Directions for preparing the Fuze for any particular range. Hold the fuze firmly in the left hand, insert the point of the bit into the required hole, place the head of the brace against the body, and turn with the right hand until the stop comes in contact with the wood. N.B.-The wood bottom of the fuze must on no account be cut off, as it supports the composition, and prevents its being disarranged by the shock at the discharge. PETTMAN LAND, SEA, AND GENERAL SERVICE FUZES. Damped with varnish, of spirits, methylated, 1 pint, and shellac 112 grs., in a proportion of 40 minims to 100 grs. E-PATTERN FUZES. Detonating Composition. Phosphorus, Amorphous, with 10 per of compo. cent, calcined magnesia parts 8 40 minims of varnish to 90 grs. compo. Damped with varnish, of spirits, methylated, 1 pint, shellac 645 grs., in a proportion of 24 minims to 100 grs. of composition. DYER PERCUSSION FUZE. Detonating Composition. Same as for E-pattern, with addition of -gill of spirit, methylated. Damped with thin varnish, of spirits, methylated, pint, shellac 645 grs., in the proportion of 32 grs. to 100 grs. composition. General Service, Gun metal. RIFLED GUNS. Used to make shells, with the "Moorsom gauge, take fuzes of the General service gauge. There are two patterns, one for Rifled shell, and one for Naval smooth bore Shell. GREASE. The composition used for greasing wheels is composed of equal parts of Tallow, and coarse sweet oil melted together; and is made up in kegs of 28 lb. each. In warm weather the proportion of tallow must be increased. GUNPOWDER. The component parts of Powder are 75 parts of nitre, 10 of sulphur and 15 of charcoal. Cylinder Powder is made from charcoal that has been burnt in iron cylinders; and Pit powder from charcoal burnt in common pits. Gunpowder, when ignited, expands with a velocity of about 5,000 feet per second; and the pressure of the fluid is about 2,000 times that of common air. One pound of powder measures 32 solid inches. A cubic foot of Government powder weighs about 58 pounds. Gunpowder is manufactured by reducing the nitre, sulphur, and charcoal to powder; they are then mixed, moistened with water, and again mixed in a mill for five or six hours, or until the mixture is as intimate as possible, for upon this the strength of the powder chiefly depends. When taken from the mill, the composition is put in a press, and formed into hard cakes about a quarter of an inch thick; these, when dry, or nearly so, are broken by wooden mallets into small pieces, and reduced into grains by being put into sieves, and forced by means of a wooden roller through circular holes of the proper diameter. Good powder should be devoid of smell, and of uniform colour, approaching to that of a slate. The particles should be perfectly granulated, and free from cohesion. It should admit of being readily poured from one vessel to another. In powder that has become damp, large lumps are formed: should the damage, however, not be very considerable, these concretions may be reduced by drying the powder in a hot-air stove, rubbing and loosening the grains; but powder thus affected never thoroughly regains its lost strength. To test the purity of powder.-Lay a dram of it on a piece of clean writing-paper, and fire the heap by means of a red-hot iron wire: if the flame ascend quickly with a good report, leaving the paper free from white specks, and without burning holes in it, the goodness of the ingredients, and proper manufacture of the powder may be safely inferred. Good powder blasted upon a clean plate of copper should leave no track or mark of foulness. Powder exposed for 17 or 18 days to the influence of the atmosphere ought not to increase materially in weight. One hundred pounds of powder should not absorb more than twelve ounces: if it increase in weight more than one per cent., the powder should be condemned. POWDER MARKS. The various sorts of powder are distinguished by the following marks on the heads of the barrels: Large grain. *Red L G, or F G, denotes powder of the best quality. † White L G, or F G, is an inferior powder for salutes, &c. POWDER MAGAZINES. To ascertain if a Magazine is damp.-Soak a piece of sponge in a solution of salt of tartar, or common salt and water: let it be well dried, and weighed, and then be placed in the magazine, which, if damp, will cause the sponge to become heavier. A small weight, suspended by a piece of catgut, or hair, will also I discover moisture, causing the former to contract, and the latter to lengthen. POWDER BARRELS. Whole Barrels contain 100 lb., and Half Barrels 50 lb., of powder, whether fine, or coarse. Weight of barrel, copper-hooped, 10 lb., hazel-hooped, 6 lb. Diameter 13 CASES, POWDER (BOXER'S). Pentagonal.-Dimensions of sides in inches. One-15.42. Two-11.044 Two-9.2. Depth of case-19-2. Weight, 68 lb. HYDROSCOPE. Instrument for measuring distancès from elevated batteries. It consists of a galvanized iron tube about 8 ft. 9 in. long, with a copper cistern at each end. Each cistern contains a zinc float carrying a straight edge on a wire, the stalk being 7 inches high, and having a small steadying weight at the bottom. The tube is let into a groove cut in a block of wood, and is secured to it by an iron plate which is screwed down to the block. To the side of one of the cisterns is attached a brass socket in which a wooden tangent scale slides, and may be clamped at any height. Two faces of this scale are graduated in yards, each face for a separate height above the level of the sea. The instrument is used as follows: A sufficient quantity of water having been poured in to fill the tube and cisterns so far as to support the floats, the block of wood carrying the tube is placed upon the parapet or other convenient resting place, and the tube directed towards the object the distance of which is to be ascertained. From the arrangement of the floats, the straight edges which they carry are always on the same level, no matter what may be the inclination of the tube. The tangent scale being then raised until the object is seen through the slit of the sight in the same line as the further straight edge, the distance on the scale which coincides with the nearer straight edge is the approximate distance of the object. |