ENGLISH AGRICULTURE. 101 



each other ; and also because a single or solitary drain in a 

 clay field exerts only a small effect. A solitary drain does not 

 act, because the pulverizing action which it exerts is speedily 

 lost in the mass of clay. It may act for a few feet on either 

 side of it, and the effect then ceases, whereas if we make a 

 series of drains, it may be twenty-one feet, or in some cases 

 only fifteen or sixteen feet apart, then each of those drains, 

 acting from its own centre, gradually pulverizes the soil. 

 The influence of the drains meets at the centre, and we get 

 that thorough pulverizing through the entire clay bed which 

 ends at last in all the advantages of thorough drainage. It 

 is clear then in this case that the nature and character of the 

 soil greatly affects the system of drainage which is employed. 

 Clay lands by which we mean both clay soil and subsoil 

 evidently require a thorough or a regular system of drainage, 

 or what has been called the furrow system. It requires that 

 the ground shall be regularly and equally divided into panes 

 of not too great width. This is Smith's system, called after 

 Mr. Wm. Smith of Deanston in the county of Perth, who 

 gave his system to the world in 1823. It is the regular, 

 or through system of drainage, and is the best for stiff clay 



Elands. 

 Passing to the consideration of the other class of soils, they 

 may be properly said to be wet from bottom to top. The 

 water passes down through such porous soil; for rain will 

 always pass by the law of gravity towards the centre of the 

 earth in a straight line, or as straight a line as is possible, 

 and if there is no obstruction it will continue to go for 

 hundreds of feet, until in fact it is stopped. That is why we 

 have deep wells as well as shallow wells. In the case of deep 

 wells the water has met no special obstruction, and it goes 

 on until it meets one of those deep clay beds which are sure 

 to occur somewhere in the vertical section. Now if a soil is 

 wet to such a degree as to interfere with growing crops, there 



