THE BIRTH OF THE BATHYSPHERE 89 



As far as actually descending ourselves, up to the year 

 1930 we had to be content with donning a helmet and 

 walking about arm in arm with a hoseful of air a few 

 fathoms beneath the surface. This is comparable to climb- 

 ing among the branches of a fallen tree in the jungle. 



Of course we could have made observations at some- 

 what greater depths in a complete suit, but even one of 

 these cannot be used much below 300 feet by profes- 

 sional divers, and its disadvantages are manifold. At these 

 greater depths the lungs must not only be supplied with 

 air, but air at a pressure equal to that outside, to counter- 

 act the pressure of the water. If we suppose a man de- 

 scends to a depth little over twice that which I have 

 reached in a helmet — 150 feet beneath the ocean — the 

 2160 square inches of the surface of his body are now 

 subjected to a total water pressure of 144,072 pounds or 

 over seventy tons. He would be squeezed into pulp were 

 it not for the air pumped into his suit. The deeper he 

 descends the more terrific is the weight of the water above 

 him, and consequent pressure on his body. 



The limit to the pressure which a human being can 

 endure occurs a little beyond 300 feet. And even at depths 

 far less than this if a diver is drawn up rapidly death will 

 certainly ensue. Just as a bottle of charged water becomes 

 filled with bubbles when it is uncorked, so the blood of 

 the rapidly ascending diver boils, giving forth bubbles of 

 nitrogen, the chief constituent of air. When a diver has 

 reached a great depth, in order for the nitrogen to be 



