DEFENSES OF SAN FRANCISCO, THE NAVY-YARD AT MARE ISLAND, AND THE ARSENAL AT BENICIA-Continued.

lime the buildings and wood breast-height revetment, and painting and puttying the wood platforms. The wood revetment and platforms in the Gravelly Beach Battery remain in fair condition, there being no noticeable deterioration during the year. The magazines in each of the batteries are dry and in good condition.

Twenty-four gun-platforms and breast-height walls for seven guns are required to complete the batteries already built. It is estimated that it will require $100,000 to do this work and to rebuild the wharf and water-tank, with other repairs. Eighty thousand dollars can be profitably used in the coming year. This estimate does not include the Point Diablo Battery, approved by the Secretary of War, which battery has never been commenced.

No appropriation having been made, no work was done at this fortification during the last fiscal year beyond its protection, preservation, and repair, as far as was possible with the general appropriation made for this purpose, and no other work is contemplated during the current fiscal year for the same reason.

Appropriation asked for next fiscal year..

$80,000 00

Fort on Alcatraz Island, San Francisco Harbor, California, in charge of Lieut. Col. George H. Mendell, Corps of Engineers.-Alcatraz Island lies in the harbor of San Francisco, two miles inside its entrance, in a very advantageous position for the defense of the channels on every side

of it.

In 1870 the work of remodeling the defenses of this island to adapt them to modern ordnance-this work consisting of the construction of heavy earthen batteries-was commenced and carried on for a few years, when it was suspended for want of funds. The last appropriation ($25,000) was for the fiscal year 1875-76, although there was some work done, mostly by the military prisoners confined on the island, in 1877.

During the year the embrasure irons of the unfinished casemated work, including twelve sets not in place, were painted. The iron-work on the wharf crane, magazine doors, and ventilators were painted. All the engineer buildings were washed with lime. Repairs were made on the fence of the office building, laborers' quarters, and boat-house. The grass on parapets and slopes was cut, the batteries policed, and drains cleaned.

The Quartermaster's Department has built two sets of quarters and a hospital on the east side of the island. It also built an extension of the wharf, upon which a storehouse was placed. The old hospital was taken down. The defensive barracks has been altered very materially. Six separate sets of quarters have been made; three openings for doors have been made in the main exterior walls; the loop-holes on the lower floor have been converted into windows. All of these operations have been conducted by the Quartermaster's Department.

The batteries and magazines remain in good order.

The appropriation asked for will be applied to the construction of gunplatforms for earthen batteries ready to receive them, and to the construction of earthen batteries not yet commenced.

No appropriation having been made, no work was done at this fortification during the last fiscal year beyond its protection, preservation, and repair, as far as was possible with the general appropriation made for this purpose, and no other work is contemplated during the current fiscal year forthe same reason.

Appropriation asked for next fiscal year...

$50,000 00

DEFENSES OF SAN FRANCISCO, THE NAVY-YARD AT MARE ISLAND, AND THE ARSENAL AT BENICIA-Continued.

Batteries at Point San José, San Francisco Harbor, California, in charge of Lieut. Col. C. S. Stewart, Corps of Engineers.-During the late civil war two temporary earthen batteries were built on this point.

In the east battery the timber platforms are decayed as well as the wood-work of the magazines, part of which has caved in. This battery is unserviceable.

Projects for new earthen batteries of heavy guns and mortars for the occupation of this important point in the second line of defense for the bay and harbor of San Francisco have been prepared by the Board of Engineers for the Pacific Coast.

No appropriation was made for the fiscal year ending June 30, 1883.
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.-The three earthen batteries on this island were built during the late civil war for temporary use. The timber platforms and the timber magazines are decayed, and nearly all the gun-carriages have been condemned.

The batteries are practically unserviceable.

Barbette earthen batteries for the heaviest guns have been planned by the Board of Engineers for the Pacific Coast, to occupy the most valuable positions on the island which bear on the channels leading to the upper part of the bay, to the navy-yard at Mare Island, and to the arsenal at Benicia.

No appropriation was made for the fiscal year ending June 30, 1883.
No appopriation asked for next fiscal year.

DEFENSES OF THE COLUMBIA.

Defenses at the mouth of the Columbia River, Oregon, and Washington Territory, in charge of Maj. G. L. Gillespie, Corps of Engineers, until July 27, 1881; since that date in charge of Capt. C. F. Powell, Corps of Engineers.-The defenses consist of Fort Stevens, an inclosed earthwork at Point Adams, Oregon, on the south side, commanding the entrance to the Columbia River by the south channel, which, after passing the outer or northern end of Clatsop Spit, skirts the eastern shore of Point Adams on the approach to Astoria; and the earthen batteries at Fort Canby, Cape Disappointment, Washington Territory, on the north side, commanding the entrance by the north channel, which passes in close to the headland, leaving Sand Island to the southward.

These earthworks were built during the late civil war in anticipation of complications with foreign powers. The walls and roofs supporting the earth coverings of magazines, which are commonly built of masonry in permanent earthworks, were, in this case, necessarily built of wood, for want of time and money, and they are subject to rapid decay in the climate of the mouth of the Columbia.

Fort Stevens.-During September and October, 1881, 400 feet of the plank walls of the interior slope of the parapet of the unarmed land front, and 450 feet of similar revetment on the right of the channel salient, which had become badly decayed and partly fallen down, were removed. That on the land front was replaced by marsh sod, which, at the end of seven months, stands well, and answers the purpose excellently. On the other front, where the old revetment was removed, a new plank one was constructed of cedar posts and anchors, and a double wall of fir planks. The space between the two parts of the wall was

DEFENSES OF THE COLUMBIA-Continued.

left open for circulation of air, and not filled with earth, as in the former

revetment.

During October and November an inexpensive shore protection of brush-work was placed on the beach in front of the channel salient for assistance against erosion; wings and spurs of brush were laid, at favorable times, in shallow trenches, and pinned to the ground or weighted with bags of sand. The part of the brush above the beach surface served to catch sand drifting under prevailing winds, and thus build up and extend the shore. Two thousand and fifty feet of brush-lines were planted. Only a small part has been destroyed or swept away by drift or sea; the shore line has been advanced somewhat, and the level of the beach raised in height about two feet over the whole area.

The mouth of the slough on the western side of the fort was closed by raising its surface by means of similar brush-work; 860 feet of lines of brush were placed across the outlet. This slough receives the drainage of adjacent low lands and swamps. The entrance of high tides by the natural outlet created fears that Clatsop Spit would be cut through, and a permanent channel formed, to the danger of the fort. The outflow of drainage and tidal water caused erosion on the fort side of the outlet. These were the reasons for closing the mouth of the slough, as done during neap tides and preceding the rainy season. To furnish escape for drainage water, a plank flume was made leading from the slough, and in a direction as nearly opposite to the fort as practicable. The flume was 350 feet long; its inside dimensions were 18 inches by 8 feet. Proper gates were made for the flume, and an apron placed at the mouth.

The flume was completely destroyed during the winter, and a natural outlet formed near its line. This outlet may be forced back by seas gradually to the position along the channel faces of the fort, when some protection against erosion will again be necessary.

During June the Engineer storehouse was rebuilt, minor repairs made to the magazine, and the drain from the fort ditch, which had been stopped up, was cleaned out.

Fort Canby.-A 12 inch rifle was furnished the fort last fall, and the commanding officer desired an additional platform made on which to mount it. After consultation with him it was decided to enlarge the center battery. During May and June the rampart was therefore extended on the left, and the platform placed at that end for the rifle. The gun has not yet been mounted.

Extensive repairs were made to the breast-high plank walls of the parapets of both the center and east batteries. As at Fort Stevens, the space between the two parts, where new walls were added, was left open. In the new gun-platform the openings between the timbers were covered by a movable grillage, instead of planks closely jointed and battened, as in the old platforms. The platform and plank breast-high walls were painted with two coats of paint.

At the west or light-house battery the breast-high parapet walls of plank were badly decayed and in a falling condition, except on the north flank. The useless portion was entirely removed, and a marsh sod revetment built in its place. The guns of the battery are not fired on account of danger to the light-house adjoining.

At the powder-house a new sill was placed under the north end, and Rew steps at the entrance; the doors were rehung, and a coat of mineral paint applied to the exterior of the building.

No appropriation was made for the fiscal year ending June 30, 1883.

No appropriation asked for next fiscal year.

BOARDS OF ENGINEERS.

THE BOARD OF ENGINEERS.

The Board of Engineers stationed at New York City, consisting of Col. Z. B. Tower, Col. John Newton, Lieut. Col. Henry L. Abbott, and, when so ordered, the officer in charge of the work under consideration, has been engaged in the duties which have from time to time been referred to it, and it has submitted the following report of its operations: Coast defenses.-The views of the Board upon the question of sea-coast defense and the leading measures needed to secure the harbors of the United States against maritime attack have been set forth with more or less completeness in various reports for the past fourteen years. It does not, therefore, seem necessary to enter into any exposition of this subject here farther than to state: First, that our defense for many years must depend up the finishing of barbette batteries designed long since, but with such modifications as will adapt them to the reception of the 12-inch rifled gun recently proposed, with its enlarged carriage, and at the same time give greater security to the magazines. Second, to make ready, without delay, to apply our system of torpedoes to all harbors by preparing bomb-proof electrical operating-rooms and deepmasonry galleries, extending therefrom to the low-water line, needed for that purpose.

The above are the two prominent features of our system of defensive works requiring prompt attention, a system which, though a preliminary one in part, has the merit of being comparatively inexpensive.

Reviewing the designs of batteries prepared from twelve to fourteen years ago, in the light of the present armaments of ships of war and of the penetrating power of projectiles now used on those ships, the necessity alluded to above for modifying the plans of our unfinished batteries is very apparent. By the introduction of a single gun between traverses, instead of two, something may be gained in the way of earth cover for the magazines; but from studies made in that direction, it seems probable that when the exposure is great new service magazines, sunk below the terreplein for security, will be required at many localities. Much time has been given to this subject during the past year, and it will doubtless engage the attention of the Board in the future until the plans of all the batteries hitherto designed for our sea-coast defense are thoroughly examined and adapted to such armaments as will be provided for them when the gun problem shall have been solved.

As plans of electrical operating-rooms and cable-galleries for the most prominent of our sea-coast works have been prepared, their construction must await appropriations for that purpose.

This Board adapted its preliminary system of harbor defense to the necessities of the day, and has advocated it from year to year as a means of arriving, in the shortest time possible, at some security for the important commercial and manufacturing centers of the sea-coast of the United States.

There can be no doubt that the future of our defensive system must look to the use of iron in some form, probably as a revolving turret, to cover emplacements for the largest and most powerful guns known to any service. The studies of the Board have been directed to this subject for more than three years, and plans have been prepared for two double-turreted iron forts, one for each shore of the Narrows at the southern entrance to New York Harbor. Each turret is intended to receive two 100-ton guns.

It is essential that our more important harbors should be made so secure as to relieve the nation of all apprehension in respect to them. It is with this view that the two double-turreted iron forts have been planned for the defense of the Narrows, for no naval ship yet built or designed could remain under their close fire long enough to do them any damage. The extending of this turret system to Boston, as suggested in our report of last year, and to other harbors of leading commercial interest, will doubtless engage the attention of the Board, in common with the revision of the barbette batteries, during the coming

year.

Reports submitted on subjects of fortifications, &c.:

1881, July 25. Views of Board as to information which it would be desirable to obtain in reference to the practice of leading foreign nations in the use of iron for forts, and especially for revolving iron turrets; with the latest improvements in carriages for depressing the gun 80 as admit of high elevations of the piece.

August 8. Views of Board as to what amounts should be asked of Congress for the next fiscal year for new works of fortification under existing plans not yet commenced; and for continuation of old works, &c.

November 18. Upon question of encroachment of the sea at Sandy Hook, N. J., and, in this connection, what protection to the shore line is necessary to protect the site of the fort at that locality.

November 30. History and progressive changes of our fortifications; in accordance with act of Congress calling for statement of their present condition and what number of them can be dispensed with.

1882, January 13. Upon question of acquiring a tract of land in rear of Fort Tompkins, Staten Island, New York, for the purpose of additional fortifications.

January 17. In reference to diminishing the recoil of guns and length of chassis, and thence to the improvements in the construction of barbette batteries which would result thereform.

February 15. Upon defensive arrangements necessary to protect our torpedo lines.

June 30. Report, with drawings, upon the iron revolving turret for two 100-ton guns, adapted to any locality, somewhat modifying the plans submitted June 30, 1881.

June 30. Upon a two turreted fort for the site of Fort Lafayette and for the shore opposite, just south of Light-House Battery, Staten Island, New York.

June 30. Upon a modification of barbette battery on Gerrish Island, mouth of Portsmouth Harbor, New Hampshire.

Studies not reported upon: Drawings have been prepared somewhat changing plans for barbette batteries previously designed for Cow Island, and for the two eastern spurs of Great Hog Island, Portland Harbor, Maine. These modifications have reference to the adaptation of these batteries, like those on Gerrish Island, to the recent 12-inch carriage designed by the Ordnance Department, and to additional cover for the service magazines. The drawings have not, however, been forwarded.

Studies have been made changing essentially former designs of service magazines for barbette batteries. By reason of the increased weights and improved forms of projectiles, the greater lengths of guns and much enlarged powder charges, penetration by shot and shell into iron, masonry, and earth has been more than doubled since our sea-coast batteries were planned. To meet these changed conditions so large an increased cover for magazines is demanded as to require that they should