This Gruson Quick-Fire Guns, Carriages, Ammunition and Ballistics.
In the first part, a complete description, with drawings, is given of the breech mechanism, together with instructions for mounting, dismounting and using it. The second part includes a description, with drawings, of the guns, their mountings and ammunition. There are three calibers given—the 3.7 centimeters, length 23 calibers; the 5.3 centimeters, of lengths of 24,30 and 39 calibers; and the 5.7 centimeters, of 25 calibers length. The third part includes the range tables for these various guns.
The gun material is crucible steel of a tensile strength (minimum) of 35.5 tons, and an elastic strength of 16.5 tons. The breech-block works similarly to that of the Hotchkiss guns, there being, however, but one handle on the right side, which throws upward and forward to close the breech. The extractor acts differently, and the action of the hammer is much more complicated. There is a great variety of ammunition, the shrapnel being fitted with a readily adjustable time-fuze which forms the head. The Desmarest fuze is used in the shell. One shell, called the ring shell, is formed internally of a number of star-shaped rings of eight points, the body of the shell being cast round these rings. Experiment has shown that these shell for the 5.3 cm. gun break on explosion into sixty effective pieces.
The charge for each gun is about one-fifth the weight of the projectile, this latter differing little from the Hotchkiss. The powder used is rather small- grained, and the initial velocity is low. Trials have been conducted with improved powders and better results obtained, but no range tables have been determined as yet. Trials for endurance have given excellent results, two thousand rounds having been fired in some cases from the same gun without a trace of erosion or other alteration internally. J. H. G.
Researches on Explosives. Fired Gunpowder. By Captain Noble (late K. A.), F. R. S., etc., and F. A. Abel, C. B., F. R. S., etc. A reprint from the Proceedings of the Royal Society, by the Artillery School Press.
These researches contain a detailed description of the numerous valuable experiments of Messrs. Noble and Abel, which, it may safely be said, form the basis of all modern theories on the action of powder in guns and enclosed spaces generally. Comment at this day on these experiments, the worth of which is so well known, is unnecessary. They show, among other things, the pressures (measured with crusher gauges) obtained when powder is exploded in various volumes. They prove that a part of the products of combustion of powder is, immediately after firing, in the liquid state, and that the volume of this liquid is about the same as the original aggregate volume of the powder grains.
From their experiments, Messrs. Noble and Abel argue that the liquid residue imparts heat to the gaseous products as the gases expand in a gun, and this is the main point in which they disagree with other authorities on the same subject, as Messrs. Bunsen and Scheschkoff, M. Sarrau and M. Sebert, who argue that the gases must have more time than that occupied in a gun to part with or absorb an appreciable quantity of heat. These, in turn, argue that the liquid residue heats the gun by radiation and contact.
Messrs. Noble and Abel’s formula for the work that can be done by a charge of powder in a gun is deduced on the supposition that the powder is all burnt at the instant of maximum pressure. A certain factor of effect deduced by experiment is then applied, to get the actual work done in the gun. This is of doubtful efficacy with slow powders, inasmuch as it is variable for different guns with quick powders. The work done in a gun by a quick powder approaches very closely to that done by the maximum powder (on the principle that a function near a maximum varies very slowly), and may, for practical purposes, be considered the same. The true theory of expansion would then give a factor of effect constant for different guns, if quick powders of the same force were used in all the guns.
Messrs. Noble and Abel do not touch on the subject of maximum powders, though the fact that such powders exist seems well established. Altogether, however, they have supplied a fund of exceedingly valuable information to students on the action of powder in guns. The subject, in view of the large charges now used in naval guns, is of especial interest to naval officers.
J. H. G.
Defense of the Sea-coast of the United States. By Bvt. Brig.-Gen. Henry L. Abbot, U. S. Army, Colonel Corps of Engineers.
General Abbot has given in this book his course of five lectures delivered before the U. S. Naval War College. These lectures contain a very clear exposition of modern thought and modern experience upon the subject of sea- coast defenses, and should be read by all naval officers. The weak points in the lectures will be found just where an army officer’s plans might reasonably be expected to be weak, that is, where the part to be undertaken by a naval force is touched upon.
In the fourth lecture, under the head of attacks by daylight and by night or in fogs, the lecturer undervalues the damage that may be done to the system of mines by creeping, sweeping and countermining, and the necessity of a naval force to prevent the destruction of his mines. In his opposition to the dynamite torpedo gun. he fails to see its usefulness to the attack when operated as a counterminer. Under the head of naval co-operation he exaggerates the importance of land defenses. He says: “So far as the position permits, the means of defense should be confined to the land; in that way only can economy, permanency, and security against torpedo attacks be secured.” As a partial illustration of this, he compares the cost of a fortress to that of a floating battery, but ignores the fact that the floating battery can move from point to point. Nothing is more clearly shown by modern experience than that without a naval force to aid the land defenses, a sufficiently powerful fleet will eventually destroy any system of mines and force a passage. Also that the land defenses should be sufficiently strong to resist the attack of two or three vessels and delay the advance of an enemy’s fleet, leaving to the naval force the duty of preventing the success of large fleets. In other words, it is necessary to protect our ports against sudden dashes of a fleet or attacks made by a few vessels; but if all of our ports, or even our more important ports, arc to be protected by land defenses against the attack of modern fleets, the cost would be far in excess of that necessary to create and maintain a naval force that would make us master of the seas. K. W.