While the report of this board contains a detailed account of the tests, it is thought that the following tabular statement of the firings from the battery to June 30, 1893, should be here reported:

From this table it will be seen that in all twenty-four rounds have been fired from the platform of the lift. Many of these, notably the twenty-first round, subjected the structure to stresses far in excess of any probable under service conditions; notwithstanding these excessive stresses, the mechanism has invariably worked smoothly and satisfactorily, and shows no signs of weakness in any part. During all the tests, there has been no delay of any kind due to the failure of the lift or its adjuncts to do the work required of them.

The official trials of the mechanism showed the desirability of some minor changes, mainly in the loading apparatus; these modifications, described below, were all made by the contractors at the suggestion of this office, and without any additional expense to the United States:

1. It was necessary to increase the speed of travel of the hydraulic rammer. The proper service of the gun requires that the projectile be so far driven home as to partly upset its rotating band in the grooves of the rifling. This condition, unknown when the rammer was designed, was not satisfactorily fulfilled, and, the weight of the rammer being fixed, the increase of its energy could be effected only by increasing the rate of travel. This was done by increasing the annular space through which the water escapes to the rear during the forward movement, so as to make this area equal to that of the inlet pipe.

2. The combined ammunition carriage and loading tray, and the auxiliary loading tray which forms the connection between the ammunition carriage and the breach of the gun when in the loading position, were modified as follows: The two charge bags which are carried upon

arms on each side of the powder tray of the ammunition carriage are now successively dropped into position, in front of the rammer, by a single motion of the operator. The auxiliary loading tray, operated by hydraulic power, is controlled by the same operator as are the ammunition hoist and hydraulic rammer. The effect of the changes will be to diminish the time required for loading.

3. The steel pin or throttling bar, which is placed in the top of the cylinder of the heavier of the two accumulators and which serves to gradually check its downward motion near the completion of the descent, was replaced by a longer one; this was deemed advisable, as in raising the lift at maximum speed it was found that the heavy accumulator seated with more force than was consistent with safety. The lengthening of the pin has removed this difficulty.

THE CARRIAGE.

As reported last year, all the parts of the gun carriage, designed and manufactured for use with the gun-lift mechanism, by Messrs. Schneider & Co., of Creusôt, France, was on the upper surface of the battery June 30, 1892. It was not until July 30, 1892, that the pintle or bedplate of this carriage was finally attached to the platform of the lift. The lower surface of this plate was irregular, and it was necessary to do a great amount of chipping upon the upper surface of the platform before it was practicable to so adjust the pintle plate as to bring its limiting lines, the circles bounding the lower roller path, into horizontal planes.

This effected, the remainder of the carriage was assembled. This work was all done by the employés of the Engineer Department, excepting the insertion and adjustment of the rams in the recoil and reservoir cylinders and the adjustment of the obturating bars and the pump, which were effected by one machinist and helper furnished by the Ordnance Department.

The carriage was completely assembled ready for the gun on August 15, 1892, at a cost divided as follows:

The 12-inch B. L. steel rifle was delivered by the Ordnance Department under the wall of the battery at a point indicated by the engineer officer in charge, at 4 p. m., August 23, 1892. It had been placed on a cradle August 12, at a point about 1,200 feet from that of delivery, from which latter point it was delivered at the battery in ten working days. The work of erecting the appliance designed for raising it had already been completed, as far as was practicable, prior to the delivery of the gun.

Final arrangements for raising and mounting the gun were completed on August 25, and the gun was successfully delivered on the wall of the battery, immediately in front of the lift platform, at noon on August 26.

The gun was finally placed upon its carriage and raised to the firing position by the hydraulic lift, at 7:30 p. m., Monday, August 29, 1892.

There are forwarded herewith, among others, a set of photographs* illustrating the method used for raising the gun.

The device for raising the gun, adopted and so successfully used by Lieut. Warren, may be briefly described as follows: A frame of timber, having a width between uprights slightly greater than that of the gun (measured from end to end of trunnions), was placed parallel to the wall of the battery and distant from it about 13 feet-6 inches greater than the distance of the axis of the trunnions from the face of the breech of the gun.

From the cap of this frame a steel bar about 4 inches in diameter (the eccentric axle of an old gun carriage) was suspended by three wroughtiron bands, from which were hung two blocks, one with four, the other with three, sheaves, through which and their falls was rove about 750 feet of 7-inch manilla rope, the standing part being made fast to the cap of the frame and the running part passing first through a single block secured to the bottom of one of the timber uprights, and thence to a secure anchorage. The gun, without preponderance, the breechblock being removed, was slung to the falls by 13-inch wrought-iron chain, the breech to the wall. Parallel to the frame first described, four smaller frames were so arranged that when capped they would form a platform at the elevation at which the gun was to be delivered. These frames were securely braced together and to the larger frame, and the whole structure tied and braced to the masonry of the battery. Leads were taken from two hoisting engines near at hand, which formed part of the construction plant, to the running part of the 72inch manilla rope, using two parts of half-inch steel-wire hoisting rope. The object in connecting the two engines was to avoid any stoppage in the raising of the gun when once commenced, from shifting the purchase, or "fleeting" as it is technically known.

The gun was then raised vertically above the level of the auxiliary platform, the caps promptly put upon the frames, stringers laid over the caps, a cradle run out upon these from the wall, and the gun lowered upon the cradle, which was then hauled in upon the masonry by means of a lead from one of the hoisting engines above referred to.

Sixteen parts of 74-inch rope were used, the safe load for a single part being 12 tons, and as the load to be lifted was 52 tons, the factor of safety was therefore about four; on the steel-wire rope the same proportions existed, while the framing was calculated with a factor of safety of six.

The actual time required to hoist the gun was one hour and fortythree minutes and the actual time of motion was twelve minutes and twenty-five seconds-a rate of 1 foot in thirty-nine seconds. The delay is attributable to the fact that the cordage was saturated with water, which rendered it extremely stiff and made it difficult and slow work to take up the slack of the main anchorage.

The operation was performed in a pouring rain, which had been falling for the preceding twenty-four hours.

SOUTH-LIFT MECHANISM.

The mechanism designed for the southern emplacement of the battery is to be, in all respects, a duplicate of that now in place in the northern emplacement.

Sealed proposals for its manufacture, advertised according to law

* Omitted.

December 21, 1892, were opened January 24, 1893, and the contract was awarded for the sum of $63,000.

Under their contract, dated February 4, 1893, for the manufacture and erection of this mechanism, the contractors have on hand, June 30, 1893, all the material for its construction, and have commenced the preliminary work of assembling the parts forming the cage.

It is expected that they will be ready to begin operations during the month of July, 1893, and to finish the erection of the lift by September 1, 1893, as the contract requires.

No carriage has yet been procured for mounting upon the platform of the southern lift. It has, however, been decided that this carriage is to be a duplicate of that now in position on the north lift, and arrangements have been perfected with the Ordnance Department by which the pintle plate of the carriage will be delivered not later than September 1, 1893. When this pintle plate has been attached to the platform of the southern lift the top carriage and gun now mounted upon the north lift will be shifted to the southern lift for use in the test of the mechanism of that lift, and for other tests required by the Ordnance Department.

The recoil test will be five rounds by the 12-inch high-power gun, fired under service conditions of extreme charge of powder and extremé elevation.

I C.

TORPEDOES FOR HARBOR DEFENSE.

CONSTRUCTION OF TORPEDO SHED.

Plans and estimate were submitted April 3, 1891, for the construction of a suitable building for the storage of torpedo material for the submarine defense of New York Harbor, and the sum of $9,000 was allotted for the work from the appropriation for torpedoes for harbor defense, act of February 24, 1891.

The general character of this structure is as follows: The building is of brick, 40 feet by 90 feet, inside measurement, with walls 1 foot in thickness and 10 feet high under the eaves. The roof is of slate, supported by eight iron trusses. The floor is of concrete, and the track of the construction railroad from the engineer wharf runs through the building from end to end. On either side of this track are racks of 4-inch by 8-inch timber, arranged for the storage of buoyant torpedo cases in two tiers. A suitable storeroom for containing the smaller parts of the torpedo system is located in the southeastern corner of the building, and an overhead hoisting and conveying appliance will be placed at the eastern end of the building for handling the heavy anchors and ground mines.

At the close of the last fiscal year the building was complete, excepting the shelving, etc., in the storeroom and the overhead trolley.

The shelving in the storeroom has been left unfinished, pending the arrival of the material to be stored therein. The overhead trolley for handling the heavy torpedo material inside the shed has been ordered, and will also be put in place at an early date.