We all remember the test of the big, eighteen-inch Gathmann gun at Sandy Hook about twelve years ago, which threw a bomb containing six hundred pounds of compressed guncotton that was exploded against the face of a twelve-inch Kruppized plate. The first shot produced no visible effect except a yellow smudge on the face of the plate. It took three shots even to crack the plate and to shift it in its setting.
In competition with the Gathmann gun, a twelve-inch army rifle was fired against another plate of the same size and thickness and mounted in the same manner. The projectile contained only twenty-three pounds of Maximite. Yet, as the projectile penetrated the plate before the Maximite was exploded, a hole was blown through it a yard wide, and it was broken into several pieces.
These tests proved the effectiveness of even a small quantity of high explosive when properly confined, as by explosion after penetration, and the utter ineffectiveness of a large mass of high explosive when not confined or when exploded on the outside of a body.
Bombs carried by an airship and dropped upon the deck of a battleship may damage the superstructure a little, but they can have no material effect upon the ship itself, unless they are made heavy enough and strong enough, with the proper armor-piercing shape, and are dropped from a sufficient height to pierce the deck. Not unless the bomb can be made to penetrate an object before exploding can it effect much destruction.
At Santiago, the Vesuvius, with its pneumatic guns, threw several six-hundred-pound bombs, and exploded them on the Spanish fortifications, but the effect was wholly insignificant.
Several years ago, when the subway was being built, a dynamite magazine accidentally exploded in front of the Murray Hill Hotel. The magazine probably contained at least a ton of dynamite. A lot of windows were broken in the vicinity, some persons were injured, and a multitude badly scared, but the damage done even to the Murray Hill Hotel was comparatively small.
It has been predicted that Germany would send across the Channel a large fleet of airships and blow up British towns with the bombs that her great gas-bags might drop out of the heavens.
Now, at last, the much-vaunted and long-anticipated Zeppelin invasion has come, and what is the result? Four peaceful citizens killed, and about ten thousand dollars' worth of property damage.
Let us suppose that the Germans should send a fleet of a hundred airships to drop bombs upon the city of London, returning to Germany each day for a new supply; and let us suppose that each airship should carry explosives enough to destroy two houses every day, which would be far more than they could actually average. Yet, if this aërial fleet should be able to destroy two hundred houses a day, or say, roughly, sixty thousand houses a year, it would succeed in destroying just about the annual growth of London, for that city has, during the past ten years, built sixty thousand new houses every year.
The dirigible balloon has one signal advantage over the aëroplane in the matter of bomb-dropping. It can both carry bigger bombs and remain stationary and hover while it drops them. With the aëroplane, however, there is necessarily great difficulty in hitting underlying objects, on account of the high speed at which it must travel to sustain flight. In order to float, an aëroplane must travel about thirty miles an hour. Even at this speed, it is moving forward at the rate of forty-four feet a second, and as a bomb travels at the same speed as the aëroplane, except for the retardation of the air, it moves forward forty-four feet the first second, while dropping sixteen feet. The next second the bomb falls sixty-four feet and moves forward forty-four feet, and so on.