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everywhere approaches this maximum transparency so that here optical methods 

 of exploring the bottom have their greatest value. In shelf waters and especially 

 in harbors and in inland waters, the presence of dissolved "yellow substance" 

 and of organic matter and sedimentary particles greatly reduces "seeing" by 

 absorption and scattering so that in these places visual methods are greatly re- 

 stricted. Some attempts have been made to partially overcome this poor "see- 

 ing" but these to date have not been of much value. It seems likely that the poor 

 "seeing" conditions in shallow water will never find a satisfactory solution but 

 this should not deter one from utilizing visual methods of exploring the deep 

 ocean where conditions are favorable. 



Three methods are available to us of examining the sea floor visually. 

 These are: (1) direct observation by lowering the eye to the vicinity of the bot- 

 tom; (2) use of a remotely operated camera; and (3) underwater television. 

 Lowering the human eye to the vicinity of the bottom is still a shallow water tech- 

 nique so that we need not consider it here. However, in passing, it is worth- 

 while to point out that the recent development of inexpensive self-contained units 

 such as the aqualung which requires somewhat less experience and ability than 

 the conventional helmet, hose, and suit gear now permits the scientist to explore 

 the bottom depths to at least 100 feet with safety. Attempts to descent to the bot- 

 tom by such devices as the Benthoscope of Barton and the Bathyscaphe of Picard 

 and Cousyn have not been successful.* Some deep dives into the volume of the 

 sea have been made such as with the Bathysphere and with the Benthoscope but 

 the use of such a device has always been a feat of engineering and of human dar- 

 ing. Such dives have never become routine enough to permit the collection of 

 useful scientific data. There is little doubt, however, that with a moderate ex- 

 penditure of funds, an undersea craft, capable of diving to the bottom at great 

 depths with a human passenger, could be developed. One can hope that the Navy 

 will some day, in the not too distant future, see its way clear to develop such a 

 craft as a research tool. 



Although underwater photography has long been employed in shallow water 

 the first really successful deep sea photography was done during World War II by 

 Ewing, Vine and Worzel (1946) using a self-winding and cocking Robot camera 

 and a flash bulb which were tripped synchronously on bottom contact. Subse- 

 quently underwater cameras have been developed and successfully used in ocea- 

 nographic research at the Navy Electronics Laboratory, at Scripps Institution of 

 Oceanography, at the Hancock Foundation (1952), at Lamont Geological Observa- 

 tory, and the Woods HoleOceanographic Institution. Some of the recent develop- 

 ments in underwater photography are: (1) the use of an electronic flash unit 

 which permits a large number of photographs to be obtained during each lowering 

 and which successfully stops all motion; (2) the development of a wide angle un- 

 derwater lens; (3) the partial development of more intense light source (lack of 

 light rather than absorption or scattering is still the factor limiting range in deep 

 sea photography). Deep sea cameras must have a self-contained power source 

 and be lowered on wire rope until it is proved feasible to lower conductor cable 

 to the deep sea floor. 



Although only a few thousand bottom photographs have been obtained to 

 date many significant findings have resulted. A few which have resulted from 

 the work at NEL are, for example: (1) Phosphorite nodules on 30-Mile Bank 

 off California were shown to form an extensive bedded deposit; (2) On the Mid 

 Pacific Expedition, manganese crusts were shown to be covering the rocks of 



* - Since the original writing of this paper it has been reported in the press 

 that Picard has attained the deep floor of the Mediterranean Sea. 



