How far it may be competent, for a State legislature to provide for, or assist in, the drainage of extensive and unhealthy marshes; or how far individual owners should be compelled to contribute to a common improvement of their lands; or how far, and in what cases, one land-owner should be authorized to enter upon land of another, to secure or maintain the best use of his own land--these are questions which it is unnecessary for us to attempt to determine. It is well that they should be suggested, because they will, at no distant day, engage much attention. It is well, too, that the steps which conservative England has thought it proper to take in this direction, should be understood, that we may the better determine whether any, and if any, what course our States may safely take, to aid the great and leading interest of our country. The swamps and stagnant meadows along our small streams and our rivers, which are taken from the farmer, by flowage, for the benefit of mills, are often, in New England, the most fertile part of the townships--equal to the bottom lands of the West; and they are right by the doors of young men, who leave their homes with regret, because the rich land of far-off new States offers temptations, which their native soil cannot present. It is certainly of great importance to the old States, to inquire into these matters, and set proper bounds to the use of streams for water-powers. The associated wealth and influence of manufacturers, is always more powerful than the individual efforts of the land-owners. Reservoirs are always growing larger, and dams continually grow higher and tighter. The water, by little and little, creeps insidiously on to, and into, the meadows far above the obstruction, and the land-owner must often elect between submission to this aggression, and a tedious law-suit with a powerful adversary. The evil of obstructions to streams and rivers, is by no means limited to the land visibly flowed, nor to land at the level of the dam. Running water is never level, or it could not flow; and in crooked streams, which flow through meadows, obstructed by grass and bushes, the water raised by a dam, often stands many feet higher, at a mile or two back, than at the dam. It is extremely difficult to set limits to the effect of such a flowage. Water is flowed into the subsoil, or rather is prevented from running out; the natural drainage of the country is prevented; and land which might well be drained artificially, were the stream not obstructed, is found to lie so near the level, as to be deprived of the requisite fall by back water, or the sluggish current occasioned by the dam. These obstructions to drainage have become subjects of much attention, and of legislative intervention in various forms in England, and some of the facts elicited in their investigations are very instructive.