March thought that ought to be simple. He had been almost that far beneath the water sometimes when he went in swimming. But then he remembered that this test was to teach the men the proper use of the Momsen Lung, the rate of climb up the cable to the surface. It wasn’t the pressure at eighteen feet that would bother anyone, unless it was somebody who had some deep fear of being under water. “Such a person wouldn’t very well select the submarine service, though,” he said to himself. “Of course some people have these fears without knowing it. Nothing has ever happened to bring it out, that’s all.” The time in the pressure chamber seemed like nothing after their fifty-pound session of the day before, and soon the students found themselves ascending to the eighteen-foot level of the tower. “Up at the top,” the Chief was saying, “there are plenty of men ready to take care of you. Nothing much is likely to go wrong with such a short escape, but we don’t leave anything to chance. So if you get tangled in the cable or decide to go down instead of up, or anything like that, there’s a few mighty good swimmers to do the rescue act. There’s one thing to remember—we send you men up one after the other, pretty fast, just the way you’d be doin’ it if you were getting out of a sub lyin’ on the bottom of the ocean. So get away from the cable buoy fast, and without kickin’ your legs all over the place. You’re likely to kick the next one in the head, especially if he has come up a little too fast.” “How fast are we supposed to go, Chief?” one of the men asked. “About a foot per second,” the officer replied. “You hold yourself parallel with the cable, body away from it a little bit, and let yourself up hand over hand. You can put your hands about a foot above each other, and count off the seconds to yourself. We’ll be timing you at both ends, so you’ll find out afterwards whether you went too fast or too slow. Then you’ll catch on to the rate all right.” March was among the first men who stepped into the bell at the eighteen-foot level. The water of the tower came up to his hips and was kept from going higher in the little compartment by the pressure of the air forced into the top of the bell-shaped room. He saw a round metal pipe shaped like a very large chimney extending down into the water. “That skirt goes down a little below the water level in here on the platform,” the Chief said. “When you go up, you fasten on your Lung, duck under the skirt, and go straight up. First, I’m going to check to be sure that the cable’s set okay.” March and the others watched closely as the Chief adjusted his nose clips and mouthpiece deftly, turned the valve opening the oxygen into the mouthpiece, and ducked under. In a moment he reappeared and removed the Lung.