ON THE PHYSICAT. VIEW OF NATURE. 



I.S9 



The exposition of Helmhollz, liDwever, does nol seem to 

 have been understood or accepted. The general recog- 

 nition of the relation of active and latent forces dates 

 rather from Thomson's and liankine's writint's in 18;")! 

 and the following years. Thomson uses the term 

 "mechanical energy" (later, from 1851, intrinsic 

 energy, or simply energy), and considers this quantity 

 to be a measure of the store of power to do work 

 which a material system possesses ; ^ and Itankine,' 

 early in 1858, introduces and defines the terms actual 

 (or sensible) energy and potential (or latent) energy, 29. 

 which are at once adopted by Thomson^ in the place tiai' and 



^ "^ '^ "actual' 



of the terms dynamical and statical energy, which he t-nerKy. 



^ The memoir of Thomson in 

 which he introduces the physical 

 conception of the quantity "energy" 

 in the place of a merely mathema- 

 tical symbol used by Clausius, and 

 inaugurates the terminology of 

 modern physics, is contained in 

 the ' Transactions of the Royal 

 Society of Edinburgh,' vol. xx.. 

 Part 3 (read December 15, 1851, 

 and reprinted in ' Math, and Phys. 

 Papers,' vol. i. p. 222), as an ap- 

 pendix to the great paper "On the 

 Dynamical Theory of Heat, with 

 Numerical Results deduced from 

 Mr Joule's Equivalent of a Thermal 

 Unit, and M. Regnault's Observa- 

 tions on Steam" (Trans. Kdinb. 

 Soc, March 1851 : reprinted in 

 'Phil. Mag.,' 1852, and '.Math, 

 and Phy.s. Pajiers,' vol. i. p. 174 

 tqq. ; see especially p. 186, note). 

 The term energy had indeed been 

 used by Thomson already in 1849 

 as a synonym for mechanical effect, 

 but he had not then accepted 

 the dynamical theory. He merely 

 puts the question in a footnote to 

 his exposition of Cariiot's theory : 

 " When thermal agency is . . . 



spent, what becomes i>f the 

 meclianical etiect which it might 

 produce ? Nothing can be lost in 

 the operations of nature — no energy 

 can be destroyed " (' Papers,' vol. i. 

 p. 118, 1849). 



• In a paper read before the 

 Philosophiciil Society of Gln-sgow, 

 January 5, 1853, reprinted in 

 'Miscellaneous Scientific Papers,' 

 ed. Millar, p. 203 sf/r/. See also 

 Rankine's note, dated 1864, in the 

 28tii vol. of the 4th series of the 

 ' Phil. Mag.,' p. 404. 



•* See the Proceedings of the 

 Glasgow Philos. Soc, January 

 1853, reprinted with additions 

 from Nichol's ' Cyclopa-dia ' (1860) 

 in ' Math, and Phys. Papers,' vol. 

 i. p. 521. In this j)a])er Thomson 

 also introduces the term '" electrical 

 capacity" of a conductor. Thom- 

 son subsequently introduced the 

 word " kinetic " in place of " actual " 

 energy. See also Thomson's Lec- 

 ture before the Royal Institution, 

 February '29, 1856, rojirinted in 

 ' Math, and I'iiys. PajK-r.t,' vol. ii. p. 

 182, and ' Pojiular lectures,' vol. 

 ii. p. 418, especially the note U) p. 



