for plugging in a photoflash bulb which serves as an angle recorder. 

 The recorder, when inserted in its case, is attached to a long thin 

 probe that goes into the bottonn of the ocean, and it is necessary to 

 know the angle with which the probe goes into the bottom. The 

 photoflash bulb is coated with a nnixture of beeswax and lampblack 

 so that when it flashes, as the stylus of the strip chart recorder 

 goes from its reference position out to record, the heat liberated by 

 the flash bulb melts the wax and the wax runs down to the lowest 

 point on the bulb. This can be readily measured with accuracies of 

 the order of plus or minus 3 degrees. It gives all the orientation 

 information necessary without much complication. 



In figure 6.14, Dr. Arthur E. Maxwell, ONR, is putting the 

 instrument in its case. He is wearing a typical tropical oceanog- 

 raphic unifornn. The instrument is then lowered over the side in 

 its pressure-protected case with the ball breaker device (fig. 6. 8) 

 above it. Sometimes it is necessary to straighten the probe 

 (fig. 6. 15) because it can be bent by the drift of the ship. A good 

 design will permit reusing the probe a good many tinnes before it 

 is permanently damaged. 



More recently we designed a current meter to test certain 

 basic principles (fig. 6.16). It is not necessarily a design that we 

 would want to repeat or duplicate. It was made to measure a 

 velocity profile while it was being raised and lowered. It included 

 an electric swivel at the very top, an electrical plug which is 

 simple to disconnect, the current sensing rotor on top, the elec- 

 tronic case hidden by the plastic fin, and the plastic fin. The 

 electronics are principally all in one narrow deck, with the direc- 

 tion element below it (fig. 6.17). This instrument telemeters 

 depth, current direction, and current magnitude simultaneously. 

 We may say that it has learned to talk. It provides an output 

 that is suitable for going into magnetic tape recorders. 



If one wishes to make instantaneous readings, the onboard 

 readout has four meters (fig. 6.18). The two on the left indicate 

 current. The first reads from zero to three knots; the next, a dual 

 scale ineter, reads from zero to 0.3 knots, eind from zero to 0.03 

 knots. The third dial is a depth meter, which is also a dual range 

 instrument. The direction indicator is on the right. The inputs to 

 the depth meter dial (fig. 6.19) are linear. The nonlinear 

 characteristic is obtained by shaping the magnetic pole pieces. 

 The scale is quite open for shallow water. If one wishes to work in 



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