NATURE AND SCIENCE FOR YOUNG FOLKS
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Diving is another interesting method of procuring sponges. The depth to which professional divers wearing the diving-dress, or submarine armor, as it is called, usually descend does not
A piece of sponge attached to a cement disk by a spindle.
This is ready for placing on the bottom in shallow sea-water. exceed 150 feet, although they sometimes stay down for two hours. Air is pumped down to them through the air-hose, and keeps their suits puffed out, the oversupply escaping from their rubber wristbands, and rising in bubbles to the surface. To change the air within the head-piece, or helmet, the diver presses his head back against a valve, which allows the air within the helmet to escape and fresh air to enter.
Six matured sponges.
These are attached to spindles upon a cement triangle, where they have grown from small pieces.
In the cases where the divers do not use the armor, they carry with them a large, flat stone to aid them in their descent, and a string attached to this is held in the hand of an attendant in the boat above. When the bottom is reached, the diver drops the stone, but clings to the rope, by which he signals if help is needed. These divers usually remain under water for not more than two minutes, although experts have stayed under for four and even for five minutes.

Sponges growing on a wire under water.
The stakes project from the surface of the water, so that the line may be readily located.
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