MISCELLANEOUS EXPERIMENTS.
The following experiments, extracted from Mr. Wilkinson’s “Engines of War,” serve to illustrate the capability of metals to resist the force of gunpowder, and may be of some practical utility, as well as prove interesting merely as matter of curiosity.
Experiment 1.—A piece about 5 inches long was cut off the breech-end of a common musket barrel. It was screwed at the part cut, and another plug fitted, so as to have two plugs, one at each end, leaving an internal space of about 3 inches. A percussion nipple was screwed into the end of one of these plugs. This being arranged, one of the plugs was turned out, and one drachm of gunpowder introduced. The plug was replaced, and the powder fired by putting a copper cap on the nipple, and striking it with a hammer. The whole force of the powder escaped at the hole in the nipple. Two, three, four, five, and six drachms were successively introduced, and fired in the same manner, without bursting or injuring the piece of barrel. At last, seven drachms forced out one end, in consequence of the screw having been carelessly fitted. This defect being repaired, Mr. Marsh, of Woolwich, repeatedly fired it with five drachms, merely holding it with a towel in his left hand, and firing it with a blow of a hammer. Six drachms of powder is the full service charge for a flint musket, and four drachms of a percussion musket; yet this immense pressure can be resisted by a cylinder of iron not more than one quarter of an inch thick, and not iron of the best quality.
Experiment 2.—A good musket barrel had a cylinder of brass, three inches long, turned to fit the muzzle, and soldered in, so as to close it air-tight. The plug, or breech-screw, was removed, and a felt wad was pushed in with a short piece of wood, marked to the exact depth the charge would occupy, to prevent the ball rolling forward. A musket ball was then dropped in, and a cartridge, containing three drachms of powder, was introduced. The breech being screwed in, left the barrel loaded. It was fired by a percussion tube, but there was no report. On removing the breech-screw, the ball was found to be flattened. A repetition of this experiment, with four drachms, produced a similar result, but the ball was rather more flattened. With five drachms, the ball was perfectly round and uninjured. Six drachms burst the barrel close under the bayonet stud; the ball escaped through the opening, disfigured, but fell close to the barrel. In these experiments the barrel always advanced, instead of recoiling, as usual.
Experiment 3.—Made at Woolwich Arsenal, with a Gomer mortar, the chamber being bored conically, so that the shell, when dropped in, fits closely all round, instead of being bored cylindrically, with a chamber in the centre. The mortar being laid at an angle of 45°, one drachm of powder was put into the bottom, and a 68-pounder iron shot over it. When fired, the ball was projected two feet clear of the mortar. A wooden ball, precisely the same diameter, but weighing only 5lbs., was scarcely moved by the same charge, and with two drachms of powder it was just lifted in the mortar, and fell into its place again. Here we find a weight of 68lbs. thrown to the distance of two feet by the same power which would not lift 5lbs., and the wooden ball scarcely moved by double the powder.
This proves that the firing of gunpowder under such circumstances is not instantaneous. In the first instance, the small quantity of powder had a large space to fill below the ball, and a heavy weight to move; therefore, could not stir it at all until the whole was ignited, when the force was sufficient to throw it forward two feet. In the second case, the first portion of gas that was generated by ignition of the powder, was sufficient to lift the lighter weight, just enough to allow all the force to escape round it before it had time to accumulate.
Experiment 4.—A cannon ball, weighing 24lbs., was placed exactly over the vent-hole of a loaded 32-pounder cannon, which was fired by a train of gunpowder, when the rush from the vent projected the 24-pounder ball to a very considerable height in the air, although the diameter of the hole was only two-tenths of an inch.
Experiment 5.—A most ingenious method of ascertaining the relative quickness of ignition of different qualities of gunpowder.
A gun-barrel mounted on a carriage with wheels, and moving on a perfectly horizontal railway, is placed at right angles to another short railway, at any convenient distance (suppose fifty feet, or yards); on the second railway a light carriage moves freely with any desired velocity, being drawn forward by means of a weight and pulleys: a cord is attached to the front of this carriage, which passes over a pulley at the end of the railroad, and is continued up a high pole or staff over another pulley at the top, at which end the weight is attached. A long rectangular frame covered with paper is fixed perpendicularly on the carriage, so that when it moves forward it passes across the direct line of the barrel, and forms a long target. A percussion lock is attached to the barrel, which is fired by a detent, or hair-trigger, and the wire which pulls it is disengaged at the same instant to admit of recoil. This wire is carried straight on to the target railroad, and fixed to a small lever, against which the front part of the target-carriage strikes as it is carried onwards by the weight. This constitutes the whole apparatus. When required to be used, the barrel is loaded with gunpowder accurately weighed, and a brass ball that fits the bore correctly: the weight is then disengaged, and the target moves quickly along, discharging the barrel as it passes, and the ball goes through it. With the same powder tried at the same time, the ball constantly goes through the same hole, or breaks into it. If the next powder tried be slower of ignition than the preceding, the ball will pass through another part of the target more in the rear; if quicker, more in advance; thus affording a means of ascertaining this important quality of gunpowder with considerable accuracy: the velocity of the target-carriage can be easily regulated by increasing or diminishing the weight which draws it forward. The differences in the distances between which the balls strike the target with different kinds of powder was frequently as much as ten or twelve inches; but it is not an apparatus commonly used, having been merely constructed for experimental purposes.