Submarine Appliances And Their Uses
Deep Sea Diving, &c., &c.

Let us now consider for a moment the conditions obtaining in a submarine after a serious collision or other accident resulting in an inrush of water into her hull. The first effect of such an accident will be the descent of the vessel to the bottom, not neces- sarily very fast, but assuming that the water is entering more rapidly than it can be expelled, the vessel will undoubtedly sink, and continue to fill until she is either full, or, if not holed in the top, until the air in the boat is compressed to a pressure equal to that of the water at the depth in which she has foundered. The rapidity with which this takes place will, of course, depend upon the size of the hole, but taking into considera- tion the strength of hull and the very small weight of a submarine in diving trim, it will in all probability take her some time to fill. The next result will be that salt water will come into contact with the stored electrical energy or open terminals, and the at- mosphere of the boat will be rapidly made poisonous by the formation of chlorine gas. These considerations point to the fact that when a large quantity of water finds its way into the body of a submarine the conditions will be such that something must be done, and done quickly :— (a) To render the crew independent of poisonous gases. (b) To preserve the crew from drowning in the boat. (c) To provide means of escape from the boat and ascent to the surface. The life-saving devices at present known are :— (i) Air-locks for escape. (j) Detachable chambers, or life-boats. (k) Self-contained dress for escape. i.—Air-locks of themselves are of little use except in shallow water, but combined with either (2) or (3) arc essential in all methods of escape. They are the first clement of escape, and are in use in every system. It must be accepted as an axiom that no aperture out of a boat can be opened until the pressure on the inside of that aperture is equal to the pressure of water outside it. The Air-lock may be a portion of the boat provided for the special purpose, or the general cavity of the boat may be used. In the latter case the pressure inside the boat is made to equal that of the water outside by simply allowing the boat to fill with water. 2.—Detachable Chambers, or Life-boats. The great objection to all forms of de- tachable chambers or life-boats is their size, weight and resistance if made large enough to contain all the crew of a modern submarine, and as such a chamber would have to be carried as a superstructure, it would be in the likeliest position to be injured in case of collision. But what is more against any device of this kind is that the crew are ex- pected in a moment of considerable excitement to undertake an entirely novel operation 83