492. Having been inspected to see that they are clean and dry, place the bombs on a block made for the purpose, or on grommets of rope, or on the ground, with the eyes up. The charge, having been carefully measured, is then poured into the chamber through a funnel, while, at the same time, the fuze is cut to the proper length by resting it on a groove made in the block, and sawing it across. The fuze is then tried in the hole, and should enter 3/4ths of its length; if it does not, it must be reduced by rasping.
493. The head of the fuze having been covered with tow to prevent breaking the composition, the fuze-setter is placed on it, and the fuze driven with the mallet until the head is about 2/10ths of an inch above the surface of the bomb.
POINTING MORTARS.
494. First give the elevation by applying the quadrant to the face of the piece, and adjusting the quoin or ratchet until the required number of degrees is obtained.
495. In pointing mortars on shore, it is an easy matter to get the direction, because the mortar is stationary; but on shipboard, owing to the motion, it is attended with difficulty, especially when the vessel is rolling and the line of fire can only be approximate.
496. On shore, the plan of giving the direction is to determine practically two fixed points, which shall be in a line with the piece and the object, and sufficiently near to be readily distinguished by the eye. These points being covered by a plummet, is the vertical plane including the line of metal, which becomes the plane of fire.
497. In mortar-vessels other expedients are resorted to, such as trunnion-sights, or a white line painted on the mortar-bed parallel to the axis of the bore when level; but the first plan is preferable.
498. The circles on which the mortars stand being fitted with eccentrics, are made to revolve so as to point the mortar at the object without the trouble of swinging the vessel or moving the mortar round with handspikes.
499. Before firing, care must be taken that the eccentrics are thrown out of gear, and the circle flat upon the platform on which it revolves.