180 STATE BOARD OF AGRICULTURE. 



surface of the drained hinds. A ditch dug through a very wet swamp or marshy 

 in muck that extends to tlio bottom of the ditch, fully four feet deep, will 

 not generally be more than a foot and a half deep at the end of two or three 

 years. The reason for this is that the muck is like a saturated sponge, and 

 when the water is drawn out, it shrinks and settles down and rots away a great 

 deal more than would be thought possible by one not acquainted with its na- 

 ture. This same fact caused another error that was very injurious to some of 

 the earlier ditches, and that was, that finding the water deeper around the 

 edges of the swamp than in the center (as is almost always the case), the draina 

 were placed along the edges, upon the theory that the ditch should run through 

 the lowest ground, and that must be where the water was deepest. The result 

 of this was, that when the water was drawn off, the surface settled most where 

 the muck was deepest, which would nearly always be in the center of the basin, 

 and as a result, you would have wet land in the center of the swatnp, which 

 the ditch, being upon the higher ground near the edge, would not draw the 

 water from. This error is a very serious one, and its effects increase from year 

 to year, as the muck keeps constantly rotting and settling more and more, 

 while the ditch near the edge, generally so near as to reach through the muck 

 into the solid soil beneath, does not stir. 



It cannot be too earnestly urged and insisted upon that the place to run a 

 drain through a swamp or marsh, to dry it most effectually, is where the muck 

 is deepest, and that is in almost every case near the center. 



There is another idea in connection with this matter of the wasting away 

 and subsidence of these drained lands. There are none of the swamp lands 

 that may not be drained in some direction by digging through a barrier in no 

 case greatly exceeding three feet above the natural surface of the swamp ; be- 

 cause any basin having a watershed sloping to it sufficient in size to fill it with 

 the annual rain-fall, and surrounded with a barrier much higher than the 

 annual evaporation — which must equal the annual rain-fall — and is about three 

 feet, will be a lake and constantly filled with water to within that distance of 

 the top of the barrier or outlet. Therefore, the natural surface of none of 

 the swamp lands is much more than three feet below the natural outlet. But 

 many of these lands ivere once undoubtedly lakes, and the basins in which they 

 lie have been gradually filled up by the annual deposit of vegetation until the 

 bottom Avas brought so nearly upon a level with the outlet as to be laid bare 

 by the annual summer evaporation, when they became lands. Now when it 

 is intended to deepen the outlet in order to run a drain through such a piece 

 of swamp, with a view to fitting it for cultivation, it is most important to know 

 what is to be the ultimate depth of such a subsidence; or we may find that, 

 after having deepened our outlet as low as the natural descent of the ground 

 below will permit, our drained laud, continuing this process of subsidence, 

 may sink below the outlet as deepened, sufficiently to render the land as wet 

 as when we began draining, and lose to us all the results of our labor. For 

 my part, I cannot tell where the limit of subsidence will be in any case ; and 

 it would often be a great assistance in deciding whether or not to attempt the 

 reclamation of a given piece of swamp land were it authoritatively ascertained 

 how far, for instance, a piece of raw muck ten feet thick would waste away 

 and settle down before the point would be reached when the annual vegetable 

 addition would equal the annual waste and the surface would remain constant. 

 If some of you farmers would select such a basin filled with muck to a consid- 

 erable depth, and so situated as to allow of its being thoroughly drained to 

 the bottom, and after so draining it and making the height of the natural sur- 



