equidistant spacing is employed for both temperature and depth. 

 Comparison between the actual grid from a calibration tank and the approxi- 

 mated grid employed to make up the standard calibration would show these 

 errors best. 



10.5.4. Reproducibility 



28. Reproducibility is best measured by the closeness with which the uptrace 

 matches the downtrace, ocean variability being accounted for. A study of a 

 series of Bathythermograms will reveal the extent of the following possible 

 characteristics contributing to reproducibility. 



(a) Mechanical Hysteresis 



Mechanical hysteresis is represented by parallel displaced lines in a 

 Bathythermogram study. Other effects of this mechanical lag might be 

 observed. 



(b) Response to Initial Depths 



Response of the Bathythermograph to the first ten feet of water should 

 be studied further experi mentally. This is particularly important to un- 

 derstand because of its bearing upon the studies of keying the surface 

 value of the Bathythermograph to a bucket temperature. It ties in with 

 BT-bucket correlation analyses. 



(c) Rate of Response to Ocean Variations 



Response rates should be experimentally ascertained. This is important 

 in relation to variability studies, internal wave studies, and will dictate 

 operational procedures in proper rates of lowering, etc. 



(d) Response Hysteresis 



It is felt that a study of Bathythermograms can incorporate a study of 

 all hysteresis effects. Response hysteresis should be able to be distin- 

 guished by the characteristic shape of the curves, and possibly some 

 quantitative information can be produced from a study of the hysteresis 

 curve shapes. 



(e) Mechanical Hesitation 



The wiggles on Bathythermograms can be due to mechanical hesitation 

 through sticky bellows, pen play, etc. This must be experimentally evalu- 

 ated through control tests. 



10.5.5. Operational Errors 



29. Studies have been made in order to evaluate personnel error. It is considered 

 feasible to incorporate into the before-mentioned anchor station studies a per- 

 sonnel factor, this being accomplished by comparing anchor stations of various 

 grades of accuracy, i.e., good, average, poor. Other studies along this line have 

 been fairly quantitative in their results. 



30. With regard to speed of raising and lowering the Bathythermograph, direct 

 experimentation is necessary, along with the hysteresis analysis mentioned in 

 Recommendation 28. 



31. Bathythermogram reading errors can be established also on an experimental 

 basis. 



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