EXPERIMENT STATION BULLETINS. 



809 



EFFECT OF UNDERHEATING ON THE SOIL TEMPERATURE 



DURING THE WINTER. 



It is a very general observation that the surface of a soil which is 

 traversed undenieath by a steam heat pipe is kept free from snow during 

 the winter, and in the spring its vegetation commences to grow much 

 earlier than that of the adjacent soil only a short distance away. The 

 logical inference of these observations is that heat escapes from the 

 steam heat pipe which keeps the surrounding soil warm. 



In the winter of 1915 it was decided to undertake a series of observa- 

 tions to determine (1) to what extent the heat lost from a steam heat 

 pipe, in the College Campus, keeps the soil immediately above warm, and 

 (2) how far distant from the pipe the influence of the heat escaping will 

 be felt. To obtain this information soil mercury thermometers were 

 placed 3 inches deep, immediately over the pipe and at various distances 

 apart, up to 10 feet, and temperature observations were made three 

 tims a day throughout the winter. The pipe ran from one building into 

 another and was very long, buried a little over a foot into the ground, and 

 was very well insulated by asbestos, cement, etc. The data obtained 

 from December up to and including April are presented in Table 90. 



The winter of 1915 was very cold, but in spite of that the heat escaped 

 from the steam heat pipe kept the temperature of the soil immediately 

 above very high, from 50 to 65 °F, and even prevented the soil 7 feet 

 away from freezing. Indeed, even at a distnce of 10 feet the soil tem- 



