The compass bowl is suspended in gimbals in order to allow it to retain its horizontal position independently of the ship's motion. From the centre of the bottom of the bowl is a vertical steel-pointed pillar; the compass needle is fitted with a brass cap, in which is fixed an agate bearing that rests on the steel point. The compass card is divided on its edges into degrees, the degree circle occupying about Jin. of the card edge; the next circle contains the numerals of degrees marked from 0 at the north and south points to 900 at east and west. Thus the reading in degrees at sea is taken from the south point for the southern semicircle - e.g. what a surveyor reads as 120° the helmsman reads S.60°E. The points, thirty-two in number, are as follows. North, N. by E., N.N.E., N.E. by N., N.E., N.E. by E., E.N.E., E. by N.; East, E. by 8., E.S.E., S.E. by E., 8.E., S.E. by S , S.S.E., S. by E.; South, S. by TV., S.S.W., S.W. by S., S.W., S.W. by W., W.S.W., W. by S.; West, W. by N., W.N.W., N.W.byW., N.W., N.W. by N., N.N.W., N. by TV. These letters are printed radially towards their respective positions at 11 1/4° apart, which equals 1 point-that is, 363° / 32. The central portion of the card is decorated with a star to help in distinguishing the points at a glance.

The card is cemented to the needle and adulated to hang horizontally by dropping sealing-wax on the under side where required; the glass lid screws on to the bowl, which is of copper.