A magnet (q.v.), when suspended horizontally, always points in a direction nearly north and south, and on this principle has been constructed the mariner's compass, an instrument of great value to sailors', as showing them in what direction to steer. In the compass the needle is fitted up in such always remain horizontal pitching or rolling. The needle is firmly attached to a circular card (called the compass card), which is divided into thirty-two equal parts by lines drawn from the centre to the circumference. The mariner's compass was brought from China to Europe during the thirteenth century.

Compass Mariners 57