In almost, if not quite every State, extensive tracts of swamp lands are found, not only unfit, in their natural condition, for cultivation, but, in many instances, by reason of obnoxious effluvia, arising from stagnant water, dangerous to health.

Of the vast extent of such lands, some idea may be formed, by adverting to the fact, that under the grants by Congress, of the public lands given away to the States in which they lie, as of no value to the Government and as nuisances to their neighborhood, in their natural condition; sixty millions of acres, it is estimated, will be included.

These are only the public lands, and in the new States. In every township in New England, there are hundreds of acres of swamp land, just beginning to be brought to the notice of their owners, as of sufficient value to authorize the expense of drainage.

To say that these swamps are the most fertile and the most valuable lands in New England, is but to repeat the assertion of all who have successfully tried the experiment of reclaiming them.

In their natural state, these swamps are usually covered with a heavy growth of timber; but the greater portion of them have been partially cleared, and many of them are mowed, producing a coarse, wild, and nearly worthless grass.

The soil of these tracts is usually a black mud or peat, partly the product of vegetable growth and decay on the spot, and partly the deposit of the lighter portion of the upland soil, brought down by the washing of showers, and by spring freshets. The leaves of the surrounding forest, too, are naturally dropped by the Autumn winds into the lowest places, and these swamps have received them, for ages. Usually, these lands lie in basins among the hills, sometimes along the banks of streams and rivers, always at the lowest level of the country, and not, like Irish bogs, upon hill-tops, as well as elsewhere. Their surface is, usually, level and even, as compared with other lands in the old States. Their soil, or deposit, is of various depth, from one foot to twenty, and is often almost afloat with water, so as to shake under the feet, in walking over it.

The subsoil corresponds, in general, with that of the surrounding country, but is oftener of sand than clay, and not unfrequently, is of various thin strata, indicating an alluvial formation. Frogs and snakes find in these swamps an agreeable residence, and wild beasts a safe retreat from their common foe. Notoriously, such lands are unhealthful, producing fevers and agues in their neighborhood, often traceable to tracts no larger than a very few acres.

In considering how to drain such tracts, the first inquiry is as to the source of the water. What makes the land too wet? Is it the direct fall of rain upon it; the influx of water by visible streams, which have no sufficient outlet; the downflow of rain and snow water from the neighboring hills; or the bursting up of springs from below?

Examine and decide, which and how many, of these four sources of moisture, contribute to flood the tract in question. We assume, that the swamp is in a basin, or, at least, is the lowest land of the neighborhood. The three or four feet of rain water annually falling upon it, unless it have an outlet, must make it a swamp, for there can usually be no natural drainage downward, because the swamp itself is the lowest spot, and no adjacent land can draw off water from its bottom. Of course, there is lower land towards the natural outlet, but usually this is narrow, and quite insufficient to allow of drainage by lateral percolation. Then, always, more or less water must run upon the surface, or just below it, from the hills, and usually, a stream is found in the swamp, if none pours into it from above.

The first step is a survey, to ascertain the fall over the whole, and the next, to provide a deep and sufficient outlet. Here, we must bear in mind a peculiarity of such lands. All land subsides, more or less, by drainage, but the soils of which we are speaking, far more than any other. Marsh and swamp lands often subside, or settle, one or two feet, or even more. Their soil, of fibrous roots, decayed leaves, and the like, almost floats; or, at least, expands like a sponge; and when it is compacted, by removing the water, it occupies far less space than before. This fact must be kept in mind in all the process. The outlet must be made low enough, and the drains must be made deep enough, to draw the water, after the subsidence of the soil to its lowest point.

If a natural stream flow through, or from, the tract, it will usually indicate the lowest level; and the straightening and clearing out of this natural drain, may usually be the first operation, after opening a proper outlet. Then a catch-water open drain, just at the junction of the high and low land, entirely round the swamp, will be necessary to intercept the water flowing into the swamp. This water will usually be found to flow in, both on the surface, and beneath it, and in greater or less quantities, according to the formation of the adjacent land. This catch-water is essential to success. The wettest spot in a swamp is frequently, just at its edge, because there the surface-water is received, and because there too, the water that has come down on an impervious subsoil stratum, finds vent. It is in vain to attempt to lay dry a swamp, by drains, however deep, through its centre. The water has done its mischief, before it reaches the centre. It should be intercepted, before it has entered the tract, to be reclaimed.

This drain must be deep, and therefore, must be wide and sloping, so that it may be kept open; and it should be curved round, following the line of the upland to the outlet. Often it has been found, in England, that a single drain, six or eight feet deep, has completely drained a tract of twenty or thirty acres, by cutting off all the sources of the supply of water, except that from the clouds. This kind of land is very porous and permeable, and readily parts with its water, and is easily drained; so that the frequent drains necessary on uplands, are often quite unnecessary. Many instances are given, of the effect of single deep drains through such tracts, in lowering the water in wells, or entirely drying them, at considerable distances from the field of operation.

When the surface-water and shallow springs have thus been cut off, the drainer will soon be able to determine, whether he has effected a cure of his dropsical patient. Often it will be found, that deep seated springs burst up in the middle of these low tracts, furnishing good and pure water for use. These, being supplied by high and distant fountains, run under our deepest drains, and find vent through some fracture of the subsoil. They diffuse their ice-cold water through the soil, and prevent the growth of all valuable vegetation. To these, we must apply Elkington's system, and hit them right in the eye! by running a deep drain from some side or central drain, straight to them, and drawing off the water low enough beneath the surface to prevent injury. A small covered drain with two-inch pipes, will usually be sufficient to afford an outlet to any such spring.

When we have thus disposed of the water from the surface-flow, the shallow springs and the deep springs, and given vent to the water accumulated and ponded in the low places, we have then accomplished all that is peculiar to this kind of drainage. We have still the water from the clouds, which is twice as much as will evaporate from a land-surface, to provide for. We assume that this cannot pass directly down by percolation, because the subsoil is already saturated; and therefore, even if all the other sources of wetness are cut off, we shall still have a tract of land too wet for wheat and corn. If the swamp be very small, these main ditches may sufficiently drain it; but if it be extensive, they probably will not. We have seen that we have some eighteen or twenty inches of water to be disposed of by drainage; so much that evaporation cannot remove consistently with good cultivation; and, although this amount might, in a very deep peaty soil, percolate to a great distance laterally, to find a drain, yet in shallow soil resting on a retentive subsoil, drains might be necessary at distances similar to those adopted on wet upland fields. To this part of the operation, we should, therefore, apply the ordinary principles of drainage, putting in covered drains with tiles, if possible, at four feet depth or more, ordinarily, and at distances of from forty to sixty feet, although four-foot drains at even one hundred feet distance, in peat and black mud, might often be found sufficient.

Through the kindness of Edmund Ruffin, Esq., of Virginia, we have been furnished with three elaborate and valuable essays, on the drainage and treatment of flat and wet lands in lower Virginia and North Carolina, published in the Transactions of the Virginia State Agricultural Society, for 1857. The principal feature of his system is based upon his correct knowledge of the geological formation of that district; of the fact in particular, that, underlying the whole of that low country, there is a bed of pure sand lying nearly level, and filled with water, which may be drawn down by a few large deep drains, thus relieving the surface-soil of surplus water, by comprehensive but simple means.

We have before referred to Mr. Ruffin as the publisher, more than twenty years ago, of "Elkington's Theory and Practice of Draining, &c., by Johnstone;" and we find in his recent essays, evidence of how thoroughly practical he has made the system of Elkington in his own State. Indeed, we know of no other American writer who records any instance of marked success in the use of Elkington's peculiar idea of releasing pent up waters by boring. Mr. Ruffin, however, has applied, with great success, this principle of operation, to the saturated sand-beds which underlie the tracts of low land in his district of country. These water-beds in the sand lie at depths varying usually from four to eight feet below the surface. This surface stratum is comparatively compact, and very slowly pervious to water before it is drained. The water from below, is constantly pressing slowly up through it, of course preventing any downward percolation of the rain-water. By running deep drains at wide intervals, and boring down through this surface stratum with an auger, the pent up water below finds vent and gushes up in copious springs through the holes, and flows off without coming nearer to the surface than the bottom of the drains; thus relieving the pressure upward, and lowering the water-line in proportion to the depth of the drains.

Mr. Ruffin gives an instance of the drying up of a well half a mile distant, by cutting a deep drain into this sand-bed, and thus lowering its water-line.

No doubt in many localities in our country, a competent geological knowledge may detect formations where this principle of drainage may be applied with perfect success, and with great economy.

Is there danger of over-draining swamp lands? In speaking of the injury by drainage, we have treated of this question.

Our conclusions may be briefly stated here. There is an impression among English writers, that light peaty soils may be too much drained; but many distinguished drainers doubt the proposition. No doubt there are soils too porous and light to be productive, when first drained. They may require a season or two to become compact, and may require sand, or clay, or gravel, to give them the requisite density; but these soils would, we believe, be usually unproductive if shallow drained.

In short, our idea is, that, in general, a soil so constituted as to be productive under any circumstances, will retain, by attraction, moisture enough for the crops, though intersected by four-foot drains at usual distances; and that cold water pumped up to the roots from a stagnant pool at the bottom, is not, either in nature or art, a successful method of irrigation.

Still we believe that peaty soils may be usually drained at greater distances, or by shallower drains, than most uplands, because of their more porous nature; and we should advise inexperienced persons not to proceed with a lavish expenditure of labor to put in parallel drains at short distances, till they have watched, for a season, the operation of a cheaper system. They may thus attain the desired object, with the smallest expense. If the first drains are judiciously placed, and are found insufficient, others may be laid between the first, until the drainage is complete.