Lieut. Col. C. S. Stewart, Corps of Engineers, was charged with an examination and survey for a sea-wall or breakwater at Trinidad Harbor, California, in compliance with act of June 10, 1872, and of an examination of Estero Bay, near Santa Barbara, Cal., provided for in the act of March 3, 1873. These examinations have been made. For Lieutenant-Colonel Stewart's report thereon, see Appendixes Z 5 and Z 6. IMPROVEMENT AND CARE OF THE PUBLIC BUILDINGS AND GROUNDS IN THE DISTRICT OF COLUMBIA-WASHINGTON AQUEDUCT. Officer in charge, Col. O. E. Babcock, Corps of Engineers. 1. Public Buildings and Grounds.-The condition of the public reservations in this city, and the detailed statement of the improvements made on them during the past fiscal year, will be found in the report of the. officer in charge. A number of the reservations that were vacant and unimproved, some of which were mere waste places, and used as dumping grounds for refuse material, have been converted into attractive places of public resort, and compare favorably with the extensive improvements made by the city. The improvement of a number of reservations has been commenced. The estimates for this work submitted for the next fiscal year will complete several of them. The officer in charge recommends the construction of a roadway 35 feet wide in the Monumental grounds, Armory Square, and through the reservations from Sixth to Third streets, which will connect the roadway in the Smithsonian and Agricultural grounds, and form a continuous road nearly two miles in length, from the Botanical Gardens, at Third street, to the Executive Mansion and Pennsylvania avenue, thus carrying out the proposed plan of connecting those points by a drive through this line of parks. He also recommends an appropriation for the construction of a substantial bridge, with stone abutments and iron superstructure, across the eastern branch of the Potomac, at or in the vicinity of the present wooden bridge known as the "Navy-Yard Bridge." The present bridge is very old, needs constant repairs, and should be almost entirely rebuilt if the construction of a new one is not authorized. The labor expended in the improvements detailed in his report is 37,595 days' labor, exclusive of 403 months of regular monthly labor, and 9,549 days of horses and carts. His estimates for the fiscal year ending June 30, 1875, are: $405, 550 For improvement and care of public buildings and grounds.. For the construction of bridge across the eastern branch of the Potomac, near the navy-yard, with stone abutments and iron superstructure..... 367, 536 55, 956 Making a total of... (See Appendix AA.) 829, 042 2. Washington Aqueduct.-The stone dam at Great Falls is in good order. The temporary dams at the head of Conn's Island have been so much damaged by freshets as to be useless for aqueduct purposes. The officer in charge recommends that the stone dam be constructed entirely across the river to the Virginia shore, so as to afford at all times a supply equal to the full capacity of the conduit. He also recommends that the Government land at Great Falls be fenced with a substantial wooden fence, and a comfortable brick dwelling and office be built for the gatekeeper, and that the wooden roof of the gate-house at this place be replaced with a slate roof, supported by a wrought iron frame. Stone bridges.-The plan adopted for completing these bridges consists of coping and parapets of solid cut-stone masonry. Cabin John Bridge is finished, and the other bridges are under contract and rapidly approaching completion. The officer in charge recommends that the roadways over Cabin John Bridge and Griffith Park Bridge be paved with asphalt pavement in order to protect the masonry from the surface drainage. The tunnels on the line of the aqueduct are all in good condition. The roadway over the aqueduct is being macadamized. It is recommended by the officer in charge that the entire line from the distributing reservoir to Great Falls be macadamized. Receiving reservoir.-It is recommended by the officer in charge that a substantial wooden fence be built entirely around this reservoir. Distributing reservoir.—The several works at this reservoir are finished, with the exception of the wooden fence, which is under contract and will be finished during the present year. It is recommended that the outer slopes of the dams be soiled and seeded; also, that the conduitembankments be soiled and seeded so as to prevent damage from the rains. The poles and wires for a dial-telegraph have been erected from Great Falls to Georgetown. It is recommended that magneto-dial instruments be purchased and the line be placed in working order. Estimates of the amounts required for the next fiscal year. For engineering, maintenance, and general repairs. $15,000 00 3,000 00 200,000 00 For building a wooden fence around Government land at Great Falls.. 1,500 00 For furnishing and setting four magneto-dial instruments in connection with the telegraph-line from Great Falls to Georgetown. For paving the roadway over Griffith's Park Bridge and over Cabin John 3,000 00 5,780 00 1,100 00 For soiling and seeding the slopes of the conduit-embankments from Great 27,050 00 Appropriated for the fiscal year ending July 1, 1873.. 70,555 00 57,583 57 12, 971 43 Expenses during the year.. Remaining on hand July 1, 1873. (See Appendix AA.) 3. Chain Bridge on the Potomac River.-Advertisements were published soliciting plans and bids for the construction of an iron bridge across the Potomac at Little Falls. After a careful examination of eighteen plans submitted, that of S. R. Dickson, of New Haven, Conn., was selected and a contract entered into with him for its construction. At the date of this report no work had been done by the contractor. (See Appendix AA.) SURVEY OF NORTHERN AND NORTHWESTERN LAKES. Officer in charge, Maj. C. B. Comstock, Corps of Engineers, who has under his immediate orders the following officers of the Corps of Engineers: Captains W. R. Livermore and A. N. Lee, and First Lieutenants D. W. Lockwood, E. Maguire, and C. F. Powell, and the following civil assistants, J. R. Mayer, O. B. Wheeler, A. C. Lamson, E. S. Wheeler, G. Y. Wisner, A. R. Flint, G. A. Marr, L. Foote, H. Custer, and F. M. Towar. Progress of the work during the fiscal year.-The field-work of the connection of the triangulations in Lakes Superior and Michigan has been about half finished. In Lake Michigan the off-shore hydrography has been carried from Grand Haven to Grand Calumet, and from Milwaukee to Racine, in all about one hundred and fifty miles along the coast. The topography has been completed from New Buffalo to Evanston, and from Milwaukee to Waukegan, leaving only about thirty miles to complete the lake. The lines of azimuth and latitude up the two shores of the lake have been continued. The triangulation has been completed on the west shore from Green Bay to Kenosha. A base line has been measured near Fond du Lac. A survey of the Detroit River has been begun and is nearly half completed. On the Saint Lawrence the hydrography and topography have been made continuous and carried to the head of Wells Island. The development of shore line surveyed during the year is about four hundred and forty miles. In the office the final latitudes of nine stations have been deduced; the triangulation between Keweenaw and Minnesota Point bases has been adjusted by least squares; the Fond du Lac base has been reduced; last season's field-work of both topography and hydrography has been plotted. Final chart No. 3 of Lake Superior has been completed, chart of Lake Saint Clair, and chart No. 1 of the Saint Lawrence, are well under way, and a chart of Sandusky Harbor has been begun. It is proposed during the present fiscal year to complete the topography and hydrography of Lake Michigan, and nearly complete its triangulation; to complete the survey of the Saint Lawrence River, and to commence the survey of Lake Ontario; to connect the triangulation of Lakes Michigan and Erie, and of Lake Superior and Green Bay; to determine, astronomically, points in Illinois; and to make such observations and measurements in the State of Michigan, and in the borders of the States of Wisconsin and Minnesota, as will render the results of the survey of the lakes and of the surveys of those States reciprocally available, and may incidentally render such assistance to those State surveys as may properly be extended. The preparation of maps and arrangements of the observations for publication to be continued. Amount expended during fiscal year 1872-73.. $175,000 175,000 Amount required for survey of northern and northwestern lakes for fiscal year ending June 30, 1875 Continuation of survey of Lakes Michigan and Ontario; survey of Lake Erie; determination of points in Illinois and Michigan; construction of maps and miscellaneous... 230,000 Estimate of funds to be appropriated for fiscal year ending June 30, 1875. Lake Ontario. To continue triangulation, topography, hydrography, and to $90,000 50,000 Lake Michigan.-Continuation of triangulation around south end of lake; determination of points in Michigan; connection of surveys of Lakes Michigan and Erie; reduction of work and construction of maps, two triangulation and two astronomical parties.... $45,000 11,000 Extension of Lake Michigan, triangulation southward, and determination of 20,000 14,000 (See Appendix BB.) ASSISTANCE RENDERED TO THE SURVEY OF STATES. 230,000 The results of the observations of the Lake Survey and its maps have been made available to the States of Michigan, Wisconsin, and Minnesota, for the preparation of topographical and geological maps of those States. The latitude and longitude determinations made in connection with the military and geographical surveys, as well as the maps of those surveys, were also made available for the same purposes. The land-office surveys of those States, connected with the astronom ical and geodetic determinations of the lake, military, and geographical surveys, and their topographical maps, as well as those of the river and harbor improvement surveys, provide valuable material for the preparation of very creditable maps. To the extent indicated above, it has been considered this Department could properly go, defraying the expenses of the determination of points in the interior, which were of use in correcting and improving the military map of the Western Territories, from the appropriation for military surveys; and the expense of the connection of the land-office and State surveys with the triangulation of the lake survey, from the appropriation for that survey. But any considerable further extension of aid, such as the determination of one or more points in each county, which is desired by the State authorities, could not be made without the sanction of Congress. If this sanction be obtained, all the requisite assistance can be furnished without any large increase of expense to the lake survey, in consequence of the efficient organization, excellent working methods, and valuable data which it possesses, and can readily apply to any other similar and adjacent work. Such a course seems highly desirable, as aiding a praiseworthy effort to produce reliable maps of these States, and as conducing to an accuracy which it is important they should possess. As other States will probably desire similar assistance, it is respectfully suggested that provision be asked for, annually, sufficient to furnish, in the manner above indicated, such requisite geodetic work in any of the States adjacent to the great lakes or the Saint Lawrence River, as may, by appropriate legislation, provide for a geological or topographical survey of their territory. The application of the States in question, with estimates of cost of executing the necessary astronomical and trigonometrical work, will form the subject of a special communication at an early day. MAPS OF CAMPAIGNS AND BATTLE-FIELDS. The survey of the battle-fields in the Shenandoah Valley, Virginia, by Maj. G. L. Gillespie, under the direction of Lieut. Gen. Sheridan, was com menced in May last. An office was established at Winchester, Va., and two parties were organized to make a detailed topographical, survey of the field of the engagement near that city, after which the battle-fields of Cedar Creek and Fisher's Hill will be surveyed in the same manner, and accurately mapped. (See Appendix CC.) The maps of the Atlanta campaign are being recompiled in this office for publication. The map of the battle-field of Gettysburg, by Maj. G. K. Warren, is now nearly ready for publication. GEOLOGICAL EXPLORATION OF THE FORTIETH PARALLEL FROM THE SIERRA NEVADA TO THE EASTERN SLOPE OF THE ROCKY MOUNTAINS. Mr. Clarence King, United States civil engineer, in charge. The geological and topographical exploration of the belt of territory, nearly one hundred miles wide, lying along the line of the Pacific Railroad, has been completed. Special examinations were made during the year to solve important questions in glacial geology. The principal field operations ceased in November, when those assistants that were necessary to work up the results and prepare the maps for publication were removed to New York. The report of the field-work up to the close of operations is appended. (See Appendix DD 1.) The finished maps of the belt surveyed, five in number, are well advanced towards completion, three of them being now ready for the engraver. The preparation of the remaining volumes of the report, and the completion of the maps, with the publication of both, will be carried on and probably be accomplished in the present fiscal year. In connection with a geological examination of Green, Bear, and Vermillion cañons, a special examination of the so called "Diamond Fields" in the vicinity of the latter cañon was made by Mr. King in the month of November, which disclosed the existence of a great fraud in connection therewith. His interesting report of the examination and result is appended. (See Appendix DD 2.) GEOGRAPHICAL AND GEOLOGICAL SURVEYS AND EXPLORATIONS WEST OF THE 100TH MERIDIAN, IN NEVADA, UTAH, COLORADO, NEW MEXICO, AND ARIZONA. Officer in charge, First Lieut. George M. Wheeler, Corps of Engineers, having under his orders First Lieutenants R. L. Hoxie and William L. Marshall, Corps of Engineers. The commencement of the fiscal year found the various parties about taking the field from the rendezvous camp near Salt Lake City. One astronomical party occupied the Mormon observatory at Salt Lake City during the season, while series of observations for latitude and longitude were made by two other astronomical parties at Beaver and Gunnison, Utah Territory; Pioche, Nev.; and Cheyenne, Laramie, and Fort Steele, Wyoming Territory. Observations at Green River, Wyoming Territory, were commenced, but not completed. Two main topographical parties extended their season's survey from the limits of the survey of the fortieth parallel, on the north, to include portions of the Great Salt Lake, Sevier Lake, and other interior basins, and of the valley and basin of the Colorado in and around the lower of the grand cañons, embracing an area of more than 50,000 square |