ON THK PHYSICAL VIKW UK .NATCKK. 131 



low temperature. By doing work, as also by conduction, 

 and radiation with absorption, this inequality of tempera- 

 ture is spent, i.e., lost. Clausius and Thomson alone 

 seem to have grasped the value of this conception. The 

 difficulty was to put it into mathematical language — 

 into calculable terms. Each did tiiis independently. 

 Thomson, more than any other thinker, put the problem 

 into common-sense language, brought the subject home 

 to the practical reason ; at the same time he put it into 

 mathematical language, allowing the conceptions of waste ^ 

 and of value and of availability (or usefulness) of energy 

 to be scientifically — that is, measurably — defined. In 

 1851 he put the axiom upon which Carnot's reasoning 

 is based (without knowing the words of Carnot quoted 

 above) into the following words : ^ "It is impossible by 

 means of inanimate material agency to derive mechanical 

 effect from any portion of matter by cooling it below 

 the temperature of the coldest of the surrounding objects." 

 He saw at once, when adopting Joule's doctrine of the 

 convertibility of heat and mechanical work, that, if all 

 processes in the world l)e reduced to those of a perfect 



' The term "wasted," as distiu- 

 guished from "annihilated," is first 

 introduced in Part 1 of the "Dyn- 

 amical Theory of Heat," 18.51, p. 

 189 of 'Math, and Phys. Papers,' 

 vol. i. ; and in the following year, 

 in a paper read before the Royal 

 Society of Edinburgh on the 19th of 

 April, entitled, " On a Universal 

 Tendency in Nature to the Dissipa- 

 tion of Mechanical Energy," the 

 8uV)ject is brought home to the 

 general understanding by a succes- 

 sioa of short theses referring to 



the dissipation and possible limited ' eternal death. 



restoration of energy (' Papers,' vol. 

 i. p. 511, &c. ) 



■■^ 'Math, and Phys. Papers,' vol. 

 i. pp. 179, 511. Helndioltz ('Vor- 

 triige und Reden,' vol. i. p. 43) said 

 in 1854 : " In any case we must 

 admire the acumen of Thomson, 

 who could read between the letters 

 of a mathematical equation, for 

 some time known, which spoke 

 only of heat, volume, and press- 

 ure of bodies, c<inclusi()iis which 

 tlireaten the universe, thuugh in- 

 deed only in infinite time, with 



