SPECIAL FARM TOPICS 261 



drainage in agriculture. Well burned clay pipes of circular form 

 and one or two feet long are laid in a continuous line through the 

 soil upon such a grade that the water in them will be carried by 

 gravity to some lower point. The water enters the pipes through 

 openings left between the ends or joints. The ends of the tiles 

 should be placed together in order to prevent the soil from entering, 

 yet not so close as to prevent the entrance of water. 



The drain being surrounded with soil, the spaces of which are 

 filled with water, the water percolating the soil enters the pipes 

 through the crevices and is carried off. Other water of the soil takes 

 the place of that removed, the water of saturation gradually passing 

 from the surface downward, the soil near the level of the drain being 

 the last to be relieved. This process does not leave the soil without 

 moisture, but only removes the surplus. It does not remove water 

 from below the level of the drain. (F. B. 187; N. H. C. B. 118; 

 Ark. Ex. Sta. B. 104.) 



Kinds of Tile. The tiles used should be round in form, straight 

 and well burned. They need not be vitrified in order to be lasting, 

 but every particle should be completely burned, no matter what kind 

 of clay is used. Such tile is then almost indestructible in earth and 

 water. When exposed to long continued freezing and thawing at 

 the outfalls, the best vitrified pipe should the,n be used. After one 

 has become familiar with the ware of a particular factory, properly 

 burned tiles may be readily distinguished by their color, and by 

 their ring when struck with a piece of steel. Good clay may usually 

 be semi-vitrified if skill be used in burning. Porosity of the finished 

 ware is not important, as all water enters the joints. Vitrification, 

 though not essential, is always a desirable quality in drain tiles. > 

 (F. B. 178 ;N. H. C. B. 118.) 



Size of Tile and Fall of Drains. The size of the main drain 

 will depend upon its fall and the area which it drains. The greater 

 the fall the smaller may be the tile. If the fall is doubled the carry- 

 ing capacity is increased about one third. A four-inch main will 

 suffice for most ordinary systems where not more than ten or twelve 

 acres are to be drained. If twenty or thirty acres are to be drained 

 into one main it should be five or six inches in diameter. Tile larger 

 than necessary should not be used, as the cost increases much faster 

 proportionally than the size of the tile; for example: Three-inch 

 tile may be listed at $25, four-inch at $45, five-inch at $75 and six- 

 inch at $100 per thousand. 



For laterals a three-inch tile will usually be found most satis- 

 factory, as it is large enough to carry off in a reasonable time all 

 the surplus water of our heaviest rains. The danger in using 

 smaller tile lies in the fact that it does not take a great deal of sedi- 

 ment to fill them, and unless they are laid on a perfectly true grade 

 with a good fall their efficiency will soon be diminished. A varia- 

 tion of an inch below a true grade will result in filling a two-inch 

 tile just half full of sediment, while an inch of sediment in a three- 

 inch tile will only reduce its carrying capacity about one-fourth. It 

 is pretty difficult to determine the proper size of tile unless the de- 



