Lieut.-Commander Vincent M. Cooper, in E. 43, also had the satisfaction of surprising an enemy at work. This was a U.C. boat, engaged not in actually firing on merchantmen, but in the still more deadly and murderous business of laying mines for them. When sighted by E. 43, she had evidently just come to the surface, as men were observed on the bridge engaged in spreading the bridge screen. Lieut.-Commander Cooper went straight for her at full speed. But as it was 9.30 A.M., and broad daylight, he was forced to remain submerged, and being in shallow water he soon had to slow down. Again and again he bumped heavily on shoals, but fortunately was never quite forced to the surface. After an hour of this he got into deeper water, and was able to go faster. At 11.0 he rose to 24 feet, and took a sight through the periscope. There was the enemy, about 400 yards away on his port beam. He dived, and five minutes later came up for another sight. This time the U-boat was on his port quarter. He turned towards her, but at the moment of attack, when the sights were just coming on, E. 43 dipped under a big wave and the chance was spoiled. Her commander was not to be thrown off; he immediately increased to full speed, altered course, and planned a fresh attack. By 11.17--nearly two hours after beginning the chase--he was in position, 2 points abaft the enemy’s beam at 550 yards’ distance. This time he took every precaution to ensure a kill. On firing he dipped his periscope, so that in case the boat rose suddenly nothing should be visible; and at the same time he yawed to starboard, so as to be ready with another tube if the first shot was a miss. Then came a trying period of suspense and disappointment; he listened in vain for the sound of an explosion, and after forty-five seconds raised his periscope to see what had happened. It was only later, on communicating with his officers and men in the forward and after compartments, that he found, as others have found, how differently sound may affect the different parts of a submarine when submerged. The central compartment may be completely deafened, either by reason of its position, when a detonation occurs directly ahead or astern, or by the much slighter continuous noises of the various electrical machines which are situated there. In this case, the dull report of the under-water explosion, which was not audible to Lieut.-Commander Cooper, was heard in both the other compartments about twenty seconds after he had fired the torpedo. At the moment when the periscope was raised, the U-boat had disappeared, and there was a great commotion in the water where she had been. E. 43 hurried to the spot and found the surface covered with a black oily substance which stuck to the glass of the periscope and put it out of action. Lieut.-Commander Cooper rose to 20 feet and put up his second periscope, but the U-boat was gone and had left no survivors.