Fig. 90.—Dial of Mariner’s Compass.
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 Compass Card | Names of Points |
| 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.
Fig. 91.—Needle for Dipping Needle.