Page:The Development of Navies During the Last Half-Century.djvu/166

 an uninjured projectile having a considerable amount of unexpended energy.

Twenty years ago we commenced experiments against iron plates 1½ in. thick on 6 in, of wood. The target thus formed was placed at a small angle from the horizontal, and fired at with a 9-inch projectile. The protection was insufficient, but succeeding experiments have led to decks of steel 3 in. thick being placed over the submerged portions of vessels. The sides of this armoured deck usually slope down to a short distance below the water line, and are given an additional thickness. This portion of the armoured deck of the 'Blake' and 'Blenheim' is 6 in. thick. Advocates of internal armour urge that, for a given weight, more complete protection can be afforded if disposed in this way than if placed externally on the hull.

Later on experiments were instituted to ascertain what effect masses of coal would have in stopping projectiles, and if it could be ignited by shell. It was found that 20 ft. of coal would stop a 6-in. shot at a short range, and 30 ft. an 8-in. shot, but this would hardly hold good with later guns and steel projectiles. The explosion of common shell did not set the coal on fire.

But this latter result only applies to coal in confined spaces. If placed between decks, it will be more readily ignited. I believe at the battle of Lissa the 'Palestro' was destroyed in this way. Her captain, impressed with the necessity of not running short of fuel, had placed a quantity of coal outside the battery. During the action