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

Asphyxia.—As already explained, a diver under water may be affected seriously by CO2 if his air supply is insufficient ; and there is no doubt that in the past divers have often been rendered unconscious from this cause. With care in testing the pumps and arranging a proper air supply, there should be no fear of such an accident. Its occurrence would be indicated by the diver ceasing to answer signals, pro- bably after signalling for “more air.” It should be remembered that loss of con- sciousness from CO2 poisoning is in itself by no means so serious a symptom as loss of consciousness from want of oxygen, and that a diver is very unlikely to suffer from the latter condition. On the other hand, if an unconscious diver were drawn rapidly to the surface, after a stay of some time in deep water, he would run a great risk of caisson disease ; and a death clearly proved to be brought about in this way was re- cently recorded in the Austrian Navy. A diver who has been rendered unconscious by excess of CO2 ought not, there- fore, to be hauled up beyond the first stopping place indicated by the table accoiding to his depth and duration of stay on the bottom. The diminution of pressure will pro- bably at once relieve him. If he does not now answer signals he should be hauled up, and, if he is not breathing, artificial respiration should be applied at once. On his recovery he ought, it possible, to be sent down again. The following is the best method of performing artificial respiration :— “ Schafer's Method.—Place the man face downwards on the ground, with a folded coat or other garment under the lower part of the chest. Not a moment must be lost in removing gear other than the helmet and corselet, which should be taken ofl before commencing—every instant of delay is serious. “ To effect artificial respiration put yourself athwart or on one side of the man’s body in a kneeling posture, facing his head. Place your hands flat on the lower part of his back (on the lowest rib), one on each side, and gradually throw the weight of your body forward on them so as to produce firm pressure—which must not be violent— upon the patient’s chest. By this means the air (and water, if there is any) is driven out of the man’s lungs. Immediately thereafter raise your body slowly, so as to remove the pressure, but leaving your hands in position. Repeat this forward and backward movement (pressure and relaxation of pressure) every four or five seconds. In other words, sway your body slowly forward and backwards upon your arms twelve to fifteen times a minute, without any marked pause between the movements. This course must be pursued for at least half an hour, or until the natural re- spirations are resumed. If they are resumed, and, as sometimes happens, again tend to fail, artificial respiration must again be resorted to. 62