UNDERDRAINING. 123 



undoubtedly be more frequent than in a climate whose rains 

 are more after the order of a drizzle. 



Next in order after the distance to be adopted between the 

 drains comes the question of depth. Tiles must of course be 

 laid below the reach of the subsoil plough and the frost. This 

 is indispensable. Beyond this opinions differ very materially. 

 The theory seems to be well established that deep drains draw 

 farther than shallow ones, which probably means that four 

 or five feet will draw better than three feet, on the principle 

 that the pressure of water is increased in proportion to the 

 depth of the drain. And it is moreover urged that deep drains 

 discharge more water, and more quickly and thoroughly drain 

 the land in winter and spring. This is undoubtedly true to a 

 very great degree. On my own land, where the depth varies 

 from two feet nine inches, (a depth which I was obliged to 

 adopt at the head of the first few laterals in the field, in order 

 to give them fall into the main at that point,) to five and 

 a half feet and less, I have found that they worked best at a 

 depth of about three and a half feet. This seems to be well 

 adapted to the stiff clay which I drained. I fixed the head 

 of the main at three feet in order to prevent the necessity 

 of digging too deep at the outlet ; and at the point in the field 

 where this drain reached a depth of about three and a half feet 

 my drainage has been most successful. Near the outlet I was 

 obliged to sink my main drain between five and a half and six 

 feet, and of course the laterals are at the same depth — perhaps 

 five feet at the head, and five and a half at the junction. On 

 this spot the drains have not worked so well. I can perceive 

 a very considerable improvement in the land from year to 

 year ; but on a small space, about three rods square, where the 

 drains are at this depth, the land has not improved to the 

 extent found in all the rest of the field. 



I have ventured to extend my statement to the committee to 

 what may, perhaps, appear to be an unnecessary length, not for 

 the purpose of throwing any new light upon thorough drain- 

 age, nor for the purpose of preparing an essay upon the 

 subject, but in order to show the importance which I attach 

 to the work. Not all lands require it, neither will every 

 part of a New England farm pay for it. It has been truly 

 remarked that thorough drainage " does not belong to pioneer 



