The gun was again referred to in the report of the select committee on heavy ordnance, appointed under Senate resolution of August 2, 1882, in the following language:

We recommend the making of such number of cast-iron guns banded with steel bands or wrapped with wire, as may be necessary to fully and thoroughly test their efficiency.

A drawing was sent to this arsenal for construction, subsequently to which the design was modified as follows:

The base band A, Plate I, was shrunk on with a taper of .05 inches, instead of being screwed on with a shrinkage.

The ring F was shrunk on with a plain cylindrical surface, instead of a screwed one.

The additional ring G was screwed on in front of ring F.

After the winding was completed, and before the rings were shrunk on, the wire wound portion was to have been incased in boiler iron and the gun placed horizontally in a soldering furnace, where it was to be heated to the proper temperature, melted solder poured into the case, and the gun slowly revolved to facilitate the penetration of the solder into and through the mass of wire. The soldering operation was omitted, experiment with a trial cylinder having shown it to be of doubtful desirability and impracticable by the method proposed.

As built is shown in Plate I.

THE GUN

The body is of cast iron. The thickness of cast iron over the powder chamber is 9.835 inches, under the trunnion band it is 8.96 inches, under ring F 10.475 inches, under ring G 9.80 inches. Forward of ring G for a distance of 28 inches the thickness decreases on a curve whose ordinates are given, from the end of which it runs down on a straight taper to the muzzle where it is 4.5 inches.

The wire is wound to a thickness of 5.49 inches over the powder-chamber and 3.957 inches under the trunnion band and sleeve. In the shallow recess extending from a little in rear of the trunnion band to the forward end of the sleeve the tension of application of the wire was 7,715 pounds per square inch; for the remainder of the wire it was 41,000 pounds per square inch. At the breech end the wire abuts against a steel spool ring, B, which is screwed upon the gun-body. The curved space at the rear of the recess in the body is filled up and given flat surfaces for winding against by a wrought-iron filling ring, which is in two parts, jointed as shown in Plate I. At the front the wire abuts against a ring composed of two concentric rings: the inner one, of wroughtiron, is in two parts, with straight radial joints, it serves to fill up the curved space in the body of the gun, and is held together by the outer steel ring, E, which is screwed upon it. The outer portion of the wire over the powder-chamber abuts at the front end against the trunnion band. All of the spool and filling rings were put on cold.

The steel ring A was bored with a conical hole, the larger diameter in rear, the difference of diameters being .05 inch. It was put on with a shrinkage of .0484 inch, equal to .00165 inch per inch of diameter. The trunnion ring C, of steel, was put on with a shrinkage of .0368 inch, equal to .00102 inch per inch of diameter, the sleeve D with .0228 inch, equal to .0006 inch per inch of diameter, the ring F with .0444 inch, equal to .00148 inch per inch of diameter. These shrinkages, except for the trunnion band, are slightly different from the theoretical ones, as will be explained later.

The front part of ring F is cut away on the outside for the purpose of easing off the pressure on the cast-iron body.

The ring G is to be made as near a fit as practicable, and screwed on cold.

The diameter of the rifled part of the bore across the lands is 10 inches, across the grooves 10.12 inches, the grooves thus being .06 inch deep. That of the shot-chamber from the front edge of the band to the base of the projectile is 10.20 inches; that of the powder chamber 10.85 inches. The length of the powder-chamber from the front end of the breechblock recess to the base of the projectile is 56.25 inches; that of the bore from the base of the projectile to the muzzle 227.25 inches. The total length of the gun is 300.75 inches, or 30.075 calibers. The form of the front end of the powder-chamber is shown in Plate I.

THE RIFLING.

The twist of the rifling increases from 1 turn in 120 calibers at the origin to 1 turn in 35 calibers at 10 inches from the muzzle, from which point to the muzzle it continues at the same rate. The developed curve is a semi-cubical parabola whose equation, referred to an element of the bore and the developed section at the origin of the rifling, is,

(y+.35256)2= .00001508(x+20.2)3

The number of lands and grooves is 50. The lands are .18 and the grooves .4488 inches wide.

BREECH-MECHANISM.

The breech-mechanism is of the interrupted screw system, designed for use with a DeBang gas check, and presents no new features. The composition of the block-carrying tray is,

The weight of cast-iron body is 17 tons, that of the steel wire 9 tons, and of other steel parts 3 tons, making the total weight of the gun, exclusive of the breech mechanism, 29 tons. The axis of the trunnions passes through the center of gravity of the gun when the breech-block is inserted; thus the gun is without preponderance.

PART II.

The plant.

THE BUILDING.

The building in which are placed the winding lathe and the furnaces for soldering and tinning was erected for this purpose. It is a frame structure with a slate roof, 66 by 42 feet, with an extension 20 by 17 feet in the prolongation of the lathe, the latter made necessary by the

determination to bore and rifle the gun at this arsenal, not at first intended.

The building was commenced on October 22, 1884; the asphaltum floor was finished on January 20, 1885. Preparations for setting the lathe, building the furnaces, &c., were carried on concurrently with the erection of the building. A railroad track of the ordinary guage runs through the middle of the building lengthwise. The building is heated by steam.

THE SOLDERING FURNACE.

It was designed by Dr. Woodbridge.

The heating-chamber is an oven 370 inches long, 54 inches wide, and 66 inches high. Running along the bottom of the oven are two 9-inch I-beams resting on cast-iron supports, forming a railway for the trucks carrying the gun. Resting on the lower flanges of the I-beams and forming the floor of the oven is a sheet-iron diaphragm. The sides and top of the oven are plastered to a thickness of 1 inch with a mixture of fine molding sand and clay, wet with equal parts of water and molasses, to this being added as much fine sawdust and chopped manila rope as would work well, the whole being thoroughly worked together. This plaster was supposed to have very little conductive power and little tendency to crack at the temperature employed.

For the purpose of determining the temperature of the oven there were to be hung within it eight mercury thermometers, opposite to glasscovered apertures or peep-holes. Six of these were distributed at equal distances along the side of the oven near the top, the remaining two being lower down and near the ends. They are marked h in the drawing. Small cranks, worked from the outside, served to move the ther mometers up and down, so as to expose a sufficient length of their scales. The ends of the oven were closed by cast-iron doors covered with the plaster before described.

Without the furnace are projections, marked W, in which to rest windlasses for hauling the gun in and out.

Below the floor of the oven and distributed equally along its length are six fire-places, with brick sides and cast-iron tops; each cover being made of separate plates, so that they might slide over each other under the expansive action of the heat.

Connecting with each fire-place is a 5-inch pipe, running into a 6-inch pipe at the rear, and finally leading through an 8-inch pipe to the flue.

The fuel was charcoal, at first intended to be burned directly on the floor of the fire-place, but trial having shown it to be difficult to attain the proper temperature at the ends of the oven, the end fire-places were provided with grates extending about half way across.

When burnt upon the floor the charcoal was passed through the upper door and burned in a little pile covering the damper.

For introducing the solder, holes were left at intervals along the top of the oven; they were covered by a casting shaped like a bucket and filled with the plaster mixture.

A continuation of the I-beam railway was provided, extending for a sufficient distance in front of the furnace to rest the trucks and gun upon it, preparatory to running them into the oven.

The gun, while in the oven, was to have been revolved by means of a shaft projecting through the door, to which was keyed a worm-wheel rotated by suitable gearing and pulley from overhead shafting.

To convey the melted solder over the furnace, an overhead crane was provided, running its entire length.

1

This furnace was used in an attempt to solder a trial cylinder, assembled in connection with the construction of this gun. The attempt not having proved successful, it was abandoned with reference to the gun, and the furnace became useless for the purpose for which it was intended.

THE SHRINKING APPARATUS.

When, in the course of the construction of the gun, the operation of shrinking on the hoops was reached, it became necessary to devise some means of heating them, and for this purpose one end of the soldering furnace was utilized.

A brick wall was built, partitioning off at one end of the oven a heating-chamber 83 inches long. The fire-place at this end was torn out and a new one built in, with a grate for burning anthracite coal. The door and damper were changed, larger ones being substituted. The draught-pipe was enlarged. The large end door was fitted with counterweights, and arranged to slide vertically. A short prolongation of the I-beam railway was arranged, for the truck carrying the ring to be run in and out upon.

The overhead crane was utilized to lift the heated ring from the truck and carry it into place on the gun. Also to carry the "following ring" for pressing the hoop, while cooling, up to its place.

The fuel used was chestnut anthracite coal.

The principal other shrinking appliances are those for producing a tight joint between a ring and the shoulder against which it is to rest. Two large castings, a and b, rest, one against a shoulder on the gun, and the other against the ring being placed. Between these castings extend four wrought-iron rods, r, each 3.5 inches square, one end of each rod being threaded for a nut. While the ring is being heated in the furnace, these rods are expanded by the flame of gas-burners g. As soon as the ring is in place on the gun, the casting h, or following ring, is brought up against it, the rods slipped into place, and the nuts screwed up.

The contraction of the rods upon cooling pulls the following ring against the hoop with such force as to keep it pressed up to its place. The amount of force is regulated by a gauge which rests against the end of the rod and the face of the nut. The rod being expanded more than necessary, the nut is placed so that the gauge fits, thus restraining the rods from contracting to their cold lengths by a fixed amount. The operation of shrinking on a hoop is as follows:

The hoop is in the heating-chamber, placed horizontally upon the truck, and encircled by an iron band with an eye in it for lifting. The door is closed. The following ring is suspended from the overhead crane, above and in front of the door of the heating-chamber. The chain · fall for lifting the hoop hangs from the overhead crane in a convenient position. The gun is directly in front of the heating-chamber, supported on blocking. As some of the rings in going to their positions had to pass the center of gravity of the gun, the latter had to be counterweighted to prevent it from tipping. A 9 inch I-beam was passed into the powder chamber, a fit being obtained by perforated wooden plugs. On this I-beam was hung an old cast-iron 8 inch gun.

The upper rods of the press are drawn up into the position for heating, and retained by ropes tied with slip-knots. The lower ones are swung out sufficiently and rest upon greased iron bars. To each rod its own gauge, properly marked for setting the nut, is attached by a thread. The gas under the rods is burning; their expansion has been

measured and found to be more than sufficient. The water-sprinkling ring for cooling the hoop is on the gun near its position for use. Two watering-pots for cooling off the rods of the press stand full of water near by, a supply of water in barrels being convenient.

The diameter of the hoop has been measured by means of a measuring-rod attached to the end of a long stick, passed in through an aperture, uncovered for the purpose, in the door of the heating chamber.

At the command the door is opened by a man on top of the furnace, the truck is pulled out, the diameter of the hoop verified, the hook of the falls engaged in the eye of the band encircling the hoop, and the hoop raised. As soon as it is at the proper height the carriage is pulled forward on the traveling crane by a rope attached to the carriage and passing through a pulley at the end of the crane. The hoop is guided by two men. As soon as the hoop is clear of the truck, the following ring is lowered and pulled forward after the hoop. The hoop being up against its shoulder the following ring is brought up against it, the gas pipes pulled from under the press rods, the lower rods slid into place and the upper ones lowered, the nuts set in proper positions by means of the gauges, the threads holding the latter to the press rods being snapped. The nuts being adjusted the rods are immediately cooled off with the watering pots. As soon as the sprinkling of the rods is commenced the water is turned on in the water-ring and the gun immediately in rear of the hoop kept cool. This ring is afterwards advanced to the rear edge of the hoop and subsequently over the entire hoop. Eleven men are required, each one of whom is of course thoroughly instructed in his duties, and all several times drilled in the operation.

For shrinking the sleeve a gas ring was also used, a circle of burners keeping the forward end warm until the rear end had clamped the gun.

THE LATHE

was brought from Frankford arsenal, where it had been used in the construction of the brazed 10-inch wire gun finished in 1876.

It is now, the head-stock having been raised, capable of swinging a piece 61 inches in diameter and 456 inches long. It is not built as a modern lathe of its capacity would be; the ways are too light and the carriage attachments are not up to date. Still it has proved and is a serviceable tool.

The additions for boring and rifling the gun were made at this arsenal, the design being by Mr. H. P. Elwell, draughtsman.

The bar is of cast iron, 9.75 inches in external diameter. It is hollow, in two pieces joined together. It rests in bearings on two deep I-beams, which are supported on castings, d, part of which rest on the ways of the lathe and part on a continuation of the ways formed of I-beams joined together by transoms and resting on masonry supports.

For boring, the gun is revolved, and the bar is fed forward by a screw which runs along its axis. The screw is revolved by a worm-gear, the motion being derived from bevel-gears and a shaft running from the head-stock, between the ways, directly under the axis of the lathe. A cutter-head carrying seven cutters is used.

In rifling, the gun is stationary, and the bar is moved forward by the same screw, but a more rapid motion is given than is possible with the worm-gear by a gear and friction pulleys at the end of the bed b. The friction-pulleys are run by a belt from overhead shafting, which again is run by a pulley on the shaft between the ways.