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[chap. 23 



decades recorded that appreciable sunlight apparently penetrated to that 

 depth. But had this experiment been made under direct observation from a 

 bathyscaph, it would have been realized that it was doubtless vitiated by the 

 flashes and scintillations of luminescent zooplankton. 



One can list several categories in which any deep-research craft may be 

 especially useful. First and most important, it allows direct visual inspection 

 of the mid-water environment and the sea floor. Secondly, such a craft poten- 

 tially enables selective sampling under visual control instead of remotely, 

 blindly and randomly. The oceanographer's concept of the general environ- 

 ment in which he is sampling and of how his sampler is operating may be far 

 from reality. A third use is as a deep, quiet and stable platform for the scientist 

 and his instruments. The chief value here lies in experiments needing elaborate 

 electronic devices which cannot be readily self-contained, so that long electric 

 cables must be used for deep measurements. Lowering a 3-mile-long multi- 

 conductor cable from a surface ship is such a formidable task that few such 

 experiments have ever been conducted. Fourthly, many geophysical measure- 

 ments such as magnetic surveys, sub -bottom acoustic penetration, etc. can best 

 be conducted in close proximity to the sea bed. 



2. Diving Chambers 



Historically, diving chambers have provided oceanographers with their first 

 means for penetrating the depths ; hence brief mention of them is made here. 

 Although such observation chambers are commonly employed for salvage, etc., 

 they have never enjoyed wide oceanographic use — or at least few scientific 

 publications have resulted. The Barton-Beebe bathysphere (Fig. 1), the French 



Telephone 

 battery box 



C0 2 absorbing 

 system 



Door 



Communication hose 



— Stuffing box 

 — Switch box 



Observation 

 ports 



Searchlight 



0? tank 



Fig. 1. A cutaway drawing of the Barton-Beebe bathysphere used for diving off Bermuda 

 to 3000 ft in the early thirties. (Redrawn from Beebe, 1935.) 



