15 16 17 18 19 20 



T4 •■ IS 16 17 18 19 20 



14 15 16 17 18 19 20 



Figure A5. Example of time series and temperature readings on recorder tape. 



every 15 minutes against that of a standard cell incorporated in the instrument. 

 Standardization may also be done at will by the operator, and is always done at 

 the beginning of each run. Thus, the amplifier-servo system acts essentially as a 

 null detector galvanometer. 



Accuracy 



The original specifications for the circuits in this instrument called for an accu- 

 racy of ±0.1°F. The Fahrenheit scale is used so that the recordings may be com- 

 pared directly with bathythermograph measurements which are made simulta- 

 neously. It was found that, by careful matching of the thermistor beads and 

 compensating resistors and by accurate calibration of the beads over each sub- 

 range, an even higher degree of accuracy is attained, as can be seen in figure A6, 

 which is a reproduction of actual records made with two beads held at two con- 

 stant known temperatures. 



33 



