On the Drainage of Land. 



289 



again, one foot in 100, up to 150 ; and one gentleman, in treating 

 of tile- draining, says that tile-drains ^xi\\ act with very little fall ; 

 one foot of fall in every 1000 feet in length will be perfectly safe, 

 though it is best to have one foot of fall to every 300 feet of 

 drain."* 



Although admitting the superiority of tiled drains in allowing 

 a free passage to the w^ater, yet the soundness of his view of the 

 subject maybe doubted; and on discussing it with an eminent 

 land-surveyor (Mr. Deane of Tottenham), who has been exten- 

 sively engaged in drainage, he stated " that in the course of his 

 practice he always found those hollow drains to continue longest 

 serviceable which had a good fall ; and that he w^ould recommend 

 not to be too sparing in giving them such a fall whenever the cir- 

 cumstances of the case would admit." Perhaps, therefore, a 

 declivity of one foot in 120 may be sufficient to secure a proper 

 current in the main; paying attention at the same time to the fact, 

 that if the water does not run at increased speed towards the 

 bottom of the drain it will probably occasion deposits of sediment. 



It should also be observed that if the field be of large size 

 receiving drains or ditches must be opened at different distances, 

 say not farther apart than 200 to 300 feet ; for otherwise the 

 necessary artificial fall of the drain at the rate of one foot in 120 

 would bring its excavation to an inconvenient depth, even if the 

 outlet be deep enough to receive it ; besides occasioning such a 

 collection of water as during continued rains might endanger its 

 safety, by causing it to burst. 



A great portion of the heavy arable ground throughout the 

 kingdom is rounded up into permanent ''lands," of various 

 breadth and height, according either to its wetness or to the custom 

 of the country, with the intention of causing the rain-water to run 

 from the surface into the furrows, which act as so many open drains 

 in carrying it off. It is thus not unusual to see good crops of corn 

 growing on the crown of these ridges, w^hile their sides, being 

 bared of the best soil by its collection on the top, are rendered 

 comparatively worthless, and the crop inferior in both bulk and 

 quality ; whereas if the lands were well under-drained, the height 

 of the ridges could be reduced, and, the soil which is taken from 

 their sides being then replaced, the crops would be found equal 

 in every part. This, it is true, is sometimes done, and always 

 with good effect ; but those covered drains are most commonly 

 sunk in the furrows, with a view of saving labour, although they 

 could often be more judiciously placed in a different direction, 

 and in no case should their distance be influenced by the size of 



* Wilson on Tile-Draining. — Prize Essays of the Highland Soc, N.S., 

 vol. vi. p. 1 14. 



VOL. II. Y 



