240 THE BATHYSPHERE OF 1 9 34 



gen that the divers were using, and if the chemicals were 

 extracting every bit of the exhalations and moisture, the 

 pressure would remain exactly as it was on sealing the 

 bathysphere. In practice, however, in order to maintain 

 adequate safety factors considerably larger quantities of 

 chemicals are used than are theoretically necessary, and 

 oxygen is supplied at a rate slightly in excess of require- 

 ments. This excess of oxygen tends to raise the pressure in 

 the sphere and the amount of rise is read on an especially 

 calibrated barometer. Thus too great an increase in pres- 

 sure would indicate the release of too much oxygen. Too 

 little would of course not be recorded, so a larger amount 

 is always necessary. 



As a result of the use of the apparatus mentioned above 

 the bathysphere is exceptionally comfortable as far as air 

 is concerned and its atmosphere may be summarized briefly 

 as having a temperature range of 68 to 85 degrees Fahren- 

 heit, depending upon the outside water temperature, hu- 

 midity of 48 to 74 per cent, carbon dioxide practically ab- 

 sent, and a somewhat richer oxygen content than the out- 

 side atmosphere. 



Oxygen Tanks and Valves: The oxygen tanks are the 

 same as those used previously, being cylinders about 17 

 inches long and 4^ inches in diameter, each containing 

 about 80 gallons of oxygen. Their position has been 

 changed this year from horizontal to vertical, one at the 

 middle of each side of the bathysphere. 



