Horse'-power

(Mech.) The work of an engine is measured by the mean pre ure on the piston X area of the piston X length of the stroke. In England and America the unit of work is the foot-pound; that is, the work performed in raising a weight of one pound through a height of afoot. Thus, to raise a weight of 14 pounds through a height of 20 feet would require 280foot-pounds. In France the kilogram metre is used; that is, the work performed in raising a kilogramme through a metre. This unit corresponds to 7-233 foot pounds. The rate of work in machines is the amount of work performed in a given time; a second or an hour, for example. In the U. States, the rates of work are compared by means of horse-power, which is a conventional unit, and represents 550 foot-pounds in a second. In France a similar unit is used, called the cheval vapeur, which represents the work performed in raising 75 kilogrammes through one metre in a second. It is equal to about 540 foot-pounds per second. [s. 463]