How to Dig the Draiiis. 1 7 



work on this subject with which we are acquainted. 

 Any one who has even a moderate amount of this class 

 of improvements in contemplation ought by all means 

 to possess a copy of the above named book, and make 

 himself master of its contents by careful and diligent 

 study. 



The author recommends a general depth of four 

 feet for drains : never admitting a less depth unless 

 where an outlet at that depth cannot be obtained, or 

 where ground is underlaid by rock. There is a general 

 concurrence of opinion amongst those who have most 

 carefully examined the subject, favoring this rule for the 

 least depth. At intermediate points occurring between 

 such (minimum) depths, the depth must be often 

 greater, because the drain must slope uniformly from 

 point to point, while the land does not. 



As regards the distance between the drains, there 

 is a difference cf opinion, in fact this is a question 

 which does not admit of any exact or detinite solution, 

 as it obviously depends in a great degree upon the 

 peculiar constitution of the soil, which is variable ; 

 and, moreover, no am.ount of practical experience 

 even will afford data for reducing practice to any well- 

 grounded theoretical rule. It is not feasible to stale, 

 in exact terms, precisely what is the operation of these 

 subterranean drains upon the moisture of the soil ; but 

 an idea sufficiently definite for all practical purposes 

 may be gathered from experience. 



In tolerably porous soils, forty or even fifty feet apart 

 is generally conceded to be sufficiently near for four- 

 foot drains. But for the more retentive clays, all 



