MEASURE

(Lat. mensura.) In Geometry, a magnitude or quantity taken as unit, and employed to expre the relations of other magnitudes or quanlites of the same kind. Euclid defines the measure of a quantity to be that which, being repeated a certain number of limes, becomes equal to the quantity measured. Thus, in Arithmetic, the measure of a number is any number which divides the given number without leaving a remainder; but this definition rather corre spends to the notion of aliquot part. In a general sense, the term measure is applied to that by which anything is compared in respect of quantity. Thus, we have measures of extension, of weight, time, force, resistance, temperature, .; in short, of everything of which greater and le can be predicated; and it frequently hap pens that the unit or measure is not taken in Ihe thing or property which is the immediate subject of consideration, but in something else which depends on it, or is proportional to it. Angular space, for example, is measured by an arc of a circle; time, by the rotation of the earth about its axis, or if.s revolution about the sun; force, by the quantity of motion it impre es on a body; degrees of heat, by tile expansion of metals or other substances; muscular strength, by the resistance of a spring, . See Angle, Chronology, Cravity, Thermometer, Dynamometer, . By measure, in an.absolute sense, is understood ihe unil or standard by which we measure extension. We have, therefore, measures of length, of super fices, and of volume or capacity; but, as the two latter may be deduced in all cases from the former, it is only nece ary to establish a unit, or standard of length. The choice of such a standard, and the different multiples and parts of it taken for the uses of society, form a metrical system, or system of metrology [s. 742]