Compass

(kum'pās.) [Fr. compas.] (Mus.) Extent or calibre of voice, or range or height of tone or sound in an instrument.-(Naut.) The Mariner's C. is an instrument used to point out the course at sea. It consists of a magnetic needle, freely suspended in connection with a circular card, the circumference of which is divided into thirty-two equal parts. This is inclosed in abox with a gla top by way of protection from the elements, allowance being made for the " variation " of the needle: the true direction of north and south is thus ascertained. Since iron ships have come into use, it has been nece ary to have recourse to various contrivances to neutralize the effect of the attraction upon the needle of the iron of the ve el.-(Math.) A pair of C. is an instrument used in describing circles, measuring figures, ., and consists of two pointed legs or branches, made of iron, steel, bra , ., united at the top by a joint, on which they move. There are also compa es of three legs, cylindrical, and spherical compa es, . [s. 212]