WATER IN AGRICULTURE. 173 



expense incurred in draining. It is certain that 

 even our uplands can be greatly improved by drain- 

 age. What is the philosophy of such apparently 

 paradoxical experiments ? It is easily understood. 

 The first great benefit of course comes from convey- 

 ing away superfluous water at the season when the 

 seeds are placed in the soil. All soils, high or low, 

 are then filled with water struggling to escape by 

 percolation and evaporation, and the farmer must 

 wait until it slowly disappears before putting in his 

 seed. In this there is not only a loss of time, but 

 often it carries crops so late into autumn that early 

 frosts nip and destroy them. This form of benefit 

 is readily comprehended, but the inquiry comes up, 

 " If drains carry away the unnecessary water in 

 the spring, why will they not carry off the neces- 

 sary water of summer? Why do they not leach 

 the soil at the very time when every atom of 

 moisture is needed to feed the growing grains and 

 grasses ? " It may be said in reply, that drains are 

 incapable of removing water which is of service to 

 plants ; it is only when it is in excess and detrimen- 

 tal, that the work of removal goes on. They are 

 active only in wet summers upon elevated lands ; 

 their useful services only then come into play. In 

 dry summers they keep the dry soil moist. There 

 is in such seasons reversed action going on. In- 

 stead of water coming out, air is passing in, and as 



