No. IT. 



'Brainivs:. 



330 



water whicli is contained in reservoirs and 

 channels below the surface. 



But frequently the water to be intercepted 

 is very near tlie surface, as between the soil 

 and subsoil, or the subsoil is so homogeneous 

 to a great depth, that no pervious strata can 

 be j^eadily reached. In such cases, the drains 

 may be of smaller dimensions, and increas'^d 

 in number, so as to afford many outlets to the 

 water with which the soil and subsoil are 

 charged. 



A system of draining-, having relation to 

 this condition of the soil and subsoil, has been 

 termed the Essex system, from its liaving 

 been extensively practised in that flat and 

 clayey district, and it is now very generally 

 termed furrow-draining. The system con- 

 sists in forming a series of small drains paral- 

 lel to one another, in the open furrows be- 

 tween the ridges. In this species of drain- 

 ing, the design is not to reach the water as 

 it percolates in pervious channels beneath 

 the surface, but to afford numerous outlets- to 

 the water which the soil and subsoil retain. 

 The system is for the most part greatly 

 more expensive than the other : yet as it is 

 efficient, is easily practised, and produces an 

 immediate effect in drying the ground, it is 

 oflen preferred even where the purpose might 

 be otherwise effected. It may often, howev- 

 er, be combined with the system of deeper 

 drains; the latter being employed to inter- 

 cept the springs and larger body of water, 

 and the former to give an increased degree of 

 dryness to the surface. 



The materials that may be employed in 

 this species of draining are tiles or stones, 

 the latter being broken to the size of small 

 road metal. Of these materials, tiles are held 

 to be tlie most convenient and economical, 

 from their requiring a smaller trench, and 

 from their being more easily carried, and 

 more readily taken up and replaced when in- 

 jured. They are formed into an arch of a 

 semi-elliptical form, and they are made to 

 rest on fiat soles in the manner shown in tne 

 figure 65. The size of the arch varies with 

 , circumstances: the us^ual size is from three 

 ■to four inches .wide within, and from four to 

 five inches'high, and the length of each tile 

 is about fourteen inches. Tlie soles are flat, 

 ,or sligiitly curved, and made to project about 

 a quarter of an inch on each side of the tiles 

 -These are the usual dimensions for the 

 smaller parallel drains; but, where main 

 drains are formed to receive the water from 

 the smaller drains, the size of the tiles is in- 

 creased to seven or eight inches wide within, 

 with a corresponding height. 



The principle adopted in laying out this 

 class of drains, is to form one or more main 

 or receiving drains across the ground to be 

 drained, and to conduct into these the minor 



drains which tbilow the course of the ridges. 

 The receiving drains are formed of greater 

 size, by employing the larger form of tiles, 

 or by placing two tiles side by side, and some- 

 times with their edges together, so as to com- 

 bine the two arches into on-e tube ; and some- 

 times three or four tiles are employed vari- 

 ously arranged. The minor drains lead to 

 these receiving ones, and the water is per- 

 mitted to enter by chipping off corners of the 

 largpr tiles, at the places where the tiles of 

 the smaller drains terminate. It is better, 

 however, that sets of tiles be prepared at the 

 tUe-works, in which easet he apertures can 

 be made either through the sides of the tiles, 

 or at the corners. 



The depth or the drains should be suffi- 

 cient to place the tiles completely beyond the 

 reach of injury from the deepest ploughing. 

 A medium depth of the smaller drains is 

 from eighteen to twenty-four inches. They 

 are formed by first taking up a spit with the 

 common spade, and then employing the nar- 

 rower spade, shown in figure 66, so as to 



Fig. 65. 



form the trench with a slope to the bottom^ 

 where the width should be just sufficient to 

 receive the soles of the tiles; and in order to 

 clear out any mud or loose earth in the trench, 

 there is employed the species of shovel, fig. 

 66. Sometimes, in order to save some ex- 

 pense in digging, the earth at the surface is 

 first removed by the plough, which passes 

 along without the mould-board, and then re- 

 turns by the same track, with the mould- 

 bo? r J attached, ^o as to push the earth to a 

 side and form a furrow. In proportion as the 

 trenches are formed by one set of workmen, 

 the tiles are laid by another. The workman 

 in laying the tiles works backwards, the tiles 

 havinir been previously laid along the line of 

 the drains, and there is usually an assistant 

 to hand them to the person in the trench. — 

 This pc^rtof the operation, must be performed 



