TiiK MoismcK IN Tin: SOIL 53 



-ic. Ciip'icitij nniij In iiirnasnl hi/ innh r -drainage 



7.'). I)i-ainiiLr»> has an intiniatf relation \o soil 

 moistun'. iJy <li'aiiiau'»' is im-anl tin' means 

 t'ini)l<>yt'(l lor the I'enioval of tho surplus IVee 

 water. Surface or open <liteiies may serve as 

 eon<hiits to carry otT surface water, hut as soil 

 • h*ains they ari' failures. The correct method 

 for removinu: the surplus water of i-ainfall is to 

 cause it to sink into the soil ami he removed 

 hy under-druins. That wiiich is removed i»y 

 surface (low tails to inijiart any heiifliria! etfect 

 t<» the soil ((i;>). 



7ti. Lamls which are well undei--.lraiiied art- 

 porous. The i-ain whieh falN upon tlieni jtasses 

 ilown ipiickly, and is not removed hy surface 

 tlow. It is remov«'d only when the level of the 

 free wat«'r risos to the level of the diain. iJy 

 •>l)servi!i,<^ the action of drains which are of dif- 

 ferent <lej)ths, it has heen foun<l that after a 

 protracted droui^ht the drains whi<di hci^in to 

 ll »w lir>t are those whieh are at the jxrcatest 

 depth, showlni; that as the level of the free 

 water rises to the chain the flow heirins, an<l 

 that it is not removed to any considerahle ex- 

 tent in its downward passap'. 



77. The sinkinir of the water thromrh the soil 

 does more pood than m«'re|y to supply moisture. 

 In the s]>ring the rain is warmer than the soil, 



