EFFECT OF DRAINAGE. 261 



but different degrees of combustion. Air is the lighting match, 

 as it were, to set the carbon on fire. The air is composed of 

 two gases, oxygen and nitrogen — one part oxygen to four of 

 nitrogen. The oxygen of the air unites with tlie carbon, pro- 

 ducing combustion or decay. 



Now, as vegetable growth presupposes decay or combustion, 

 and within the soil being, as will be shown, the proper place for 

 that combustion to take place, what is the soil's proper mechani- 

 cal condition, that this decay, or combustion, as well as other 

 processes of nature, yet to be considered, may be facilitated ? 



As the carbon or vegetable matter of the soil must be acted 

 upon by the oxygen of the air to produce decay, the mechanical 

 condition of the soil should be such as to allow the free circu- 

 lation of the air to the desired depth. That this may result in 

 the most thorough manner, a large part of New England soil 

 must be underdrained. This should be to the depth of three 

 and a half or four feet. 



Water is often dead and stagnant on the surface and at various 

 depths in the soil, which would be otherwise penetrated by the 

 roots of plants and trees. The stagnant water is nearly always 

 colder in summer than the air. Its evaporation from the sur- 

 face cools the earth ; whereas, if by underdrains it was permit- 

 ted to pass off at once, the rays or heat of the sun would pene- 

 trate and take the place of the stagnant water, preparing the 

 land for earlier cultivation in the spring and later growth in the 

 fall. Tiie water of the summer rains would also readily pass 

 through the soil, leaving the drain often many degrees colder 

 than when it entered, having imparted its heat to the soil. This 

 circulation of air and water greatly promotes the pulverization 

 of the soil, thus assisting the farmer, who is laboring by plough- 

 ing and hoeing to effect the same thing. And the heated air is 

 doing the work in a most effectual manner down at a depth not 

 usually reached by the plough, and thus enriching the subsoil 

 and preparing it to be turned up to the surface, when the farmer 

 shall have found that there is his source of wealth, rather than 

 adding to his number of acres. 



The effects of drought are much lessened by this drainage. 

 In addition to the moisture held by the sponge-like soil, there is 

 an almost constant condensation of moisture from the air as it 



