Page:Reflections on the Motive Power of Heat.djvu/227

TABLE B.

Various Engines in which the Temperature of the Boiler is 121° C.^[1] and that of the Condenser 30° C.

Theoretical Duty for each Unit of Heat transmitted, 371 foot-pounds.

Cases.	Work produced for each lb. of coal consumed.	Work produced for each lb. of water evaporated.	Work produced for each unit of heat transmitted.	Percentage of theoretical duty.
	Ft.-lbs.	Ft.-lbs.	Ft.-lbs.
(3) French engines, according to contract	........	98,427	160.3	43.2
(4) English engines, according to contract	565,700	${\tfrac {614}{618}}$ × 80,814	130.8	35
(6) Common engines, consuming 12 lbs. of coal per horse-power per hour	165,000	${\tfrac {614}{618}}$ × 23,571	38.1	10.3
(7) Improved engines with expansion cylinders, consuming an equivalent to 4 lbs. best coal per horse-power per hour	495,000	${\tfrac {614}{618}}$ × 70,710	114.4	30.7

1. Pressure 15 lbs. on the square inch.