This last course proves disastrous to the submarine nine times out of ten, and so she usually gets her guns into action and a regular little sea battle is fought right then and there.
=Shooting the Guns of the Chaser.=—Having found, chased, and caught the submarine, the next thing to do is to put her out of commission. On the guns with which the chaser is armed, and on her gunners, depend to a large extent the success or the failure of the attack.
A gun which had a long range and a _flat trajectory_[38] was quick in action, and rapid-firing, was thought to be all that a gun should be for submarine execution; and it was all right for shooting at conning towers and similar targets which showed themselves above the water-line, but it was useless for a gun of this kind to try to hit anything that was even a few feet under water.
The reasons for this are somewhat deep and scientific but if you will read carefully, look at the diagrams shown in Figs. 66 and 67, and do a little thinking as you go along you will be able to _visualize_ the whole thing—that is, to see it.
[Illustration: FIG. 66. HOW A FLAT TRAJECTORY AFFECTS THE PROJECTILE.]
Now, the way this gun was made was to _rifle_ the barrel of it, and this gave a turning motion to the projectile when it was fired, that is, it spun around on its _long axis_, and the _trajectory was flat_, which means that the path of the projectile in its flight from the gun to its target was only slightly curved.
[Illustration: FIG. 67. HOW A BOW TRAJECTORY AFFECTS THE PROJECTILE.]
Both of these things made the projectile deviate from its course the instant it struck the water, or _ricochet_ (pronounced rik-o-sháy) as it is called; that is, it bounced from the water in exactly the same way that a flat stone skips along when you throw it close to the surface of a pond or lake.
The right kind of gun to use on submarine chasers is not rifled, and the projectile should be given a trajectory, or path, that is much the same as that of an arrow; the result is that a shot can be fired at a submarine which is submerged to a depth of 20 feet or so and be effective because the curve of the path is such that the projectile drops straight, or nearly straight, down on the submarine and penetrates the water as shown in Fig. 67.