8 Inch Gun. Length, 9 feet; Weight, 65 cwt.; Height of gun above the plane, 5 feet 7 inches. 1. When adopted in the field, the guns should seldom be elevated above 3 degrees, as the objects fired at are generally cavalry, and infantry, and the lower the angle the longer will the shot preserve its force, and have effect. 2. In the ricochet of a fortification of any kind, the elevation should seldom exceed 10 degrees to throw the shot over the parapet a little higher than the level of the battery; and, on the whole, the best elevation to enfilade a work is from 6 to 9 degrees, measured above the crest of the parapet with corresponding charges. 3. The charge, and elevation being known for any range, when the gun, and parapet are on the same level, the same charge, and eleva-, tion may be used so long as the difference of level does not exceed one-twentieth of the horizontal distance between them, the elevation being given by the tangent scale, and the gun laid at the parapet, whether above, or below its own level. 400 lb. oz. deg. lb. oz. deg. lb. oz. deg. lb. oz. deg. lb. oz. deg. lb. oz. deg. lb. oz. deg 600 1 12 7 800 12 64 9 64 1 8 8 8 4 12 7 8 4 222 86 1 8 6 91 9 44 67 12 54 1 44 9 7 * NOTE.-When Shells are fired from the 68 Pounder Carronade, the Elevation must be decreased about half a degree. MORTARS. Practical rules. To find the Charge for a given Range at 45° elevation. 13 inch Mortar.-To the range, in yards, add half the range, multiply the sum by 03 for the charge, in ounces. 10 inch Mortar.-When the range is under 1350 yards, add to the range 160, and multiply by 02; and if the range is over 1350 yards, add one-fifth of the range, and multiply by 02 for the charge, in ounces. 8 inch Mortar.-To the range, in yards, add 20, and the sum multiplied by 015 will give the charge, in ounces. 5 inch Mortar.-To the range in yards, add 150, and multiply by ⚫08, for the charge, in ounces. 4 inch Mortar.-To the range in yards, add 300, and multiply by 06 for the charge, in drams. To find the time of flight, the range being given. Divide the square root of the range, in feet, by 4.5 for the time of flight, in seconds. To find the Range, the Time of flight being given. Multiply the time of flight, in seconds, by 4.5, and square the product for the range, in feet. To find the length of Fuze,* for a given range. Multiply the time of flight, in seconds, by 22, for the 13, and 10 inch mortars, and by 24 for 8, 5, and 4 inch mortais, for the length of fuze, in tenths. . * Old pattern. G PART V. STORES, IMPLEMENTS, COMBUSTIBLES, ETC., REQUIRED IN BATTERIES. BALLS, LIGHT. LIGHT Balls are thrown from mortars at night, to discover the operations of the enemy's working parties, &c. Light balls burn from 10 to 20 minutes. Smoke balls are fired from mortars to suffocate the men in mines, &c., or to prevent them continuing their work. They are also used to conceal manœuvres, &c., from an enemy. Smoke balls burn from 25 to 30 minutes. To construct hollow Globes, or Cases for Light balls, &c. The canvas, or paper, may be formed in the following manner, viz.:-With radius of half the intended calibre, describe the circle ABCD (vide Figure 20, Practical Geometry), and divide the same into four equal parts. From B with radius A B describe arc A E, from A with radius A B describe arc B E, and from E with radius E A describe arc A B. Eight pieces, as E A B, will form a ball nearly spherical, the edges being brought close together. CARCASSES. Carcasses, a species of shell, are filled with composition, the flame from which is extremely powerful, and nearly unextinguishable. They are much used in bombardments of towns, setting fire to shipping, &c., and are discharged from guns, mortars, and howitzers, similarly to common shells; from which, however, they differ, in |