Deep-Sea Diving (continued)
About a century later an apparatus was evolved in which air was forced down to the diver by means of a large pair of bellows. This possibly suggested the air-pump, that was afterwards employed for supplying the diver with air, and which is still the method adopted in the majority of instances.
Early in the nineteenth century, a Devonshire man, John Lethbridge by name, invented a "water tight leather case for enclosing the person", and this invention of a simple diving suit was the prototype of the modern diver's dress. Made of leather, and containing an ample supply of air, the diver could, by the use of this suit, freely move his arms and legs, and walk along the bottom of the sea. Lethbridge, it is believed, made a considerable sum of money out of his clever invention.
A modern diving suit is a model of ingenuity and skill, every device and precaution being taken to ensure the safety of the occupant. The diver puts on the lower part of his elastic, water-proof, rubberised suit like he does a pair of trousers. A highly planished copper shoulder-piece fixes tightly to the shoulders, and thus forms a firm base for the helmet. When this has been donned, the helmet is adjusted very carefully to the breast-plate, to which it is fastened by means of metal screws. After the diver's boots, each of which, by the way, has a lead or gun metal sole, and weighs from fourteen to sixteen pounds, have been buckled on, the diver is in an air-tight suit, which envelops his body from the neck to the toes. The sleeves, it may be added, are made in such a way that they form a water-tight joint at the diver's wrists.
The helmet, which is the last part of the diving suit to be adjusted, is provided with a flexible air tube, through which air from above is pumped to the diver by means of a pumping machine, usually worked by hand. It also contains an arrangement by which the foul air breathed out by the diver can escape, and when the diver is under water this can be seen issuing in the form of a series of bubbles. These bubbles are very anxiously watched by those on board, for their regular appearance affords an indication that all is well with the diver. Should they, from any cause, cease to appear, this shows that something has happened, and the diver must be raised to the surface at once. The helmet is generally provided with three eye-holes in front, covered with glass, and protected by strong guards made of brass wire.
A diver is further supplied with a life-line, as it is called, made of stout manilla rope, which he always holds in his hands. With this line he can signal to those on deck, in accordance with a prearranged code. The life-line has also the advantage of serving to guide the diver in returning to the ladder by which he descends and ascends. Modern diving suits, it may be interesting to note, are supplied with a telephone apparatus, and this enables the diver to keep in close telephonic communication with the men on board.
The above is a simple description of the diving suit in common use. Of course, there are different kinds of diving suits, each having certain modifications and improvements. One type of diving suit, for example, contains an arrangement that enables the diver to obtain his own supply of fresh air, and thus avoids the necessity of his depending on the air supplied to him by the air-pump. The cost of a modern diving suit varies from £75 to £200.