tances on the Mississippi, Missouri, Ohio and Arkansas Rivers, involv'ing journeys many thousand miles in the aggregate. If I recollect rightly, the new snag-boats have six pair of engines. This fact must be taken into consideration in estimating the comparative efficiency and amount of work performed by the two classes of boats, the old and the

new.

In respect to accommodations for officers and crew, the new boats are so superior to the old that no just comparison can be instituted between the two.

In conclusion, I beg leave to say that, from opportunities afforded of conversation with river men, I am of the opinion that there is but one expression in regard to the operation of the snag-boats, and that is of universal commendation. They have already accomplished a great deal, but much more remains to be done.

Very respectfully, your obedient servant,

Brevet Major General G. K. WARREN,

HENRY C. LONG, United States Civil Engineer.

Major Corps of Engineers,

Sup't Northwestern River Surveys and Improvements,

St. Paul, Minn.

F.

PITTSBURG, May 13, 1869.

GENERAL: Being recently in St. Louis, at the time when Colonel Macomb happened to be there with the United States snag-boat J. J. Abert, he kindly invited me to accompany him up the Mississippi, in order that I might witness her working.

I had for some time desired to see for myself how that class of boats operated, and was very glad to embrace this excellent opportunity.

The Abert started from St. Louis shortly before noon of Friday, the 7th of May, and made excellent progress-from five to six miles an hour-against a current of nearly five miles an hour. Three miles up, just below the new city water works, we met the first snag, which was pulled and on board in just six minutes from the time the Abert stopped her headway. The steamer was then immediately put under way, moving slowly up stream, searching for another snag, and at the same time sawing up with steam saws the one on board. This was a sycamore, fifty feet long and thirteen and a half feet in circumference at the butt. The total time, from the beginning, when we were entirely clear of the tree, was twenty minutes. Within ten miles of the city, two more snags were met, pulled on board and cut up-one being forty feet long and eleven feet in circumference. The first was brought on board in six minutes, and the other in eight minutes from the time of stopping headway. About fifteen miles up she took a fourth large snag, ninety feet long and fourteen feet in circumference. This proved to be more difficult, on account of the limbs, though it was on board so as to apply one saw in five minutes, and the boat put under slow motion. We were entirely clear of it in one hour and thirty-six minutes, during which time, however, we ran several miles up. Just above the mouth of the Missouri River, she took another large troublesome tree, which had large limbs buried in the sand, and the root partly afloat, and which had to be pulled out root foremost, but seemed to make little difference. This was seventy-five feet long and twelve feet in circumference. It was on board

and the boat under slow way in eight minutes. This was at seven o'clock, or about seven hours after leaving Saint Louis. Thus she pulled five snags between noon and seven p. m., and made twenty miles on the river. We then ran over to Alton for the night, twenty-four miles from Saint Louis, arriving after eight o'clock.

I carefully watched the working of the Abert, and the use of her gearing, chains, and saws, and the management, and the conclusion in my mind is that the whole arrangement is almost perfect for the purpose of rapidly taking up and disposing of large snags, even the very largest. I only say "almost" perfect, because slight improvements doubtless may be made in the building of another boat.

The improvement recently introduced, carrying the steam saws forward, and placing one of the side saws near the bow, so as to cut off the stump at once when desired, with the other steam saw making another cut at the same time, seems to me admirable. It certainly worked beautifully on the occasion I refer to. The motion of the gearing might be made in future boats rather slower, but as a whole, as a snag machine, just as she is, the Abert is very far superior to anything I ever saw in operation anywhere. I am entirely satisfied that this boat, or a similar snag-boat, is precisely what is needed for the purpose of removing snags from the Mississippi, Missouri, Arkansas, and other snaggy rivers, and that it would be well if one of these boats could be detailed to work up the Ohio River as far as Louisville, and, if she should get by the falls, to work up to Cincinnati, or as far as she could go. I believe that a light-draught steamer, built on the same general arrangement, would remove snags to a great advantage on the upper Ohio, if snags were abundant, or if they were the chief obstruction on that part of the river. But on the upper Ohio more time is required for the removal of wrecks of coal boats, barges, steamers, &c., which require for each case special management, sometimes partial dredging of coal, gravel, &c., and lifting, and occasionally blowing up.

I have no doubt that if the government had adopted, or should have occasion to adopt, a permanent system for removing obstructions from the Ohio River, that a light-draught steamer could be arranged on a somewhat similar plan, so as to do work advantageously. But in the absence of any permanent system at present, and without yet knowing to what extent the removal of obstructions annually may be required in the future, our method of working by contract with, say, two light-draught steamers, is, I think, the best for this season between Pittsburg and Cincinnati; and below Cincinnati, as far as Louisville, in case one of the government snag-boats referred to can be spared this season, and can get above the falls, it would probably be economy to let her work up as far as she could go. Meanwhile two contract steamers, as indicated in my letter dated April 5, 1869, could be employed to advantage working down stream at different points from the head of the Ohio.

The government snag-boats being on hand, I have now no doubt that one of them could work at removing snags between Cairo and Louisville to better advantage than with our contract system. I therefore respectfully recommend that Colonel Macomb be authorized to use one or more of them, whenever he can conveniently place them, on the Ohio River below where any contract steamer may be working.

Very respectfully, your obedient servant,

W. MILNOR ROBERTS,

U. S. Civil Engineer, in charge Ohio River Improvements.

Major General A. A. HUMPHREYS,

Chief of Engineers, U. S. A.,

Headquarters Corps of Engineers, Washington, D. C.

.

G.

UNITED STATES STEAMER OCTAVIA, St. Louis, Mo., June 29, 1869. COLONEL: We arrived at this place early this morning, having since we left here pushed nearly a thousand miles up the Missouri River. As I informed you in my hurried note from Cairo, the river fell very low after the early spring rise, and for some time was nearly impassable. I kept in company with the snag-boats as far as Lisbon, and then pushed ahead to clear the way for them. The lower river had cut out very fairly, but the upper portion was still reported in very bad condition. We did some dredging at a place called Eureka, with good success. Above Leavenworth the river began to shoal fast, and at Smith's Bar, twentyfive miles below St. Joe, we were unable to cross, ourselves. After some delay by wind, we cleaned this bar out successfully, and it has since remained in very good shape. Twenty miles above here we dredged again at the head of Hell's Half Acre. This place has also held out well. After this we kept on up to Omaha, examining the river carefully and dredging wherever necessary. We turned back from Omaha, and kept on down the river to Smith's Bar, meeting the De Russy and Long, on the way. Finding the river at a good stage, I turned back to see about getting the De Russy above Omaha. Found her below Omaha unable to stem the current. We helped her up stream, however, and the river beginning to fall, she came on all right. We kept up the river about eighty miles. I found the river getting very small and shoal, and falling fast. The De Russy looked in it like a whale in a mill-pond. There were very many snags, but she could only pull those directly in her road. I could have taken her up to Sioux City and back, by digging and hauling her over the bars, but I thought the game would hardly pay. The snags were all bedded very deep, and would not stand a pull, but broke off short in the sand. Finally I gave Captain Birch orders to drop below Omaha. The river was falling fast and we just got the De Russy out, and no more. Below Omaha the river is deeper than above, owing probably to the frequent passage of boats, and also to the considerable accession of water from the Big Platte. Below there I do not anticipate any very serious trouble, till toward the close of the season. Leaving the De Russy at Omaha, I kept on down the river, examining everything very carefully. Dredged at Sonora, Hell's Half Acre, and Weston. Below this last point no work was found necessary. On the way down, I visited the Long and Abert, and had a good opportunity of judging of the amount of work done by them. The snag-boats are all working with great zeal and efficiency. They have already done an immense deal of good. I propose to keep them at work in the Missouri as long as I can safely, gradually working them down the river as the water falls. When they get tolerably near the mouth, I shall feel confident of being able to extricate them with the scraper. This latter machine works far better in the Missouri than I dared to hope for, but the one on board the Octavia is too small for any but a very small river. After careful consideration and planning, I have decided on building one with six buckets, and ten feet additional length. All the iron work of the present scraper can be used on it, and it will soon be finished. The same machinery will handle the new scraper as did the old one. The expense of the new scraper will be trifling. This work will probably take me about a week, after which I shall be ready for any new work. The rivers are all swelling at present. I have heard from Mr. Abert,

who informs me that the present rise is likely to put an end to his hydrographical work.

I am, colonel, very respectfully, your obedient servant,

CHAS. R. SUTER,

Brevet Major United States Army, Captain Engineers,

Assistant in charge Field Operations, United States Snag-boats, &c. Colonel J. N. MACOMB,

Engineer, Sup't Western River Improvements.

H.

CINCINNATI, OHIO, August 28, 1869.

COLONEL: I have the honor to submit the following preliminary report of the survey of the Arkansas River, from Fort Gibson to Little Rock, a distance of two hundred and ninety-nine and a half miles.

After receiving your instructions as to the objects and method of the survey, the party was organized with the following named officers: Ernst Rühl, R. E. McMath, H. A. Pattison, J. D. McKown, assistants; H. G. Webber, draughtsman; C. A. Good, clerk.

One mate and thirty-four men were employed, in the various capaci ties of chainmen, sounders, axemen, deck-hands.

The portion of the river surveyed has its course partly in the Indian Territory, and partly in the sparsely settled counties of the State of Arkansas. It was represented to be subject to freshets, and during the intervening stages to be much obstructed by snags. To transport securely and expeditiously the party employed, it was necessary that a substantial boat should be built for the special purpose.

The approach of winter delayed the completion of the survey boat. It was not until January 15 that the party embarked, in tow of the United States steamer Octavia.

Leaving the mouth of the Arkansas River, January 24, in tow of a river packet, the party reached Fort Gibson February 7, being detained by high water and head winds.

The day after reaching Fort Gibson the symptoms of small-pox were manifest, and the survey was temporarily deprived of the services of three officers and two men. For a time the success of the expedition

seemed doubtful.

The sick were immediately placed in camp, and the survey commenced the same day was continued, with several short interruptions from high water, to its completion at Little Rock on June 30.

Here operations were suspended, according to your instructions.
The method of survey was as follows:

The course of the river and topography was noted by two parties, one on each bank.

The line upon the left bank was surveyed with the solar compass; the true meridian being determined at every station when the sun was visible, and all the lines of the survey were referred to it as the standard. The latitude was also approximately determined by this instrument, and occasionally checked by observations with a Würdemann sextant.

The right bank was surveyed with a transit, (Würdemann,) all angles being referred to the standard meridian, as determined by the solar compass. The correctness of this standard was further verified by

observations upon the elongation of Polaris. The two lines above described were connected every mile by triangulation.

The same parties also established hydrographic stations, consisting of flags, lettered alphabetically, which served as terminal points for the lines of soundings. The points were occasionally fixed by the hydrographers.

The hydrographic party sounded the river from bank to bank. Shoals, reefs, and the edge of bars were carefully determined by soundings fixed by triangulation, but as far as the channel remained unobstructed, the soundings were taken by cadence, or at fixed intervals of time.

Sub-surface velocities were taken, and also all observations requisite for determining the discharge of the river at intervals of ten to twenty miles, according to the suitability of the locality for this purpose.

The floats employed in these measurements were composed of pieces of tin, placed at right angles, so as to present four vanes to the action of the water, and were secured by cords to corks bearing small red flags. The cords were lengthened, so as to bring the vanes to mid-depth, whenever velocities for ascertaining the discharge were measured.

The vanes were launched from a boat at distances sufficiently near to give the mean velocity at many points along the line of the cross-section, and their transit was observed from two theodolites at the extremity of a base of one hundred feet in length. This length of base left no space for eddies or changes in the current, and always gave favorable results. The measurements were usually taken when the river averaged eight hundred and fifty to one thousand feet in width.

These observations were conducted in the manner described in the delta report of Generals Humphreys and Abbot.

The leveling party were directed to touch upon the surface of the water every half mile, and to assist in the establishment of gauge-rods, and to carry lines of levels across the valley, from bluff to bluff, at all points where measurements for discharge were taken. Gauge-rods were established at intervals of from twenty-five to thirty-miles, and observers were employed to keep a record of the stage of the water every morning and evening.

Similar observations were kept up hourly at the boat, during the day and night.

These observations, besides illustrating some of the phenomena of the river, are useful in eliminating the oscillation, and also to enable the hydrographer to reduce his sounding to a co-instantaneous plane of the water surface.

The plane of reduction of all the sounding was assumed at three feet above low water, being the lowest stage observed during the survey, and exhibits the river anterior to the condition when it begins to cut through the shoals.

Permanent marks were left at stated intervals along the line of survey by all the parties.

During the period of the survey the oscillation of the river ranged from three feet above low water to twenty feet, and reached twenty-six feet about 6th July, just after the conclusion of the survey.

The low water was accurately determined at several points by the testimony of competent observers, but these points were so distant that it became requisite to assume that this plane varied in inclination in conformity with the slope of the surface as determined by each day's observation with the level. A succession of inclined planes was thus obtained, agreeing, as near as possible, with the co-instantaneous plane of the low-water surface.