I beg leave to refer to the report upon the Mississippi river, prepared by Captain A. A. Humphreys and Lieutenant H. L. Abbot, topographical engineers, and submitted by Captain Humphreys to the bureau of topographical engineers, August 5, 1861.

The knowledge of a few simple facts concerning the region in question, well known to those who live upon the alluvial lands of the Mississippi, would lead one to distrust the feasibility of such a project.

The swamps and shallow lakes of the alluvial region are filled with rain water long before the river reaches its flood condition, and remain so filled until the river goes down. Any material additions to their volume made by crevasses cause an encroachment upon the cultivated lands, and should the breaks in the levees be extensive and the high water of long continuance, the most serious inundations occur, involving the loss of crops and stock worth millions. The explanation of this is that the fall of rain upon the alluvial lands is excessive, and the surface so flat that the eye can detect no deviation from a level, careful instrumental measurements being necessary to ascertain the direction as well as amount of the slope that exists. The lakes are shallow, except those along the river which once formed portions of it and still retain in part its great depth. The facts cited indicate that no large volume of river water can be let in upon the alluvial lands without serious injury to the cultivable portions, the highest parts of the alluvion.

General Roberts proposes to draw off from the river, during the period of high water, and spread upon the alluvial lands all the volume in excess of that of the medium flood. This would bring the surface of the river very nearly to the level of the natural bank. In other words, would restore the conditions existing before any levees were built, and subject the whole alluvial region to overflow. Perhaps he may dissent from this exhibit of his proposition, but he will not object to my using, in a discussion of the project, the quantity of sedimentary matter contained in the volume of river water indicated. Let us see, then, how much earthy matter that volume would spread upon the alluvial lands. The area of those lands is

The St. Francis bottom..

The Yazoo bottom..

The Tensas and Macon bottom...

The alluvial lands below the mouth of Red river.

Total....

Sq. miles.

6,300

6,800

4,000

12,300

29,400

I will take the most favorable case for the project, the great flood year of 1858. The river during that year was less than 130 days above the natural bank. Let us assume it to have been 130 days. The surplus volume discharged by it during that time over and above the volume discharged by the river when just bank full, was 1,200,000,000,000 cubic feet.

Now, had this quantity escaped from the river into the alluvial lands during the period of high water of 1858, it would have flooded the whole alluvial region, cultivated as well as uncultivated, from Cairo to the Gulf, during the entire period of 130 days.

For the quantity of earthy matter held in suspension by the river water, I will use the largest proportion found in the investigations made upon the Mississippi river under my direction. That proportion in 1200 by volume. That is, for every 1,200 cubic feet of water, there was one

cubic foot of earth. This is double the amount of sedimentary matter carried by the river water during the mean flood period. The propor tion of 20 would give for the volume of water just noted 1,000,000,000 cubic feet of earth.

I should explain here that when there were no levees, the water thrown off by the river into the St. Francis bottom returned to the river again by the returning bayous and the St. Francis river, having depos ited its sedimentary matter upon the bottom lands. It thus protracted the duration of the flood.

The river water similarly thrown off into the Yazoo bottom, returned to the river by the Yazoo river. The same is to be observed of the Tensas bottom, the water returning to the Mississippi by Red river.

Again, in order to make the most favorable case possible for General Roberts's project, I will suppose that the whole volume of water necessary to bring the river within its banks in the flood of 1858 entered each bottom land in succession, that is, the bottom lands of the St. Francis, the Yazoo, and the Tensas.

We have seen that that volume of water carried in suspension 1,000,000,000 cubic feet of earth. That bulk when spread upon an area of 6,000 square miles (the area of the St. Francis bottom) would have a thickness of 1 15 of a foot. At this rate it would require 12 years to make a deposit one inch thick upon the St. Francis bottom.

But the time that the flood of 1858 was above the natural bank of the river was more than double that of the average floods, and we should have, for an average effect of flooding, yearly, all the St. Francis alluvion, less than one inch of deposit for 24 years of overflow. The mean difference of level of that swamp and the bank of the river is 10 feet. To bring up the swamp to the level of the river bank would require more than 2,880 years. If the smaller quantity of sedimentary matter were used, the number of years would be about doubled.

If the sedimentary matter could be concentrated instead of being spread over the whole bottom, the depth of deposit would of course be increased. But the shape of the country is not adapted to this process. Moreover, the project of General Roberts comprises the whole area of the alluvion.

Here let me remark, that the project is not new to me. It is probably as old as the levee system, and is a fruitful subject of discussion with persons living on the alluvion, especially those who have noticed the deposits made by crevasse water at the edge of the swamp in the immediate vicinity of the crevasse, when the break in the levee was large and the high water long continued. A notable example of it was given by the great Bonnet Carré crevasse of 1850, which, although only six miles from Lake Pontchartrain, and having therefore comparatively free flow to the Gulf, flooded an extensive district and destroyed a large amount of property. Such notable deposits are made only when the crevasse is so large that immense damage to the plantations on the alluvion is incurred.

It seems to me unnecessary to illustrate the subject further, or apply figures to the other bottom lands. So long as there are vast districts of the higher portions of the alluvial land along the Mississippi river that are unoccupied and will remain so until the river is effectually leveed, it appears to me unnecessary to set investigations on foot to ascertain whether some limited localities of the lower portions of the alluvion can be raised by letting in upon it the turbid river water, espe cially as the features of the country are not adapted to the economical use of such processes.

The figures exhibited show that such a process upon a large scale is impracticable. The only practicable mode of reclaiming the swamp lands is to levee the river banks securely, and as cultivation extends inward, to establish a proper system of drainage.

The second view presented by General Roberts is that by spreading a portion of the sedimentary matter of the river upon the swamp lands, there will be less of it deposited in the Gulf at the mouths of the river. In his opinion the bars will not then extend so rapidly into the Gulf as now, and as a consequence the surface of the river in its lower course, or near the sea, will not be raised as rapidly as it is now, (the rise of surface due to the extension of the mouth of the river into the Gulf,) and the height of the levees on the lower plantations will not have to be increased as frequently as now. Further, he is of opinion that there will then be a greater depth of water upon the bars at the mouth of the river than there is now.

Respecting the increase of height to be given to the levees in the lower course of the river, owing to the progress of the mouths into the Gulf. I beg leave to refer to pages 435 and 436, "Report upon the Mississppi river," &c., where it is shown that it will require an extension of the mouths of the river 25 miles into the Gulf to raise the surface of the river one foot at Fort St. Philip, and that according to the present rate of progress, five centuries will elapse before the river accomplishes that extension.

Owing to the great depth of the Gulf where the mouths of the river now lie, the rate of progress into the Gulf will be slower in future than it has been in past days.

As to increasing the depth of water upon the bars by reducing the quantity of sedimentary matter brought to the Gulf, I beg leave to remark that the depth upon those bars depends upon the quantities of water discharged over them, and not upon the quantity of suspended sedimentary matter brought to the Gulf by the river water. Further, the bars are not formed by the deposit of the sedimentary matter of the river, but by the deposit of the earthy matter pushed or moved along the bottom of the river. Hence a reduction of the sedimentary matter of the river will not diminish the magnitude nor affect the form of the bars.

Should any further information or views concerning the bars be desired, reference can be made to the last chapter of the report already mentioned. Having thus shown the impracticability of attaining the ends proposed by General Roberts, I trust I may be excused from presenting a view of the cost necessary to carry out his plans.

The popular impression that the floods of the Nile are allowed to spread upon its alluvion has been sometimes referred to, by persons ignorant of the totally different conditions of the two rivers, as a reason for allowing the floods of the Mississippi to flow over its alluvion.

The floods of the Nile are regular in their recurrence, the greatest height being attained usually in September; the planting and sowing season follows the subsidence of the flood. Egypt is in the rainless region and the overflow of the Nile fills periodically all the reservoirs, tanks and canals from which the fields are irrigated and supplies of water for every purpose are furnished. The best authorities state that its floods are not permitted to spread over its banks.

The floods of the Mississippi are irregular in their period, height and duration, but on the average may be said to reach their height about the 1st of April. The river then remains in high water condition, falling and rising until about the middle of July; and there is no means of pre

dicting whether it may not be above the natural bank during all that time. There are, indeed, two maximum high water points reached each year, the one about the 1st of April, the other about the 1st of June.

The planting and sowing season on the Mississippi begins just as the river reaches its height, and the high water condition extends so late into the summer that no extensive crops can be gathered from any planting done after the river has begun to sink to its low water condition. Wherever its floods spread thick-growing willow and cottonwood spring up, destroying the cotton and sugar plants, and requiring years for their eradication.

Very respectfully, your obedient servant,

A. A. HUMPHREYS,

Major General Volunteers.

Brig. and B'vt Maj. Gen. RICHARD DELAFIELD,

Chief of Corps Engineers, U. S. A.

Report of the Adjutant General on the publication of documents relative to the rebellion, &c.

FEBRUARY 20, 1869.-Laid on the table and ordered to be printed.

WAR DEPARTMENT, February 18, 1869.

The Secretary of War, in answer to the resolution of the House of Representatives dated February 5, 1869, has the honor to submit the accompanying report of the Adjutant General as to the progress made in the preparation for publication of the official documents relating to the rebellion and the operations of the army of the United States.

Under the provisions of joint resolution No. 91, of 1866, Hon. Peter H. Watson was appointed to supervise the preparation of these documents, but he performed no duty nor received any pay under such appointment, which expired, by the limitation of the joint resolution, on July 27, 1868.

J. M. SCHOFIELD.
Secretary of War.

ADJUTANT GENERAL'S OFFICE,
Washington, February 12, 1869.

SIR: In compliance with your instructions endorsed on resolution of the House of Representatives, of February 5, 1869, "that the Secretary of War be directed to inform this house what progress has been made in 'the preparation and publication of the official documents relating to the rebellion and the operations of the army of the United States,' as provided by joint resolution No. 91, approved July 27, 1866," I have respectfully to report that, upon instructions from the Secretary of War based on the resolution of May 19, 1864, the Adjutant General has caused copies to be made of the official reports of battles filed in his office. He has also taken all the steps in his power to procure missing reports, and to collect from the records of discontinued commands all documents which would be of interest in this connection. All these