DISCOVERY OF DISSIPATION OF ENERGY. 1 23 



wherein the confusing error lay, he was able to reconcile 

 what was true in the old with the new theory. 



The last note shows how strong was the temptation 

 upon Sir William Thomson to dismiss Carnot's theory as 

 erroneous in the same way as Joule had dismissed the 

 hypothesis of caloric without seeing that he had really 

 established it on a rational foundation. To the fact that 

 Thomson resisted this temptation we undoubtedly owe the 

 maintenance of Carnot's theory as constituting, together 

 with Joule's law, the only perfectly general foundation for the 

 science of thermodynamics ; and perhaps, more important 

 still, it was as the solution to his doubts that Sir William 

 Thomson was led to perceive the general tendency of the 

 energy in the universe to "dissipation," until all action ceases,, 

 and a uniform temperature prevails. 



This grand generalisation, expressed as the "universal ten- 

 dency in nature to the dissipation of energy," though distinct 

 from the law of the universal conservation of energy, which 

 Joule had exposed, was a necessary complement to reconcile 

 the former with the observed phenomena of nature. In his 

 exposition of his law Joule had said, " Nothing is lost," and, 

 in the time of his doubt, Thomson had repeated, " Nothing 

 can be lost in the operations of nature — no energy is lost ; " 

 experience all the same showed that something was lost,, 

 and as the solution of his doubts, Thomson finds some- 

 thing is lost, — not energy, but concentration of energy. 



In December, 1849, there was presented to the Royal 

 Society of Edinburgh, a paper by William John Macquorn 

 Rankine, on " The Mechanical Action of Heat, especially in 

 the case of Gases and Vapours." As Rankine was then only 

 known as a promising young engineer, 29 years of age,, 

 this paper, containing as it did the complete mathematical 



