tuberances, which throw them down at such angles as often to make their tops disappear below the surface, until they have got over the obstruction; and when such is the case they at once erect themselves as before. We have had many opportunities of witnessing the descent of vertical timber, and frequently when their coming in contact with the projecting parts of the bottom manifested itself; and it is otherwise well ascertained, that the bed of the river projects many protuberances above its general surface, some of which rise to and even project above extreme low water-as, for instance, that represented on the diagram-so that they very much endanger river navigation at the low water stages. They constitute obstructions, with which trees descending in a vertical attitude often come in contact, and by which they are so tossed and agitated, that no particular form of any tree could make its projecting part seem to be perpendicular, while its submerged portion was inclined, conformable with a current which was not uniform in its whole depth; for were the under current more sluggish than that on the top, the lower end of the tree would be correspondingly impeded in its progress, so as to give to the tree an inclined attitude; but the observed circumstance shows that there can be no such inclination, for when agitated by striking against the projecting parts of the bottom, they turn freely round in every direction, and present their several sides to the direction of the current, without any seeming preference as to position.

Our observations induce in us the conviction, that in a descending aqueous current, there is no appreciable difference of velocity throughout the vertical quantity; and unquestionably for the reason, that the superincumbent pressure urges forward the under stratum to the point of least resistance, with the same velocity that it may itself have acquired.

Governed by the foregoing considerations, and estimating quantities by the method adopted in book "A," your Committee have found the aggregate annual quantity of water discharged by the Mississippi river, to be 14,883,360,636,880 cubic feet, or 551,235,579,143 cubic yards. 101.1 cubic miles = 101.

Now the fact being notorious, that the Mississippi river is the only visible outlet for all the surplus waters of that vast valley, through which it passes on its way to the ocean, there are involved considerations of no little importance; for the Mississippi valley has been found to contain an area very little, if any, short of fourteen hundred thousand square miles.

What then is the relative difference between the quantity of rain

water falling annually in this valley, and that discharged by the river.

We find by examination of the meteorological register of the late Dr. H. Tooley, of Natchez, kindly furnished by his family, that the mean quantity of rain water, which falls annually at Natchez, is between fifty-five and fifty-six inches; but, as such is the quantity for the southern extremity of the valley, it may be regarded as over estimating, if taken for an average of the whole area, we will therefore assume the mean quantity to be 52 inches, and then we will have for the whole valley, 169,128,960,000,000 cubic feet, which is about 11 or 11.3636 times the quantity which is discharged by the river.

There can be but two ways by which this immense quantity of water can make its escape from the valley; one is by the course of the river, and the other by evaporation. Hence, we perceive that there is but one relative portion of this quantity passing off by the river, for every 10 parts which are exhaled into the atmosphere, or parts are carried off by the river, and parts by evaporation. Thus we arrive at a fact of the most momentous importance to the planting interests of Louisiana and Mississippi; for it will be at once perceived, that the more exhalations are promoted, the less liable will the low or bottom lands of these two states be to the periodical inundations by the river.

If it be asked, by what process it is expected that evaporation can be promoted, over such an extensive area as the Mississippi valley, so as visibly and permanently to affect the planting interests of the above named States, the answer will be found in the fact, that the process has been, and is now, in the most rapid and successful progress, and of that kind which is the best calculated to produce so desirable a result, viz: the clearing of such large portions of the valley of its forests for the promotion of agriculture, and the consequent exposure of the lands to the action of the sun and winds, the very best promoters of the evaporating process, particularly on a large scale.

It will not be difficult to perceive the great difference there must necessarily be in the evaporation from a surface of country exposed to such action, and that which is covered by the primitive forests and their almost impervious undergrowth, through which neither sun nor wind can penetrate but with difficulty.

So rapid is the progress of this increased exposure, and its consequent evaporating tendency, and so visible has been its effects on the Mississippi river, that we may hazard the assertion with safety,

that there is not now, by twenty or twenty-five per cent., as much water passes down the Mississippi as there was twenty-five years ago; for at and prior to that time there were annual inundations of many feet, and long periods of submergence of almost all the bottom lands, from the bluffs or highlands on one side of the river bottom to those on the other side. Such lands were at that period in a great measure accounted valueless; and to such a degree, that but little or no hopes were entertained of the practicability of their redemption by any artificial means, that is, on any general scale; but such has been the diminution in the annual quantity of water discharged from the valley, that those lands have been progressively and rapidly redeemed from overflow, until very great portions of them are now in the very highest state of cultivation, and with but comparatively slight assistance from art in the way of embankments, and these such as could not have been at all available against the overwhelming effects of floods, and the length of time of their continuance; for then there were annual inundations, both deep and expansive, of the waters, over almost all the bottom lands; but now the river seldom rises to the same elevation as formerly, and when it does, it is of much shorter duration, and the waters are almost exclusively confined to the channel of the river, in place of being spread over almost all the bottom lands the whole spring and early part of the summer.

These changes in the quantity of water discharged are so progressive, that they fail to excite general notice; so that the lands which are at one time considered to be of little or no value, are subsequently taken up, occupied and improved with success, without any consciousness that such an important change is in progress, the opinion being prevalent, that in nature there can be but little change, and that the annual quantity of water descending the river at one period must approximate very nearly to the quantity that descends at every other, there being no visible cause for suspecting it otherwise.

All the advantages are progressively but rapidly extending themselves while the cause remains unsuspected or overlooked, but none the less sure. As a further evidence of the altered condition of this river, we may mention the circumstance, that in former times, and in the spring of the year particularly, steamboats ascending or descending the river were detained about half their time by dense fogs, while now hardly any such obstructions prevail; so that steam-packets succeed in making their trips to an hour, with no fear of such retardation.

Assuming that the diminution of the waters will continue in some

what the same ratio they have recently done, the time cannot be very far distant when all apprehension from inundation will have in a great measure passed away.

We will further remark, as an evidence of change, that the quantity of floating timber or drift wood passing annually down the river, has diminished in a far greater ratio than that of the water; for the drift now passes at longer intervals, in smaller quantities, and for much shorter periods than it once did, so that the aggregate quantity cannot now be over fifty per cent. of that which formerly passed down. The cause of the diminution is similar to that of the other, and is to be found in the circumstance of the banks of the river and its tributaries being denuded of their timber for steamboat fuel, and as a process preparatory for agricultural pursuits, the immediate banks being the location at first usually selected for such purposes.

Second Section of Report.

This section will be found to contain a further statement of facts in relation to the quantity of solid matter, with which the waters of the Mississippi are annually charged, together with its effects in the formation of lands, or filling up of depressions.

In order to arrive at these required facts the following methods were adopted :-First, a series of glass vessels, of a cylindrical form, were procured, to one end of which (that being the section of a cylinder), there was attached a tin tube of the same cylindrical diameter as that of the glass vessel to which it was attached; in this tin tube, immediately above its junction with the glass cylinder, there was inserted a small brass cock, by which the tin tube could be conveniently discharged of its contents at pleasure, without causing any disturbance to the contents of the glass vessel below; this attached tin tube was in length, above its lower opening, 48 inches.

This tube was charged with water from the Mississippi river, and that water allowed time to deposit its contents into the glass vessel below; that being accomplished, the water was drawn off, and the tube recharged by more water from the river, each particular change being carefully noted; this process was successively repeated for the different conditions and stages of the river's height and velocity, which very materially affected the quantity in suspension. Thus, by a succession of such changes and dischargings of the tin tube, amounting in all to four hundred and eighty-four times, or, in the aggregate, to a column of water of 1936 feet, there was deposited a column of sediment or solid matter of 46 inches (such column of sediment

herein submitted), enclosed in three of the respective glass cylinders above named, and in which the same was deposited from the water in the attached tin tube. But this sediment still seems to evince some slight disposition for further settlement, and with a knowledge of its former habits, we would say that it would be unsafe to decide on its final quantity being more than 44 inches; greater certainty would have been obtained by giving it another year; but as the most of it has been long collected, it cannot now, we think, shrink to less than 44 inches. Assuming that, therefore, to be the true quantity, and the product of a column of river water of 23,232 inches, it necessarily follows, that as 44 is to 23,232, so is the quantity of solid or sedimentary matter contained in the water, to the volume of the river; or, in words and figures, the mean proportional quantity of sediment to the river, is as 1 to 528. We have, therefore, already ascertained the quantity of water annually discharged by the Mississippi river to be 14,883,360,636,880 cubic feet, there must then be deposited from that quantity of water, 28,188,053,892 cubic feet of solid matter.

In collecting the test-water, from which the above 44 inches of sediment was obtained, much care was taken to procure it from that part of the current where it was sufficiently agitated to prevent, in any measure, a subsidence of such matter as should be held in suspension. It was fully decided, after many trials, that there was no sensible difference of quantity contained in any part of the water throughout its whole depth, or from the top to the bottom of the river, provided it was in the main current, for where agitation was equal and effective, there also the suspension of sedimentary matter was found to be equal.

There can be no question but that much matter, in the character of coarse sand and gravel, is transported by the river current; of the quantity of this your Committee could have no possible opportunity of estimating the value, or even ascertaining its existence, only that the many sand and gravel bars visible at low water stages of the river are composed, to a considerable extent, of such matter, and they are subject to a perpetual change of position, and consequent tendency of their matter to the river's mouth.

Being in possession of the data, by which may be computed with some approximation to certainty, the effects of the Mississippi deposit in the formation of land, or in filling up the gulf into which it is emptied, we will avail ourselves of such data, and endeavour to present the quantities deducible therefrom. In estimating the delta of the Mississippi we have adopted for it the designation and superficies