and creek. A slight change in the location of the railroad at this place would save much earth-work in the construction of a canal.

The bottom-lands of Bureau Valley are composed of sand and gravel with a covering of from 1 to 3 feet of soil and clay. The underlying material would probably give ready passage to water, and I have, therefore, endeavored to avoid cutting into it by making the upper clay the bottom of the proposed work, where practicable. The bluffs are composed of clay mixed with some gravel, and will furnish excellent material for the construction of water-tight banks. The swamps crossed upon the summitlevel have from 4 to 6 feet of vegetable soil over a substratum of good clay. Immediately west of lock No. 19, and on the summit-level, quicksand is found 19 feet below the surface, and probably exists at about the same depth for some distance along the line.

The western division extends from the junction with the feeder to the Mississippi, near Watertown, and is 39.45 miles long, making the total length of the main canal 65.31 miles. It will require the construction of nine locks, with an aggregate fall from the summit to the Mississippi of 92 feet, three railroad and thirteen common draw-bridges, twelve culverts and aqueducts, and one dam. The cost of the division is estimated at $4,429,566 13, or $112,283 05 per mile.

From the junction the line runs nearly due west until it crosses Mud Creek, near Annawan, 3,800 feet north of the railroad. From this point several lines were run. One, nearly parallel with the railroad, and intended to pass through the town of Geneseo, was found to require a long cut of 30 feet, besides other heavy work, and was abandoned. Another line, crossing Spring Creek near the railroad and bearing off from thence toward Green River, was also rejected. The route adopted crosses Spring Creek about two miles north of the railroad, passes through the cross-roads on the line between sections 13 and 14, Geneseo Township, and joins the valley of Green River near the covered bridge. A more direct line between the junction and this point would place the canal too low to easily cross Mud Creek and other streams flowing into Green River from the south. From the covered bridge the canal would continue down the valley, lying most of the way under the low bluffs and becoming parallel with the railroad at the fifty-fourth mile; then passing through the town of Mount Oakley it would cross Green River on an aqueduet 200 feet long, run through a deep cut at Colona and encounter Rock River at the sixtieth mile. It is here proposed to raise the water of that river 7 feet by a dam placed a short distance above the railroad bridge, ard to connect the canal by a lock with the pool thus formed. From here the line of canal will be almost direct to the Mississippi River near Watertown, five miles above Moline and eight miles above the city of Rock Island. Another route between this point and the Mississippi is naturally presented in Rock River itself. In this connection I would refer to the maps and report of the survey of Rock River, made in the fall of 1866 by James Worrall, civil engineer, under the direction of General Wilson. By adopting this route, the dam above the railroad bridge would be superseded by one corresponding to dam No. 21 of the proposed Rock River improvement, which would be located about half a mile below the mouth of Green River. The estimated cost of that portion of the Rock River improvement extending from the railroad bridge at Colona to the city of Rock Island, and provided with locks 150 feet long and 30 feet wide, is, according to the above-mentioned report, $902,283 45. The estimated cost of a cross-cut canal between Rock River at the railroad bridge and the Mississippi near Watertown, and having locks 350 feet long and 75 feet wide, is, by my estimate, $979,005. An examination of the prices upon which the Rock River estimates were based, shows that at present rates the total would be somewhat less. But there would. still be a large margin in favor of the cross-cut canal when it is considered that the estimates by that route are for locks of over four times the capacity of those proposed for the other line. I therefore felt justified in neglecting to make an instrumental survey and detailed estimate of the Rock River route.

For the supply of the canal it will be necessary to bring water from the Rock River at Dixon to the summit-level north of Sheffield. The amount of water flowing in Bureau Creek was, at the time of the survey, not more than 50 cubic feet per second at any available point, and West Bureau Creek was nearly dry.

On the eleventh mile water could be admitted from Bureau Creek, but as the chief demand is at the summit-level, the lockages and leakage of the gates at that level would probably supply all the lower reaches. The length of the main canal between the Illinois and Rock Rivers, or that portion to be be supplied through the feeder, will be sixty miles. The length of the feeder will be 38.12 miles, making a total of about ninety-eight miles. The loss from evaporation and leakage I assume at 2.5 cubic feet per second per mile, or 245 cubic feet per second total loss. Assuming the number of passages over the summit-level as ninety in twenty-four hours, corresponding to one hundred and eighty lockages, 656 cubic feet per second will be required to supply the locks, making the total demand for the canal and feeder 901 cubic feet per second.

We were fortunate in making a careful measurement of the amount of water flowing in the Rock River at a time, October 11, 1870, when, according to the residents of

power

that city, the river was at its lowest known stage. The amount of water at that date was found to be 2,446 cubic feet per second, which, under the present available head of 7 feet, gives, theoretically, 1,943 horse-power. To economize earth-work upon the feeder line and summit-level, it will be advisable to raise the crest of Dixon Dam 2 feet, thus increasing the head of water to 9 feet. After deducting 901 cubic feet per second for the canal, there will be available for manufacturing purposes in the dryest times 1,545 cubic feet, or 1,578 horse-power under the 9-foot head. The loss of at this point, after allowing for the increased height of dam, will be equal to 365 horsepower, or 18.8 per cent. of that at present available. The loss at Sterling not being compensated for by a higher dam, will be equal to 36.8 per cent. of the present power. The dimensions of the feeder section recommended and estimated upon are, 140 feet in width at the water-surface, 112 feet on the bottom, and 7 feet deep, giving an area of 82 feet and calling for a velocity of nearly 1.1 foot per second to pass the necessary supply. The slope given to the bottom of the feeder, as shown on the profile, is a little over one-tenth of a foot to the mile, or 4 feet in thirty-eight miles. The banks, both for the main canal and feeder, are to be built 3 feet above the surface of the water, and to be 12 feet wide on tow-path, and 7 feet wide on berm. It is proposed that the head-gates and guard-locks at Dixon be placed at the lower end of the water-power canal, which would require enlargement. From thence the feeder would be located near the left bank of Rock River for 10.5 miles, at which distance, 1.75 miles beyond the crossing of the Chicago and Northwestern Railroad, it leaves the valley of the river and takes a southerly course across the prairies. For a great portion of the way in Rock River Valley, the construction of only one bank will be necessary.

Four miles from Dixon the river takes an abrupt turn under a steep ledge of rock, and the work at this point will be expensive and require considerable protection.

Guard-gates and a waste-weir have been estimated for at the creek crossed on the tenth mile. After leaving Rock River the general direction of the line is somewhat. south of west, and requires no cutting of more than 17 feet until just beyond the twenty-sixth mile, when it cuts through a narrow ridge 30 feet above grade. Immediately before reaching this point, and on the twenty-fifth mile, the bottom of the canal will be from, 3 to 7 feet above the level of the marsh. From the twenty-sixth mile the course is nearly straight to New Bedford, where Green River will be crossed on an aqueduct 200 feet long and 13 feet above the low-water level. The fall in this river between this point and the covered bridge north of Geneseo is 35.5 feet. Between New Bedford and the junction considerable earth-work will be required. The very long slopes of the ground lying between Rock River and the junction make it impossible to select the best route by reconnaissance, and it would be necessary to run several lines before a final location could be made. The lateness of the season prevented any such examination, but in case of future action I would recommend that between the twenty-third and twenty-ninth miles, and between the thirty-second and thirtyfourth, surveys be made west of the line shown upon the maps.

The material found upon the line is mostly clay and soil, the ridges being composed of sand. No protecting wall has been estimated for on this portion of the work. The feeder will be 38.12 miles in length, will require two railroad and fourteen common bridges, eight culverts and aqueducts, one guard-lock, two waste-weirs, and the raising of Dixon Dam, and will cost $2,270,849 90, or $59,571 08 per mile. The estimated cost of the whole work appears from the following summary: Eastern division...... 25. 86 miles...

$5,779, 277 24

4,429, 566 13 2,270,849 90

12, 479, 693 27

The details of the above are given in the tabular estimate for ship-canal accompanying this report.

Locks of the size contemplated would admit a steamer and tows of barges capable of carrying 2,000 tons.

The supply of water calculated upon will be sufficient for one hundred and eighty lockages per day under the most favorable circumstances, that is, with an equal amount of travel each way, and the locks always full to descending and empty to ascending boats. With the travel in one direction only, the supply of water would limit the number of lockages to ninety per day. Neither of these extremes is to be expected in practice, and taking the mean of the two cases, the number of possible lockages can safely be counted at 135. This would correspond to sixty-seven passages over the summit level which, at 2,000 tons each, will give a capacity of 134,000 tons in twenty-four hours. Should the travel be wholly in one direction, this would be reduced to 90,000 tons per day. Should more than one hundred and eighty locks full per day be used, the level of the water in the summit-level would be lowered and the velocity in the feeder be increased.

The objections to the construction of a canal of the size contemplated in the foregoing portion of this report are, its immense cost, the interest on which, at 6 per cent., would amount to $748,781 60 per annum; the large amount of water to be taken from Rock River, to the injury of the manufacturing interests; the quantity of water necessary to the lockage of boats should they present themselves singly, or in small tows; and the expense of tending and keeping in repair a work of such magnitude.

The proposed enlargement of the Illinois and Michigan Canal, and the lock and dam in course of construction in the Illinois River, contemplates the passage of iron-clad gun-boats between the Gulf and the lakes; but since boats suitable for use on the Gulf and lakes would be unfit for the Upper Mississippi, it is inferred that this project is for commercial purposes only. This being the case, a smaller canal would probably be better suited to the situation, both from its reduced cost and the smaller amount of water required by it.

The facts in relation to the large canal having been brought to your notice, you verbally directed me to report and estimate upon a canal of smaller section. I have, therefore, proposed a canal section 60 feet wide at the water-line, and 6 feet deep, and having slopes of 2 to 1, with locks 150 feet in length and 21 feet in width. These dimensions correspond to those adopted by J. O. Hudnutt, civil engineer, in his estimates for a canal over nearly the same route, based upon surveys made in the summer of 1866.

The line recommended for this work corresponds nearly with that shown upon the maps for the larger canal, and the elevation of its water-surface and bottom are indicated by broken and dotted lines upon the profile. Upon the main portion the bottom of the channel corresponds with that before proposed, making its water-line 1 foot lower. Composite locks have been estimated for, and in number, location, and lift are similar to those already enumerated. No swing-bridges, or inside protecting walls will be necessary. The amount of water required for this canal is estimated as follows: For evaporation and leakage, 1.33 cubic feet per mile per second, or 130 cubic feet per second for canal and feeder; for two hundred lockages in twenty-four hours, 87 cubie feet per second, making a total demand from Rock River at Dixon of 217 cubic feet per second. With a feeder 50 feet wide and 6 feet deep, with slopes of 2 to 1, the sectional area will be 228 square feet, and the velocity required to the above quantity 0.95 feet per second. To obtain this velocity through the above section, it will be necessary to give to the bottom of the feeder an inclination of 0.16 feet to the mile, or 6 feet fall from Dixon to the junction with the main line.

The eastern division, from the Illinois River to the feeder, is estimated to cost $1,467,202 44, or $56,736 37 per mile. The western division, from the feeder to the Mississippi, $1,429,708 50, or $36,241 03 per mile. The feeder, $1,002,811 70, or $26,306 71 per mile, making the total for the whole work $3,899,722 64, or $8,579,970 63 less than for the larger canal. A tabular detailed statement of this estimate accompanies this report. The surveys were made wholly for the purpose of locating a canal 160 feet wide, and the narrower section would probably adinit of following the bluffs more closely and thus effect a large saving of earth-work.

The locks proposed for this work will admit boats of a capacity of 280 tons. At three locksfull to a boat, 18,760 tons could be passed daily.

Freight could be brought in tows from points on the Upper Mississippi to the canal, and then by horse-power through this canal to the Illinois River, and through the Illinois and Michigan Canal to Chicago without breaking bulk. I have not considered it any part of my duties to report upon the commercial advantages of this project, nor have I at hand sufficient data for the purpose. I have endeavored to make the estimate sufficiently high, and am of the opinion that the amount stated above would fully cover the cost of construction. The amount of earth-work would probably be some what reduced upon a final location. No estimate has been made for land damages, but it is presumed that the counties and cities immediately benefited by the work would relieve the Government from any expenditure under that head.

Very respectfully, your obedient servant,

Colonel JOHN N. MACOMB,

GORHAM P. LOW, JR.,

Civil Engineer, Assistant.

Corps of Engineers, U. S. A., Rock Island, Illinois.

APPENDIX I (1.)

OFFICE WESTERN RIVER IMPROVEMENTS,

St. Louis, Missouri, July 28, 1871.7

GENERAL: In compliance with the regulations, I have the honor to submit this my annual report of operations upon the improvement of the Mississippi, Missouri, and Arkansas Rivers.”

On the 12th of July, 1870, I reported in Cincinnati, under orders to relieve Colonel J. N. Macomb, Corps of Engineers, of the duties under his charge, and to remove the office to this city. Colonel Macomb had, previous to my relieving him, completed the surveys previously under his charge, the only duty in progress at the time being the improvement of the Mississippi, Missouri, and Arkansas Rivers, for the prosecution of which a fleet of four snag-boats and one dredge-boat were turned over to me.

These boats were all, at that time, lying at Mound City, Illinois, where they were undergoing extensive and thorough repairs, which were nearly completed. I at once visited Mound City and inspected the fleet, gave instructions for at once taking the field, and then returned to Cincinnati, receipted to Colonel Macomb for the funds and property belonging to the work, made arrangements for shipping the office records and furniture to this city, then came here and made preparations for opening an office as directed.

Field operations had been conducted, for some time previously, under the direction of Captain C. R. Suter, Corps of Engineers, under whose immediate charge the repairs and improvements of the several boats had been in progress. I found all the boats were being put in splendid order, and I receipted to Colonel Macomb for five boats better fitted for the duty for which they were designed than any which had ever been

in use.

I availed myself of the experience of Captain Suter in getting the fleet started, and under his immediate direction the whole fleet was. under way by the 28th of July, their destination being the Mississippi River, above this city, and the Missouri from Omaha to its mouth.

OPERATIONS IN THE MISSOURI RIVER.

The fields first assigned to the several snag-boats were as follows: The S. Thayer, between Omaha and St. Joseph.

The R. E. De Russy, between St. Joseph and Lexington.

The S. H. Long, between Lexington and Eureka.

The J. J. Abert, between Eureka and the mouth of the river.

Under date of August 6, 1870, I was ordered by the Department to dispatch a snag-boat at once to White River. This order rendered a change of programme necessary. The R. E. De Russy, not having yet reached her field of operations, was withdrawn from the Missouri and sent to White River; the S. Thayer was withdrawn from above St. Joseph and assigned to the Missouri between Lexington and St. Joseph, thus preventing any work above St. Joseph.

On the 14th of August, the dredge-boat Octavia, after having been up the Mississippi as far as Keokuk and deepened all the bars between this city and that point, went into the Missouri to aid the snag-boats in their operations, and to provide against the danger of their being caught in this stream by low water and thus rendered unavailable for service in the lower rivers.

Operations were continued in the Missouri until the 1st of November, when the several boats were withdrawr and assigned to duty in the Lower Mississippi and Arkansas Rivers.

The details of operations in the Missouri are included in the table of work done, herewith submitted, marked A. Such a table, however, gives little idea of the benefit conferred upon commerce, nor can this be fully appreciated by any excepting those immediately interested in navigation. Four years ago, or before, the snag-boats commenced their

operations, the navigation of the Missouri was so dangerous that boats did not attempt to run at night; now they always do so. This change has been brought about entirely by the operations of the snag-boat. The saving in time in a round trip from this city to Saint Joseph and return cannot be estimated at less than four days, or in money at less than $1,000. There is of course a proportionate saving on shorter trips, and as not less than two boats daily leave this city for the Missouri River during the season of navigation, it will be seen that, in runningexpenses alone, a benefit has been conferred upon the commerce of this one stream far exceeding the amount of the total appropriation for the three rivers. To the saving in running expenses we must also add the saving in risk, or rate of insurance, to form an estimate of the real benefit conferred. The saving in the expense of running boats on the river does not benefit the owners only; competition at once brings about a corresponding reduction in the rates of freight, so that the saving inures directly to the benefit of shipper and producer.

It is very desirable that the snag-boats should be able to take advantage of the annual spring rise to get into the Missouri River, and be on hand to commence work as soon as the stream is low enough. To do so they should be ready to start for the field by the 1st of April. They should extend their field of operations at least as far as Sioux City. To clear the stream of the annual deposit of snags and logs would require about six months' work. My estimate for this duty is therefore as follows:

Running-expenses of four snag-boats, six months each, in all twentyfour months, including proportionate amount of repairs, at $5,000 per month, $120,000.

OPERATIONS IN THE MISSISSIPPI RIVER.

The dredge-boat Octavia left this city for the Upper Mississippi on the 3d of August, and proceeded up the Mississippi to Keokuk. She dredged the channel at the following points:

Piasan Bar, four miles above Alton; Hat Island, thirty-five miles above Alton; Worthington Point; Armstrong's Landing, four miles above Hannibal; Scott's Landing, five miles above Louisiana; Thomas's Chute; Two Branches Island, and left the stream in good navigable condition.

The shoals in the Mississippi River being composed of light shifting sand, it is not expected that the dredging done will be a permanent benefit. The next rise in the river washes in the sand and leaves the channel in about the condition it was when the dredging commenced. The only remedy for this is to keep a boat at all times ready for servicewatching the changes in the stream-and as soon as the shoals begin to obstruct navigation, to have them visited, and, by means of the dredge, conduct the water into a single channel of sufficient depth for the purposes of commerce. This will be required as far down as the mouth of the Ohio, and it is doubtful if a single boat will be able to accomplish the work. This question will be tested the present season, as it is proposed to keep the Octavia at work between Keokuk and Cairo as long as the limited appropriation will admit. To do so throughout the year would require an appropriation of $60,000 for this work alone.

On leaving the Missouri River the snag boat J. J. Abert was assigned to that portion of the Mississippi between the mouth of the Missouri River and Memphis, Tennessee. The S. H. Long was directed to work between Memphis and the mouth of the Arkansas, and up the Arkansas