The farmer who adopts this system is less at the 

 mercy of the fickle elements; for an efficient drainage 

 carries off the water so rapidly that his ground is fit 

 to work as soon as the rain has ceased, and he is not 

 obliged to " wait for the land to dry." He has also a 

 longer season for his work, since the ground is ready 

 for crops earlier in the spring, and can be worked 

 later in the fall. 



Another great advantage which follows the prac- 

 tice of thorough draining, is the effect it has in raising 

 the temperature of the soil. 



Heat will not pass downward in water, and, before 

 a soil can be warmed, the water must be removed. 

 Again, water escapes from retentive, undrained soils 

 by evaporation only, — a process which uses up a 

 great amount of heat ; one pound of water in pass- 

 ing into a state of vapor absorbing and carrying away 

 972° of heat, which is rendered latent or insensible to 

 the thermometer. This amount of heat might have 

 raised the temperature of the soil, and materially assist- 

 ed the process of growth had it not been lost by evapo- 

 ration. Prof Henry gives, in the last Patent Office 

 Report, a table by M. Schubler showing the max- 

 imum temperature of various earths exposed to 

 the sun, while the surrounding air was at about 78°. 

 One column exhibits the temperature of moist earth, 

 and the other that of dry earth. He remarks, that 

 " the differences of temperature exhibited by the two 

 columns are due to the heat expended in the evapo- 

 ration of a portion of the water in the moist earth." 



2 



