The U-boat poked up its double periscope three times, each time submerging as she saw the patrol ship's guns turned toward her. She could not launch a torpedo with any success in that raging sea; neither could the _Remlik_ drop a depth-bomb on her, as the _Remlik_ could make only two knots against the gale and a bursting depth-charge might damage her as much as it would the "sub." There they maneuvered like two tigers, unable to spring at each other. After a few minutes the submarine, which had never shown enough of herself for our gunners to plant a shell in her, finally submerged and stayed under. The Americans kept sailing over the locality, hoping she would reappear; but, not wanting to risk a gunfire contest, the "sub" had given up the fight. Tossed about by that stormy sea, a more imminent danger threatened the _Remlik_. The waves breaking over the stern tore loose one of the huge depth-bombs. The box that held it fell overboard, but the bomb was hurled in the opposite direction. There it went, rolling around the deck, while the crew amidships watched it with the fascination of danger. [Illustration: BREST, CENTER OF THE GREAT SYSTEM OF NAVAL OPERATIONS IN FRANCE] [Illustration: A GERMAN "SUB" AND SOME OF ITS ENEMIES Above: The German submarine UC-56 in internment at Santander, Spain, where it was forced by the Christabel, the smallest of the American armed yachts in European waters. Inset: High officers of the French and American Navies. Left to right: Vice Admiral Moreau, Assistant Secretary Roosevelt, Vice Admiral Schwerer, Rear Admiral Benoit, Vice Admiral Wilson. Below: Patrol Boats and Sub-Chasers at Finisterre Dock, Brest, Base Section Number 5.] "The safety-pin's come out!" some one shouted. They all knew what that meant. If the firing mechanism should hit, sending off that bomb; if its 300 pounds of TNT should explode, the _Remlik_ would be shattered. To catch and hold that heavy bomb, with the vessel rolling and pitching as it was, seemed almost impossible. Even to venture into that part of the ship was to risk life. The seas were breaking over it, threatening to sweep off anyone who went down the deck. All knew the ship faced destruction; that anyone who went after that bomb risked being swept overboard or blown to pieces. But quickly a voice rang out: "Watch me; I'll get it!" Mackenzie dashed down the deck and flung himself upon the plunging cylinder. He almost had his arms around it, when it broke away. He jumped for it again, and again it tore loose from him. "Hey!" he yelled. "Stand by and lend a hand. It won't do for this colt to get away from me."