FOR YOUNG TREES. 35 



requiring drainage, ascertain by the spirit-level how 

 deep a main drain can be made there, in order to 

 have, at the same time, a proper descent to carry 

 off the water from it ; having fixed this point, cut a 

 main drain along the lowest part of the ground, at 

 least three feet deep, and endeavour to give it as 

 good a descent as possible. The main drain being 

 made, say three feet and a half deep, and five feet 

 wide at the top, lay off your smaller or common 

 drains at proper distances, and at right angles to 

 the main drain ; and in making the common drains, 

 say that you wish to have them twenty inches deep, 

 make them of that depth at the top, or the end 

 farthest from the main drain, and proportionally 

 deeper, as you approach it; and when you finish 

 the small drains into the main one, you can have at 

 least one foot and half of descent between the two 

 ends of your drains, which is quite enough for a 

 drain of any ordinary length. If this main drain 

 have to receive water from a considerable number 

 of small ones, as will be the case if it is of any con- 

 siderable length, and if it have to receive water from 

 drains laid oif upon each side of it, great care must 

 be taken to make it large enough. In many cases 

 it may be found necessary to make a main drain 

 even larger than the dimensions 1 have specified 

 above ; but this must in all cases be regulated ac- 

 cording to the number of drains that may have to 

 be emptied into it, and much also depends upon the 



