"There are the fire-controls," said the officer, pointing down into the "well" at a lot of shapeless apparatus swathed in heavy, waterproof cloth. "We keep the range-finders and other apparatus covered while we are in port or in a damp climate." "The fire-controls?" echoed Herc, with half a suspicion that his unfortunate head was coming in as the subject of more joking. But it was not, as the next remark of the boatswain's mate showed him. "The gunnery officer is seated in that well, with two orderlies, at battle practice, or in actual warfare," he explained. "He is screened there from the enemy's fire; but, through narrow slits cut in the steel, he sees what is going on about him, and telegraphs the range and directs the fire. His commands are transmitted to the gun-control room electrically, and thence to the turrets." The boys listened with deep interest. "We will now go below again and look at the gun-control room," said the boatswain's mate, as he trotted off once more. "He must be made of the same material as the ship," groaned Herc, as the two boys followed him. As before, they traversed innumerable passages, passing several officers on the way, whom they, of course, saluted. In each case the salutation was returned by a brief touch of the officer's fingers to his cap rim. "If you'd ever get lost here, you could wander round for a week without finding your way out," grumbled Herc. "Not much chance," laughed their guide; "every part of the ship, huge as it is, is visited at least once a day by some officer. Not a corner is allowed to escape notice." Suddenly the boatswain's mate plunged downward through a very narrow square opening, which seemed almost too small to admit his body. The boys followed, though for a moment they had been quite startled at his sudden disappearance. "This is a part of the ship no stout man can ever hope to penetrate," said their guide, as he clambered down a steel ladder, which the opening, through which he had crawled, led to. "I should say not," muttered Herc, squeezing through. "It doesn't speak very much for navy food," he added to himself, "if all the sailors can squeeze through such a place as this." At the bottom of the ladder they found themselves in a small chamber, looking not unlike the central office of a telephone exchange. It was quite hot, owing to its proximity to the boiler room. Everywhere wires ran, with head-pieces, like those worn by operators, dangling from them. Small bells were affixed to the steel bulkhead, and a system of tiny signal lights was arranged above them. "This is the place from which the fire is directed after the commands have been sent from the fire-control well," explained their guide. "As you see, it works like a telephone exchange. In action, an officer and four men are stationed here to attend to the signals." "Are we under the water-line now?" asked Ned breathlessly.