Spherical Projectiles

are fired mainly from smooth-bore guns. They are solid shot, shells, spherical case or shrapnel, grape, canister, carca es, grenades, light and fire-balls. The advantages which they po e over the oblong are their uniformity of resistance to the air, presenting the least extent of surface for a given weight, the coincidence of their centres of form and inertia; they are le liable to wedge in the bore, as they touch the surface at only one point; and they are best adapted for rolling and ricochet fire on account of the regularity of their rebounds. Solid shot are usually made of cast iron, and are designated by the diameter of the bore of the piece in which they are to be used, or by their weight. Shells are cast with a core of sand (greater or le according to the thickne required), which is afterwards removed. The mortar-shell has the thinnest walls, and contains the greatest bursting charge for the same caliber; the gun-shell is thicker, and the battering-shell is nearly as strong as the solid shot. Shells are usually designated by the weight of the solid shot of the same diameter.