I 7 6 RELATIONS OF SOIL TO HEAT 



of the influence of the water contents of a soil on its tem- 

 perature. Thus on April 24, between 3.30 and 4 p.m., the 

 temperature of the air being 6o-5 F., the temperature of 

 the surface inch of a wet and dry soil was as follows : 



Well-drained Sandy Loam . . . 66-5 

 Undrained Black Marsh ... 54-0 



On July 31, the temperature of two soils, each more than 

 half saturated with water, was as follows : 



First Foot. Second Foot. Third Foot. 



Alluvial Sand ... 71-2 ... 70.l ... 67-6 

 Red Clay 67-2 ... 654 ... 63-6 



On August 6, two soils, less than half saturated with water, 

 were found to have the following temperatures : 



First Foot. Second Foot. Third Foot. 



Sandy Loanx ... 76-5 ... 74-7 ... 72.l 

 Clay Loam ... 69-5 ... 69^3 ... 67.0 



Thus throughout the summer the wetter soil is in every 

 case distinctly the colder. 



One of the most instructive illustrations of the influence 

 of water on the temperature of the soil is furnished by the 

 observations made long ago by Parkes on the temperature of 

 a peat bog, known as the Bed Moss, in Lancashire (Jour. Roy. 

 Agri. Soc. 1845, 140). This bog was 30 ft. in depth, and of 

 the wettest description. Below the depth of i ft. the natural 

 bog was found to have a constant temperature of 46 F. 

 during three years of observation. A portion of the bog 

 had been drained by open drains 3 ft. in depth, and the 

 drained portion had been dug to the same depth. Ther- 

 mometers were sunk to various depths both in the drained 

 and undrained portion. The observations of temperature 



