CHAP. XI. 



ADVANTAGES OF DRAINAGE. 



875 



"Drainage alone," remarks Mr. Sutton, "will go a long way towards 

 turning a marsh into a profitable pasture, and it renders other improve- 

 ments possible at a trifling expense. No undrained land should be 

 laid down to grass. Otherwise careful tillage, costly manures, and the 

 finest grass seeds will certainly be wasted. The result is only a 

 question of time. Sooner or later the valuable grasses which are sown 

 will be supplanted by sedge and rush and other semi-aquatic vegeta- 

 tion, until the pasture gradually deteriorates to the worthless state into 

 which undrained land invariably falls. It is a safe general rule not to 

 make any single drain too long, and plenty of fall should be given, or 

 the pipes may not work well after they have been laid some time. A 

 good fall renders them to a considerable extent self-cleansing, and the 

 small drains should not enter the large drains at right angles, but 

 always obliquely, so that the water may retain the momentum received 

 in its previous career. Then the occasional flushing after a sharp 

 storm will prevent the pipes from becoming choked. For short 

 distances near hedgerows or trees, the use of socket pipes securely 

 jointed with cement not clay is to be strongly recommended. The 

 slight additional expense may save a large subsequent outlay. As to 

 the depth at which the pipes should be laid, and the distance between 

 the rows, no definite rule can be laid down. Experience has proved 

 that in heavy land they must be near together, and not too deep ; but in 

 lighter land the lines may be comparatively far apart. About three feet 

 deep with the rows fifteen feet apart is the usual proportion, but almost 

 every field has some peculiarity of conformation or subsoil which 

 affects the question. After the pipes are covered in, one man should 

 always be held responsible for periodical examination of the outlets, to 

 ensure their being kept in working order. Sometimes there is an 

 indurated pan, or hard mass, formed beneath the cultivated surface by 

 the weight of the plough and the horses' feet through a long series of 

 years. A similar condition resulting from natural causes is found on 

 some heath lands, four or five inches below the surface. These hard 

 subsoils are as impervious to water as beds of cement. Before putting 

 drain-tiles into such land an experiment should be made to ascertain 

 whether satisfactory drainage cannot be obtained by breaking up the 



