20 WILSON 



ART. C 



stant volume, pressure varying with the temperature, give best 

 results. Clausius in his 1850 memoir brought order into the sub- 

 ject of thermodynamics — with references to Clausius in the 

 original and in translations, and to Maxwell's Theory of Heat. 



Lecture II. Heat capacity (specific heat) at constant pres- 

 sure and at constant volume. Work, dW = pdv. Relation 

 between heat and work — first and second laws of thermody- 

 namics. We take the second law first (Carnot's law). Carnot 

 was a French army officer, son of a minister of war. He pub- 

 lished his results at about 28 years of age. His father was also 

 a mathematician and wrote on geometry and mechanics. (He 

 was uncle of the late President Carnot. ) Carnot's father named 

 him Sadi after the Persian poet. Carnot's results meant an im- 

 portant question solved and interpreted.* The Carnot cycle or 

 Carnot engine, a reversible cyclic process: Given a cyHnder im- 

 pervious to heat, except for the bottom which is a perfect con- 

 ductor, filled with some medium (as air). Given a large hot 

 and a large cold reservoir at assigned temperatures. Place the 

 cylinder on the cold reservoir until the medium has taken the 

 temperature of that. Carry out the following process. (1) 

 Insulate the cylinder and compress the medium until the tem- 

 perature has risen to that of the hot reservoir and then place 

 the cylinder in contact with this reservoir. (2) Decompress 

 the medium while the cylinder remains in contact with the 

 reservoir thus absorbing heat and doing work at constant tem- 

 perature. (3) Insulate and further decompress the medium 

 until the temperature is lowered to that of the cold reservoir. 

 (4) Place the cylinder in contact with the cold reservoir and 

 compress to original volume. The result of the process is that 

 some heat has been removed from the hot reservoir, som» has 

 been given to the cold reservoir, and some external work has 

 been done. 



Lecture III. Carnot's law: The same results are obtained 

 with any medium when working between the same temperatures, 

 or all reversible engines are exactly equivalent between the same 



* The class notes of Mr. Hewes, carefully written up, show that Gibbs 

 did not think it infra dig. to go into interesting bits of scientific history. 



