

258 LMPROVEMENT OF THE SOIL 



that they may not be injured by the tread of cattle, and the 

 heavy loads, which may pass over them. The sides should 

 be a little flaring, that is, the drain should be a few inches 

 wider at the top than at the bottom. 



Fig. 16. 



The materials used for filling up the lower 

 portion of the drain, may be small stones, tiles 

 or any hard substances. 1. If no water of con- 

 sequence is to flow in them, they may be filled 

 up, with these small stones, to the depth of 

 from ten to fifteen inches, and the remainder 

 filled up with gravel and loam. 2. But in 

 case water is expected to flow in them, a con- 

 duit must be laid on the bottom (Fig. 16.) 

 This is made by building a wall, on each side 

 with stone or brick, about six or eight inches 

 in height and six in width, and covering it over 

 with flat stones so tight that mice or moles 

 through it, and let in the soil from above and choak it up. 

 If the earth is soft, the bottom also should be lined with 

 stones. Upon the top of the flat stones, and upon the sides, 

 fill in small stones c to the height of several inches according 

 to the depth of the drain, and then cover the whole with 

 earth a b, rounding the surface, so that when the whole set- 

 tles, it may be even with the ground. 



The conduit, in case stones cannot be found, may be 

 made of tiles from clay, resembling earthen ware. These 

 are laid together and form a complete tube for conducting 

 away the water. 



In some cases the surface may be drained by digging deep 

 pits and filling them with stone. This mode is adopted when 

 the sub-soil is hard or clayey, and a few inches below, are stra- 

 ta of sand or gravel. By digging through the retentive sub- 

 soil, the surface-water will run off". 



3. Draining the sub-suil. This process becomes necessary 



