BY OPEN OR COVERED DRAINS. 253 



they need seldom be more than 4 feet. The main drains will, of 

 course, be a few inches deeper, according to the size of pipes to be 

 used, and this will depend upon the wetness of the sod, and the 

 number and length of the common drains to run into the mains. 

 Pipes with a bore of 1^ to 2 inches are usually large enough for 

 common drains. Pipes with collars have many advantages over tiles 

 or pipes without collars. These assist to keep the pipes in their 

 proper position, and prevent any sediment from entering the joints, 

 and the pipes are more easily and quickly laid in the drains. 

 Before the pipes are laid, a little straw is good for forming a clean 

 and firm bed where the ground is soft, or very wet and slushy ; 

 the wooden and tde soles often used are liable to sink at the ends in 

 soft ground, and the straw bed therefore is preferable. If main 

 drains or leaders are of great length, or if two or three unite at a 

 given place, a cesspool or tank may be made to receive any sediment 

 that may be in the pipes ; it may be budt with bricks, or stones 

 and mortar, as most convenient, say 6 feet long, 2 wide, and 2 under 

 the flow of pipes in depth, floored with pavement stones, and 

 covered with the same material, or wood, to open with a lid or door. 

 The length stated facilitates its being cleared out, giving room for 

 the use of the necessary tools, which would not be the case if the 

 cesspool were 2 or 3 feet square. 



Open drains should seldom be less than 2 feet deep, and they are 

 inconvenient in many respects if more than 3 feet deep, except in 

 particular cases. In young plantations, open drains 2 feet deep, 

 3 feet 4 inches wide at top, 6 inches at bottom, and from 24 to 40 

 feet apart, act well and give satisfactory results. A width of 3 feet 4 

 inches at top gives a good slope to drains 2 feet deep, and with 

 corresponding widths at top they may be made to any desirable 

 depth. But the narrower open drains are at the bottom, the better 

 will the water run, and the less liable are they to be choked by 

 leaves, &c. Confined to a limited space, the water acquires force, 

 runs more regularly, and thus more easily carries away leaves and 

 small particles of soil with it. If the water were allowed to spread 

 over a foot or more of bottom surface, any small obstacles would be 

 backed up with such soil or leaves as might come down the drains, 

 and in a short time the deposit would become quite fast, and when 

 heavy rains came, causing an extra flow of water, the flood would 

 be forced into the sides, and undermine the slopes of the drains, 

 which in time would fall in, causing trouble and expense in repairs. 

 It is evident that the greater the breadth at the top, the more 



