Since the sextant is so important an instrument in navigation, it should be handled carefully and treated well. It is delicate and therefore easily thrown out of adjustment. When not in use it should be kept securely in the sextant box with the index arm clamped in position, and the box should be placed so that it cannot be thrown about by the movement of the ship. The mirrors should be kept dry, preferably with a chamois. The graduated are and vernier should be cleaned when necessary with ammonia, never with polishing fluids. The arc may also be cleaned by rubbing lightly with cotton moistened with sperm oil. Movable parts should move freely. The eyepieces of the telescope should turn easily and move in and out without binding. The bracket that holds the telescope should be strong and made secure to the frame of the sextant. The vernier should lie close to the graduated are but should not bind or be too loose toward the ends of the arc. Before accepting a sextant, the navigator should have evidence that the sextant has been properly examined and tested. It is then the navigator’s duty to keep the sextant, so far as life on shipboard permits, in the same excellent condition in which the instrument was originally received.