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

DESCRIPTION OF THE APPARATUS. The helmet, which is made large enough to allow the head free movement within it, is sloped away to fit the shoulders, and is continued into a short jacket of strong waterproof material. In front of the jacket, inside, is a pocket containing- a combined purifier and oxygen generator, consisting of two small chambers formed in one case. These chambers arc charged with a patented substance which, when in contact with the water vapour of the breath, gives off pure oxygen gas and forms a caustic alkali. The alkali then takes up the carbonic acid gas of the respired air, and forms an alkaline carbonate. In this- way the same air, purified and re-oxygenated, is used over and over again. The total weight of the whole outfit is only 16 lbs. Folded up for stowage (as shown in photo on page 82), it occupies a space of i2in. by 12m. by 15m. It has been used in the thickest smoke and sulphur fumes, and the wearer has not felt them in the slightest degree. The dress, which can be put on without assistance in thirty seconds, thus fulfils the first of our three conditions, viz. : that the crew should be rendered independent of poisonous gases which may be generated in the boat. I he chief ol these, as already explained, is chlorine which forms when salt water gets into the batteries, and which is fatal in very small quantities, and even apart from being actually dangerous to life, the smallest trace in the air will cause so much coughing that work is impossible just when work is most needed to enable the crew to get rid ol the water in the boat, and perhaps get her to the surface. The second condition was that the dress should be able to preserve its wear ci from drowning whilst the boat was being flooded. In this connection we would men- tion that the dress is now in every-day use, with perfect success, underwater, the wearer being as comfortable in it as he would be in an ordinary diving dress. The third condition is fulfilled by the dress acting as a lifebuoy, and keeping the wearer afloat on the surface (see photo on page 84). A. special device is fitted to enable the wearer, when he reaches the surface, to inflate a flexible chamber which surrounds the jacket, and thus forms a life-belt. Whilst the apparatus is self-buoyant when it contains all the air originally in the jacket and helmet, yet it is not sufficiently buoyant to maintain the wearer alloat at the surface of the water when the window of the helmet is opened and permits the en- closed air to escape. The necessity of opening the window to permit ol the access of fresh air to the helmet arises from the fact that the artificial air supply given by the apparatus is limited, and a wearer may not be rescued for some time after reaching the 85