that chilled shot of this nature are able to penetrate wrought-iron plates without breaking up or distortion. They are of cylindrical shape, with a pointed head, which against armour acts like a punch, forced into the plate by the energy of the other portion of the shot behind it. All are cast with a hollow core, which can be utilised for a bursting charge, but the space is so limited that such an addition is of little value. A great merit of these projectiles is their cheapness as compared with those now made of steel, so that they are still largely used for practice, and would be efficient against thinly armoured ships, though unable to cope with the thick steel or compound armour which has superseded wrought-iron for protection.
Other kinds of missiles are common shell and shrapnel shell. The former being required to contain a large bursting charge, have not sufficient strength to pass intact through armour, but are most destructive against any unarmoured portion of a ship. Shrapnel are iron cases containing a great number of small round shot, the case being fractured by a small burster at the required moment. The small shot then spread with the impetus previously acquired in flight. Against boats or bodies of men on shore they are very effective.
It has been mentioned that an improvement in the velocity obtained with the later muzzle-loading guns resulted from modifications in the powder employed. Not in the ingredients, because they had remained unaltered for centuries, and the same may be said of the proportions of the mixture, but by making each indi-
