A history of the growth of the steam-engine . ork,has an exponent less than unity, and which, when doingwork by expanding behind a piston, partially condenses, thevalue of X increases to, in the case of steam, accordingto Rankine, or, probably more correctly, to or more,according to Zeuner and Grashof. This fact has an im-portant bearing upon the theory of the steam-engine, andwe are indebted to Rankine for the first complete treatiseon that theory as thus modified. Prof. Rankine began his investigations as early as 1849,at which time he proposed his theory of the molecular con-sti
A history of the growth of the steam-engine . ork,has an exponent less than unity, and which, when doingwork by expanding behind a piston, partially condenses, thevalue of X increases to, in the case of steam, accordingto Rankine, or, probably more correctly, to or more,according to Zeuner and Grashof. This fact has an im-portant bearing upon the theory of the steam-engine, andwe are indebted to Rankine for the first complete treatiseon that theory as thus modified. Prof. Rankine began his investigations as early as 1849,at which time he proposed his theory of the molecular con-stitution of matter, now well known as the theory of molec-ular vortices. He supposes a system of whirling rings or THE HISTORY OF ITS GROWTH. 443 vortices of heat-motion, and bases his philosophy upon thathypothesis, supposing sensible heat to be employed in chang-ing the velocity of the particles, latent heat to be the workof altering the dimensions of the orbits, and considering theefEort of each vortex to enlarge its boundaries to be due to. Prof. W. J. M. Eankine. centrifugal force. He distinguished between real and ap-parent specific heat, and showed that the two methods ofabsorption of heat, in the case of the heating of a fluid, thatdue to simple increase of temperature and that due to in-crease of volume, should be distinguished ; he proposed, forthe latter quantity, the term heat-potential, and for the sumof the two, the name of thermo-dynamic function. Camot had stated, a quarter of a century earlier, thatthe efiiciency of a heat-engine is a function of the two limitsof temperature between which the machine is worked, and 444 THE PHILOSOPHY OF THE STEAM-ENGINE. not of the nature of the working substance—an assertionwhich is quite true where the material does not change itsphysical state while working. Rankine now deduced that general equation of thermo-dynamics which expressesalgebraically the relations between heat and mechanicalenergy, when energy is changing from t
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Keywords: ., bookcentury1800, bookdecade1870, bookidc, booksubjectsteamengines
