The air chamber in the war-head caused it to rise. As it rose it unwound the mooring cable from a reel in the sinker. It rose to within eight feet of the surface and then stopped. A hydrostatic valve had operated a catch which stopped the reel unwinding. The valve could be set to hold the war-head at any depth under the surface required.
The pull of the war-head on the mooring cable closed an electric switch, and the mine was ready for business.
In accordance with The Hague Convention a switch was fitted to the mine, which would open, rendering it harmless, if the war-head broke away from the cable; but it had been carefully put out of action before the mine had been put in its tube.
The Commander of the U-C 1 crossed the parallelogram and laid all his mines at close intervals. His work finished, he slipped off toward the open sea, thinking with satisfaction of his row of mines with their ugly warty heads swaying to the tide below the surface of the water.
He pictured the Harwich flotilla coming out in line ahead, a light cruiser leading, her four hundred and thirty-six feet of slim grey length driven through the water by her forty-thousand horse power. He thought of her 3-inch protective plating, but this he knew only went two and a half feet below her water-line. He gloated over her armament—two 6-inch guns, six 4-inch guns, and one 4-inch high angle anti-aircraft gun—all useless when pitted against his mines.
He saw her in his mind's eye touch a mine. It rolled along her side. The soft metal protruding horns were bent. The glass tubes inside them were broken. The liquid in the tubes fell into cups in which were two solid elements of an electric battery. A current was generated. The exploder was detonated, and the charge of high explosive went off with a chattering crash.
But all that would happen to-morrow. He was well pleased with himself as he slipped along.
How could he know that the emergency war-channel had been shifted, that the four green buoys had been laid there for his special benefit, that the mine-sweeping was a bluff, and that his successor to the job of minelayer-in-extraordinary to the Harwich Light Forces would in his turn discover the green buoys, blunder into the mines intended for the light cruiser, and so depart this life.
Next morning he brought his boat to the surface this side of the North Hinder, and started for home. There was a light mist, no wind, and everything appeared ormolu.
But behind him at Felixstowe Commander Porte, who was back on the station for a short time, had determined to lead out a patrol of five flying-boats—a greater number than had ever been out together. It strained the resources of the War Flight, but five machines were finally shoved down the slipway into the water. Commander Porte was leading in F 2 C, his latest experimental boat, piloted by Queenie Cooper, the test pilot.