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

There are two positions for the cock : (1) When the lever is moved over to “ One diver, deep water," the air from both cylinders is delivered at the left-hand nozzle only, none issuing from the right-hand nozzle ; (2) When the lever is moved over to “Two divers," each cylinder delivers air through its own nozzle, so that two divers can work indepen- dently of each other. Nozzle for One Diver, Deep Water. Lever to Right-hand side. Nozzle for Second Diver, Ordinary Depths. Lever to Left-hand side. Copy of Direction plate placed near Air Delivery Nozzles of Pump. Photo No. 12. When sending a single diver down, his air-pipe must always be joined to the left-hand nozzle, even if it is intended to use one cylinder only. Should the diver ask for more air, the second cylinder can then be switched on ; but were the diver joined up to the right-hand nozzle, putting the handle over to “ one diver, deep water, would cut off his air supply altogether. Instructions as to when one double-acting cylinder may be used, and when both are necessary, will be found on page 47. DIVING HELMETS. There are eight different types of Diving Helmet in use, each pattern having its particular adherents in different parts of the world, viz. : 12-bolt; (with round and square-shaped corselets) ; 8-bolt ; 6-bolt ; 3-bolt ; 2-bolt ; lock—without bolts (two patterns).* The 12-bolt and 8-bolt helmets have four metal bands, between which and the outer edge of corselet the flat indiarubber collar (punched with 12 and 8 holes respectively) of the diving dress is clamped watertightly. * Illustrations and further particulars of these will be found in Siebe, Gorman & Co.s’ General Catalogue. 23