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

REGULATING OUTLET VALVES. Copyright. Photo No. 13. (fl) For regulating by hand. (Z>) For regulating by hand. (c) For regulating by pressing the head against it, inside the helmet. (<Z) For regulating by hand. This valve, which in general construction is similar to (0), has been specially designed for use with helmets fitted with the telephone. When receiving a message, the diver presses the spindle which passes through the cap of the valve. This holds the valve on its seating and thus stops the noise caused by vibration and by the air escaping into the water. This arrangement is specially useful to divers who may be somewhat deaf, as is often the case with men who work under compressed air. Helmets and Corselets (Breastplates).—The following is a description in detail of the patent helmets as used in the British Navy. The other types of helmet described differ only in mechanical detail, the principle, being the same in all. Corselet (12-BOLT and 8-bolt).—The corselet, or breastplate, is made of tinned copper; the outer edge is strengthened with a broad metal band (sometimes the whole corselet is made in one solid gun-metal casting, but this, of course, is heavier), twelve or eight brass screw studs being securely fixed in it at intervals. These pass through corresponding holes in the indiarubber collar of the diving dress, and also through metal straps (four in the case of the 12-bolt and 8-bolt helmets) which are forced down 25