102 



In commencing the important operation of deep and thorough 

 draining, the first thing to be attended to is, to provide deep and 

 clear channels, into which the covered drains are to discharge 

 their water. Unless such can be made it -will be of little use to 

 under drain. The whole outlay of draining hinges on having 

 good discharging channels. If the bottom of the main ditch, chan- 

 nel or drains, brook or river, be scarcely below the bottom of the 

 covered drains, they will be rendered almost inefiective. The 

 main drain, or the one into which the lesser ones discharge, should 

 be five, and if possible, six feet deep, provided the former are four 

 feet deep. Too much precaution can hardly be used in keeping 

 these main drains free from all obstructions. Let these once be- 

 come gorged and the whole will suffer damage. 



But the advocate for deep and thorough drainage is constantly 

 confronted by intelligent farmers, " what is drainage, and how or 

 why is it so important, as you claim it is, to permanent improve- 

 ments ?" It is right that such questions should be put, and the 

 advocates for drainage should be able to answer them and all simi- 

 lar inquiries, or else tarry awhile longer at Jericho. 



The first reason or necessity for drainage is predicated of the 

 supposition or fact, that the soil and subsoil are charged with an 

 excess of water, rendering it impossible to produce maximum crops 

 until it be removed. The first evil is mechanical. If the soil be 

 clayey and tenacious the circulation of the air through it is pre- 

 vented and it remains cold and sour, and is less productive. This 

 complaint is made by the tillers of such land every cold and wet 

 Spring, because they cannot plant or sow ; and if they do not 

 withhold the hand by reason of the wet, in consequence of the 

 stagnant water in the soil, it produces but a poor crop. 



The words, ivet and cold^ are significant, thus applied. Evapo- 

 ration is productive of cold, says the chemist, a fact the farmer 

 knew before chemistry came to his aid. Evaportion, then, it will 

 be admitted, lowers the temperature at the earth's surface. It re- 

 quires as much heat to evaporate a cubic inch of water, it is said, 

 as would raise the temperature of 5| inches from the freezing to 

 the boiling point. To evaporate the fall of an inch of water from 

 an acre of land demands an amount of solar heat sufficient to raise 

 the temperature of the dry soil of an acre to the depth of 10 inches, 

 no less than 99 degrees. Then when the fact is considered 

 that 40 or more inches of water fall annually upon every acre of 

 soil, the importance of under drainage, as a means of keeping up the 

 temperature of the soil, cannot but be observed and acknowledged. 

 Owing to radiation and other agencies, the difference between the 

 temperature of drained and undrained land is not so great as 

 theory would make it. Much of the heat is rendered latent — i. e. 

 not perceptible by a thermometer. The vapor yielded by a cubic 



