1826 The Cornell Reading-Courses 



protection of joints 

 The upper half of the joint either should be very close, or should be 

 covered with a strip of tar paper or burlap or a handful of thick cement 

 mortar. This will force the water to enter from the under side of the joint. 

 In heavy clay soil a very close joint is not desirable, and openings to an 

 eighth of an inch in width are permissible, especially if the upper part of 

 the joint is protected, as indicated above. Collars and bell-shaped ends, 

 like those on sewer tile, are not necessary, although the latter may be 

 serviceable in soil inclined to afford a soft bottom on which the tile rests. 

 Such construction will protect the alignment. 



ARRANGEMENT OF DRAINS 



The arrangement of the drains, of course, will always depend on the 

 structure of the soil and the slope of the land, a factor that determines 

 the direction of movement of the water. The aim should be to intercept 

 the flow of the water and to remove it from the land by the shortest prac- 

 ticable course. 



On flat land the drains must be arranged generally in more or less 

 parallel lines at such intervals as will accommodate the soil. Their 

 purpose is to remove the water derived from rainfall on that area. 

 In clay land they may be forty to sixty feet apart for the common field 

 crops. On sandy soil that is moderately porous they may be eighty to 

 one hundred and fifty feet apart. For intensive cultivation, as in grow- 

 ing truck crops, a greater frequency may be justified. Where the surface 

 is undulating and where there are strata more porous than others, so that 

 the surface or the underground water is concentrated, the drain should 

 be located only after careful study, in order to determine the way in which 

 the water moves. Much land that is unditlating is particularly wet 

 only in the low places, and a line or two of tile through these places will 

 suffice. Sometimes surface water from a hillside accumulates at the foot 

 of the slope and spreads out over the low land. In that case there should 

 be a drain near the foot of the slope. If there is seepage from the hill- 

 side, the drain should be cut near the upper edge of the wet soil and should 

 be deep enough, if possible, to let the tile be laid on the impervious sub- 

 stratum and thereby intercept the flow. Whether the drains shall be laid 

 across the slope or down the slope depends much on the local conditions. 

 In many cases an arrangement diagonally across the slope at a high angle 

 is best, for it combines many of the advantages of both the other arrange- 

 ments. 



Clearly defined springs should be tapped by the most direct route. If 

 the water seeps out of a considerable area of ground around the spring, 

 Y-shaped spur drains may be helpful. 



