arithmometer

[From Gr. ἀριθμός (arithmos) = a number, and μέτρον (metron) = a measure.] A machine which enables a person, however unskilled, to perform the operations of multiplication and division with facility, rapidity, and unfailing accuracy. The arithmometer of M. Thomas (De Colmar), highly commended by General Hannyngton (Journal of Actuaries, vol. xvi., p. 244) and by Mr. Peter Gray, F.R.A.S., and others, does more, for, in forming the product of two given numbers, it can either add that product to, or subtract it from, another given number, according to the pleasure of the operator. The machine is provided on its face with spaces for the reception of three numbers, say P, Q, and R. These being properly placed, the turning of a handle brings out the value of P+QR or PQR, according as the regulator was adjusted for addition or subtraction.