276 EXPERIMENTS IN DEAINING. 



This rule has been important, for when opening 

 ditches on the low grounds the water has flowed with 

 a force to induce most people to believe that it was 

 derived from springs close by, when possibly the 

 spring may be some 60 or 80 rods distant at or near 

 the most elevated part of the field, which, when 

 reached, may save much expense in draining the 

 lower lands. This shows the necessity of thoroughly 

 examining the land to be drained in the wettest 

 season. The main drains occupy the valleys or 

 lowest grounds, receiving the lateral drains and col- 

 lected water. They are constructed of larger tiles, 

 and discretion and care are very necessary to 

 apportion the main drains to the quantity of water 

 to be discharged. In several instances I have found 

 it necessary to lay a double row of four-inch tile in 

 main drains to carry oif the quantity of water col- 

 lected by the smaller tile. I have generally used 

 the half round or horse-shoe tile, as they are called. 

 The four-inch tiles are in most cases large enough 

 for main drains, and they discharge a body of water 

 far greater than most persons would believe, unless 

 they witnessed their action. There may be places 

 where larger tiles are needed. In one instance I 

 found it necessary to use six-inch tiles for sixty rodo, 

 and laid them in double rows. This would only be 



