SHRAPNEL SHELLS, so called from the inventor, Major Shrapnel, R. A., are a most destructive description of projectile ; they are principally used against skirmishers and scattered bodies of troops beyond the range of common case, 300 yards, nr of grape shot, about 600 yards.
A Shrapnel shell or spherical case shot, consists of a thin shell of cast iron, containing a number of musket balls and a small charge of powder just sufficient to burst it, and free the balls ; a FUZE, by which the charge is ignited and the shell burst at the proper instant, is fixed in it, as in an ordinary shell.
The effect of the musket, bullets in the Shrapnel is duo to the velocity imparted to them by the gun, and not by the bursting charge which only frees them. A spherical case shot when loaded is about the same specific gravity as a solid shot of the same diameter. A musket ball is effective when impelled with the same velocity as that retained by a solid shot from a 6-pounder or 9-pounder at a range of about 1200 yards. If therefore the spherical case shot be projected by the ordinary service eharge, and be made to burst at any distance up to 1200 yards, the musket balls which it contains being freed, will, spreading out like a fan, and covering some extent of ground, strike effectively. For at the instant of the explosion they have the velocity of the shell, and they will proceed forward, generally In the direc tion in which the shell was going, for the path of the common mitre of gravity after explosion will (disregarding the greater effect of atmosphere) be the same as that of the shell before the explosion, and the velocity with which the bullets strike will be the same as that of shell, or at least sufficient to make them effective.
The common spherical case was attended with many inconveniences, and in the larger descriptions of ordnance more especially, was very liable to burst in the gun. This was supposed to be caused by the shell, which was necessarily thin, not being strong enough to resist the explosion of the full service charge; the charge was therefore reduced, but the experiment, besides not being always successful, had the dis advantage of reducing the velocity so much that the bullets were not effective_ Captain Boxer, R. A., showed that the cause of the shells bursting was the concussion caused by the different relative motions of the external case and the bullets in the interior, when the former was first put in motion by the eharge-.a concussion sufficient to ignite the charge of powder. He therefore invented the diaphragm shell, in which the bursting charge is kept separato from the bullets in a chamber formed by a thin iron diaphragm fixed in the shell when it is mat.
The form of the shell will be readily understood from the accom parrying cut. It has been found perfectly efficient. The Shrapnel from the Armstrong guns is described under RIFLED 01IDNANCE. SHROUDS. [SIIIPBULDINO.]