Lieut. Col. R. S. Williamson, engineer twelfth light-house district Maj. F. Harwood, engineer fifth and sixth light-house districts. Maj. G. L. Gillespie, on staff of Lieutenant-General commanding military division of the Missouri Capt. Asa H. Holgate, on staff of commanding general Department of Texas.. First Lieut. J. G. D. Knight, on staff of major-general commanding Military Division of the Pacific... 1 1 1 1 First Lieut. R. L. Hoxie, chief engineer of the District of Columbia, under the direction of the board of commissioners. 1 Capts. William J. Twining, J. F. Gregory, and First Lieut. F. V. Greene, on duty under Department of State, upon joint commission for the survey of the boundary line along the forty-ninth parallel.. 3 Capt. C. W. Raymond, First Lients. E. W. Bass, and S. E. Tillman, on duty under the superintendent of the United States Naval Observatory in connection with observation of the transit of Venus 3 Capts. A. M. Miller, T. H. Handbury, First Lieut. J. C. Mallery, and Second Lieut. C. F. Palfrey, on duty at the Military Academy.. 4 Total.. 24 The following principal civil engineers and geologists were employed on the 30th of June: General J. H. Wilson, member of board of engineers upon improvement of the Des Moines and Rock Island Rapids, and improvement of the Illinois River; Clarence King, geologist, in charge of geological exploration of the fortieth parallel; and S. Thayer Abert, in charge of river and harbor improvements on Potomac River and Chesapeake Bay. SEA-COAST AND LAKE-FRONTIER DEFENSES. The progress during the past year, of the works for the defense of our harbors from naval attacks, has been satisfactory, and some of the works for the protection of the harbors of our principal cities, are approaching completion. As has been mentioned in my previous annual reports, the class of works now in progress are mainly earthen barbette and mortar batteries, having great thickness and height of parapets, and thorough protection from enfilade and reverse fires, by massive traverses and parados. The barbette-batteries for guns are being arranged for the new ordnancecarriage of increased height, but will also be available for the depressing-carriage when that shall have been provided. Every step taken in the location, construction, or modification of our sea-coast defenses is in accordance with the general conclusions and principles agreed upon by the board of engineers in 1869, which received the approval of the Chief of Engineers, the General of the Army, and the Executive, and which have repeatedly commended themselves to the intelligence of Congress. In comparison with the large number of harbors and anchorages along our coasts, but a limited number are being fortified, and appropriations are asked only for those having sufficient depth of water to admit the entrance of the enemy in iron-clad vessels carrying the powerful rifled modern armaments, and where interests covering millions of dollars would be sacrificed by a successful invasion. But a small number of our works are what could be called new; that is, planned entirely in accordance with the requirements for resisting the modern heavy ordnance. Nearly all have been handed down from former periods, when small guns and wooden ships only were to be contended with, and the present operations at these works consist in enlarging and strengthening the earthen portions to resist the heavy rifled shot. The eathern parts of modern fortifications have assumed such extensive proportions that they are no longer capable of being thrown up and constructed in short and limited periods, while the guns and armaments are of so great dimensions, and so massive, that special machinery, skilled labor, and considerable time are required to place them in position. Unlike the armaments used in them, no two sea coast works are of the same model, plan, or tracé. Every work is a special one, which must be adapted to the peculiarities of the site, of the harbor, the channel-ways, and of the interests involved in the defense. The preparation of the plan for each site requires careful surveys, investigation, and study; and the time required for construction renders it now imperative that our sea-coast works should be planned and built before the sudden and decisive wars of modern times are either imminent, or actually in progress. The appropriations for mortar-batteries have been judiciously distributed for the erection of these valuable auxiliaries against iron-clads in five of our principal harbors, and a further appropriation is asked for their continuance. The trials with torpedoes, which have been in progress at Willet's Point for some years past, have developed a practical and efficient system for the location and operation of this most valuable obstruction to the entrances of our harbors, giving us a means whereby we can hold the enemy's vessels under the fire of our guns, and prevent their running past our batteries. The system is described more in detail in the body of this report, and consists, as all systems for the defense of harbors should, of stationary torpedoes, both ground and buoyant, exploded either by the medium of the contact of the vessel or by the judgment of the operator. Moving torpedoes, alone, will not answer the purpose of barring the entrances to harbors. To operate this class of torpedo they must either be seen, or the enemy must be in view, and so, just in those periods of fogs or darkness when a daring commander would seek to penetrate a harbor, this class of torpedo would be of no avail against him. To continue the purchase and storing of such portions of our torpedo apparatus as could not, in event of war, be speedily obtained, the sum of $150,000 is asked. No plans of iron shields for casemated defenses have as yet been perfected. In several of our important harbors this class of works will be needed, but the cost of such structures renders it important that they should be designed only for the most powerful rifled ordnance practicable. And until this class of guns, with their carriages, shall have been determined upon by the proper Department, the plans must be delayed. The progress made and anticipated upon the several works on the coasts is given in detail in the following portions of the report. The estimates submitted, based upon the estimates of the several officers in charge, which have been carefully revised, present those amounts which, in the judgment of this Department, are necessary for the completion, continuance, or commencement of projects for the coming fiscal year. FORTIFICATIONS. Fort Wayne, Michigan, in charge of Maj. F. Harwood, Corps of Engineers. This work was in good condition at the close of the fiscal year. No operations were in progress during the year, and none beyond minor repairs are contemplated during the present year. The perishable equipment and material on hand were sold at public auction, and the watchman discharged. No preparations have been made or are intended for any change in the armament of the work. No appropriation was made for the fiscal year ending June 30, 1875. Fort Porter, Black Rock, near Buffalo, New York, in charge of Maj. F. Harwood, Corps of Engineers.-This work remains as last reported, excepting additional adornment of the grounds by the city of Buffalo, under act of Congress approved July 11, 1870. Nothing has been done upon the fort during the past year, and nothing is proposed for the present fiscal year. No appropriation was made for the fiscal year ending June 30, 1875. Fort Niagara, mouth of Niagara River, New York, in charge of Maj. John M. Wilson, Corps of Engineers.-This work is situated at the mouth of the Niagara River, commanding its debouch into Lake Ontario. During the past fiscal year the operations in progress have been confined to those necessary for the proper care and preservation of the work and materials on hand. During the present fiscal year it is proposed to relay the brick, where necessary, in the coping of the scarp-wall, to repair the slope-wall protection of the sea-wall at the salient angle of the north bastion, and to make the temporary repairs to the old shore-protection near the northwest angle. No appropriation was made for the fiscal year ending June 30, 1875. Fort Ontario, mouth of Oswego River, New York, in charge of Maj. John M. Wilson, Corps of Engineers.-This work protects the city of Oswego from a sudden attack or coup de main, or the levy of a contribution by a small force of an enemy on shipboard. The work in progress upon the fort is the replacing of the old timber-scarp by more durable materials and the modification of the barbette for the heavy modern orduance. During the past year the operations in progress have been confined to those necessary for the proper care and preservation of the work and materials on hand. No operations are proposed for the present fiscal year other than are necessary for the preservation of the work. No appropriation was made for the fiscal year ending June 30, 1875. Fort Montgomery, outlet of Lake Champlain, New York, in charge of Lieut. Col. John Newton, Corps of Engineers.-This work occupies an important strategic point, and commands the entrance to Lake Champlain from Richelieu, or Saint John River. No operations were carried on during the past fiscal year. Projects for the modification of this work to suit its armament to heavy guns have been prepared by the board of engineers for fortifications, and should be carried out. No appropriation was made for the fiscal year ending June 30, 1875. Fort Knox, Bucksport, Penobscot River, Maine, in charge of Lieut. Col. J. C. Duane, Corps of Engineers.-During the past fiscal year no work other than that necessary for the care of the property having been performed, the condition of this work remains the same as at the close of the fiscal year previous. No appropriation was made for the fiscal year ending June 30, 1875. Fort Popham, Kennebec River, Maine, in charge of Lieut. Col. J. C. Duane, Corps of Engineers.-During the past fiscal year no operations were carried on, except for the care and preservation of the property, so that the condition of this work remains the same as at the close of the fiscal year previous. No appropriation was made for the fiscal year ending June 30, 1875. Fort Gorges, Portland Harbor, Maine, in charge of Lieut. Col. J. C. Duane, Fort Preble, Portland Harbor, Maine, in charge of Lieut. Col. J. C. Duane, Corps of Engineers.-During the past fiscal year two permanent platforms in the redoubt, one in the north battery, and one temporary wooden platform in the south battery, were made ready for guns; the traverses and parapets, exclusive of the breast-height walls of the south battery, were completed, and the concrete-magazine, parados, bombproofs, breast-height walls, the greater part of the embankments, and the roadway of the north battery were built. Amount appropriated for the fiscal year ending June 30, 1875 $20,000 40,000 During the present fiscal year it is proposed to construct all the breast-height walls of the south battery, and complete six additional gun-platforms. Fort Scammel, Portland Harbor, Maine, in charge of Lieut. Col. J. C. Duane, Corps of Engineers.-During the past fiscal year the concrete bomb-proof covering, three-fourths of the superimposed embankments, the breast-height walls, and the long concrete communications of the east and west bastions were completed. In the upper level of the main work nearly all the slopes of traverses and parados upon fronts I, IV, and VI were sodded, and all but one of the remaining positions made ready for gun-platforms. Amount appropriated for the fiscal year ending June 30, 1875... $30,000 50,000 During the present fiscal year it is expected to complete all but the barbette gun-platforms of the east and west bastions, together with the works in their rear, and to construct breast height walls and platforms for three guns in the main work. Battery on Portland Head, Portland Harbor, Maine, in charge of Lieu'. Col. J. C. Duane, Corps of Engineers.-This is a new work, upon the me. C commanding site at the entrance to the main ship-channel to the harbor, three miles below the city. Operations were commenced early in the past fiscal year. The parapet embankment for seventeen guns was mainly filled in, and four of the concrete traverse-magazines, with a greater part of their embankment, were built. No appropriation was made for the fiscal year ending June 30, 1875. $50,000 During the present fiscal year it is expected to complete two breastheight walls and gun-platforms. Fort McClary, Portsmouth Harbor, New Hampshire, in charge of Lieut. Col. J. C. Duane, Corps of Engineers.-During the past fiscal year three temporary wooden platforms for heavy guns, with a sufficient parapet, on the site of the old circular battery, were nearly completed. Otherwise the condition of the work remains the same as at the date of the last annual report. No appropriation was made for the fiscal year ending June 30, 1875. Fort Constitution, Portsmouth Harbor, New Hampshire, in charge of Lieut. Col. J. C. Duane, Corps of Engineers.-During the past fiscal year a temporary position was prepared for one heavy gun in the southwest angle of the old fort, and the platform partially laid. No appropriation was made for the fiscal year ending June 30, 1875. Battery on Gerrish's Island, Portsmouth Harbor, New Hampshire, in charge of Lieut. Col. J. C. Duane, Corps of Engineers.-During the past fiscal year the parapet was raised nearly to its full height, and rock excavations for a part of the roadway in rear of the terrepleins and for two of the six traverse-magazines were completed. Amount appropriated for the fiscal year ending June 30, 1875 Appropriation asked for next fiscal year $15,000 35, 000 During the present fiscal year it is proposed to prepare the foundations for all the traverse-magazines and to build three of them. Battery on Jerry's Point, Portsmouth Harbor, New Hampshire, in charge of Lieut. Col. J. C. Duane, Corps of Engineers.-During the past fiscal year two-thirds of the parapet embankment has been raised to its full height, and the earth and rock excavations for the foundations of all the traverse-magazines completed. Amount appropriated for the fiscal year ending June 30, 1875. $15,000 35, 000 During the present fiscal year it is expected to complete the concrete work of all the magazines and breast-height walls, and make ready all the positions for gun-platforms. Fort Warren, Boston Harbor, Massachusetts, in charge of Col. Henry W. Benham, Corps of Engineers.-During the past fiscal year operations in bastion A consisted in the completion of the five new 15-inch gunplatforms and their breast-height walls, the completion of the masonry of the two traverse magazines with the connecting-parados arch, and the necessary doorways, staircases, &c.; about one-half of the earthcover has been put in place, and the new sand-parapet essentially completed from the salient of bastion A to include three-quarters of the curtain front I. In bastion B, two of the four new 15-inch gun-platforms have been completed, and a third finished except the setting of the pintle and the traverse rails. In the parade of this bastion the foundations of the new arch-piers have been completed. In bastion E, the parados arch has been built, connecting the two traverse-magazines, with entrances, drains, &c., and from each extremity an arched covered stairway has been constructed leading to the flank casemates. An inclined way, (with stationary engine,) from the wharf to the terreplein of this bastion, has been built, to aid in the moving of material. In the demilune, of the five new gun-platforms, one is ready for its armament and two others are ready except iron-work. The breast-height wall for the |