harbors, one can still read with fair accuracy. If we get down be- 

 low fifty feet, the smallest scale unit on the dial is five feet. 



It is possible to obtain a current profile when velocity is 

 plotted against depth by a function plotter. The direction trace is 

 not recorded in figure 6. 20, but does exist on the nnagnetic tape 

 original. 



A more recent model used circuit boards (fig. 6.Z1). These 

 are assembled in stacks one above the other. The circuit boards 

 shown are multiple binary decks with associated telemetering am- 

 plifiers and filters. 



There are electrical background problems in the ocean (fig. 

 6. 22) of which you should remain cognizant if you are going to tele- 

 nneter electrically or make certain types of measurennents. 

 Electromagnetic energy exists in the ocean. The electrical spec- 

 trum in the audio frequency range from about 0.2 kc. up to around 

 20 kc. has been integrated and recorded as a function of azimuth. 

 The sensor was towed behind a submarine as the submarine was 

 turning at a constant depth. There are directional characteristics 

 to this. This is basically generated by what the meteorologists 

 call sferics, electromagnetic disturbances that are propagated 

 great distances from electromagnetic storms, lightning, and so 

 forth. 



Everything isn't quite what we might expect in the ocean. The 

 more you work with it, the more you realize this is true. For 

 instance, data was taken to measure the cmnoiint of light as a 

 function of depth on a moonlight night. One would expect that it 

 gets darker as you go deeper. One record shows that such is not 

 always the case (fig. 6.23). Down to about 100 meters, the light 

 intensity does decrease. However, at about 100 meters the light 

 intensity stops decreasing and may increase. In this case the 

 record only goes down to about 300 meters. The light is essential- 

 ly due to the presence of luminescent organisms existing within the 

 ocean in this region. 



Power sources, of course, are extrennely important to the 

 oceanographer . Here we can only scratch the surface, and I shan't 

 attempt to make anything like an all-inclusive coverage. Primary 

 batteries represented by the Leclanchg' cell, the common dry cell, 

 are quite reliable in the ocean. They have to be protected, of 



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