472 



STATE BOARD OP AGRICULTURE. 



near the surface is subject to freezing, and freezing may result in the 

 cracking of the tile or in causing a shaling of the tile, which is likely 

 to result in its complete collapse. A depth of less than three feet fails 

 to give to the roots of the crop a sufficient amount of room for develop- 

 ment. 



THE DISTANCE APART OP TILE DRAINS. 



In very heavy clays it may be necessary to place tile drains not over 

 thirty feet apart, while in very open soils they may be placed as far 

 as a hundred feet apart. 



In muck soils they may be placed from sixty to eighty feet apart. 



In ordinary loams they may be placed from forty to sixty feet apart. 



Fifty feet apart is probably a fair average. 



Where the soil is underlaid with a heavier sub-soil lying so near the 

 surface that the tile must be set down into it, the drains must be placed 

 closer together than would be necessary if the sub soil were more nearly 

 like the soil above in openness. 



SIZE OF TILE TO USE. 



Ordinary drain tile ranges in size from two inches up to twelve and 

 even to fifteen inches. 



Fig. 5. The lower 1060 ft. section of main is sufficiently large to carry the water from all the field. 

 The next 720 ft. section is large enough to carry all the water from the field above b. The upper 660 

 ft. section is large enough to carry all the water from the field above c. 



The capacity of tile to carry water varies as to the square of the 

 diameter. Three-inch tile Avill carry two and one-quarter times as much 

 water at the same rate of flow as will two-inch tile. The square of three 

 is nine; the square of two is four, and four is contained in nine two 

 and one-fourth times. The square of five is twenty-five. The square of 



