CHAP. xi. DEPTHS AND DISTANCES OF DRAINS. 869 



and this is, in fact, a test of the work. Or, as Mr. Parkes puts it, this 

 is the true expression of the work done, as a mere statement of the 

 cost of drainage per acre of surface conveys but an imperfect idea a 

 very erroneous idea of the substantive and useful expenditure on any 

 particular system. 



The distances between the drains is a point which has been as keenly 

 disputed as the depth to which they should be cut. It is obvious that 

 circumstances of soil must decide the distances between, as well as the 

 depths of, the drains. The distance which suits a light free soil will 

 not suit a close heavy one. Much practical evidence on the depths and 

 distances of drains was given in a Parliamentary Report, from which 

 the following extract is taken : 



" The circumstance which has the most influence in ruling the 

 distances of drains, and through these in some degree the depths, is 

 the arrangement of the existing ridges. The width of the ridges runs 

 generally from 12 to 24 feet, most commonly 18 feet; and as the 

 ridges are usually thrown up in the middle from 12 to 18 inches above 

 the levels of the furrows, a great saving in the cutting is effected by 

 placing the drain in the line of the furrow ; and besides, when the 

 ridges are much raised, there is a tendency of the surface water to run 

 towards the old furrow, even after the land has been drained ; and if 

 there is not a drain below or near to the furrow, there is an undue 

 collection of water, which obtains for some years after the drainage has 

 been executed, and until the ridges have been levelled down and the 

 subsoil fully opened. The loss by this wetness or damp, or incom- 

 pleteness of thorough and uniform dryness, is greater than the cost of 

 having the drains somewhat less distant. There is also some difficulty 

 practically in getting the drains cut to uniform depths, when the 

 surface in the lines of the drains is of various altitudes from the datum 

 level of the bottom of the drains. 1 Practically, therefore, it is found to 

 be a much more ready method, and upon the whole cheaper and much 

 more immediately fully effective, to adopt the furrows for the lines of 

 the drains. In some cases, when the ridges are under 12 feet in 

 width, I have found it expedient to place a drain in every second 

 furrow only ; and in cases where an inequality in the width of the 

 ridges existed, I have found it proper to adopt those unequal 

 distances for the drains. Where such distances have been adopted 

 generally, it has been found that depths of from 2 to 3 feet have, 

 on all soils, and at all times, produced a thoroughly dry condition of 

 the soil." 



The Materials used in the Construction of Drains. Stone drains 

 may be made where stones are very plentiful. Fig. 374 shows a mode 

 of filling up a drain with stones ; a b the trench, c stones on edge, 

 d small stones, e a turf or sod, /soil. Fig. 375 shows the almost obsolete 

 mode of filling up drains with horse-shoe tiles ; a b the trench, c the 

 " sole," on which the tile (d) rests. These " tops and bottoms " are the 



1 This a good drainer overcomes by finding the proper level by means of the flow of 

 water. Where there is no water in the soil to act as an indicator, it is necessary to use a 

 proper instrument for ascertaining the level. 



