THE DRAINAGE OF GRASS LAND 9 



and western counties/ or between the West of England and 

 Ireland, will regulate the nearness of the lines of drains and 

 the size of the pipes. But these differences do not touch 

 the main question, whether to drain or not to drain. Soils 

 which rest upon a porous subsoil certainly do not need drain- 

 ing. Other land may be retentive, and yet lie so high, or at 

 such a steep inclination, that the water is discharged with 

 sufficient rapidity without artificial aid. Indeed, draining 

 may always be considered unnecessary where the best natural 

 grasses grow luxuriantly. With these exceptions all clay 

 lands, whether the clay is only in the subsoil or rises to the 

 surface, and aU peat lands, whether the peat has clay beneath 

 it or not, and in fact all land which is habitually saturated with 

 water, must be effectually drained before a pasture of any 

 value can be established. 



The prejudice occasionally expressed against the adoption 

 of a system of drainage can generally be traced to some 

 instance where the workmanship has been bad, or where no 

 care has afterwards been taken to maintain the efficiency of 

 the pipes, which ought not to be covered in until they have 

 been proved to work satisfactorily. As draining is usually put 

 out to contract, this matter needs close personal supervision. 



It is a safe general rule not to make any single drain too 

 long. Plenty of fall should be given, or the pipes may not 



^ The following statistics, compiled from the Reports of the Meteorological Office, 

 show the difference in rainfall which occurred during 1909 in various districts in Great 

 Britain : — 



England (Highest rainfall) — Counties of Cumberland, 

 Westmorland, Lancaster, Chester, Derby, and 



Stafford 38-87 inches 



„ (Lowest rainfall) — Counties of London, Middlesex 



and adjacent on the North and East . . . 24'95 „ 

 Scotland— North-East ....;.. 31-96 „ 



„ North-West . . .... 48-78 „ 



■\^'ales 87-82 „ 



The case named by Professor Ansted in his Physical Geography is stUl more 

 remarkable. He says : ' At Seathwaite the fall is 127 in., and a few miles off, at 

 Bishop's Wearmouth in Durham, on the other side of the moors, it is only 17 in.' 



