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

By embedding the wire in the walls of the pipe, instead of winding it inside the bore, it is protected from corrosion, and, the bore being thus kept quite smooth, the friction of air passing through is lessened. The internal diameter of the air pipe is about gths of an inch. It is tested to 200 lbs. to the square inch, and under this pressure should not shew any increase of diameter. 1 he strength of the piping lies in the layers of canvas and the steel wire, the indiarubber only serving to protect them from the action of the water. Leather washers must always be inserted in the female couplings when joining up the air pipes. 4-Way Junction (Photo No. 16).—The junction is used for connecting up two or more pumps to one diver when going into very deep water (see tables on pages 47-49). It has four connections ; three of them, fitted with shut-off taps, are for joining up pumps; the fourth, which has no tap, is for connecting the air pipe of the diver. A Photo No. 16. If, when using this junction, the diver being under water, it is desired to take off one of the pumps, the tap on the connection to which that pump is joined up must -first be shut. When putting on an additional pump, it must first be hove round, delivering its air against the shut-tap till its gauge shows the same pressure as the other pumps heaving for this diver; after this the tap may be opened. The greatest caution must be exercised in opening taps on the junction when a diver is down, as, should the air be allowed to escape, the diver would most likely be killed, particularly if his inlet valve failed to act. On no account whatever should the pipes of two divers be joined up to THE SAME JUNCTION. o