Machinery and processes of the industrial arts, and apparatus of the exact sciences . In this change the temperature rises through as many degrees asit fell during the second period; and the same amount of heat whichthen seemed to disappear now makes its re-appearance. The work donewith positive effect in one of these two stages balances that which isexpended unprofitably in the other ; so that the amount which is finallyavailable for use is the difference between the work which is performedduring the expansion in the first stage and that which is consumed inthe compression which takes place i
Machinery and processes of the industrial arts, and apparatus of the exact sciences . In this change the temperature rises through as many degrees asit fell during the second period; and the same amount of heat whichthen seemed to disappear now makes its re-appearance. The work donewith positive effect in one of these two stages balances that which isexpended unprofitably in the other ; so that the amount which is finallyavailable for use is the difference between the work which is performedduring the expansion in the first stage and that which is consumed inthe compression which takes place in the third. And this, as we haveseen, is measured by the heat received from the fire, diminished by theheat imparted to the refrigerator. The foregoing propositions may be visibly illustrated by means of asimple geometrical figure. If we suppose a body of air, or other elasticmedium, to be confined in a cylinder between the closed extremity anda movable piston, the distance between this extremity and the pistonwill be always proportional to the volume. In the annexed figure let O. Fig. I. be the closed extremity of the supposed cylinder, and A7, B7, C7, D7, posi-tions occupied by the movable piston at the end of the successive stagesof expansion and compression which we have supposed the air toundergo. Then let AA7, BB7, CO7, DD7 be perpendiculars proportionalto the pressure exerted by the air upon the piston at those several first stage of expansion is represented by the movement of the pistonfrom A7 to B7, during which the temperature is constant, and the pres-sure falls off gradually. The work which is done during this period isproportional to the area ABB7A7. The second stage of expansion cor-responds to the movement of the piston from B7 to C7. During this periodno heat is supplied by the source, and the temperature falls. The pres-sure also diminishes more rapidly than before, and the work doneis proportional to the area BC07B7. The first stage of compressiono
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Keywords: ., bookcentury1800, booksubjectmachinery, booksubjectscientificappa
