CONSIDERATIONS OF OCEANOGRAPHIC INSTRUMENTATION 



John D. Isaacs 



We are here to discuss a great and curiously diverse assemblage of 

 ships, dredges, thermometers, intricate electronic devices, plankton nets, hy- 

 drophones and water samplers. This list is diverse, yet it includes only tools 

 and instruments -- tools that permit us to reach where we otherwise could not 

 reach; and instruments that permit us to see or hear where to our unaided 

 senses all is black and silent. And these two are fused by singularity of pur- 

 pose --to disclose the nature of the oceans to the mind of man. 



We plan to consider these extenders and amplifiers of our motor and 

 sensory abilities as they are brought to bear on an understanding of the oceans. 

 Yet they are only temporal links between the two basic realities, the sea and the 

 mind of man. We cannot consider instruments as an isolated problem more 

 than we can consider the ocean isolated, without top nor bottom. We first must 

 consider the characteristics of the two fundamental systems between which in- 

 struments must weld a link. The basic matches are not of compression waves 

 between a crystal and water, not of magnetic waves between steel and the sea, 

 but between man's mind, together with its sensory outgrowths, and the realm to- 

 ward which his compelling curiosity is directed. The physical linkage of an in- 

 strument to the sea usually is concurrent with its operation, but before final 

 presentation of its information to the mind many complex steps may be inter- 

 posed, often including manual transfornnations which we must consider part of 

 the link, that is, part of the instrument. Throughout this discussion I will con- 

 sider the presentation of the sea to the mind in two intergraded parts, first a 

 presentation of data to individuals who can relate the data to known or partly 

 known unit concepts to be secondly presented to other individuals for inclusion 

 or consideration in a more general concept. Thus the reading of the reversing 

 thermometer is only the primary presentation and the completed dynamic topog- 

 raphy a much more inclusive presentation. Each grade of presentation has its 

 peculiar problenns. Nevertheless, the steps between the sea and final presenta- 

 tion to the mind are all a part of the instrument and one goal of instrument de- 

 velopment must be to include more and more of the steps of presentation in the 

 mechanism. The STD (Salinity-Temperature-Depth Recorder) is an example of 

 this trend. 



First, let us consider the relationship between an understanding or con- 

 cept and the instruments upon which its furtherance must depend. Can we say 



that the basis of all understanding is experience? I recently have become con- 

 vinced of a point which others have understood much more easily. Somehow it 



had seemed to me that there was a basic difference between such understand- 

 ing as, for instance, that light intensity varied with the inverse of the distance 

 from the source and such concepts as the Pauli Exclusion Principle which sets 



forth the conditions under which an electron can occupy a position in an atom. 



The first case fitted into my general concept, seemed to be naturally logical and 



* - Contribution No. 678 from the Scripps Institution of Oceanography 



