The computed height of trajectory, for a projectile of 610 pounds hav ing a muzzle velocity of 1,000 feet, and fired at an elevation of 60 degrees, is 3,197 yards; angle of fall about 67 degrees, velocity at impact 787 feet, and the penetration in iron 8 inches under normal impact.

With regard to accuracy of fire, some of the targets made are excellent, fully equalling the best results attained abroad with sea-coast B. L. mortars, but there is a very considerable want of uniformity. On the other hand, it may be remarked that the published records of firings made with B. L. mortars abroad are not as full and complete as could be desired for purposes of comparison. In order therefore to determine by careful and extensive trial the relative merits, as regards accuracy of fire, of muzzle-loading and breech-loading mortars, the Department has placed under fabrication a 12-inch B. L. mortar of cast-iron, hooped with steel, similar to the present M. L. mortar, except as to such details of chambering, rifling and type of projectile as are peculiar to breechloading systems. The body for this mortar has been cast at the South Boston Iron Works, and is nearly ready for the hoops. The hoops and forgings for breech mechanism, are being made at the Midvale Steel Works, and will soon be completed. The trials of the 12-inch M. L. mortar have also demonstrated the necessity of using a sabot made with great care and possessing the necessary degree of sensitiveness, which are certainly objectionable features for service, and which do not obtain with the breech-loading system. It is even possible that, to obtain the maximum of efficiency with M. L. mortars, sabots of different degrees of sensibility are a necessity. The target records with the 12-inch M. L. mortar are given in the report of the Board. (Appendix 11.)

With regard to endurance, the mortar has been fired thus far about 400 rounds. The star-gauging after the last round shows no material en. largement of the bore, and the piece is apparently in as good condition as ever. The construction is therefore abundantly strong. The rapidity of fire has been from 7 to 8.5 rounds per hour, which has included the placing and renewing of a loading platform at each fire,-an inconvenience that would not occur in actual service, as a permanent banquette would be provided.

The shells for the mortar are designed for use with the Hotchkiss base fuze, but no trials have as yet been made to test either the action of the fuze or the effect of explosion of the charged shell.

The endurance test of the mortar will be continued up to 500 rounds, and some further modification or form of sabot will be tried with the object of improving the accuracy of fire.

Experimental 10-inch B. L. Rifles.-Cast-iron, wire-wrapped; steel, wirewrapped.

These guns were under manufacture at the Watertown Arsenal. The cast-iron gun is well along towards completion. There only remains to

be applied four layers of wire, after which the gun is to be finished on the outside, finished bored and rifled, and the recess for the breech block threaded. A very interesting and able progress report on the fabrication of this gun has been submitted by Lieut. William Crozier, Ordnance Department. (Appendix 25.) The work on the gun has been stopped owing to the failure of Congress, at its last session, to make the necessary appropriation for continuing it.

Progress towards completing the 10-inch wire steel gun has been slow, owing mainly to the novelty and manifold detail of the construction. This gun is still in a very backward state, that stage not having yet been reached in which the various parts are being finished for assemblage. Work has ceased on this gun also, for the same reason as the above.

Experimental 10-inch B. L. Rifle, steel-hooped.

The tube, jacket and trunnion hoop for this gun were ordered from Sir J. Whitworth & Co., and the hoops principally from the Cambria Iron Works, though the chase hoops, with the breech mechanism forgings are being manufactured by the Midvale Steel Company. Progress in the manufacture of hoops at the Cambria Works has been slow, but the results obtained have been very gratifying, fully conforming to the high requirements specfied in the contract; and it should be remembered that this is the first effort made by this company in the production of gun steel. The delay in completing this gun will be more directly chargeable to a failure to secure prompt delivery of suitable tube and jacket forgings.

Experimental 8-inch B. L. Rifle, steel.

This gun was completed the last of June, 1886, and sent to the proving ground for trial. The tube and jacket were procured from Sir J. Whitworth & Co., the hoops and the forgings for breech mechanism from the Midvale Steel Company. The gun has a total length of 21.5 feet, with 30 calibers length of bore, and weighs 13 tons; the hooping extends over the breech and part of the chase, stopping at 91 inches from the muzzle. (For description of gun and manufacture see Appendixes 17 and 18.) The proposed powder charge was 100 pounds, and the projectile 285 pounds, of 3 calibers length, with which it was expected to realize a velocity of 1,825 feet without exceeding a pressure of 16 tons-36,000 pounds-per square inch in the powder chamber. (See Appendix 33, Report of the Chief of Ordnance, 1885.) The gun has been fired, under the supervision of the Ordnance Board, 24 rounds, the firings thus far having been mainly for the purpose of determining a suitable grade of powder and the best width of forcing band for the

projectile. Following are some representative results, using brown prismatic powder:

In firing two series of five shots each at a target 3,000 yards distant to determine which of two different forcing bands submitted for trial, was of the better width, the following results were obtained with the band adopted

or the centers of all the shot-holes were contained within a circle of 64 feet diameter, which denotes a very high degree of accuracy.

The Du Pont brown prismatic powder has given a muzzle velocity of 1,820 feet, with a pressure of 35,450 pounds per square inch, using a charge of 100 pounds and a projectile of 286 pounds, and although this result is quite satisfactory, as compared with results obtained abroad, yet it is thought that some improvement may still be made. Some further samples have accordingly been ordered for trial. The firing of the experimental 8-inch steel rifle has enabled the Department to settle through its own experiments and with a minimum cost the recently vexed question as to whether or not the modern steel guns of this caliber should be hooped to the muzzle. The question came into prominence in Europe after the manufacture of this gun had been commenced, and was raised by the bursting of several foreign guns having no hoops over the chase. The remedy generally adopted abroad has been to hoop the gun throughout. The principal objections to this are the increased weight and cost of manufacture. In the 8-inch gun the Department possessed a tube the tests of which at the muzzle showed exceptionally fine quality of metal, and was of such dimensions as to give abundant strength for anticipated pressures. Instead then of changing the design of the gun to conform to foreign methods the Department determined to settle the question for itself. The gun was provisionally finished without the

chase hooping, sent to the proving ground and fired with heavy charges. The most careful attention has been paid to enlargements of the bore within the unhooped portion of the chase. During the firing of the twenty-four rounds the bore was star gauged after the first, fourth, seventh, thirteenth, twenty-third and twenty-fourth rounds. Even after the thirteenth round the maximum enlargement in the unhooped chase was but of an inch. After the twenty-fourth round for about 12 inches in the length of the bore near the muzzle the enlargement was Too of an inch. This enlargement is in itself small, showing an extension of only 10% of an inch, per linear inch, or less than one-half of one per cent. of the ultimate extensibility of the metal after rupture, as determined by tests of bars cut from the tube forging itself. A careful consideration of the results, however, led to the conclusion that the chase should be hooped to the muzzle, having also in view the purpose of the Testing Board to fire the gun to extremity. This modification in the design will permit, with a suitable powder adapted to a high density of loading, of increasing the present powder charge, if desired, and will enable the Department fully to develop the ballistic properties for guns of this class. The gun has been returned to the West Point Foundry, where it is now in the lathe being turned for its chase-hooping. It is expected that the trial will be renewed in about two months. This 8-inch gun is made largely of imported steel. The first forgings imported were rejected as not up to our standard of what the metal should be. The machining of the steel and fashioning of the gun, was done in this country. The technical work, such as determining the specifications, and the details of the construction, the shrinkages, &c., and the daily supervision and inspection, was the exclusive work of ordnance officers. In the manufacture of high-power steel guns such as these no rule-of-thumb methods can be followed. Scientific study, and technical skill and devoted attention to the work can alone reach successful results. The few rounds already fired prove that the work was well done, and gives us every reason to believe that the qualities of steel required for guns and the manufacture of guns can be intrusted with entire confidence to the officers of this Department.

I may here remark, that, owing to the failure of the fortifications bill, and the consequent inability of the Department to procure new supplies of powder, it would have been impracticable to test this new 8-inch gun after its completion, except for the fact that the Department had an existing contract with the Messrs. Du Pont for a supply of brown powder.

Since writing the above the chase of the 8-inch rifle has been turned down for the reception of its hoops, and after removing the necessary metal on the exterior it was ascertained that the bore had undergone considerable restoration, which has materially reduced the above-noted enlargement. This fact points to the existence of initial strains in the original tube, due probably to faulty treatment in manufacture, and which, acting in the same direction as the powder strains, caused an enlargement of the bore such as was not to be expected from the action of the powder alone.

Production of steel gun forgings.

The Midvale Steel Company, has completed its contract for the delivery of twenty-five sets of forgings for 3.2-inch B. L. field guns. The steel furnished has been of a superior quality, exceeding the requirements of the contract. These works have also completed all the parts for the 5-inch B. L. siege gun, excepting the jacket, and that will be delivered in November. A tube and trunnion hoop for an 8-inch B. L. rifle have also been successfully forged and accepted. The production of the 8-inch rifle jacket has been attended with considerable difficulty, and a number of failures have been experienced, this being the largest gun forging thus far undertaken at Nicetown. But the last attempt has, there is reason to believe, proved entirely successful, and the manufacturers have gained in compensation for their failures most valuable practical knowledge of how to deal with large forgings, and thus have broken fresh ground in the development of the steel,industry.

Prior to ordering the trunnion hoop for the 8-inch gun, as the production of a forged steel trunnion hoop-at least of any considerable size-had not hitherto been accomplished in this country, and as it was very desirable to know accurately the mechanical qualities of such a forging, the Department procured from the Midvale Steel Company, for purposes of test, a forged trunnion hoop of about the same size as that required for the 8-inch rifle. When completed this trunnion hoop was sent to the West Point Foundry, where it was cut in half along a plane passing through the axis of the trunnions and perpendicular to the axis of the hoop. One of the halves was then subjected to thorough mechanical test by means of test specimens taken from various parts along the inner face, while the other half was subjected first to an elastic, and then to a strength test by being shrunk successively on two cast-iron cylinders. The results by both methods of test were satisfactory and demonstrated the ability of the Midvale Steel Company, to cope with these difficult forgings. Following are some results obtained from the 8-inch tube and trunnion hoop. The test specimens were taken tangentially, those from the tube being 3 inches long and of .564 of an inch diameter, and those from the trunnion hoop 6 inches long and of .564 of an inch diameter: