SOILS AND FERTILIZERS 



89 



shovels and spades. The ditches are made just wide 

 enough to work in. 



As it is necessary for the ditch to be dug so that the 

 tile laid in it shall have a uniform slant or fall from the 

 highest point to be drained to the outlet, it is essential 

 that a careful survey of the land be first made by one 

 who understands drainage engineering if the fall be 

 very slight. If there is a considerable fall, a farmer who 

 can use a level can do sufficiently accurate work for 

 practical purposes. 



He maps out the location of the drains and, by means 

 of an instrument called a level, determines at what 

 depth the ditch must be dug over its entire course. If 

 this work is not accurately done, or if his directions are 

 not carefully followed by the ditch diggers, the tile 

 may become clogged up and thus be rendered useless. 



After the tiles are laid in the bottom of the ditch, fitted 

 end to end as closely as possible, the ditch is filled in 

 with dirt, usually with a scraper and a team of horses. 



Note. Some may be puzzled to know how the water gets into 

 the tile. The tile is not like a long pipe to take water in at one end 

 and discharge it at the other. It rather serves as a means of directing 



DRAINAGE 

 ATER 



FIG. 33. Water seeps in at the Joints. 



the flow of water in the soil through which it is laid. Water finds 

 this passageway through the fact that the tiles placed end to end are not 

 fitted water-tight. The water seeps in at these slight openings, and 



