Juliers, were carried on in the month of September, 1860, especially with reference to the effect of rifled breech-loading guns.

The following brief summary of the breaching experiments is taken from the report of Lieutenant Colonel A. Ross, Royal Engineers:

Four 12-pounder iron guns and two 12-pounder brass guns, weighing, respectively, 2,700 pounds and 1,300 pounds, throwing a conical ball weighing 27 pounds, and fired with a charge of 2.1 pounds, at 800 Prussian paces (640 yards), made a practicable breach 32 feet wide in a brick wall 3 feet thick, with counter-forts 4 feet thick, 4 feet wide, and 16 feet from center to center, the wall being 16 feet high, and built en decharge, after firing 126 rounds. Thee first six rounds are omitted from this calculation, as they did not strike the wall, the wall being entirely covered from the guns. No difference was observed between the effects of the brass and the iron guns. The bursting charge of the shells was fourteen-fifteenths of a pound. The penetration was 15 inches.

Six 6-pounder guns, four of iron and two of cast steel, weighing, respectively, 1,300 and 800 pounds, throwing a conical shell weighing 13 pounds, and firing with a charge of 1.1. pounds, at 50 paces, made a practicable breach 70 feet wide, in precisely the same description of wall as that above described, after firing 276 rounds, the battery being situated on the counterscarp opposite the wall. No difference was observed between the effects of the cast steel and iron guns. The bursting charge of a shell was half a pound. The penetration of the first single shot averaged 18 inches.

Four 24-pounder iron guns, weighing between 53 and 54 hundredweight, throwing a shell weighing 57 pounds and firing with a chargee of 4 pounds, at a distance of 60 yards made a practicable breach 62 feet wide in a loop-holed brick wall 24 feet high and 6 1/2 thick after firing 117 rounds, the wall being seen from the battery. The bursting charge of the shell was 2 pounds. The penetration of the two first single shots was 2 1/2 and 3 feet.

The same guns, after firing 294 rounds with the same charges and at a distance of 96 yards, made a breach 46 feet wide in a brick wall 40 feet high and 12 feet thick at the foot, with a batter of about 4 feet. The wall was 12 feet thick, and built en decharge, with counter-forts 6 feet wide and 16 feet from center to center, and connected by two rows of arches, one above the other. The penetration of the first single shot was 3 feet and 3 1/2 feet. All the above-mentioned guns were rifled breach-loaders.

It is impossible to institute a very close comparison of the relative value of rifled and smooth-bore guns for breaching purposes from any data which experience has thus far developed.

The experiments at Eastbourne, hereinbefore mentioned, are the only ones on record where they have been tried side by side to the extent of actual breaching against the same kind of masonry and at the same distance. We have seen how on that occasion the rifles were a complete success, while the smooth-bores were an utter failure.

At Fort Pulaski an excellent opportunity was afforded on the scarp wall near the breach for obtaining the actual penetration of the several kinds of projectiles. An average of three or more shots for each caliber was taken, giving the following results, which may be relied upon as correct:

Table of penetrations in a brick wall, as determined at the siege of Fort Pulaski, Ga., April, 1862.

Kind of gun. Distance Kind and Eleva- Charge. Pene-

from weight of tion. trati-

wall. projectiles. on.

Yards. ^ Lbs. Ins.

Old 42-poun- 1,650 James, 84 4 1/4 8 26

der, rifled Ibs., solid

Old 32-poun- 1,650 James, 64 4 6 20

der, rifled Ibs., solid

Old 24-poun- 1,670 James, 48 4 1/2 5 19

der, rifled Ibs., solid

Parrott 1,670 Parrott, 30 4 1/2 3 1/2 18

rifled gun Ibs., solid

Columbiad 1,740 Parrott, 128 4 1/2 20 13

(10-inch), Ibs., solid

smooth bore round

Columbiad 1,740 Parrott, 68 5 10 11

(8-inch), Ibs., solid

smooth bore round

The above table indicates very prominently, although it affords no exact means of measuring, the great superiority of rifle over smooth bore guns for purposes requiring great penetrating power.