UNIT, in arithmetic, the least whole number or one, represented by the figure 1. Numbers are collections of things of the same kind, each of which is a unit of the collection. Thus 20 feet is a col lection of 20 equal spaces, each of which is equal to 1 foot; here 1 foot is the unit or base of the collection. In mathe matics or physics, any known determi nate quantity by the constant repetition of which any other quantity of the same kind is measured. It may be a length, a surface, a solid, a weight, a time, as the case may be. Abstract unit, the unit of numeration; the abstract unit 1 is the measure of the relation of equality of two numbers. It is the base of the sys tem of natural numbers, and incidentally the base of all quantities. Decimal and duodecimal units, those in scales of num bers increasing or decreasing by 10 or 12 respectively. Dynamic units: Unit of force, a dyne; a force which, acting for one second on a mass of one gramme, gives to it a velocity of one centimeter per second. Unit of work done, a watt; the power developed when 44.25 foot pounds are done per minute=one 746th part of a horse-power. Fractional unit,
the unit of a fraction. Thus in the frac tion 54 there is an assemblage of three units, each of which is one-fourth of the whole number. Integral unit, the unit 1; the unit of integral numbers. Spe cific gravity unit, for solids or liquids, one cubic foot of distilled water at 62° F.=1; of air and gases, one cubic foot of atmospheric air at 62°. Unit of il lumination, the light of a sperm candle burning 120 grains per hour. The stand ard for gas is that the flame, burning at the rate of five cubic feet per hour, shall give a light equal to the light of 14 sperm candles, each consuming at the rate of 120 grains per hour. Unit of measure, the unit of measure of any quantity is a quantity of the same kind, with which the quantity is compared. Unit of value, in England, a pound sterling, represented by a gold coin called a sovereign. In the United States, a gold dollar, weighing 25.8 grains, one tenth of which is alloy.