Compass

—The magnetic compa consists of a magnetic needle pivoted on a fine point within a suitable case; below the needle is placed a card graduated to degrees and the cardinal points, so that the movements of the needle, which lies N. and §., always indicate the bearing of any object. The mariner’s compa consists of a skeleton card mounted upon the needles, two or four parallel magnets being employed. There are two graduated circles, the inner showing the 32 points, halves and quarters, the outer graduated to 360°. The N. and S. diameter of the cards is parallel with the needles, the N. point being indicated by a fleur-de-lis; a black line (the lubber’s line) is drawn vertically on the case in line with the ve el’s keel, so as to show the direction of her head, (The compa is mounted on gimbals, to preserve its horizontal position, the whole being mounted upon a binnacle, containing provision for counteracting deviation. A spirit compa is filled with a mixture of 1 alcohol, 2 water, within which the card floats, and is hermetically sealed.