1,228 cubic yards of masonry were put in place; 55,717 cubic yards of excavation were made; 7,980 square yards of soil were hauled from a distance for parapets and magazine-coverings; 7,480 square yards of soddings were laid on the parapets and traverses. The battery at Point Cavallo was completed with the exception of gun-platforms and breastheight walls. The parapets and traverses in the Gravelly Beach Battery, having yielded under the winter-storms, they were filled with soil to the proper level and partially sodded. The road to the new site near Point Diablo was commenced, and 4,200 lineal feet completed. The masonry-work at Point Cavallo was put upon two magazines and on the necessary drains.

Amount appropriated for the fiscal year ending June 30, 1875.
Appropriation asked for next fiscal year....

$30,000 50,000

During the present fiscal year it is proposed to complete the road begun, to build the advance battery at Point Cavallo, and to execute such work at Point Diablo as proves practicable.

Fort on Alcatraz Island, San Francisco Harbor, California, in charge of Maj. George H. Mendell, Corps of Engineers.-During the past fiscal year 1,185 cubic yards of masonry were put in place, and 59,160 cubic yards of excavation and filling were made. The south caponnière was partially remodeled. Two magazines, with bomb-proofs, were built. The breast-height walls for two guns were built and two stone platforms laid. Parapets for four guns were made; 6,300 square yards of sodding were laid on parapets, magazines, and slopes. The timber-work on the greater part of the old wharf was renewed. The wood revetment in rear of the wharf was replaced by a substantial stone wall laid in mortar. The retaining-wall in battery 1 was extended thirty-five feet. Amount appropriated for the fiscal year ending June 30, 1875..... Appropriation asked for next fiscal year...

$20,000 50,000

During the present fiscal year the south caponnière and shell-room will be completed. Magazines R and S will be covered and sodded. The filling in battery 7 will probably be completed, and the excavations on the south end of the island will be completed.

Batteries at Point San José, San Francisco Harbor, California, in charge of Lieut. Col. C. S. Stewart, Corps of Engineers.-East Battery.-The six wooden front-pintle platforms are rotten and unserviceable. The timbers of the magazine are so rotten that it has not been used for years.

West Battery.-The three platforms on the left are serviceable, the three on the right unserviceable from decay of timber. The timber of the magazine has not yet fallen in. No work has been done during the past fiscal year and none contemplated during the present year. No appropriation was made for the fiscal year ending June 30, 1875. No appropriation asked for next fiscal year.

Batteries on Angel Island, San Francisco Harbor, California, in charge of Lieut. Col. C. S. Stewart, Corps of Engineers.-These three temporary earthworks, constructed during the late war, are essentially unserviceable. The platforms are decayed, and most of the carriages have been condemned. It is proposed to postpone the commencement of batteries of a permanent character, projected to replace them, until more advanced points are fortified.

No appropriation was made for the fiscal year ending June 30, 1875.
No appropriation asked for next fiscal year.

Fort at San Diego, California, in charge of Lieut. Col. C. S. Stewart, Corps of Engineers.-During the past fiscal year work has been directed chiefly to the completion of buildings and the construction of embankments.

The stable, 24 by 50 feet, has been finished, and a stone house, 24 by 50 feet, a carpenter's shop, 14 by 24 feet, and overseer's quarters, 24 by 34 feet, built. The site has been cleared, and 27,626 cubic yards of embankment made along the right and left faces, and in the parade to about reference (20.00). Concrete drains have been built for a length of 380 feet, and the foundations of one magazine laid, and its walls carried up to the spring of main arch, requiring 313 cubic yards of concrete. No appropriation was made for the fiscal year ending June 30, 1875. No appropriation asked for next fiscal year.

Defenses of the mouth of the Columbia River, Oregon, in charge of Maj. Henry M. Robert, Corps of Engineers, from July 1, 1873, to October 22, 1873; since that date in charge of Maj. N. Michler, Corps of Engineers.-These defenses consist of Fort Stevens, on the south side, and three detached batteries at Cape Disappointment, Washington Territory, on the north side of the entrance. The works are in a very dilapidated condition, the entire wood-work of Fort Stevens, except the magazine, which is sadly in need of repair, being rotten. The wooden revetment of the interior slopes all around the fort is fallen, and several traverses lying in a confused mass of earth and timber; the sea threatens the site of the fort. All the magazines at Cape Disappointment are in such a dilapidated condition as to be useless.

No appropriation was made for the fiscal year ending June 30, 1875.
Appropriation asked for next fiscal year..

$20,000

During the past fiscal year the operations were confined to making the annual survey of Sand Island and Point Adams.

BOARDS OF ENGINEERS.

The board of engineers for fortifications, stationed in New York City, consisting of Col. J. G. Barnard, Col. Geo. W. Cullum, (until January 13, 1874,) Lieut. Col. Z. B. Tower, and Lieut. Col. H. G. Wright, and, for the time being, the officer in charge of the defenses under consideration, has submitted during the past fiscal year reports upon applications of the Treasury Department for transfer of a portion of Presidio reservation, known as Mountain Lake, for the erection of a marine hospital, and for permission to build a road through Fort Stevens military reservation, Oregon, from the fort to the site of light-house; in reference to manner of finishing traverses and breast-height walls of batteries, showing a method of securing thicker and higher traverse and greater security to gunners serving the piece; upon project of Capt. C. W. Howell, substituting for the proposed battery above Fort Jackson, La., a battery of like number of guns on the Fort St. Philip side of the river and below that work; upon project of Maj. Wm. P. Craighill for changing the advanced casemate battery of Fort Monroe into a barbettebattery; upon the subject of the introduction of the Gatling gun into our service for flank-defense of fortifications; upon question of expediency of using concrete in breast-height walls in northern climates; upon House resolution of February 16, 1874, relative to the sale of Horn Island military reservation, Gulf of Mexico; upon application of Mr. John V. Cockroft to purchase or hire the property at St. Augustine, Fla., known as Fort Marion; upon proposed plan for mortar-battery at Fort Johnson, S. C.; upon proposed modification of Fort Pickens, and plans for construction of batteries exterior to that work; also on opposite side of channel, near Forts McRee and Barrancas; upon subject of defense of harbors of New York and Philadelphia by torpedoes, the manner of leading cables to shore, and construction of operating-rooms, &c.,

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 anchorage 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., modification 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.

TORPEDO-DEFENSE.

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 application 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 relations, 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