SOIL HEAT 



237 



for fine sandy loam, constructed from Patten's data, 1 illus- 

 trates its effect and indicates how heavily it must override the 

 factors already mentioned: 



5 to 15 20 25 



Fig. 44. — Conductivity curve for Podunk fine sandy loam, showing the 

 influence of moisture content upon the rate of heat transfer. The 

 curve apparently flattens out at a high moisture content indicating 

 that good conductivity may he obtained at optimum moisture. 



At first glance it appears peculiar that the heat movement 

 through a soil, the mineral constituents of which possess a 

 conductivity coefficient of about .01066, should be accelerated 

 by the addition of a liquid possessing a value for K of about 

 .00149. The explanation lies in the lowering of the transfer 



1 Patten, H. E., Heat Transfer in Soils; U. S. Dept. Agr., Bur. Soils, 

 Bull. 59, p. 27, 1909. 



