In the mariner’s compass, which is used at sea, the compass card and the magnetic needle are fastened together. The card is made of a circular sheet of mica and the points of the compass, which are called _rhumbs_, are marked on the edge. The needle and card float in a bowl of mercury. The card is marked with 32 _rays_, forming a many-pointed star, and each of these points has a name, the names of the four _cardinal points_ being _north_, _east_, _south_ and _west_. To know all of the points by heart and be able to name them, beginning with the north and going round the card to the north again, is what sailors call _boxing the compass_. See Fig. 90. Points on Names of Points Compass Card N North N bE North by east NNE North, northeast NE bN Northeast by north NE Northeast NE bE Northeast by east ENE East, northeast E bN East by north E East E bS East by south ESE East, southeast SE bE Southeast by east SE Southeast SE bS Southeast by south SSE South, southeast S bE South by east S South S bW South by west SSW South, southwest SW bS Southwest by south SW Southwest SW bW Southwest by west WSW West, southwest W bS West by south W West W bN West by north WNW West, northwest NW bW Northwest by west NW Northwest NW bN Northwest by north NNW North, northwest N bW North by west N North DIAL OF A MARINER’S COMPASS =How to Make a Simple Dipping Needle.=—When a compass needle is pivoted so that it can swing up and down, that is, to and away from the earth, it is called a _dipping needle_. Such a needle will dip toward the nearest pole of the earth. At the magnetic equator there is no dip, that is, the needle will stand _parallel_ with the Earth’s surface. [Illustration: FIG. 91.—NEEDLE FOR DIPPING NEEDLE.]