Compass

An apparatus for utilizing the directive force of the earth upon the magnetic needle. It consists of a circular case, within which is poised a magnetized bar of steel. This points approximately to the north, and is used on ships and elsewhere to constantly show the direction of the magnetic meridian. Two general types are used. In one the needle is mounted above a fixed "card" or dial, on which degrees or points of the compa , q. v., are inscribed. In the other the card is attached to the needle and rotates with it. The latter represents especially the type known as the mariner's compa . (See Compa , Mariner's--Compa , Spirit, and other titles under compa , also Magnetic Axis--Magnetic Elements.) The needle in good compa es carries for a bearing at its centre, a little agate cup, and a sharp bra pin is the point of support.