THOROUGH-DRAINING. 



103 



cracking- or contraction v/ill take place in it, so as to allow 

 water to descend. ; on wliicli account tlie best way, probably, 

 is just to dig' throug-h tlie soil, and lay the tile into a groove 

 cut in the subsoil. This subsoil we call " moorband ;" in 

 other parts it is called " pan," and is a concretion of g-ravel 

 and clay with oxide of iron, so hard that it is scarcely pos- 

 sible to break it up.' One thing- I have omitted to remark, 

 and that is, that in making- drains it is desirable that they 

 should be done, as much as may be, in the spi-ing- or in dry 

 weather. When bottomed out, care being- always taken to 

 lay the tiles or pipes level, and directly opposite each other, 

 let them be covered just so much with clay, taken from the 

 bottom of the drain, as to keep them safe, and then leave the 

 drains open for as long- a time as may be convenient for 

 working- the land, because the volume of air which in this 

 way has access to the drain is so much greater than that 

 which can pass throug-h the tile or pipe, tliat the contraction 

 of the soil or clay takes place more rapidly, and the drains 

 come so much sooner into full action. Then, as to the tile 

 or pipe which it is advisable to use : for a long- time we iised 

 tiles of unnecessary size, and in many situations those tiles 

 could not be used with safety without soles, which became 

 very expensive. Of late years pipes have been substituted 

 for tiles, and are, I think, in ever}- respect deserving- a pre- 

 ference ; I prefer them because they are safer against stop- 

 page, stronger, more durable, and more economical. The 

 circular shape is that which in all sewers and carries of water 

 is found to be le-ast liable to be stopped up, because the 

 current is always deei)est and strongest in the centre, into 

 which every substance that comes must fall and be carried 

 ofl"; whereas a Hat bottom admits of deposits and accumula- 

 tions which the shallow current cannot always remove. 

 Pipes are less apt to be sanded up- on this account than tiles, 

 in Hat ground ; and on steep hill sides they are safer, as, 

 when once fixed, the current cannot displace or undermine 



' Analysis of Moorland. 



From Flodden Field. 



120 



From Milfield Plain, 



120 



