WORCESTER SOCIETY. 155 



the unprodudtiveness of our wet, swaley, and some of our hill 

 lands, and must be removed, before the most valuable results 

 can be obtained by cultivation. The most obvious way of 

 doing this, is by draining, and the question arises, how drains 

 should be cut to produce the best effect? Water will rise by 

 capillary attraction in wet retentive soil, 18 or 20 inches ; 

 wateer oozing from wet soils into a drain 30 inches deep, is 

 one or two degrees colder in the vegetating season than water 

 oozing from the same soil into a drain four feet deep, and the 

 latter is generally colder than the water in a contiguous well. 

 From this we may conclude that the influence of evaporation 

 is considerable at thirty inches, less at four feet, and little or 

 nothing at greater depths. The water, then, must be laid 

 thirty inches below the surface to protect it against the influ- 

 ence of evaporation, eighteen inches to guai'd against attrac- 

 tion, or four feet in all, to protect the land against the cold 

 produced by the two causes combined. The temperature of 

 water drawn from a wet soil into drains three feet deep is sel- 

 dom higher in the vegetating season than 50 degrees ; air 

 above the surface of the earth at the same time is often 80 or 

 90 degrees, and sometimes much higher; drains then four feet 

 deep draw out water of 50 degrees temperature, every particle 

 of which is replaced during the season of vegetation, by air 

 and rain water of a much higher temperature, constantly 

 warming and assimilating the soil to the depth of the drain, to 

 their own temperature. Thus, drained lands, in the season of 

 vegetation, are 10 or 15 degrees warmer than undrained lands; 

 in winter, when the air and water above the earth's surface is 

 generally colder than the soil below, drained lands are colder 

 than undrained lands. This is no disadvantage ; for, in our 

 climate, plants do not suffer so much from cold in winter, as 

 from a deficiency of warmth in summer — the frost descends? 

 disintegrates the soil deeper, becoming a good substitute for 

 subsoil ploughing. Feculent water, filtered through 30 inches 

 of retentive soil, comes out more or less colored, but when 

 filtered through four feet of the same soil, comes out nearly 

 pure, leaving most of its fertilizing matter in the soil to aid 

 the growth of plants. Water gets into the drains by gravity, 

 or fall, the upper particles pressing upon those below, shoving 

 them aside, in the line of least resistance, which is the drain, 



