I hope you will carry home with you two final thoughts. The 

 first is that considerable understanding of environmental problems 

 which apply to a modern navy has developed throughout the Bureaus 

 in the past twenty years. This is because we, too, just like Mr. 

 Gilbert Jaffe, have watched a parade of instrument problems go by. 

 Even in those problems where the final solution is not yet clear, 

 much is known about what will not work -- and usually something 

 is known about what may work, I do not believe the Bvireau will 

 again be so naive as to favor a manufacturer like the one who de- 

 veloped a beautiful black box and a slick report many years ago 

 for a device dependent on wave motion at sea. The report con- 

 tained a "safety clause" sonnewhat like this: "This device will per- 

 form properly provided that the ocean surface acts like a pure sine 

 wave ! " 



I think that we can expect from Industry today a higher esti- 

 mate of the Bureau than that, and a more realistic solution of prob- 

 lems in the marine environment. 



The second and closing thought I have is to beg you to consider 

 and reconsider the effects of pressure wherever they may apply. 

 Please do not be lulled into a sense of slide-rule security by the 

 low compressibility of water and its almost straight-line relation- 

 ship with depth. There is no more terrible demon hidden anywhere 

 in the sea than pressure. Conditions with which we "land animals" 

 are familiar (under one atmosphere) may not be controlling in the 

 ocean depths. The recognition of pressure hazards and effects 

 takes a conscious effort, a deliberate cold-blooded appraisal to be 

 checked and rechecked throughout all stages of your instrument 

 design work. There are ways of conquering or allowing for pres- 

 sure effects. But you must think of them to use them. For it is 

 well to remember that into every crevice of the bathyscaphe, 

 Trieste, on its deep dive, and into your cable connections, seals, 

 and coverplates of instruments at the deepest depths, a devil is 

 seeking to deliver a wallop of over 8 tons per square inch. 



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