On Draining. 191 



that is properly and substantially executed, may last for 

 ages. 



8. The expense is calculated at from 20s. to 60s. per acre ; 

 except in very wet soils, where it is sometimes higher than 

 even 60s. ; but in most cases the whole of the expense is 

 repaid by the first arable crop. 



9. The best period for making these drains is, when the 

 land is in grass, or in fallow. 



10. Hollow drains have several enemies, as moles, field 

 mice, the roots of trees, (in particular the poplar, and the 

 ash) ( l37 ) ; and a plant which sometimes grows in them, in- 

 tercepts the course of the water, by degrees weakens the 

 current, and at last chokes up the drain (ityty. 



3. Arched Drains. The expense of arched drains, of stone, 

 or brick, prevents their being adopted, unless where the 

 ground is very loose, or where open drains are inadmissible. 

 Where flat stones abound, drains covered by them may, in 

 general, be made large enough, for every essential pur- 

 pose ("'). 



Vertical, or Pit Drains. Drains of this description may on 

 some occasions be useful. If the spot where a confined re- 

 servoir of water exists, can be ascertained, (which sometimes 

 may be done by boring with an auger), a pit should be sunk 

 into the place, of such a size, as will allow a man to work 

 within its bounds, (or about three feet in diameter), until it 

 reaches the water meant to be brought up, which will rise, as 

 soon as the pit reaches it. The pit should then be filled with 

 stones or pebbles^ and the water be conveyed by a proper 

 drain, to some adjoining ditch, and thence to the nearest 

 stream or river ( t4P ). 



Spouts or springs also, rising in the middle of a field, may, 

 on some rare occasions, be led into a pit sunk through the 

 clay, aud the water may thus escape downwards, into a po- 

 rous substratum ( 141 ). 



In regard to the proper season for carrying on the opera- 

 tions of draining, bogs should be drained in summer, but 

 winter and spring are the proper periods for general draining, 

 because strong soils are then more easily cut, and the work- 

 men are enabled to take true levels, from having water, (an 

 unerring'guide), which frequently cannot be obtained in sum- 

 mer. 



4. The Instruments employed. 



The instruments employed in draining, are more nume- 

 rous than is commonly imagined. The principal are, 



