"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." "I see. Firing a gun isn't so easy as one would imagine." "Easy enough if you want to waste ammunition, as those Spaniards did at Manila. Gun practice is expensive, and Spain hasn't any money to waste in that direction. Come, we'll have to get up to sleeping quarters now," concluded the old gunner, as a drum beat was heard sounding throughout the warship. "That's tattoo. It will soon be two bells, nine o'clock, and then comes pipe down." "All right, I'm willing enough to go to sleep," said Walter. "But just one question more. How do you count the time by bells on a warship?" "Just the same as on any ship, lad. The bell strikes at each half-hour, starting at half-past twelve at night, which is one bell. This makes one o'clock, two bells, half-past one, three bells, and so on, up to four o'clock, which is eight bells, when you start again from the beginning. By this means the day and night are divided into periods of time called watches, as morning watch, middle watch, dog watch, and the like. You'll get the lay of it soon," finished Walton, and then, having reached the berth deck, the pair separated for the night. CHAPTER IX COMMODORE WINFIELD SCOTT SCHLEY In a couple of days Walter began to feel at home on the flagship, and he could no longer be termed a "greeny," strictly speaking, although there were still a great number of things for him to learn. He was much interested in the _Brooklyn_ as a whole as well as in detail, and was proud to learn that this armored cruiser was the largest of the class in our navy, having a displacement of 9215 tons, as against her sister ship, the _New York_, which had a displacement of about a thousand tons less. "This ship is just four hundred feet and six inches long," said Caleb. "She don't look so long as she rides the water, but as a city block is ordinarily two hundred feet deep, so to speak, she would cover two blocks of a side street, providing the street was sixty-five feet wide, for her to rest in. That's pretty big, eh?" "And how much water does she draw, Walton?"