it at high water. For the improvement of navigation at this place, the engineer in charge recommends 1. Boiler Rock to be removed to a depth of twelve feet, requiring seventy cubic yards of blasting, which, at $50 per cubic yard, would cost... 2. The point of ledge contracting the channel at Upper 3. Deepening the bar about midway between Upper Hell Total required for the proposed improvement. $3,500 00 6,000 00 5,500 00 1,500 00 16,500 00 All of which could be profitably expended during the fiscal year ending June 30, 1871. (See Appendix U.) 7. Survey and improvement of the Penobscot River, Maine.-This survey has been completed. Very extensive and accurate soundings and borings made in the river show that from Crosby's Narrows up to Ban-, gor, a distance of some three and a half miles, the bed of the river is seriously obstructed with slabs, edgings, and sawdust, to an average depth of ten feet, and in some localities more than eighteen feet; and that the harbor of Bangor is also obstructed with several large sunken rocks. To restore the channel to the original river bed would require an excavation of more than 5,000,000 cubic yards of its accumulations. But a passable channel could be made at a cost estimated at from $100,000 to $500,000, according to its width and depth. (See Appendix U.) 8. Improvement of Union River, Maine.-A careful examination of this river, from its mouth to Ellsworth, has been made. The engineer in charge estimates that for the improvement of the navigation between these points, by clearing it of slabs, edgings, and sawdust, removing boulders and sunken rocks, and erecting five stone beacons, there will be required an appropriation of $40,000, which, in view of the large lumber trade, he recommends to be made. (See Appendix U.) RIVERS AND HARBORS ON THE PACIFIC COAST. Officer in charge, Brevet Lieutenant Colonel R. S. Williamson, major corps of engineers, assisted by first Lieutenant Wm. H. Heuer, corps of engineers. 1. Improvement of the Willamette River, below Portland, Oregon.-The operations on this river during the past fiscal year have been confined to dredging on Swan Island Bar, and the bar at the mouth of the river, and to removing snags at each of these localities. Surveys were made of the Willamette slough and of the mouth of the river. Many difficulties were encountered causing delays in the prosecution of the work. In December, 1868, when the dredging was temporarily suspended, a channel had been cut over Swan Island Bar, admitting vessels drawing fifteen feet, during the low water stage. The total length of channel excavated since the commencement of the work in 1867, at this locality, is 3,200 feet. The estimate of the cost of deepening Swan Island Bar to eighteen feet was based on the supposition that the cost of dredging at a depth between fifteen and eighteen feet would not vary materially from the cost of the previous dredging. From a report received from the officer in charge, it appears that the dredging at this place has been greatly retarded during the summer by numbers of large, sunken trees imbedded in the bar, the removal of which has been found to consume much time, besides causing frequent breaks in the machinery. For these reasons he deems it advisable to increase his estimate of the amount required for the fiscal year ending June 30, 1871, as follows: For Swan Island Bar......... For keeping open the channel at the mouth of the Willamette River Total.... $25,000 00 6, 000 00 31,000 00 which he believes will complete the work on the Swan Island Bar, and keep open the channel at the mouth of the river up to that date. Amount of appropriation and allotments for the improve ment of Willamette River... Amount available July 1, 1869 $79,500 00 26, 923 74 31,000 00 which can be profitably expended during the fiscal year ending June 30, 1871. (See Appendices V V 1 and V 1, a.) 2. Removal of Blossom Rock in the harbor of San Francisco.-After the allotment of $50,000 had been made from the general appropriation of 1868 for rivers and harbors for the removal of this rock, the work was advertised and proposals invited. Only one proposal was made, and that being unsatisfactory was rejected. A plan for the removal of this rock was submitted to the officer in charge, accompanied by an offer to remove it to a depth of twenty-four feet at mean low water for $75,000, no payment to be made until the satisfactory completion of the work. This offer has been accepted, and the officer directed to enter into contract in accordance with the foregoing terms. Amount allotted from appropriation of 1868. (See Appendices V and V 3.) $50,000 00 25, 000 00 75,000 00 SURVEYS AND EXAMINATIONS ON THE PACIFIC COAST. 1. Survey of the Upper Columbia River, Oregon.-Portions of the Upper Columbia River, Homly Rapids, and Rock Creek Rapids, have been examined with a view to ascertaining the position and dimensions of certain rocks, and to preparing estimates of the probable cost of removal of these obstructions. (See Appendix V.) 2. Harbor of San Pedro, (Wilmington,) California.-An examination of this locality has been made with a view to preparing a project for the improvement of the harbor. The report of the officer in charge, with estimate of the probable cost of improvement, is transmitted herewith. (See Appendices V and V 2.) SURVEYS AND EXAMINATIONS WITH THE VIEW TO THE IMPROVEMENT OF RIVERS AND HARBORS. The following estimates of appropriations showing the amounts required for the purpose of making further surveys and examinations of localities, the improvement of which has been heretofore, or that may be hereafter authorized, were submitted in my last annual report; and there having been no appropriation made for this purpose, the estimates are again submitted. For the Atlantic coast. For the Pacific coast For the western and northwestern rivers. WORKS IN THE DISTRICT OF COLUMBIA. $30,000, 00 25, 000 00 125,000 00 PUBLIC BUILDINGS, GROUNDS, AND WORKS, IN THE DISTRICT OF COLUMBIA. Officer in charge, Brevet Brigadier General N. Michler, major corps of engineers. For the condition of the public buildings, grounds, and works, and recommendations for their further improvement, see the report in detail of the officer in charge. His estimate for the next fiscal year is— For the improvement, care, and repair of public buildings, grounds, and works, in the District of Columbia... For compensation of persons employed on and about public buildings, grounds, and works, as above Total (See Appendices W and W 2.) WASHINGTON AQUEDUCT. $584, 192 00 49, 002 00 633, 194 00 A report in detail upon the condition of this work will be found in Appendices W and W 1. The officer in charge submits estimates for the fiscal year ending June 30, 1871, as follows: For continuing the constructionof the distributing reservoir $200, 000 00 For completing unfinished work and for superintendence and repairs... Total... 188, 190 00 388,190 00 BISHOP'S CANAL LOCK. By authority of the Secretary of War a board of engineers was detailed February 21, 1867, to examine the model of an improved canal and ship lock submitted by Mr. Martin Bishop, of Ohio. The report of this board will be found in Appendix W 3. SURVEY OF NORTHERN AND NORTHWESTERN LAKES. Lieutenant Colonel and Brevet Brigadier General W. F. Raynolds, corps of engineers in charge, assisted by Captain and Brevet Lieutenant Colonel F. M. Farquhar until the month of November, 1868; by Lieutenant J. F. Gregory during the entire year; by Lieutenant B. D. Green until April, 1869; by Lieutenants E. H. Ruffner, J. C, Mallery, and W. E. Rogers during the entire year; by Lieutenant L. M. Haupt until January, 1869, and by Lieutenant J. E. Griffith until April, 1869. Captain and.Brevet Major J. A. Smith reported for duty on the survey in the month of June, 1869. In addition to the above-named officers of the corps of engineers, General Raynolds was assisted by Messrs. D. F. Henry, O. N. Chaffee, J. R. Mayer, and H. Gillman, as principal assistants. Messrs. Chaffee and Gillman tendered their resignations, and did not enter upon the field-work in the season of 1869. They were succeeded by Messrs. A. C. Lamson and O. B. Wheeler, principal assistants. During the season of 1868 the operations of the survey were carried on by the three steamers belonging to the lake survey and five shore parties on Lake Superior; three astronomical parties, one at Ogdensburg, one at Watertown, and one at Oswego, in the State of New York; three gauging parties, measuring the outflow of the rivers St. Clair, Niagara, and St. Lawrence; thirteen meteorological observers at different localities on the lakes; two draughtsmen, reducing maps for publication; two assistants, in office and attending to chart distribution; three assistants, engaged in reducing meteorological observations, &c. During the season 1869, in consequence of the late date at which the act of partial appropriation of funds was passed by Congress, the field force was reduced proportionately, and the operations of the survey progressed with the following organization, namely, two steamers and two shore parties, six astronomical and triangulation parties on Lake Superior, and two river gauging parties on the rivers St. Clair and Niagara. The stations for the primary triangulation of Lake Superior have been selected. This duty involved an examination of heights near the shore, and as they are all covered by a dense growth of forest trees, the amount of labor required for selection was far greater than would have been the case in a region under cultivation. General Raynolds expresses the opinion that the reconnaissance leaves but very little doubt that a system of triangles can be obtained that will cover the entire lake. The off-shore hydrography of the northern coast has been completed, and the greater portion of that of the southern coast will be completed this season. A portion of the general hydrography as well as a portion of the pri mary triangulation will remain incomplete, the season having proved unfavorable for field operations far worse than hitherto known in the history of the survey. The district of Isle Royale embraces numerous harbors and anchorage grounds which have never been used, and many dangers to navigation which have been discovered during the survey. A chart of the district will be prepared exhibiting all the features of the locality, which will be of essential benefit to navigation. The district extending from the western end of Isle Royale to the extreme western end of the lake presented many difficulties not met with in more favored localities, due to the almost entire isolation, to the absence of harbors, and to a great extent of even boat landings, and to the rough, mountainous country, covered by a dense growth of forest trees. The survey of this district has been completed successfully without an accident. The survey of the district at the head of St. Mary's River and north ward, and including the triangulation of the large bay south and west of White Fish Point has been completed. The survey of Lake St. Clair was resumed after the surveying parties had been withdrawn from Lake Superior, and considerable progress made. In addition to the ordinary duties of the lake survey, it became necessary to detach portions of the surveying parties to make minute local examinations and surveys connected with the improvements of harbors and rivers, in some of which the use of the steamers was unavoidable. Among these local surveys the dredged channels at St. Clair Flats and in St. Mary's River, at Lake George, and that of Maumee Bay required the aid of steamer. Maps of the above surveys were made as well as copies of manuscript maps of previous surveys, and supplied to the officers of engineers requiring their use. The meteorological observations at twelve stations have been continued, and the reductions and computations incident thereto have been made, but the means of the reductions, &c., only have been incorporated in this report. The distribution of charts has been continued at the offices in Detroit and Buffalo. The number issued exceeds that of previous years very largely, with the exception of that of the year preceding. A detailed chart of the survey of Huron Bay and Huron Islands, Lake Superior, has been reduced and is now in the hands of the engraver. A series of charts, three in number, covering the entire Lake Superior, are in progress, and await the completion of the primary triangu lation. A preliminary chart of the east end of the lake, similar to that of the middle portion, has been issued to meet the wants of commerce until the finished and more perfect charts of the same region are prepared for engraving and publication. A general map of the entire chain of lakes, on a scale of one twelve hundred thousandth, has been commenced. The unusually unfavorable season for the field-work has prevented the completion of the survey of Lake Superior, as was confidently anticipated at the period of submitting the last annual report. The failure in receiving the large theodolites, manufactured in Berlin and imported for the primary triangulations, has also contributed in some measure to delay the completion of the survey of this lake. The amount of the last appropriation, together with the amount made available of the partial appropriation of 1867 withheld, but reappropri ated, aggregating $150,000, will be exhausted by the close of the fiscal year, June 30, 1870. The estimated amount required for continuing the survey during the year ending June 30, 1871, is $159,000. (See Appendix X.), RECONNAISSANCES AND EXPLORATIONS. Officers of engineers have been on duty at most of the headquarters of the military divisions, departments, and districts, where they are charged with the preparations of detailed maps and sketches required by the commanding general, and with the collection of topographical information requisite in the compilation of the military maps engraved and distributed by the Engineer Department. The following officers have been thus serving, namely: Major Henry M. Robert, at the headquarters military division of the Pacific; Brevet Colonel W. E. Merrill, division of |