66 THE SOILS AND CROPS OF THE FARM. 



the soil, the size of the tile, the distance apart and the 

 depth of the drains, as well as on the rate of fall, the 

 skill with which the work is done and the character of 

 the outlet. 



The total rain- fall for a year is of less consequence 

 than the quantity which may fall in twelve or twenty- 

 four hours. It is useless to undertake to carry off at 

 once the water which may fall in extraordinary cases. 

 Comparatively little harm is done by standing water if 

 it be removed in a few hours. The percentage of water 

 which will pass through the soil depends not only on 

 the amount which falls but upon the character of the 

 soil. 



ISize of Tile. — Smaller tile are used in England 

 than in this country. Those one inch in diameter 

 were formerly used, and two-inch tile are not un- 

 common. In many parts of this country tile less than 

 three inches in diameter are rarely used. A two-inch 

 tile is abundantly large for use in many places, but 

 there is danger of mistakes in deciding this point and 

 errors in laying small tile are more serious in their 

 effects than with large tile; hence it is safer to use 

 larger sizes. The carrying capacity of tile varies with 

 the square of their diameter. Thus a six-inch tile 

 will carry four times as much as a three-inch tile; in 

 fact somewhat more, because the resistance from fric- 

 tion against the sides is relatively less in the larger 

 tile. It is a mistake to lay a long line of tile all of 

 the same size. The quantity of water to be carried 

 increases as the line extends, and the rate of fall is 

 rarely great enough to allow an increase in velocity. 



For ordinary farm drainage, tile varying from three 

 to six inches in diameter are most commonly used in 



