In due course followed the salvage of the unlucky K.13. It was effected solely by the use of compressed air, which was pumped down one pipe into a compartment until it had driven all the water away through another pipe to the surface. In this way she was pumped out compartment by compartment, but even when all the water was expelled she still stuck in the mud. For two or three days the salvors strove to drag her from the clinging mud, but not until she was freed of the overlying silt by sand-pumps did she bob to the surface just like a cork. Proving little the worse for her adventure, she was put into commission again under another number, so the unlucky K.13 vanished for ever from the British Naval Lists. CHAPTER XI Quite as thrilling as the experience of the men who went down in the K.13 was the adventure which befell the crew of an American submarine, the S.5, and it is doubtful if any popular novelist, with all his imagination and powers of invention, ever thought out a more remarkable situation than that in which these American sailors found themselves. The American submarine concerned had been travelling on the surface, when the commander gave the order to prepare to dive. Down she went, and for a time glided unseen in the depths. Then her commander got ready to bring her up once more. Of a sudden something went wrong. The air failed to blow out the forward tanks. The men felt the floor slip away under their feet as they rose. They were thrown on their backs, on their faces, rolling sideways in all directions. There was no shock, not the slightest jar. The submarine just swung like a pendulum, and when the officers and men managed to disentangle themselves from the various positions into which they had been thrown, they found the bulkheads had changed places with the floor of their craft. The submarine was actually hanging perpendicularly, bow downward, with just the end of the stern showing above the surface. It was a terrible plight to be in, and every man aboard recognized at once that he was face to face with death. Their only hope was that a vessel would sight them and manage to rescue them before their air gave out, yet there was so little of the stern peeping above the surface of the sea that the odds against it being noticed were tremendous. Most submarines nowadays are equipped with a portable telephone which can be floated to the surface, where it is supported by a buoy. This telephone was designed for just such an emergency, and the commander quickly uncoiled the cable and sent the telephone floating upward.