166 On I he Drainage of Land, 



Thorn-drains are so general!)'' known as not to need any particular 

 description. They are preferable to tile-drains in this respect, that, 

 being open on all sides to the surrounding earth, they admit the water 

 more freely than tiles do. Where tiles are laid in a tenacious clay, the 

 clay in a wet sea?on becomes so " puddled " round the tiles, as scarcely 

 to allow the percolation of the surrounding water. I have tile-drained 

 seventy acres of land, of which the subsoil was a chalkstone clay. 

 Stubble was laid upon the tiles. During the late wet season the water 

 stood in many of the furrows : the drainage was by no means good. 

 Wherever the furrow had in the course of successive ploughings been 

 carried a foot or more from the line of drain, there the water stood. 

 The drains were not above a foot deep, yet the water could not pene- 

 trate ; even where an opening was cut from the furrow to the tiles, the 

 water could scarcely gain admission through the intervals of the tiles, so 

 tightly was each interval stopped wdth clay. Very different was the 

 drainage of about fifty acres of much more tenacious clay w?iich had 

 been drained with thorns. The drainage there was perfect. 



Thorn-draining has an advantage over tile-draining in point of cheap- 

 ness also. The comparative expense of draining an acre of land with 

 each kind of drain may be seen from the following estimate. The 

 prices of labour and of tiles are such as are usually given in this neigh- 

 bourhood. The quantity of stubble to be laid on the drains, and the 

 number of tiles required for the main drain, would be the same in each 

 case, and are therefore omitted : — 



£. s. d. £. s. d. 



1500 tiles at 305. per 1000 . . 2 5 



Carriage of do., say 5^. per 1000 . 7 6 



Laying and filling 20 running acres (the 

 running acre is 24 yards) of drains at 

 6rf. per acre . . . . 10 



Total expense of draining an acre 



with tiles 3 2 6 



One load of thorns, and carriage of do. 10 

 Laying and filling 20 acres of thorn- 

 drain, at \0d. per running acre . 16 8 

 Additional expense of deeper main-drain 4 



Total expense of drainmg an acre 



with thorns 1 17 



Balance in favour of thorn-drains . . . 15 6 



The disadvantages of thorn-drains are, that they are not permanent ; 

 and that, being deeper, it is more difficult to obtain a good outfall for 

 them. 



The duration of a good thorn-drain depends greatly on the firmness 

 of the soil in which it is laid. When the thorns have perished, the 

 superincumbent clay still forms an arch for the drain. Perhaps fifteen 

 years may be taken as the average duration of a thorn-drain. 



