were open about 10 feet above and below, the water rushing with great violence from under the ice in front, and disappearing like a torrent under the ice behind. Still a severer test came with high water. I took it from good authority that, as the height of the water over the obstructions would increase, the disturbances would decrease; but this was not the case. As the water rose the disturbance increased, so that, in some cases, with 4 feet of water over the dam, the sand was excavated from 12 to 16 feet deep in continuation of the slope of the back of the dam, which again filled as the water receded. None of the dams were disturbed. Appended is a diagram of water-gauges for the year, reduced to the lowest water of 1871. Respectfully submitted.

Captain A. M. MILLER,

JOHN NADER, Assistant United States Engineer.

United States Corps of Engineers, Milwaukee, Wisconsin.

PORTAGE, July 13, 1872.

The work will be continued during the present season, and the funds. available will be exhausted.

It is believed that the practicability of the plan of improvement has been sufficiently proved by the operations up to this time, and an estimate of $250,000 is submitted for the fiscal year ending June 30, 1874.

Amount available July 1, 1871.

Amount expended during the fiscal year ending June 30, 1872.

Amount available July 1, 1872..

Amount required for fiscal year ending June 30, 1874.

Respectfully submitted.

D. C. HOUSTON,

Major of Engineers, United States Army.

A 21.

IMPROVEMENT OF THE WISCONSIN RIVER.

UNITED STATES ENGINEER OFFICE,

Chicago, December 28, 1871.

GENERAL: I have the honor to submit the following report of operations on the improvement of the Wisconsin River during the past

season.

On the 10th of June, 1871, I submitted, in compliance with your instructions, the following project of operations, which was made after a consultation with Major G. K. Warren, Corps of Engineers, under whose direction a survey of the Wisconsin River was made in 1867 :

WASHINGTON, D. C., June 10, 1871. GENERAL: I have the honor to report that I have seen General Warren, and examined the detailed maps of the survey of the Wisconsin River, with a view to preparing a project for the expenditure of the funds available for the improvement of that river. I find, upon consultation with General Warren, that it will not be practicable to submit at once a detailed project for this purpose, for the reason that the bed of the river is constantly shifting, and that a very different state of things may now exist from that shown by the survey made four years ago.

It will therefore be necessary, in order to locate exactly the works of improvement, to make a re-examination of the river at those points where improvements are designed. The object to be had in view, in expending the present appropriation, is to test the practicability of improving the navigation of the river itself, without resorting to slack-water navigation or to a canal.

General Warren has laid down, upon the map of the river, a canal-route, from Portage City to Prairie du Chien, which he recommends as the most practicable plan for obtaining a reliable navigation from Green Bay to the Mississippi River.

The canal crosses the Wisconsin River at three points, where it is proposed to make use of the river. At these points it will be necessary to improve the river-channel, and it is proposed to use the means now available in attempting the improvement. The works required in improving the navigation of the river should be designed, first, to so direct the current as to insure a permanent channel-way. This can be done by protecting the banks and constructing wing-dams.

In order to illustrate, without further loss of time, the general character of the work to be done this season, I inclose Sheet No. 13 of the survey, giving in pencil the location of the second canal-crossing, and a proposed location of the works and wing-dams for giving direction to the current. The precise location of these dams can only be determined upon the ground, as the course of the river has probably changed. This is the worst crossing, and where I propose to commence operations. What I would propose is to go upon the ground, taking with me the person designated as superintendent of the work, and, after consultation with parties familiar with the river, locate the dams. The dams should be constructed (I think now) of brush and stone, and I would employ men accustomed to this kind of work. In order to economize in time and labor, the materials should be obtained from the nearest locality, and what purchases are necessary should be made without resorting to the contract system, which, for work of this character, cannot be resorted to without serious delays and interruptions.

It is supposed that, in many instances, the materials can be procured at simply the cost of moving them, so that the main expense will be that of labor. I would propose this plan for the preliminary operations at least.

I would respectfully request an order to visit Portage City, Wisconsin, with a view to employing a vessel (if necessary) to make a personal examination.

Very respectfully, your obedient servant,

Brigadier-General A. A. HUMPHREYS,

Chief of Engineers, Washington, D. C.

D. C. HOUSTON,

Major of Engineers.

The project of operations having been approved in your letter dated June 12, 1871, I proceeded to carry it out.

I had hopes that, before commencing this work, I should have received copies of all the maps and records of the survey, together with the final report of Major Warren, giving his views and the results of his observation and experience. As, however, it was proposed to limit the operations of the season to the improvement of the river at the points where the proposed canal was to cross the river, and the operations incidental thereto, it was not absolutely necessary that I should have more of the survey than referred to these points, and these were furnished in detail, together with a general map of the river on a scale of 10 inches to the mile. The detailed map of the river was on a scale of 200 feet to 1 inch, and comprised twenty-four sheets; of these I received seven sheets especially referring to the locations above mentioned.

The work to be done was to improve the navigation of the river at the points where the proposed canal was to cross the river, and in so doing to determine the practicability of improving the navigation of the river itself. The proposed canal starts from a point on the canal now connecting the Wisconsin and Fox Rivers, near Portage City, and proceeds on the left bank of the river to a point about 4 miles below Portage City, where it connects by a lock with the river. The canal then commences on the opposite bank of the river and proceeds on the right bank to a point about 56 miles below Portage, when it again connects with the river by a lock. Commencing again on the left bank opposite, it proceeds to a point 885 miles below Portage, when a similar crossing becomes necessary, and then proceeds on the right bank to Prairie du Chien, when it connects with the Mississippi River, 106 miles from Portage.

The depth of the proposed canal is for vessels drawing 5 feet, and the length of the river to be improved, to enable boats navigating the canal to cross the river, is, at the upper crossing 2,300 feet; at the middle crossing, 7,000 feet; and at the lower crossing, 2 miles.

It was proposed to commence work at the middle crossing, but the navigation of the river by boats of any class had been closed at the railroad-bridges of the Milwaukee and Saint Paul Railway, near Spring Green and Lone Rock. Work was therefore commenced in July at the upper crossing, and the first operation was the construction of a dam of brush and stone, 700 feet in length, at a point just below the crossing, and designed to close up one channel of the river here, divided by islands, and to confine all the water of the river into one channel.

The drawings accompanying this report show the method adopted in building this dam, which was generally followed in all subsequent work. The crest of the dam was placed about one foot above the lowwater stage, it being only designed to confine the river during the season of low water, and to allow the water during freshets to pass freely over the dams.

The brush used in building this dam was obtained from the islands in the vicinity, and the stone from a point below Dekorra, two miles below the dam.

This dam is markel Dam No. 1 on Tracing No. 1, accompanying this report.

Our works having been confined to the upper and middle crossing, I will first describe those at the upper crossing, shown on Tracing No. 1. It was proposed, after the construction of Dam No. 1, to build a dam on the opposite side of the river, so as to confine the current and cut out a channel on the line of the crossing; but the effect of Dam No. 1 was to so alter the current below as to cause a shifting of the bars, and interrupt navigation between the point of operations and the source of one class of our material, stone. It was then determined, if possible, to improve this portion of the river for a distance of two miles, so as to admit the passage of our boat. Accordingly, the dams marked Nos. 2 to 9 were successively constructed.

On the 15th of September I visited Dekorra, at which time all the dams above mentioned had been built, except Nos. 7, 8, and 9. I found that the steamer engaged in carrying materials could not pass over the bars at Dekorra. I then directed the construction of Dams Nos. 7 and 8, and the T to No. 3. The river here is straight and wide for a distance of 13 miles. It is one of the worst portions of the river. It was a good opportunity to test the efficacy of wing-dams or dikes, and it was necessary to do something or the work would stop for lack of materials. The effect of Dams Nos. 3 and 8 was very marked, and resulted in a channel through the bar full 4 feet deep, when before there were only 2 feet. The channel in that portion of the river where the dams have been built is now 5 and 6 feet in depth.

There seems to be no doubt that by an extension of the system which has been adopted any required depth of channel can be obtained.

In order to carry on the improvement at the lower middle crossing, 14 miles below the Lone Rock railroad-bridge, a steamer was sent down from Portage and encountered a serious obstacle at the railroad-bridge near Spring Green.

The direction of this bridge, as well as that at Lone Rock, makes an angle with the direction of the river, so that the bridge-piers offer a great obstruction to the current, and act as dams to throw the current toward the lower end of the bridge. The draws of these bridges were placed at the upper ends, where, at the time they were built, there was found the deepest water; but they were almost entirely filled with sand at the commencement of our operations. By putting in a small wing-dam, so as to turn a portion of the current through the

draw, and removing the sand in the draw with a common scraper, the boat was passed through the Spring Green bridge. At the Lone Rock bridge the draw was not only closed, but a large, dry sand-bar was found immediately above it. In order to open a channel through this bar the dams shown on Tracing No. 2, and marked Nos. 1, 2, and 3, were constructed. As it was the season of extreme low water, the effect of the dams was not as rapid as was wished, but the ultimate effect of confining the current and changing its direction was to cut through the sand-bar and open a deep channel through the draw. The Dam No. 9 was then put in to open a channel below the bridge to the site of the middle canal-crossing, after which Dam No. 10 was constructed. This dam and a proposed dam below are the principal works designed for this crossing, but navigation closed before the latter dam could be 'put in.

No work was done at the third or lower crossing, as we were not able to get boats there without considerable delay; but as the character of the river is the same at that point, the practicability of improving it will be determined by the results of the works at the other points.

The Tracings Nos. 1 and 2 show the condition of the river before and after the improvements were made. Tracing No. 3 shows the variation. in water-level during the season of operations, and Tracings Nos. 1 and 2 the details of the dams.

I also inclose plans of the scraper used, which is the same as that now in use on the Upper Mississippi, and a photograph showing it attached to the steamer. This scraper was not used until late in the season. Its cost was $150, and it can be attached to any steamer. Its use will greatly facilitate our subsequent operations. The draws of the bridges over the Wisconsin, particularly those of the Milwaukee and Saint Paul Railroad, which cross the river obliquely, will require to be enlarged and improved, should the project of river-improvement be carried out. They are at present wide enough for the passage of vessels which navigate the Fox River, the locks on which are 35 feet in width, and it is not deemed necessary that any extensive changes should be made until the character of the improvement is finally decided upon and the work more advanced.

It will be necessary to remove the stone in the draws, which has been placed there to protect the piers, and to put in pile-protection above the draws, to facilitate the passage of vesels and prevent injury from collisions. This, no doubt, the railroad authorities will attend to when called upon, as they have shown every disposition to facilitate the progress of our work.

The cross-section of the river at Portage is, at low water, 1,447 square feet, having a width of 700 feet, and an average depth of about 2 feet. The velocity is 1.91 feet per second, giving a discharge of 2,764 cubic feet per second. In many places the river is much wider, with a much less depth.

The problem of improving the navigation of this river is to contract the channel, so as to obtain at low water a greater depth. If we put in a dike extending from one bank of the river, say half-way across, the effect is to cause a rise above, and an increase of velocity at the point of construction, in consequence of which a channel is scoured out through the light and easily moved sand composing the bed of the river. This cutting out will go on until the velocity at the bottom is reduced to a point not sufficient to move the sand. The sand moved by the current is deposited in the eddy formed below the dike.

The mean velocity of the water in the contracted portion is greater