22 



which the temperature was maintained at or near 25°C. As the 

 temperature of the room in which the thermostat was placed 

 sometimes rose above 25°, it was necessary to install appar- 

 atus for absorbing heat at such times. To accomplish this 

 several coils of thin-walled copper tubing carrying a con- 

 tinuous stream of tap water were placed at the top of the 

 thermostat, surrounding a small motor-driven fan, to ins- 

 ure air circulation. The air of the chamber then tended to 

 assume a temperature several degrees below that of the lab- 

 oratory, and the thermostat acted as though standing in a 

 cold room. 



