the Eoyal Institution on Robert 

 Mayer. 7 I shall remain silent on the extremely bitter controversy, 

 between Tvndall and Tait, regarding Mayer's researches. 8 Tait and 

 William Thomson placed a low estimate on Mayer's work and brought 

 the charge that Tvndall, by praising Mayer, was belittling the work of 

 Joule. One would suppose that gross historical errors would have 

 been eliminated by this time from a subject like the conservation of 

 energy, about which so much has been written. Such is not the case. 

 Professor E. T. Glazebrook, writing in the great " Dictionary of 

 National Biography" (article, "Joule"), said in 1892, just before 

 the publication of Mayer's correspondence, that Mayer in 1842 en- 

 deavored to measure the heat produced in the compression of air, but 

 committed the very serious mistake of assuming without experimental 

 evidence that " all the mechanical energy spent in compressing the air 

 was used in producing change of temperature." This same criticism 

 was passed upon Mayer by Joule, Tait and Helmholtz. A funda- 

 mental question is here involved, but the charge is not true. As early 

 as September 12, 1841, in a. letter to his friend Professor Baur, Mayer 

 explained Gay-Lussac's experiment of 1807 on the flow of gas into a 

 vacuum, and drew upon it to complete his argument on the equivalence 

 of the work of compression and the heat generated by the compression. 

 Gay-Lussac had found that when a gas expands into a vacuum it under- 

 goes no change in temperature large enough to be detected by his 

 thermometers. Hence, during compression practically all the work 

 done upon the gas goes to produce change of temperature, and Mayer's 

 argument is sound. That the criticism of Mayer's reasoning is invalid 

 is not generally known to recent writers on the subject, but can now 

 be verified by any one who will examine Mayer's collected works and 

 letters, edited by Weyrauch in 1893. 9 It should be added, however, 

 that Mayer himself is partly to blame for the strictures passed upon his 

 paper of 1812. Gay-Lussac is not mentioned and the whole matter is 

 disposed of in a single sentence, though that sentence, we admit, is 

 somewhat Germanic in its structure and linear dimensions. 



publications became known, consult " Die Mechanische Warmetheorie," von R. 

 Clausius, dritte umgearbeitete und vervollstandigte Auflage, Erster Band, 

 Braunschweig, 1887, pp. 394-403. 



7 Proceedings of the Royal Institution, June, 1862; Philosophical Magazine, 

 Vol. 24, p. 57. 



8 See Thomson and Tait's article in the Philosophical Magazine, April, 1863, 

 and various articles by them and Tyndall in Vols. 25 and 26 of the Philosoph- 

 ical Magazine, as well as translations into English of Mayer's papers. 



9 "Kleinere Schriften u. Briefe," p. 131; " Mechanik der Warme," pp. 53, 

 130, 269. 



