10 



But before closing I have one more word. I know the exploratory phase 

 of the study of the ocean will never be completed. I have much faith in the value 

 of detailed examination of specific areas and generalized examination of greater 

 areas, by proper instrumentation. But, I sincerely hope that instrumentation 

 never becomes so sophisticated that it is unable to convey to us the unexpected 

 and the inconceivable, for upon the acceptance of these depends the stimulation 

 of our science and the better disclosure of our universe. 



DISCUSSION: Roger Revelle* 



From its beginning 75 years ago in the great British CHALLENGER ex- 

 pedition, the scientific exploration of the sea has tended to run in cycles. Each 

 cycle of exploration has been initiated not only by the conceptual growth of new 

 questions, but also by the development of new instruments and techniques. 

 Throughout this period, however, one can trace a continuing trend - the increas- 

 ing recognition of the unity of the earth sciences. We can not separate the his- 

 tory of the ocean from that of the earth as a whole, nor can we understand the 

 processes now occurring in the ocean without taking into account what is happen- 

 ing in the atmosphere above us, and in the solid earth and liquid core beneath. 

 Moreover, the scientific study of the earth as a whole is becoming evermore 

 dependent on increased understanding of that part of the earth which is covered 

 by sea water. Our definition of oceanography is thus gradually broadening to 

 be simply: The science which is done at sea. A comprehensive discussion of 

 oceanographic instrumentation should therefore include a description of the tech- 

 niques of all the earth sciences, as modified for use above, or in, or under the 

 ocean. From this point of view the present symposium may be regarded as a 

 representative sampling, with the objectives of indicating the scope of the sub- 

 ject, the state of the art, and the lines of development. 



The sea-going scientist labors under several disadvantages. First is 

 the great disproportion between the area to be covered - almost three-quarters 

 of the earth's surface - and the tiny number of full time professional workers. 

 Second is the expense and difficulty of work at sea as compared to its rewards - 

 the fact that man is a land mammal will be enthusiastically confirmed by any one 

 who has been seasick in the small, oily and uncomfortable craft which are uti- 

 lized as research laboratories by oceanographers. In this harsh environment 

 the oceanographer must be as much seaman as scientist, and his instruments 

 tend to be rugged and crude with attendant loss of precision and flexibility. 

 Third is the stubborn opacity of the ocean to visible light - this has produced 

 the paradox that we know more about the surface of the moon than about the to- 

 pography of the ocean floor. Fourth, for the most part the oceanographer must 

 make measurements, at a series of discrete points in space and time, of para- 

 meters which vary widely and often unpredictably from point to point and from 

 time to time. Finally the oceanographer is largely denied the benefits of con- 

 trolled experiment, that peerless tool of the laboratory scientist. His methods 

 must be akin to those of the detective who patiently pieces together all possible 

 clues in his attempt to reconstruct what has happened. 



Surprisingly enough, however, many kinds of geophysical work at sea 

 can be conducted with relative ease compared to corresponding investigations 

 on land. In seismic work, consistent signals can be obtained through the sea 

 floor out to distances of 60 miles with an 80 pound charge, and on occasion rec- 

 ords up to 100 miles are obtained. On land, a distance of 10 miles with an 80 



