130 MOSQUITO ERADICATION 



the complete drainage of 40 acres, while a 4-inch tile will drain 

 only 6 acres. On the level soils of the South Atlantic and Gulf 

 States, where the rain-fall is heavier, only about three-fourths of 

 these areas can be drained with the same size of tile, according to 

 the same writer. 



PLACING THE TILE 



"Laying the tile, like digging the ditch, should begin at the outlet," 

 says Smith. 1 " Under ordinary conditions, tile should be laid every day 

 as far as the ditch is made. Any delay in laying may cause injury to the 

 ditch by rain or by particles falling into it. If the banks are likely to 

 cave, the tile should be laid as fast as the ditch is completed. 



"The smaller sizes are laid from the bank with a hook. Large sizes 

 must be laid by hand from the bottom of the ditch. All mis-shaped and 

 cracked tile should be discarded. If a tile does not join closely with a 

 preceding one, it should be turned over until it fits at the top. Any 

 large cracks are covered with pieces of tile. Where a lateral joins to a 

 main or sub-main, the connection should be made with a Y. Neither 

 a T nor an elbow is desirable, as these check the flow of the water. 



"When the tile are laid and inspected, they are ready for priming. 

 This is done by caving a little earth from the sides of the ditch and letting 

 it settle gently, so as to keep from knocking the tile out of line. In 

 sandy soils, there may be danger of sand entering the tiles and clogging 

 the drain. This can be prevented by covering the joints with pieces of 

 old sacks or straw. 



"After the tile are primed, they may remain without injury for several 

 days until all the ditches are ready for filling. If the soil is close and it is 

 desirable to aid the water in reaching the tile quickly, the ditch can be 

 partially filled with straw or brush, or, better still, with stones and 

 pieces of brick. Under ordinary conditions, the ditch is most easily 

 filled with a turn-plow and an evener, which is 12 or 14 feet long. Two 

 horses are hitched to this plow, one on each side of the ditch and, with 

 one man to lead or drive and another to hold the plow, the earth is 

 turned in. There may be extraordinary conditions, however, when a 

 plow cannot be used. By placing the team on one side of the ditch and a 

 wooden scraper on the other side in such cases, the dirt can be pulled in 

 rapidly. Filling by hand is usually the most difficult and most expen- 

 sive method." 



In laying tile for the purpose of intercepting seepage water, 

 best practice seems to call for a stone or gravel fill over the tile, 

 instead of the usual earth fill. 



i"Tile'Drainage on the Farm," Farmer's Bulletin No. 524, U. S. Department 

 of Agriculture, 1917. 



