bridge is checked against a standard 10-ohm re- 
sistance. 
The main time consumed is in allowing the ther- 
mometers to come to equilibrium at each new tem- 
perature at which a calibration is required. In making 
macrotemperature changes, a constant increase of 
12°C/hr with 3000 watts in the heating element 
and a decrease of 8°C to 12°C/hr are possible. This 
latter change becomes slower as the tank tempera- 
ture approaches that of the external tank. 
Thermometers may be aligned and read rapidly. 
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. 
