ILLUSTRATIONS 



1 Calibration tank with control panel. . . page 6 



2 Calibration tank lid (view from left side). . . 7 



3 Viewing window and telescope unit. . . 9 



4a Rack for holding 24 reversing thermometers and including 

 stirring propellers at diagonal corners. . . 11 



4b Platinum resistance thermometer and quartz 

 temperature probe. . . li 



5 Auxiliary thermal system (hot and cold tanks). . . 12 



6 Temperature controller with Mueller bridge and 



null detector. . . 14 



7 Schematic of circulating system. . . 16 



8 Access to all controls by operator. . . 17 



9 Pressure vessel for calibration of unprotected reversing 



thermometers. . . 20 



10 Deadweight pressure gage with hand pump and valving 



system. . . 20 



11 Exercising and storage rack for reversing thermometers. . .21 



12 Reversing thermometer calibration sheet. . . 22 



13 Resistance bridge for calibrating thermistors. . . 26 



TABLES 



Al Thermometer grouping. . . page 29 



A2 Comparison of laboratories' facilities. . . 30 



A3 Cross-calibration tolerances to be used for future work. . .30 



A4 Thermometer cross-calibration. . . 31-37 



A5 Repeatability of reversing thermometer calibrations 



by NUWC._ 38 

 A6 Comparison of Va determinations by the four laboratories 



and the manufacturer. . . 39 

 A7 Q-factor cross-calibration comparison for six unprotected 



reversing thermometers. . . 40 



