34 LAYING OUT GROUNDS. 



a direction does not so effectually answer the purpose as a diagonal 

 drain. The number and direction of the main-drains must also be 

 regulated by the situation of the ground, and the flow of water likely 

 to pass through them ; one main-drain will frequently be found suf- 

 ficient for an acre : the branch-drains must be conducted on their 

 descent into the main-drain, at acute angles, as a preventive from 

 obstructions. The dimensions of the main-drain must be greater 

 than the branch-drains; but much depends on the material to be 

 used. When curved tiles are used in stiff land, the drains are cut 

 with an angle at bottom, having shoulders for the tiles to rest upon : 

 these drains, in many situations, have answered every expectation. 

 Stones are sometimes employed for filling up drains ; brush-wood is 

 also used, as black-thorn, alder, beech, &c. It has been ascertained 

 that any of these placed in a drain while in a green state, have 

 lasted for many years. 



When land is of a stiff and cold nature to any considerable depth, 

 and retains water on its surface, it is necessary to cut the drains 

 entirely through it to a new stratum, which will frequently be 

 either gravel or sand ; and it must be observed, that unless the 

 draining be effectually accomplished, the fruit-trees and crops will 

 not flourish. 



When the moisture of the ground proceeds from springs, it is 

 necessary to ascertain where they originate, by boring, or by cutting 



