Shortly thereafter the lieutenant in command of the submarine appeared at the foot of the hatchway and informed the captain that they were at liberty to ascend. Never did the sun appear to be more beautiful or inviting, although there was a perceptible chill in the atmosphere. The submarine was moving along at a speed of twelve knots an hour. Four men were engaged in taking down a bent and partially ruptured periscope tube. The captain glanced at it and drew the attention of the boys to its structure. It was the tall periscope that received the shot, which struck it about four feet from the top. "It must have been hit on the water line," said the captain, addressing the lieutenant. The latter merely nodded, but made no remarks in response. They were permitted to walk to and fro for an hour, when the order came to descend, and they again entered their prison. As before, they were subjected to total darkness, but there was no necessity for this deprivation, and it is not clear why an enemy should treat prisoners in this manner, for such actions necessarily leave only resentments and do no good whatever. It was a long, long, dreary afternoon and night, which they tried to while away in sleeping, for conversation, under the circumstances, soon became irksome. When they awoke, or, rather, when all were again alert and felt as though the night must have passed, the captain was the first to break the silence, as he said: "We have been resting quietly for more than an hour, I should say, probably lying in wait in one of the steamer lanes for new victims." "Isn't it likely we are on the bottom of the ocean? Don't they go down sometimes and wait there?" asked Ralph. "Yes; but not in deep water, such as is found in this bay. At no place is it less than 150 fathoms, and in the central portion, where our ship went down it is more than 2,000 fathoms." "Why, that's two miles deep, or more," said Alfred. "Yes, the Bay of Biscay is one of the deep holes in the Atlantic coast line of Europe. The average depth of the Irish Sea, St. George Channel, the English Channel and the North Sea is only about 250 feet, and there are thousands of places in the North Sea, particularly, like the Dogger Banks, where the water is not more than a hundred feet deep," remarked the captain. "Then the submarines could easily rest on the bottom if the depth is not more than one hundred feet?" asked Alfred. "Submarines have, in several cases, gone down as far as 200 feet below the surface, but it is at a great risk," said the captain. "You mean risk from the pressure of the water?" said Ralph. "Yes," was the reply. "What would be the pressure of the water on a submarine at that depth?" asked Alfred.