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THE PROBLEM 
Develop a controlled-temperature tank for calibrating deep-sea reversing thermometers 
and other precise temperaiure-measuring instruments. 
RESULTS 
A 70-gallon controlled-temperature tank has been constructed and tested. The tempera- 
ture can be reproduced and held to +0.002°C over the range —3°C to 40°C. The tank’s 
large size and remote operation permit calibration of 24 reversing thermometers at 
one time. It eliminates tedious calibration data reduction, since both main and auxiliary 
thermometer stems are read at temperature of reversal. 
RECOMMENDATIONS 
1. Continue development to include installation of electronic time-proportioning switches 
in metering of heat transfer. 
2. Study the possibility of an instrument to record temperatures at two points in the 
tank, throughout any operation. 
ADMINISTRATIVE INFORMATION 
The work was done under IO 15401, NE 120221-13 (NEL L4-1, part 1). This report 
covers work from January 1952 to November 1956 and was approved for publication 
6 May 1957. 
The author wishes to acknowledge the valuable help of J. C. Roque and B. E. Holtsmark 
in functional design of the equipment. Thanks are also extended to A. A. Arnold, Ronald 
Jones, S.L. Polansky, and S. Houseknecht for assistance in the technical design and 
construction. 
