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REPORT

OF

THE CHIEF OF ENGINEERS

OFFICE OF THE CHIEF OF ENGINEERS,

Washington, D. C., October 25, 1869. GENERAL: I have the honor to present for the information of the General of the Army, in ccordance with the instructions of the Secretary of War of the 23d instant, the following report of the duties devolving upon the Corps of Engineers for the fiscal year ending June 30, 1869 :

OFFICERS OF THE CORPS OF ENGINEERS.

The number of officers in the Corps of Engineers at the end of the year was one hundred and eleven on the active list, and six on the retired. In addition, the corps was aided by officers detailed from other arms of the service, and a number of civil engineers, geologists, &c., &c.

Since the last report the corps has lost by death an able and distinguished officer, Major M. D. McAlester, brevet brigadier general United States Army. There has been one resignation during the year, and one officer has been retired.

On June 30, 1869, the officers were distributed as follows: On duty in the office of the Chief of Engineers, including the Chief 6 On duty with boards of engineers for fortifications.

7 On duty with battalion of engineers... On duty, construction of fortifications . On duty, construction of river and harbor improvements On duty, construction of fortifications, and river and harbor improvements.

21 On duty in charge of public buildings, grounds, &c

1 On duty, survey of the lakes.

6 On special duty ..

1 On leave of absence till date of resignation.

1 Awaiting orders

1 Detached on duty with generals commanding divisions, departments, &c.

22 Retired, off duty..

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Total...

117

The officers detached were on duty as follows:
Brigadier General Richard Delafield, brevet major general United

States Army, and Colonel Hartman Bache, brevet brigadier gen-
eral United States Army, members of Light-house Board.
Major C. B. Comstock, brevet brigadier general United States Army,

aide-de-camp to the General of the Army

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Major O. M. Poe, brevet brigadier general United States Army,

engineer, secretary to Light-house Board Major Henry M. Robert, on staff of major general commanding mil

itary division of the Pacific .... Major Wm. E. Merrill, brevet colonel United States Army, on staff

of the lieutenant general commanding 'military division of the

Missouri
Major 0. E. Babcock, brevet brigadier general United States

Army, on duty with the President of the United States
Captain G. L. Gillespie, brevet lieutenant colonel United States

Army, engineer tenth light-house district.
Captain George Burroughs, brevet major United States Army,

engineer sixth light-house district
Captain Wm. J. Twining, brevet major United States Army, on

staff of commanding general department of Dacotah Captain G. J. Lydecker, brevet captain United States Army, engi

neer eighth light-house district, west of Pearl River. Captain Charles B. Phillips, brevet captain United States Army,

on staff of commanding general department of Missouri. Captain Chas. W. Raymond, on temporary duty at headquarters

military division of the Pacific Captain Lewis C. Overman, on staff of commanding general fifth

military district.... First Lieutenant George M. Wheeler, on staff of commanding gen

eral department of California
Captain P.S. Michie, brevet lieutenant colonel United States Army,

Captain W. H. H. Benyaurd, brevet major United States Army,
First Lieutenant M. R. Brown, First Lieutenant James C. Post,
First Lieutenant Henry M. Adams, First Lieutenant James Mer-
cur, and First Lieutenant Charles E. L. B. Davis, on duty at
Military Academy...

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22

The following officers of the army were on duty during the year under my orders, namely: Brevet Major General J. H. Wilson, lieutenant colonel United States Army; Second Lieutenant E. T. Hoffman, United States Army.

The following principal civil engineers and geologists were employed during the year: W. MilnorRoberts, Clarence King, H.C. Long, and D. C. Jenné, while besides these were many others employed as assistants on the works of survey and improvement.

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SEA COAST AND LAKE FRONTIER DEFENSES.

During the past year very moderate progress has been made, and only upon those portions of the defensive works 110 questions concerning which are involved in the solution of the problems that are the subject of experiment. Progress was thus restricted, because of the smallness of the appropriations for fortifications. Much larger sums have been .asked for by me, and could be used with advantage as well as economy.

Investigations relating to the use of metals for defensive purposes have been continued, and with results which have at least shown in what cases we cannot yet enter upon the use of materials, the preparation of which in this country has not att: the perfection which our pur

poses require, and suggest the question whether the results reached in other countries have proved satisfactory. But little information is made public in Europe upon the subject. It cannot be ascertained whether the use of iron or its compounds has been definitely adopted as a constituent of those parts of defensive works that are exposed to the fire of heavy artillery, while thus far it appears that in its application to ships this metal does not afford the desired resistance to heavy shot.

In these investigations varieties of iron from different parts of the country have been procured and tested, and experiments have been made with lead concrete in combination with iron, and with several other forms of compound targets. These experiments were made with a gun of small caliber, and in connection with a testing machine and other apparatus; some of the tests applied being such as to develop information relative to the use of the materials for purposes of civil as well as military engineering. A detailed report of these experiments has been nearly completed, which should be printed and distributed to the corps.

The importance of securing additional cover for barbette guns in earthen batteries, a point also presented in last year's report, has received due attention. Drawings and descriptions of numerous inventions for this purpose have been collected and distributed to the corps, and sev. eral new devices have been originated by officers of engineers. One of these latter, a modification of the present barbette carriage and platform, mounting a fifteen-inch gun, has been tested experimentally with maximum charges of 100 pounds of powder, and solid shot weighing 432 pounds. The results are believed to justify the opinion that this method of mounting guns is not only practicable so far as to secure the necessary cover, but that our heavy guns may be worked in this manner with a reasonable number of men, and without the aid of steam power or other auxiliaries of questionable utility.

The magnitude of this experiment compares with that of Captain Moncrieff, the only similar one of which we have information, as follows: Weight of gun.

50, 000 pounds. Weight of shot used in the experiments, (old pattern). 432 pounds. Weight of charge.

100 pounds. Caliber of gun.

15-inch. Descent of gun during recoil...

5 feet. Weight of gun, (Captain Moncrieff?s)

15, 000 pounds. Weight of shot... do..

115 pounds. Weight of charge.. ..do..

22 pounds. Caliber of gun. ..do.

7-inch. Descent of gun during recoil.do.

3 feet. The experimental structures at Old Point Comfort and Fort Delaware mentioned in last year's report, have been completed and subjected to the necessary firings. Several important results have been developed by these trials. It may be anticipated that with further research and deliberation the use of iron will be found practicable in shielding casemate guns in our existing masonry casemates, in cases where such protection is considered necessary. The present difficulties are its excessive cost, and the insufficiently developed condition of the processes of metal working in this country. Before applying iron or its compounds as a sole: material for gun covers in new works, its cost must be reduced and the means of supplying it must be increased.

For these reasons it appears to be inexpedient at present to press the question of the special employment of iron in our defensive works to a solution which would probably be premature. While investigation

as to such employment goes on, it is proposed to strengthen our defenses by the use of approved materials, and by the introduction into them of elements and accessories, the value of some of which has been developed by the events of our late civil war, while the changes in naval construction have given a prominence to others heretofore recognized as serviceable, but which have not as yet been systematically applied.

Such accessories and meliorations of our works, with comparatively few casemate covered guns, will as fully assure as heretofore the security of our great seaboard cities, naval establishments, and harbors of refuge and rendezvous.

As the early completion of these proposed modifications of our defenses involves only moderate expenditures, it is earnestly recommended that Congress provide for this by making the requisite appropriations.

To exhibit the subject somewhat more in detail, it is to be said the board of engineers for fortifications, to which was committed the duty of preparing the experimental structures referred to, and of making the necessary trials of them, presented the following conclusions in their report upon the subject, recommending:

First. The preparation at appropriate positions of powerful barbette batteries for the largest calibers of guns, carefully protected by traverses and parados, and liberally furnished with magazines and bomb-proofs.

Second. The substitution of a depressing gan-carriage for the model now in use. This substitution will provide for the descent of the gun upon discharge entirely below the level of its earthen covers, so that the piece and its gunners will be thoroughly sheltered from an enemy's fire.

Third. The free introduction of large mortars in the defensive arrangements. These will act effectively upon the thin decks of vessels whose sides are heavily armored; and they admit of being placed upon ground not suitable for gun batteries, are easily isolated and covered, and of moderate cost.

Fourth. The employment of torpedoes as an accessory, using the engineer battalion for experimentally developing the system and for applying it to actual defense. Torpedoes are of litttle cost, can be easily preserved, and readily placed in position. Their value has been weil shown in the Crimean war, in the Baltic, and in our southern waters during our late war.

Fifth. The use of obstructions and floating batteries, as heretofore recommended in previous projects for the defense of our coast.

The views of the board are in accordance with my own convictions, and have been approved by the General of the Army and by the Secretary of War, upon being laid before them by me, with favorable recommendation.

Specific projects for the defense of our principal ports and harbors are now in process of preparation, in conformity with these approved determinations, and it is for the execution of these, so far as presented, as well as for the furtherance of work already in progress which conforms to these views, and for necessary repairs and preservation of sites, that the estimates of the year have been made. It is hoped they will receive the approval of Congress.

The board of engineers for fortifications has already submitted the projects, in great part, for modifying the defenses of New York, Philadelphia, and Boston, and a brief statement in relation to them will be found under the heading of each work or position, together with the estimates of cost.

At other points similar meliorations, in a greater or less degree, have been considered in preparing the estimates for the next fiscal year.

FORTIFICATIONS.

Fort Wayne, Detroit, Michigan, in charge of Colonel T. J. Cram, brevet major general United States Army.-Operations at this work have been carried on through the year, resulting as follows: The widening of the ditch has been completed, and its bottom covered with soil and seeded. The embanking, soil-covering, and sodding of the counterscarp have been completed except at the demilune. The glacis has been completed on the northwest or land front, and the east face of the north bastion, and the counterscarp raised to the same height as for the rest of the counterscarp of the main work. At the foot of the glacis an open ditch for drainage has been constructed and sodded. The gap left in the scarp of the main work for communication has been appropriately filled. Nothing has been done on the lateral exterior batteries except embanking in their parapets five hundred and fifty cubic yards of earth from the ditch, and the making of the arch centers and doors of the magazines. A substantial fence to inclose the glacis has been commenced. The old cellar excavations have been completely filled, leaving the parade ground in good condition. The operations contemplated for the present year are: To complete the fence and drain around the foot of the glacis; to complete the thickening of the embankment in front of counterscarp crest; to cover the arch of the demilune magazine with mastic and earth; to complete soiling and seeding the glacis, and to remove the present road leading from the engineer dock out, so as to be exterior to the lateral battery.

No appropriation asked for the next fiscal year.

Fort Niagara, mouth of Niagara River, New York, in charge of Lieutenant Colonel C. E. Blunt, brevet colonel United States Army, Major M. D. McAlester, brevet brigadier general United States Army, and Major Nicholas Bowen, brevet colonel United States Army.During the past year the force on this work has been employed as follows: The sallyport arch and entrance, with parapet above it, have been completed; casemate arches concreted, covered with mastic and finished; entrance to flank casemate completed; rampart and parapet of the flanks have been extended forward to the scarp wall; brick masonry of the flanking gallery finished except the coping; the walls of the small postern communicating with the gallery have been built and the arch turned; all dry stone filling behind walls finished, and the old scarp timbers entirely removed. During the year ending June 30, 1870, it is intended to continue and complete the land front, and repair United States buildings, wharf and crib jetties.

No appropriation asked for the next fiscal year.

Fort Ontario, Oswego, New York, in charge of Lieutenant Colonel C. E. Blunt, brevet colonel United States Army, Major M. D. McAlester, brevet brigadier general United States Army, and Major Nicholas Bowen, brevet colonel United States Army.-During the past year the force on this work has been engaged on the scarp wall; forming and sodding parapet of front No. 4; completing the masonry and joiners' work of the two guard. houses, and making them ready for occupancy. During the year ending June 30, 1870, it is proposed to continue the raising of the scarpwall on all fronts to the required references; commence masonry of loophole galleries of bastions D and E, and quarry and dress stone for same; continue the formation of parapets and slopes; grade and drain the ditch; make and hang gates for sallyports, &c.

No appropriation asked for the next fiscal year.
Fort Montgomery, outlet of Lake Champlain, New York, in charge of

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