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��Popular Science Monthly
��compartments are completely filled. In this way the great pressure of the water on lop of the hatches is relie\ed.
In an emergency, the crew immediately put on light di\ing-suils. These contain oxygen apparatus which not only prevent suffocation, but also prevent the water from crushing the body. Three or four men enter each compartment and shut the water-tight door behind them. Letting in the water, they open the hatch and climb out. After they ha\'e emerged, the hatch is closed by gears con- nected to it in the inside of the sub- marine. The water in the compartment is then ejected into the ocean through drain- pipes connected with a h^'draulic hand-pump which the imprisoned men operate. Then three or four more of them may enter the compartment and escape in the same way.
After all the crew reach the top of the boat they release a buoy which nio\-cs upward towards the surface cable with it. Up this the men nnist climb.
It seems strange that they must climb out and are not forced Ujnvartls as .soon as they touch the water. The reason for this is that the weight of the suits is so great that, peculiarly enough, it tends to keep the men at \vhale\er level the\- happen to be.
Due to (he fact that (he men have to ex- pose themseKes to the |)ressiire of the water,
this plan cannot be used at a greater depth than .?25 feet. Kven at this depth, the l)ressure is H'.j tons pers(iuare fool. Divers have gone down this far; but one, who went down 28S feet, at the time of the F-4 disaster, permanently injured his linigs.
���In an cmcrnincy in lliis Mibin.uiiu-. tla- crew put on liRlit ilivini; j.ncki'Is. escape to the top of the boat tlirouRli the com- partments and hatches, and climb to the surface on the cable attached to a buoy
which are the hose.
��The manner in which the oxygen is supplied from these suits is extremely interesting. A small cylinder strapped to the back of the wearer contains the oxygen, which is stored at an enormous pressure of one hundred and fifty tons per square foot. The oxygen is slowly released from this by an automatic ejector which regulates its pressure as it is supplied to the body so that it nearly equals that caused by the ocean outside. After the ox>gen has been consumed, it is thrown oft by the lungs as carbon dioxide, and this the lungs force into a cartridge of chemicals where it is completeh' absorbed. Alter this absorption, only the nitrogen of the air remains, but this is again passed o\er the ejector and mixed with fresh oxy- gen before it enters the lungs once more. In this way the same nitrogen is used over and o\er again.
In a third class of devices, the men do not leave the sub- marine at all. Two buo\s arc fitted in the superstructure at both ends of the sub- marine. Attached to each are a cable and two flexible hose, while directly under the ]ioint where each buo>- is held on the submarine is a com- partment into which the crew get in time of danger. Then the lnio\s are released. .\s the\- rise, the\' carry liu' cables and hose with them. An un- limited amount of fresh air can now be had by working air- connected to the lower
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In the two compartments, the men must stay imprisoned until a saU'age vessel answers their <listress signals, given out by an electrical llashlight within the buoys.
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