84 HOW TO MAKE THE FAEM PAY. 



Next determine carefully the number a,nd position of tbo 

 drains. This is the most difficult part of the operation. A few 

 general rules will aid you. As far as possible tbe drains 

 should run parallel with the inclination of the slope. When 

 laid three feet deep they should be forty feet apart; i<n sandy or 

 light soils, they should never be less than four feet deep, and 

 may be sixty feet apart. If other lands drain into the field, 

 there should be a three-incb drain at the head across the whole 

 field with which the smaller drains should be connected. For 

 convenience we will call these, head drains, or headers and sub 

 mains or minors ; and the large drain into which they all enter, 

 the main drain. If there are marshy places lower than the 

 stream into which the drainage must be carried, they may be 

 drained into wells dug at their lowest points. If you have no 

 outlet in your own field, after it is drained into one main drain, 

 it may be carrii'd under a highway or a neighbor's field to some 

 outlet, without great expense. If possible, there should be but 

 one general outlet for the whole system of drains, as the outlets 

 are the most exposed portion of the whole work. Having 

 determined the proper point for an outlet, the whole work can 

 be directed towards this point. 



Fig. 9 represents an irregular field, which it seemed impossi- 

 ble at first sight to drain thoroughly, and as it illustrates the i 

 general principles of drainage, we shall describe it in detail, A 

 was a sluggish stream almost stagnant ; at the bottom of the 

 field, h a knoll some nine or ten feet in height, cc an entirely! 

 useless swamp, d the main drain laid about forty feet from the! 

 brook, EE the minor drains sixty feet apart, and entering the 

 main drain at an angle to prevent obstructions, jf wells into! 

 which the northwest and southeast corners were drained. It 

 was thought at first that the southeast corner could not be 

 drained, but on applying the span, it was found that there wa-^i 



