The steamship _Headlands_ was then sighted by the commander of the submarine and he immediately started to pursue her. The steamship steered a zigzag course, but the submarine got in a position to launch a torpedo, and at about half past ten in the morning the crowd on the shore saw steam escaping from her in large quantities. Some time after they saw a large volume of black smoke and debris fly upward and they knew that another torpedo had found its mark. She then settled, her crew and the men from the _Indian City_ reaching St. Mary's in small boats. To keep British harbors free from the German submarines the British admiralty had to set their engineers to work to devise some method of trapping the underwater craft automatically, for there seemed to be no sort of patrol which they could not elude. Steel traps, not unlike the gill nets used by fishermen, were finally hit upon as the best thing to use against the submarines, and by March 13, 1915, a number of these were installed at entrances to some of the British harbors. They were made of malleable iron frames, ten feet square, used in sets of threes, so arranged that they might hold a submarine by the sides and have the third of the set buckle against its bottom. They were suspended by buoys about thirty feet below the surface of the water. When a submarine entered one of these it was held fast, for the frame which came up from the bottom caught the propeller and made it impossible for the submarine to work itself loose. The disadvantage to the submarine was that, while traveling under water, it traveled "blind"; the periscopes in use were good only for observation when the top of them were above water; when submerged the commander of a submarine had to steer by chart. By the end of March, 1915, a dozen submarines had been caught in nets of this kind. By the 18th of March, 1915, three more British ships had been made the victims of German torpedoes. The _Atlanta_ was sunk off the west coast of Ireland only a day before the _Fingal_ was sunk off Northumberland. And the _Leeuwarden_ was sunk by being hit from the deck guns of a German submarine off the coast of Holland. There was no loss of life except during the sinking of the _Fingal_, some of whose men were drowned when she dragged a lifeboat full of men down with her.