70 



MOTIVE POWER OF HEAT. 



operations above described, it is reduced to the fol- 

 lowing : 



(1) Contact of the gas confined in abed (Fig. 2) 

 with the body A, passage of the piston from cd to ef. 



(2) Eemoval of the body A, contact of the gas 

 confined in abef with the body B, return of the 

 piston from efto cd. 



(3) Removal of the body B, contact of the gas 

 with the body A, passage of the piston from cd to 

 ef, that is, repetition of the first period, and so on. 



The motive power resulting from the ensemble 

 of operations 1 and 2 will evidently be the differ- 

 ence between that which is produced by the expan- 

 sion of the gas while it is at the temperature of the 

 body A, and that which is consumed to compress 

 this gas while it is at the temperature of the 

 body B. 



