The adjustment of the fuze to the distance and the altitude of explosion are regulated to the elevation; and, therefore, the three conditions to good effect may be said to depend mainly on a correct knowledge of distance.
63. The 12-pdr. shrapnel contains 80 musket-balls, and if its explosion occurs at one hundred or one hundred and twenty yards in front of and fifteen to twenty yards above the object, one-seventh of the number of balls may be relied on to take effect upon an object 20 by 10 feet in size.
64. Shells may be advantageously substituted for shrapnel when the hostile force is sheltered, especially by such quarters as small craft or merchantmen afford, or when material of any kind is the object of the fire.
65. At two hundred yards canister, only, is required.
In case of a want of canister, the shrapnel or common shell furnishes an excellent substitute by cutting into the magazine of the Bormann fuze, which will cause it to explode at the muzzle.
66. When provided with the Bormann fuze, the shrapnel, or shell, as issued, is complete. The upper surface of this fuze is graduated into seconds and fourths of seconds; and it is only necessary to lay bare the composition contained in the fuze, by the cutting-tool, to prepare the projectile for instant use. In this respect the Bormann fuze has an advantage over the ordinary fuze. The length of the fuzes limits the distance within which the fire of these guns is considered as effective.
67. The introduction of the 12-pounder rifled howitzer has greatly extended the accuracy and effective range of the boat and field artillery.
Solid shot and shell have sufficient penetration to be effective against ordinary wooden vessels at any distance which the elevation allowed by the respective carriages will reach. See Table of Ranges.
The shrapnel has sufficient velocity at 2,000 yards to disable men and horses.
Hitherto no certain or efficient time-fuze has been adopted for rifled howitzers.