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

BRITISH ADMIRALTY DEEP DIVING EXPERIMENTS The main conclusions arrived at by the Deep Water Diving Committee appointed by the British Admiralty may be summarised as follows :— (tz) Experiments carried out by Drs. Haldane and Boycott and Lieut. Damant, R.N., have shown that the dangers arising from the formation of bubbles of nitrogen in the blood and tissues on the ascent of a diver from very deep water can best be met (i) by limiting the time spent in deep WATER, and (2) BY ASCENDING MOST OF THE DISTANCE RAPIDLY, AND AFTERWARDS making the last part of the ascent in stages, with stoppages interposed. In ORDER TO LIMIT THE TIME SPENT IN DEEP WATER, THE DESCENT, AND MOST OF THE ASCENT, SHOULD BE RAPID. THIS NEW METHOD, WHICH, BESIDES SAVING MUCH TIME, IS FAR SAFER, HAS BEEN PRACTICALLY TESTED AT SEA UP TO 35 FATHOMS by the Committee, the depth named being the greatest hitherto definitely re- corded AS HAVING BEEN REACHED BY DIVERS. A TABLE HAS BEEN DRAWN UP SHOWING TIME LIMITS OX THE BOTTOM, zXND THE CORRESPONDING PRECAUTIONS RECOMMENDED IN ASCENDING, FOR DIFFERENT DEPTHS UP TO 35 FATHOMS. (See pages 47 to 49.) (a) I he respiratory distress which, under the old system of dix 7ing, usually pi evented divers from working at depths exceeding about 20 fathoms, although a few men of exceptional skill and endurance have succeeded in working for short pci iods at as much as 30 fathoms, was solely due to pressure of carbonic acid g"as in the air of the helmet, but such distress can be entirely obviated by in- creasing THE SUPPLY OF AIR IN DIRECT PROPORTION TO ITS INCREASE IN ABSOLUTE PRESSURE, AND A DIVER CAN WORK AS COMFORTABLY AT 30 FATHOMS, OR MORE, AS IN SHALLOW WATER, APART FROM THE HAMPERING EFFECTS OF TIDE AND DARKNESS. Tables have been drawn up showing the air supply necessary for the diver AT DIFFERENT DEPTHS. (See page 97.) (c) The risk of “ blowing up ” to the surface can be greatly diminished by lacing up the legs of the diving dress. (d) In cases of accidental “blowing" up,” or too rapid ascent from deep water, the danger of air bubbles in the blood can be avoided by sending the diver down again, even after serious symptoms have already developed, or by placing* him in a recompression chamber, carried on the deck of the diving vessel, and raising the air pressure. (See page 18.) 7