86 AQRICULTUKE. 



By retentive soils, we mean those which, in their natural 

 state, retain the whole or the greater part of the rain 

 which falls upon them, until it has run off by superficial 

 discharge, or has been exhausted by evaporation. Of the 

 terms cut, trench, and drain, we shall use exclusively the 

 latter ; and as the word sough or surf has been popularly 

 extended beyond its original meaning, which was simply 

 the artificial aperture left in the re-filled drain for the 

 passage of the water, we shall drop that word altogether, 

 and substitute the word conduit. Our predecessors have 

 used almost indifferently the phrases surface-draining, 

 hollow draining, the frequent drain system, furrow-draining, 

 and thorough-draining. Of these we shall select the last, 

 as best descriptive of our object. We call that thorough- 

 draining which assimilates retentive soils to porous to this 

 extent, that it enables them to filter through themselves 

 to the depth of the drains all the rain which falls upon 

 their surface; or if that object cannot be entirely attained, 

 the thoroughness of the draining varies inversely as the 

 quantity of water got rid of by other means. By water of 

 drainage we mean all water existing among the particles of 

 soil beyond that which they are able to retain by attraction. 

 The water of drainage in any soil will stand at a level like 

 any other dammed-up water. In order to avoid circum- 

 locution, we shall ask leave to call this level the water- 

 table. In using the word attraction, we shall drop capil- 

 lary, which is a favourite with writers on draining. We 

 drop it because it conveys no definite idea to our mind as 

 connected with particles of soil ; because attraction is per- 

 fectly intelligible ; and because every one may, by the 

 simplest experiments, and the use of his own eyes, convince 

 himself that particles of soil have an attraction for water 

 so strong as to overcome to a certain extent the force of 

 gravity. 



Imperfect attempts at thorough-draining were probably 

 first made in the southern counties of England. The 

 conduit was usually formed of thorns or other twigs, the 



