Indicator-card or indicator-diagram

. (a.) (Steam-eng.) A figure drawn by the working steam of a steam-engine, by means of an indicator. The diagram is shaped like a foot; its length represents the stroke, and its height from 0 to 30 the steam pressure in pounds, and from 0 to 15 the vacuum. The numbers 14 to 42 represent the pressure at the different points in the stroke. The average pressure and the speed of piston are the elements for calculating the horse-power. (b.) A diagram made by any dynamometer.