southeast, southeast-by-south, south-southeast, south-by-east. South, south-by-west, south-southwest, southwest-by-south, southwest, southwest-by-west, west-southwest, west-by-south. West, west-by-north, west-northwest, northwest-by-west, northwest, northwest-by-north, north-northwest, north-by-west, north.

From this it can be seen that the cardinal points are eight points away from one another, and four points away

from the nearest quadrantal point. The name of the opposite point to any given point is known at once by simply reversing the name or the letters that indicate the name of the given point. Thus, the opposite point of NE by E is SW by W, that of N N W is SSE, that of E by S is W by N, and so on.

TABLE II

NAMES OF POINTS AND THE NUMBER OF DEGREES, MINUTES, AND SECONDS CORRESPONDING TO ANY NUMBER OF POINTS AND FRACTION THEREOF

North to East North to West South to East South to West

NE by EEN W by WWSE by EES W by WW
NE by EEN W by W WSE by EES W by WW
NE by EEN W by W&WSE by EES W by W3 W

39. The space between each point is divided into four equal parts, called half and quarter points. Thus, an expression NW means "north a quarter point to the west,' and SE by EE means "southeast-by-east three-quarter point to the east." There is no particular system in expressing half and quarter points, but experience has taught that the simplest is the best. Hence, the expression N NEE is preferable to NE by NN, although they both indicate the same point; and likewise N by EE is preferable to NNEN. Absurdities like W by NW and N by EN should never be used.

40. Quite frequently a ship's course is given in degreesespecially on steamships, as they can be steered more closely than a sailing vessel-and a course of this kind is expressed as so many degrees east or west from either north or south; for example, N 23° E, S 48° W, S 60° E, etc.

The preceding table showing the relation between points and degrees will be very convenient to refer to when it is required to convert a course expressed in degrees into points, and vice versa.

41. The compass bowl is generally made of brass or copper, the last named metal being preferable on account of

its tendency to dampen or diminish the oscillations of the card. On the inside of the bowl is a vertical line called the lubber line, or lubber's point (see a, Fig. 11), which, together with the center of the bowl, indicates the direction of the ship's longitudinal center line. The pivot, which is attached to the bottom of the bowl, is of a conical form (see Fig. 9) and should be screwed into the exact center of the bowl, and its point should be made of some hard metal,

FIG. 11

preferably bell metal. The bowl, which is sufficiently large to admit of the card moving freely, is weighted at the bottom and is fitted with gimbals, so that the card may always preserve a horizontal position, even when the motion of the ship is most violent.

42. The binnacle, Fig. 12, is a stand firmly secured to the deck in front of the helmsman's position (in case the compass it contains is

used for steering) or in any other suitable place where disturbing forces I will have the least effect on the compass. It is made either of wood or brass and may be of any shape-round, square, or octagonal. Within it are supports on which the gimbals of the compass bowl are placed. The top of the binnacle, which is movable, is furnished with glass so that the card may be seen, and also with lamps at the sides to light up the card at night.

43. Lord Kelvin's Compass. - Among

the

many good compasses in

FIG. 12

use may be mentioned Sir William Thompson's (now Lord Kelvin), patented in 1876. Its principal features are as follows: A thin aluminum ring (see Fig. 10) is connected by radial silk threads to an aluminum cap having a center piece of sapphire poised on an iridium point. Instead of one single needle there are not less than eight strips of magnetized steel fastened to the silk threads, as shown in the figure. The paper rim

bearing the points is divided at intervals, so that the contractions and expansions due to change of temperature may not produce warping of the aluminum. The entire weight of the whole arrangement is about 170 grains, which is little more than of an ounce and but of the weight of the ordinary 10-inch compass previously in common use on merchant steamers and large sailing ships. The bowl of this compass is saved from violent oscillations by having in the bottom a quantity of castor oil, and a simple device prevents the card from jumping off the pivot when heavy guns are fired. The binnacle has complete provisions for stowing away the magnets, soft-iron bars, and spheres used to counteract the magnetism of the iron surrounding the

compass.

44. The requirements of a perfect compass may be summed up as follows:

1. The pivot and the cap working on it should be accurately in the center of the bowl as well as in the center of the card.

2.

The divisions of the card, particularly the points, should be perfect.

3. The direction of the magnetism of the needle or needles is parallel to the north and south line of the card.

4. The compass should be comparatively steady when subjected to the rolling and pitching motions of the ship, and sensitive when at rest or when the ship is in smooth water.

45. Care of Compasses. - In order that a compass shall be as faultless as possible, the pivot, cap, and margin of the card should be frequently examined to see that they are in good order and working freely; when the card works sluggishly or an injury from any cause occurs, a new cap or pivot should be put in, taking good care when screwing the pivot into the bowl to preserve its point from injury and to place the card lightly upon it. When the bowl does not work freely in the gimbals, the axis of the latter and their bushings should be examined and, if necessary, slightly