Disaster overtook a certain British submarine one day and she filled and sank. Before the engulfing water could reach the after-compartment, however, the solitary occupant, a stoker petty officer, succeeded in closing the watertight door. This compartment was the engine-room of the boat, and, save for the glimmer of one lamp which continued to burn dimly through an “earth,” was in darkness. Now it happened that this solitary living entity, in the unutterable loneliness of the darkness, imprisoned fathoms deep below the wind and sunlight of his world, had a plan. It was one he had been wont to discuss with the remainder of the crew in leisure moments (without, it may be added, undue encouragement) by which a man might save his life in just such an emergency as had now arisen. Briefly, it amounted to this: water admitted into the hull of a submarine will rise until the pressure of the air inside equalises the pressure of the water outside: this providing the air cannot escape. A sudden opening in the upper part of the shell would release the pent-up air in the form of a gigantic bubble; this, rushing surface-wards, would carry with it an object lighter than an equal volume of water--such, for instance, as a live man. It was his idea, then, to admit the water as high as it would rise, open the iron hatchway through which torpedoes were lowered into the submarine, and thus escape in the consequent evulsion of imprisoned air. It was a desperate plan, but granted ideal conditions and unfailing luck, there was no reason why it should not succeed. In this case the conditions for putting it into execution were, unfortunately, the reverse of ideal. The water spurted through the strained joints in the plating and through the voice-pipes that connected the flooded forepart with the engine-room. With it came an additional menace in the form of chlorine gas, generated by the contact of salt water with the batteries; the effect of this gas on human beings was fully appreciated by the Germans when they adopted it in the manufacture of asphyxiating shells.... To ensure a rapid exit the heavy torpedo-hatch had to be disconnected from its hinges and securing bars, and it could only be reached from the top of the engines. The water was rising steadily, and the heat given off by the slowly cooling engines can be better imagined than described. Grasping a heavy spanner in his hand, the prisoner climbed up into this inferno and began his fight for life.