HOW DRAINS SHOULD BE MADE* 169 



In and among the spaces or interstices between the finer par- 

 ticles of the soil. This necessarily has a close connection 

 with the depth of the drains ; and in this manner. 



If the level of the stagnant water, or the under current 

 which flows from higher land, be, 1, 2, 3 or 4/feet below 

 the surface and the drains are made at either of these depths, 

 it will be clear that the water will flow in the drains ; but 

 that if the drains are 20, 30, 40, or 100 feet apart, the cap- 

 illary attraction of the soil will cause the water to rise at 

 the center line between the drains, to certain heights, vary- 

 ing with the distance between the drains. Thus if the 

 drains are 20 feet apart the tendency of the water to seek its 

 level and flow into the drains will overcome the capillary 

 attraction and the tendency of the water to rise in the soil, 

 to a greater extent than if the drains were 30, 40, 50 or 100 

 feet apart. Therefore the distance between the drains must 

 be regulated by this property of the soil, the quantity of 

 water which exists in the soil, and the character of the land 

 in regard to its absorbent power and its ability to retain the 

 water in its pores. In clay land or in peaty soil the drains 

 would need to be closer than in open gravel or sandy loam 

 soils, which are underlaid by clay or hard pan; and neces- 

 sarily they should be made deep enough to reach .and pass 

 through this impervious water bed. 



Upon these principles it is not difficult to decide upon 

 the depth of the drains and the distance between them to 

 make them most effective. 



Open ditches should be made not less than 4 feet wide for 

 3 feet in depth, or 3 feet for 2 feet in depth ; and if the sur- 

 face soil is open and porous and the water rises from the 

 subsoil, a depth of 2? or 3 feet will be sufficient. As a rule, 

 the water flows into the drains from the bottom; the press- 

 ure of the surface water, tending to force its way down- 

 wards, causing the water to rise in the drains just as it does 

 in the case of a spring or a well; as has been explained 

 above. 



Ditches for covered drains need be made no wider than 

 is required for the convenience of working in them and the 



