operations above described, it is reduced to the following:
(1) Contact of the gas confined in abcd (Fig. 2) with the body A, passage of the piston from cd to ef.
Fig. 2. Fig. 3.
(2) Removal of the body A, contact of the gas confined in abef with the body B, return of the piston from ef to 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 difference between that which is produced by the expansion 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.
