On Draining. 519 



ally passes off bj filtration at a depth of 3 feet, how is it possible 

 in the retentive clay subsoils to obtain the proper proportion at a 

 depth of 4 feet^ with any wide interval between the drains? A 

 judicious difference may be made where the land is intended to 

 remain permanently in grass, and where it may be sufficient to 

 remove merely the really injurious surplus water, without laying 

 it so perfectly dry as is essential to the most profitable cultiva- 

 tion of arable land. Much has of late been said upon the efficacy 

 of what are termed air-drains — that is, a drain at the head of the 

 field connected with each of the parallel drains, and so with the 

 main-drain, producing a current of air through the whole. In a 

 former paper before the Wakefield Farmer's Club in 1843, and 

 which was published at the request of that body, I suggested the 

 adoption of head-drains, showing, as I then conceived, their be- 

 nefit ; but further reflection led me to doubt their advantage, 

 and to discontinue their application- They not only add to the 

 cost of the work, but, having a current of air through the drains, 

 must necessarily tend to the early decay of all the pipes of a pe- 

 rishable character, as we see exemplified in the brickwork of 

 many of the railway tunnels ; as well as to promote the growth 

 into the pipes of any roots that may approach them. 



There yet remains to be attained one other desideratum in the 

 execution of drainage, which perhaps more than any other would 

 facilitate the operation and reduce its cost, and so in all the strong 

 clay lands allow of the drains being sufficiently near to ensure 

 completeness without an extravagant outlay. I allude to the 

 application of some better mode of cutting the drains, either 

 wholly or in part mechanical, whereby a more suitable section of 

 cut would be obtained without the removal of so much of the 

 subsoil as is now necessary. A course of experiments are being 

 made, which, so far as they have yet gone, promise success, and I 

 hope ere very long to be able to announce the attainment "'' of 

 the object. 



York, Oct. 1849. 



* I am since fully satisfied, by further experiments, of the practicability of con- 

 structing a very efficient implement, ro be worked by manual power, whereby the 

 cutting of drains to a depth of 3 feet in suitable subsoils may be accomplished at a 

 cost of Jd. per yard, hi lieu of |d, as by the present means, and without encumbering 

 the land with so much of the subsoil. 



2 M 2 



