TILE DRAINAGE 



27 



should be had as possible, as they are always a source of 

 trouble. Next locate the main, having it follow the line 

 and direction of the lowest lying ground. This can be 

 done by noticing the channel in which the greatest amount 

 of surface water tends to run after a heavy rain. The 

 main will thus be likely to have a location somewhere near 

 the center of the area drained rather than on one side of it. 



/ 



u. 



Fig. 2. Two different arrangements of drains. 



Of course, when this is done, the laterals entering from 

 both sides drain a certain amount of ground already 

 drained by the main, but as the main in this case is sup- 

 posed to be in the lowest ground most needing drainage, 

 the extra amount does no harm. On a comparatively flat 

 piece of ground, where there are no particularly low-ly- 

 ing channels, it is better to locate the main at one end or 

 side and place the laterals in parallel lines at nearly right 

 angles to it. These two arrangements are illustrated in 



