SUCCESS IN MARKET GARDENING 



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 sub- 

 ject, favouring this rule for the least depth. At 

 intermediate points occurring between such (mini- 

 mum) 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 of opinion, in fact this is a 

 question which does not admit of any exact or 

 definite solution, as it obviously depends in a great 

 degree upon the peculiar constitution of the soil, 

 which is variable; and, moreover, no amount of 

 practical experience even will afford data for 

 reducing practice to any well-grounded theoretical 

 rule. It is not feasible to state, in exact terms, 

 precisely what is the operation of these subterran- 

 ean drains upon the moisture of the soil; but an 



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