APPENDIX I.

REPORT OF THE COMPARATIVE PROOFS OF FIVE EXPERIMENTAL 24-POUNDER GUNS.

SIX experimental 24-pounder guns-cast under the direction of Mr. Fairbairn by the Bank Quay Foundry, Warrington, during the months of August and September 1855-were made for the purpose of ascertaining by experiment in how far it was possible to improve the quality of the iron, and under what conditions cast-iron ordnance should be treated in the operation of moulding, cooling, &c. The castings were lettered A, B, C, D, E, and F. Letter F was cast with a core, but the great heat caused it to adhere to the metal, and the cast was in consequence a failure. The other five were gauged, examined, and proved in the Arsenal on the 9th and 23rd October 1855. Subsequently they were removed to the marshes, and the experiments for testing their comparative merits commenced on the 30th November and ended on the 21st December of the same year.

After three days' firing letter C gun burst. It was then deemed expedient to substitute cylinders of equal gross weight to the large number of shot and wads which had been used up to that time. In consequence of this arrangement an interval of ten days elapsed, during which the cylinders were prepared.

The guns were placed on the ground, their muzzles being supported by blocks of wood, as used in the proof of ordnance. Sods of earth were placed behind them for the first few rounds, but they diminished the recoil to such a trifling extent that large beams of wood were substituted. Even these proved insufficient to resist the recoil when the guns were heavily shotted. One beam 12 inches square was split through its entire length, 13 feet, by a single discharge, the force of the discharge having been against the breech or the button end of the gun. As the guns continued to recoil up the slope, holes were dug in the stiff clay about 2 feet deep to receive them; this reduced the recoil from 10 or 12 feet to as many inches. Still they steadily worked their way even into the clay, in consequence of which new holes were dug,

and heavy piles of timber driven into the ground with cross-beams to receive the first shock. By this means the labour of loading was much diminished, and the bulkheads effectually resisted any further recoil. The guns too, being sunk below the surface of the ground, were prevented from injuring the adjacent ones when they burst.

The proof was carried on with portfire and clay in the usual

Cylinders averaging 144 lbs., or equal to six spherical shot, were here substituted for that number, and one wad over the powder was henceforth only used :

D having burst at the second round, it was considered better to give the remaining ones another round with the same charges of powder and weight of shot, instead of increasing them as usual after two rounds. The result proved this had been judiciously proposed, as B burst after the 3rd, and A and E together at the 4th round.

From the foregoing it follows that

It was not possible to recover the whole of the fragments, but in each case the greater number have been found, and, as far as can be ascertained from these data

The muzzles of the guns in each case (except E, which was not observed) were found pointing to the left after bursting.

From the position in which each stood at the time of bursting, the breeches were prevented from flying off far to the rear. Those of B, C, and D buried themselves in the bank; that of A, and also of E, fell into the ditch a few yards in rear. In these two guns the first fracture evidently took place in the lower half of the gun, for the holes made in the earth were deeper and wider than the rest, some fragments of E being buried 3 feet in the earth. The cascable of each of the guns was blown upwards clear of the bulkheads in rear, and fell into the ditch in one case, and on the bank in the other. The fragments of these guns also were carried to a greater distance by the explosion than those of the others, some falling into the river on the left, and others going several hundred yards to the right-one as much as 700 yards. This proves the resistance offered by these guns to the bursting force of the powder to have been very great.

The directions in which the principal fragments of each gun flew were very similar. It was observed that in almost every case two pieces from about the first reinforce fell into the field on the further side of the manor ward.

A fragment from the second reinforce of D, which must have risen to a considerable height, struck the top of the traverse beneath which the party had taken shelter, and fell close to them.

Another from the same part of B, and of a similar size and shape, fell within three yards of the same spot.

The trunnions of B, with but little metal attached, were found nearly touching each other in their original position, the body of the gun having been blown from between them.

The cylinder and shot where each gun burst were driven out by the explosion as usual, except in the case of A, where one-half the cylinder was found among the pieces of the gun, and near the spot on which it had stood. The gun had evidently burst before the vis inertia of the charge had been overcome, and the escaping gas forcing the sides of the cylinder against the fracture broke it in two-one part going into the butt, the other remaining with the fragments of the gun. The fracture of the muzzle portion of this gun bears marks of having acted

as a fulcrum. The fractured surfaces of C and D guns and the general direction of the lines of separation indicate great similarity in the structure of the metal. It will be observed that they broke at the same distance from the muzzle, the left trunnion remained on each, and they broke into 19 and 17 pieces. B burst nearer the muzzle than any other, and into the greatest number of pieces. The fractured surfaces were regular and even, with the exception of the cascable which was much torn.

The surfaces of A are irregular and ruffled except the cascable, which is very smooth. This gun and also E burst in the line of the vent, and the end of the bore in each of the five guns was left perfect.

The appearance presented by the fragments of E was indicative of a greater degree of tenacity than any of the others. The cascable especially was torn in a singularly irregular manner.

Judging from the appearance of the fragments, the order in which the guns would stand are E (best), then A, C, D, and B.

One fragment of C 2 cwt. fell 250 yards to the right.

Minute portions of each gun were also examined under the microscope, and gave results as follows:

(A) This specimen did not exhibit a crystalline structure, its surface was much indented with a few pointed projections bright silvery globules in considerable numbers.

(A)

(B)

(B) Specimen larger than A, moderately-sized crystals apparently cubical. Surface less rugged than A, and inferior to it in general indications of tenacity.