and a preliminary report on project for the modification of Fort Pickens and other works of defense in Pensacola Harbor. It has likewise submitted reports on the purchase of land on northern extremity of Tybee Island, Ga.; on the establishment of batteries for defense of Tybee Roads; on the construction of additional casemates to the rear of barbette-battery at Willet's Point; for storage of torpedo-cables, &c.; on the purchase of Cow Island and portions of Great Hog Island, Casco Bay, Me.; on establishment of batteries to command the Hussey Sound entrance to Portland Harbor, Me., and to control the inner an chorage to the northeast; on the constructions of breast-height walls, recommending that the masonry steps be omitted, and on the taking down of experimental targets at Fort Monroe and utilizing the material in other works.

The board has likewise reported upon the question of a project involv ing the use of iron or its equivalent in the scarps of casemated works; upon proposed change, suggested by the Ordnance Department, in lengthening the 12-inch rifle and 15-inch smooth-bore guns; and has examined and reported upon projects for various objects, among them Major Baylor's design for an iron platform for 13-inch sea-coast mortars, Mr. Ed. Brady's project for construction of iron turrets, and Mr. Robt. C. Totten's design for an experimental target of chilled and cast iron. It has also submitted a project for the expenditure of appropriation of $125,000 for torpedoes for harbor defense.

Besides the subjects reported upon, the board has been engaged in the consideration of defenses for the entrance of Cape Fear River, N. C., defenses for Tybee Island, entrance to Savannah River, Ga., modifica tion of Fort Clinch and batteries at New Bedford and New London, which questions are still before it and for most of which plans are now in progress.

During the first three months of the year, Maj. H. L. Abbot, Corps of Engineers, the member of the board of engineers in immediate charge of the subject of the trials of torpedoes for harbor-defense, was absent in Europe on torpedo-duty, and the trials at Willet's Point were suspended. Since his return they have been actively prosecuted, and much has been accomplished in the way of preparing for the practical appli cation of the system to the defenses of our harbors.

The electrical laboratory has received suitable additions, and the building has been extended to comprise a model operating-room, in which are placed all the parts of our own system, in their proper rela tions, for easy study.

The whole material of the service has received careful study, with the following results: Satisfactory forms of buoyant and ground torpedoes, with their buoys, have been provisionally adopted. They are designed to be planted at feet intervals, and are harmless to each other at that distance with proper charges of dynamite; neither does the explosion close the circuit-closers of neighboring mines.

After much experimental study, the circuit-closer has been perfected. Its cost is trifling, and it seems to fulfill all requisite conditions. In the investigation a plan was devised which enabled all the various patterns to be accurately compared with each other, by making them print an electrical record of their action under a concussion closely assimilated to that of a vessel, but which could be repeated at will under identical circumstances.

In order to make it more convenient to vary the number of mines at

different stations, a box-form of operating-apparatus, adapted to seven cables, has been perfected. It works admirably.

The discovery made last year, that induction in neighboring cables, occasioned by electricity of high tension, could be overcome by a simple device, has been confirmed and extended to the multiple cables, and an improved form of apparatus for judgment-firing has been perfected.

Tests of cable imported two years ago, and stored in light sheds exposed to variations of temperature, have been carefully made and shown to have experienced no deterioration.

A device by which the tampering with a mine or its cable can be made to discharge a volley of guns previously pointed along the line, has been perfected. Its value in the night, or in fogs, is apparent, especially as the explosion is effected without exploding the torpedo itself.

As heretofore, much time has been devoted to fuse-testing, and after a strict comparison of those to be had abroad or in this country with our own, the result is all that can be desired. There are none better, and but few so good as our own. This investigation has included cutoffs as well as platinum and tension fuses.

After careful trials, extending over many months, a form of Le Clanche battery has been adopted for both signal and firing batteries. Other forms could be used if necessary, but it seems to combine every requisite for a good service-pattern.

The possession of an admirable collection of instruments in the laboratory, has enabled the co-efficients of the galvanometers, stored for torpedo-service, to be accurately determined, and thus the different stations will be able to refer all results to a uniform standard, an advantage of no slight importance. The tests of cables, joints, &c., have been rendered easy and accurate by the construction of a 1,000-cell sal-ammoniac battery, by the engineer troops, and a standard Clark battery by the officers.

Trials with explosives have been continued, but not so extensively as heretofore. Rendrock is the only new one added to the list, and it has shown itself inferior to dynamite. An old barge, worn out in service, was blown up last autumn, but it was too rotten to afford data of value. Considering that the subject of torpedo-defenses has been sufficiently discussed to justify detailed plans for applying these new engines to the closing of our more important harbors, the board of engineers has taken up that subject for careful study. Projects for adapting the forts in the harbors of New York and Philadelphia to receive the cables, electrical apparatus, &c., have been already submitted, with diagrams of the proposed lines of torpedoes, and detailed drawings of the latter are in progress. Other harbors will be considered in turn.

Another very important investigation has been that reported upon on the manner of leading cables from the forts to deep water, accompanied by model-plans, &c.

The board expresses the opinion that our torpedo-system is satisfactory, and that moderate stores for applying it should be collected at the depot at Willet's Point. These stores should be increased for the present by large annual appropriations, as it is certain that no money devoted to fortifications is more directly applied to preparing for sudden defense. In this connection it must be understood that trained soldiers are absolutely necessary in using the mines, and that the number of enlisted men of engineers now authorized is entirely insufficient. At least three times as many will be needed for protecting even a few of our more important harbors.

The experimental target for determining the action of torpedoes on

the double bottoms of iron-clads is completed, and in readiness for the tests to which it will soon be subjected.

An appropriation of $150,000 is respectfully recommended for the next fiscal year, to be expended in the purchase of such parts of the torpedo-apparatus and material as cannot be suddenly obtained in case of need.

The board of engineers for the Pacific coast, consisting of Lieut. Col. B. S. Alexander, Lieut. Col. C. S. Stewart, and Maj. Geo. H. Mendell, has been engaged during the past fiscal year in completing the project for field-works for the protection of the rear of the permanent sea-coast defenses at Fort Point, in maturing details for the permanent defensive works at Fort Point, at Lime Point, and at Alcatraz Island, and in the examination of San Diego Harbor, for the purpose of ascertaining the amount of sediment brought into this harbor by floods in the San Diego River.

The board has also reported on the question of water-supply and roads in case a marine hospital be erected on the shores of Mountain Lake; on the necessity of San Clemente Island for purposes of defense; and on the application of the Light-House Board to place a fog-signal on Yerba Buena Island.

In addition to the regular duties of the board of engineers for the Pacific coast, the members of the board have given a great part of their time during the year to the study of other subjects; to making an examination of the Sacramento, San Joaquin, and Tulare Valleys, in California, and making a report on the irrigation of these valleys; and to making an examination and report on the improvement of the harbor of Oakland, San Francisco Bay.

BATTALION OF ENGINEERS AND ENGINEER DEPOTS.

Battalion of Engineers, commanded by Maj. Henry L. Abbott, Corps of Engineers, headquarters Willet's Point, eastern entrance to New York Harbor.

The strength of the five companies of sappers, miners, and pontoniers, constituting the Battalion of Engineers, on the 30th of June, 1874, was 10 officers and 318 enlisted men, 36 recruits being needed to complete the organization, as determined by General Orders No. 122, series of 1870, from the War Department.

The companies of the battalion were stationed and commanded as follows: At Willet's Point, Company A, Second Lieut. William T. Rossell; Company B, Capt. W. R. King; Company C, Capt. William R. Livermore; Company D, (a skeleton organization,) under command of the battalion adjutant, First Lieut. James Mercur.

At West Point, Company E, Capt. O. H. Ernst, also instructor of practical engineering and ex-officio member of the academic board.

During the year, and for limited periods, detachments from the battalion served as follows: One sergeant and 5 first-class privates at Jefferson Barracks, Mo., guarding and caring for the engineer property there. This detachment left Jefferson Barracks and returned to the battalion July 15, 1873. At headquarters Department of Missouri, 2 sergeants and 5 first-class privates; at headquarters Department of Dakota, 2 sergeants and 5 first-class privates; on field-duty under First Lieut. George M. Wheeler, in Utah, Colorado, and Wyoming Territories, 1 first-class and 5 second-class privates.

Recruiting for the battalion has been carried on during the past year on the same system as during the preceding; but one rendezvous, how

ever, that in New York City, having been kept open. During the year 96 men were enlisted, 9 re-enlisted, 47 deserters were apprehended, and 57 men deserted.

The duties of the battalion generally have been confined to guarding, receiving, and issuing the engineer property at the depots; in furnishing instruction to cadets of the Military Academy, under the instructor of practical engineering; in pontoniering, signaling, telegraphing, and practical engineering generally; the detachments serving at the several headquarters in the field assisting the engineer-officers in the duties assigned them.

At Willet's Point the troops have been employed in the construction and repair of the buildings and grading the grounds, and in the vari ous drills and instructions necessary to keep them in a proper state of efficiency and ready for active service. Good progress has been made in field-fortification, pontoniering, military reconnoissance, photography, and infantry tactics, while, in addition to the usual target practice furnished by regulations, the men have been encouraged to compete at the neighboring range. Theoretical instruction of the non-commissioned officers was had during the suspension of the drills in the winter, and the school of enlisted men, directed by General Orders No. 56, AdjutantGeneral's Office, 1866, was open to voluntary attendance, under the personal supervision of the commissioned officers.

The instruction of the officers has been extended, so as to include as far as practicable preparation for and familiarity with duties upon which they are liable to be ordered. By the authority of the Secretary of War each officer was, during the winter, required to visit and report upon some specified public work, selected with a view to obtaining information useful for the engineer service. These reports are of a creditable character, and will be used by the officers when examined for promotion.

The work of the torpedo-school has been actively prosecuted, and the results obtained are of a satisfactory character. The investigations necessary to discover the laws which govern the action of subaqueous explosions, the perfecting of the electrical apparatus, and the trials designed to determine the practical details of the mines, cables, fuses, &c., have all received careful attention. A system, believed to be superior to any in use abroad, has thus been perfected. To render it available in harbor defense, a body of trained officers and men is essential, and the instruction of the Battalion of Engineers has been specially directed to this end. The preparation of a torpedo manual has been commenced, and it is tested page by page by practical use as it proceeds.

In torpedo-materials we have collected about six hundred miles of cable, some three hundred mines, and electrical apparatus sufficient to equip some twenty stations; in fine, great progress has been made during the past year in reducing the theoretical system to a practical form for actual use. To make use of our materials, however, a trained body of men must be at hand and ready upon any emergency for the several torpedo-stations, but to this end the strength of the Engineer Battalion should be increased.

I would respectfully recommend an appropriation of $1,000 for the purchase of engineer-material to continue the present system of instruction of the battalion, and $10,000 for continuing the trials with torpedoes, and for the instruction of the engineer troops in their application to harbor and land defenses.

I would also renew my recommendation of former years, that the organization of the battalion be completed by the addition of two principal musicians, allowed by law to troops of other arms.

Engineer post and depot at Willet's Point, New York Harbor, commanded by Maj. Henry L. Abbot, Corps of Engineers.

The engineer-depot at Willet's Point contains the ponton-trains, siege and mining tools, torpedo-materials, astronomical and surveying instru ments, &c., pertaining to the engineer-service of the Army. It is gar risoned by a portion of the Engineer Battalion, which furnishes the needful guard, and issues the stores to officers of the corps upon requisition duly approved.

The public buildings are essentially completed, so that only a small appropriation of $500 for repairs is needed.

For continuing the remodeling of the ponton-material to make it conform with the patterns adopted at the close of the late civil war an appropriation of $1,000 is needed. Most of the labor will be supplied by the troops. Experience has shown that it is necessary, in order to avoid loss of time in fitting surveying parties for the field, to have at the depot a small supply of the instruments in common demand. For this purpose, and for repairing those returned in an injured condition, an appropriation of $5,000 is asked.

For incidental expenses of the depot, such as coal, forage, stationery, chemicals for use in the laboratory, extra-duty pay for soldiers employed in mechanical work, in photographic and lithographic plans, and in printing engineering blanks, torpedo-instructors, &c., $2,500.

RIVER AND HARBOR IMPROVEMENT.

The "act making appropriations for the repair, preservation, and completion of certain public works on rivers and harbors,” approved March 3, 1873, furnished the means for continuing, during the past year, operations at the several localities named therein, in accordance with approved projects. A brief account of the work done at each locality, and the present condition of the improvement, together with a moneystatement, is given below; but for more detailed information a reference to the reports of the officers having charge and immediate supervision of the operations is respectfully suggested.

The annual estimates of the officers in charge of the separate works have been carefully revised in this office, and in many cases reduced. The surveys and examinations directed to be made by the second section of the act, with but few exceptions, have been completed, and the results of those received in time were reported during the last session of Congress. These, together with such as have been completed since the adjournment, are submitted herewith in the appendix to this report. The provisions of the third section of the act, requiring the organi zation of a board of engineer officers" whose duty it shall be to inquire into and report upon the practicability of bridging, consistently with the interests of navigation, the channel between Lake Huron and Lake Erie," &c., have been complied with, and the report of the board was submitted to the Department and transmitted by you to Congress on the 224 January. A copy of the report is appended hereto.

The river and harbor act approved June 23, 1874, in addition to mak ing appropriations for continuing improvements heretofore begun, made provision for some new works. With the amounts thus made available operations have been continued during the present working season, and the necessary preliminary steps have been taken for the execution of the new work specified.

The act further directed that surveys be made and estimates submit