permanent bottom -mounted installations, where it is not possible 

 to get air, the thermonuclear, thermoelectric unit represented by 

 the SNAP series and their successors are obviously very promising. 

 I won't argue on the economics of these because factors other than 

 simple econonnics will determine their use. 



Environmentals have been referred to earlier. Here may be 

 the place that requires our greatest attention and the nnost work in 

 the future; we need to approach this ocean environment with a great 

 deal of caution. For instance, the failure of subnnarine telegraph 

 cables at depths approaching one mile caused by entangled sperm 

 whales is well documented. Their skeletons have often been hauled 

 back up with the cables. The general problenns of marine fouling 

 varies as a function of depth, location, and season. It takes a long 

 time to check out an instrument's ability to withstand this type of 

 environmental hazard. 



Dr. William S. Richardson of Woods Hole Oceanographic 

 Institution encountered a little-understood corrosion at the junction 

 between nylon line and stainless steel thimbles. We now avoid 

 this combination. Cables jacketed with neoprene, one of the fami- 

 lies of plastics used for cable insulation, must also be used with 

 great care. Some marine organisms flourish on this cable. They 

 attach themselves at points where there has been a small abrasion 

 or scratch and proceed to grow and spread, just like a root growing 

 in a rock. They may ultimately cause insulation failure. Optical 

 windows foul quite readily, depending on the environnnent. 



The hazards of environment are well illustrated by an account 

 of "mine-eating" bacteria. A number of experimental mines were 

 shipped from the east to the west coast for testing in a given 

 environment. These mines had a design life of six years. They 

 were planted at various locations in sufficient quantity so that they 

 could be sampled from time to time to determine the effects of the 

 environment. Imagine the chagrin of the experimenters when they 

 picked up their first sample at the end of six months and found 

 that vital parts of the exploder mechanism had disappeared. This 

 was critical. The mine could not have operated, and it probably 

 didn't work very long after it was planted. A substantial amount 

 of metal had simply disappeared. In the particular environment 

 tested there dwell a species of sulfate -reducing marine bacteria, 

 anaerobic in their action. They form their own little electrolytic 

 cell and corrode the metal. They work fast. Our Navy colleagues, 



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