within that distance, as that of a 68-pound shot when it first leaves the muzzle of the gun, since the mean velocity of flight in passing over a distance of 2,150 yards was exactly 1,200 feet a second, the time of flight being 5.31 seconds. I believe it is in contemplation to arm the "Warrior" and ships of her class with thirty-six 100-pounder Armstrong guns, which are of about 4 tons each, whilst the gun I have just mentioned is of about 6 tons. Now it appears to me that twenty-four guns of this description would prove a much more efficient armament than thirty-six of the Armstrongs, which have not shown much power against iron plates. There would be besides several advantages attending such a change. One of which would be, that two portholes only would be necessary where there are now three, and that in the future construction of this class of vessel the parallel sides would require to be of less length by 90 feet, since the same intervals only (15 feet) would be required for the purpose of working the guns. Those who heard Mr. Scott Russell's most interesting lecture at the Institution of Naval Architects will both understand and appreciate this suggestion.

But to return to the subject more immediately under discussion, I would remark that I believe no sea-going vessel can carry plates of any description which shall render her sides proof against the penetration of solid shot, and therefore that these vessels should only be protected as far as may be possible, without depriving them of other and vitally important qualities, and this, I believe, may be done in a manner to prevent the penetration of incendiary and explosive projectiles of a very heavy description, by some such distribution and arrangement of the metal as that which I have now the honour to introduce to your notice.

A powerful armament and great speed are matters of the very highest importance, and not to be lightly sacrificed; in fact, an iron-cased vessel wanting these qualities would present a mere inert target to a more active and better-armed opponent; and her certain capture and destruction would be simply a question of time. A ship of war is commissioned to "burn, sink, and destroy," and not simply to save herself from being burnt, sunk, or destroyed. In conclusion, I would remark that, having no experience in ship-building, but having had great experience in the effect of shot upon various materials, I have regarded the sides of a ship in this question in the light simply of a protection against destructive missiles, that is, in what manner the greatest protection can be afforded with the employment of the smallest possible weight.

The following is an explanation of the plate:

Fig. 1 represents a transverse section of the side of an iron ship protected by the armour-plates, a a being the side or skin of the ship of a zigzag form; bb the outer or "louvre" plates; c is the bolt which fastens the latter on to the former. The spaces between the louvre plates may be filled with some elastic substance.

Fig. 2 gives a front view of the bolt c.

Fig 3 shows the manner in which the inside plates are connected one with another in a longitudinal direction, d d d being the rivets, which are placed at certain intervals apart.

Fig. 4 is a front view of the vertical join, a a being the plates which

form the side of the vessel, and e the plate which is placed at the back to strengthen them at the joint. This plate is also made fast with three rows of rivets.

In reply to various questions, Mr. Thomas stated that the gross weight involved in the proposed form would be one-fourth less than, and, according to the calculations of a well-known Iron Company, the expense about one-half (251. instead of 50l. a-ton) the expense of the "Warrior,"-that the saving would result chiefly from all the plates being rolled at the cost of about 81. a-ton, whereas the "Warrior's" plates are very expensive, especially where there is tongueing and grooving,-that repairs could be made with great facility, without disturbing any but the injured parts. The width and thickness of the armour-plates would be adapted to the size and tonnage of the vessel. It will be impossible to give a small vessel a protection equal to that of a large vessel; the effect of the shot's impact is diverted, so that the blow upon the inner plate is not felt in the direction in which the shot is moving, but at a point above it, which considerably lessens the destructive effect. The spaces between the plates may be packed or not with some elastic substance, but the packing was objected to as giving rise to the deposit of a great deal of moisture. The inside plates of iron, or skin of the ship may be flat instead of a zigzag form, but the latter offers a better resistance to shot.

The CHAIRMAN conveyed the thanks of the meeting to Mr. Thomas for his interesting and instructive paper, and the proceedings then terminated.

Monday, June 24th, 1861.

COL. P. J. YORKE, F.R.S., in the Chair.

NAMES of MEMBERS who joined the INSTITUTION between the 17th and 24th June, 1861.

LIFE.

Browne, Henry, R., Lt.-Col. 87th Royal Irish Fus. 91.

Arkwright, A. P., Comr. R.N. 11.

ANNUAL.

Greville, A. C., Major Unatt. 1.

Le Geyt, W. B. Esq. Assist. Mil. Storekeeper, Cape of Good Hope.

ON THE INFLUENCE OF ATMOSPHERIC PRESSURE UPON THE BURNING OF TIME-FUSES.

By E. FRANKLAND, F.R.S.,

Lecturer on Chemistry at St. Bartholomew's Hospital.

[Abstracted from a paper read before the Royal Society, June 20th, 1861, entitled "On the Influence of Atmospheric Pressure upon some of the Phenomena of Combustion."] WHILST engaged in some experiments on the influence of atmospheric pressure upon the rate of combustion of candles, which were found to burn with the same rapidity on the summit of Mont Blanc as in the valley of Chamonix, Colonel Philip Yorke directed my attention to some analogous experiments with the time-fuses of shells, made in India by Quartermaster Mitchell, and which led to a different result. These latter experiments are described in a letter dated Jan. 6, 1855, an extract from which appeared in the Proceedings of the Royal Society.* Quartermaster Mitchell found from a series of carefully conducted experiments, that the rate of combustion of time-fuses was subject to considerable retardation, which he attributed to the diminution of atmospheric pressure at elevated stations causing a more scanty supply of oxygen. The following is a short statement of the results of these experiments, in which three-inch fuses were burnt under different atmospheric pressures.

Comparing the amount of retardation with the corresponding reduction of pressure, we have the following results:

Although these results are perfectly compatible with those obtained with candles above alluded to, yet the subject seemed to me of sufficient techni cal importance to warrant a repetition and extension of these experiments in artificially rarefied air. With this object in view, a large iron cylinder was connected on the one hand with an air-pump, and on the other with a piece of gas-pipe six feet long and four inches internal diameter, the opposite end of the pipe being furnished with an arrangement by which the end of the fuse to be ignited could be introduced air-tight within the pipe, whilst the closed end of the fuse projected about two inches into the external air. The fuses were ignited at a given instant by a voltaic arrangement consist ing of ten cells of Grove's battery, an instantaneous contact-maker, and a piece of thin platinum wire which was inserted into the priming of the fuse. In order to ascertain with precision the moment when the deflagration was finished, the lateral hole at the posterior end of the fuse was bored through to the opposite side; a piece of thread was passed vertically through this aperture and secured above to a convenient support, whilst an iron ball was affixed to its lower extremity at a distance of a few inches above a metallic plate upon which the ball fell when the fire reached the thread, thus indicating the moment when, under ordinary circumstances, the fire of the fuse would be communicated to the contents of the shell. The pressure was indicated by a mercurial gauge inserted into the gas-pipe.

The experiments were made with six-inch fuses (for which I was indebted to the kindness of Mr. Abel, the Director of the laboratory at the Woolwich Royal Arsenal) in the following manner. The fuse being inserted into the end of the gas-pipe, and the necessary degree of exhaustion in the iron cylinder and pipe having been obtained, the fuse was ignited at a given signal. During the continuance of its deflagration an assistant worked the air-pump, so as to prevent any great rise in pressure, whilst another observed the vacuum gauge at the moment when the iron ball dropped. The mean between the pressure at the commencement of the deflagration and that at the end, was assumed to be the mean pressure under which the fuse had been burnt; but it is obvious that this assumed mean pressure can only be approximative, although the gauge fell very regularly and gradually during the continuance of the deflagration.