APPENDIX. 499 



mound: a drain laid round the base will take off all the water which arises 

 from this cause, and the lower part of the land will be effectually laid dry. So 

 likewise where there is a hollow or depression of which the bottom is clay with 

 sand in the upper part, a drain laid along the edge of the hollow and carried 

 round it, will prevent the water running down into it, and forming a marsh 

 at the bottom. 



When the drains cannot be carried to a sufficient depth to take the water 

 out of the porous stratum saturated with it, it is often useful to bore numerous 

 holes with an auger in the bottom of the drain through the stiffer soil, and, ac- 

 cording to the principle explained in the diagram, the water will either rise 

 through these bores into the drains and be carried off, and the natural springs 

 will be dried up, or it will sink down through them as at G. in the section, if 

 it lies above. This method is often advantageous in the draining of pear 

 mosses, which generally lie on clay or stiff loam, with a layer of gravel be- 

 tween the loam and the peat, the whole lying in a basin or hollow, and often 

 on a declivity. The peat, though it retains water, is not pervious, and drains 

 may be cut into it which will hold water. When the drains are four or five 

 feet deep and the peat is much deeper, holes are bored down to the clay below, 

 and the water is pressed up through these holes, by the weight of the Avhole 

 body of peat, into the drains, by which it is carried off. The bottom of the 

 drains is sometimes choked with loose sand, which flows up with the water, 

 and they require to be cleared repeatedly; but this soon ceases after the first 

 rush is past, and the water rises slowly and regularly. The surface of the peat 

 being dried, dressed with lime, and consolidated with earth and gravel, soon 

 becomes productive. If the soil, whatever be its nature, can be drained to a 

 certain depth, it is of no consequence what water may be lodged below it. It 

 is only when it rises so as to stagnate about the roots of plants that it is hurtful. 

 Land may be drained so much as to be deteriorated, as experience has shown. 



When a single large and deep drain will produce the desired effect, it is much 

 better than when there are several smaller, as large drains are more easily kept 

 open, and last longer than smaller; but this is only the case in tapping main 

 springs, for if the water is diffused through the surrounding soil, numerous 

 small drains are more effective: but as soon as there is a sufficient body of 

 water collected, the smaller drains should run into larger, and these into main 

 drains, which should all, as far as is practicable, unite in one principal outlet, 

 by which means there will be less chance of their being choked up. When 

 the water springs into a drain from below, it is best to fill up that part of the 

 drain which lies above the stones or other materials which lonn the channel 

 with solid earth, well pressed in, and made impervious to within a few inches 

 of the bottom of the furrows in ploughed land, or the sod in pastures; be- 

 cause the water running along the surface is apt to carry loose earth with it, 

 and choke the drains. When the water comes in by the side of the drains, 

 loose stones or gravel? or any porous material, should be laid in them to the 

 line where the water comes in. and a little above it, over which the earth may 

 be rammed in light so as to allow the horses to walk over the drain without 

 sinking in. 



It sometimes happens, that the water collected from springs which caused 

 marshes and bogs below, by being carried in new channels, may be usefully 

 employed in irrigating the land which it rendered barren, before; not only re- 

 moving the cause of barrenness, but adding positive fertility. In this case the 

 lower grounds must have numeron* drains in it, in order that the water let on 

 to irrigate it may not stagnate upon it, but run off after it has answered its 

 purpose. 



The third branch in the art of draining is the removal of water from imper- 

 vious soils which lie flat, or in hollows, where the water from rain, snow, or 

 dews, which cannot sink into the soil on account of its impervious nature, and 

 which cannot be carried off by evaporation, runs along the surface and stag- 

 nates in every depression. This is by far the most expensive operation, in con- 

 sequence of the number of drains required to lay the surface dry, and the ne- 

 cessity of filling them with porous substances, through which the surface water 

 can penetrate. It requires much skill and practice to lay out the drains so as 

 to produce the greatest effect at the least expense. There is often a layer of 



