Page:Fighting in Cuban Waters.djvu/128

106 the angle between the bead and an imaginary line drawn between his station and that taken by the other fellow. The three points—that is, the two range-finders and the enemy—form a triangle, and having one line and the two angles to work on, the working out of the problem gives the distance the gunners are hunting for."

"That makes pointing a gun nothing but a mathematical problem doesn't it?"

"It makes it partly a mathematical problem, lad. But having the distance isn't everything, for that will only give us the height at which a gun should be elevated in order to make its charge cover that distance and hit the mark, instead of flying over it or ploughing the water below it. After getting the distance we have to calculate on how the enemy's vessel is moving, if she is under steam, and then, most important, we have to let the gun go off at just the right motion of our own craft. In some navies they discharge the guns on the upward roll of the ship, and in others on the downward roll. My private opinion on that point is, a downward roll in clear weather, and an upward roll in a choppy sea, when you don't know just what is coming next."