DIRECTION IN WHICH DRAINS SHOULD RUN. 73 



iistances apart, according to the abundance of water 

 and the nature of the soil. From 20 to 50 feet be- 

 tween them, would probably be the limits for most 

 cases. It is sometimes necessary to make a little cross 

 drain, to carry away the water from some strong spring. 

 In all ordinary cases, the drains running straight down, 

 and discharging into a main cross drain at the foot, 

 are amply sufficient. 



Tile machines are now introduced into this country, 

 and tiles will soon come into extensive use. Their easy 

 portability, their permanency when laid down, and the 

 perfection of their work, will recommend them for 

 general adoption. It is also to be noticed that it takes 

 less time to lay them than stones, and that the ditch 

 required for their reception is smaller and narrower. 

 The bottom of it need only be wide enough to receive 

 the tiles. The upper part of the earth is taken out 

 with a common spade, and the lower part with one 

 made quite narrow for the purpose, being only about 

 four inches wide at the point. The bottom is finished 

 clean and smooth, with a peculiar hoe or scoop (fig. 10). 

 Pj This is necessary, 



  -- — '--'—- because the tiles 



must be laid on 

 an even smooth 

 foundation. 



SECTION V. ON SUBSOIL AND TRENCH PLOUGHING. 



In connection with draining, must be noticed an- 

 other mode of mechanical improvement; this is subsoil 

 ploughing. The subsoil plough is an implement 

 contrived to stir up and loosen the lower soil, without 

 bringing it to the surface. It follows the furrow of an 

 ordinary plough, and goes down as deep as it can be 

 forced, in some cases from 20 to 22 inches. The sub» 

 7 



