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A Military Dictionary, explaining and defcribing the Technical Terms, Phrafes, Works, and Machines, used in the Science of War. Izmo. 2s. 6d. Jerved. Robinson.

HE prefent hoftile appearance in many parts of the king

dom, and the impending war between Great Britain and France, seem to have given rife to this publication; and as our newspapers are daily entertaining their readers with reviews, rencounters, manœuvres, battles, fieges, &c. &c. at the feveral encampments, this performance appears to be intended as a vade-mecum for the military quidnuncs, to whom an explanation of terms and phrases peculiar to the art of war, will be an useful and acceptable prefent. We are the rather inclined to confider the publication in this light, as we meet with little more than definitions or defcriptions of the technical terms, machines, and works, frequently made ufe of. These are in general tolerably exact, and not ill drawn up, though sometimes they have much the appearance of tranflations from fome French work; which nevertheless may be owing to the frequent defcriptions taken from the numerous French writings on this subject, where only such accounts are to be met with.

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The compiler of this Dictionary, however, does not seem to be fufficiently acquainted with the fubject, or at least not to have confulted the alterations and improvements in the military art, of modern times. This appears from his frequent ufe of obfolete terms, and fometimes giving accounts of things as laid down by old writers rather than from modern and improved relations. Thus under the term Bullet, he says,

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According to Marfenne, a bullet fhot out of a great gun, flies ninety-two fathoms in a fecond of time, being equal to five hundred and eighty-nine English feet and a half; but according to fome very accurate experiments of Mr. Derham, it only flies at its first discharge five hundred and ten yards in five half feconds."

That is, about 500 or 600 feet in a fecond of time; whereas it is now well known that fuch balls are usually projected with a velocity from 1000 to 1500, or even zooo feet per second. Again, under the word Cannon, he remarks,

The metal of which cannons are compofed, is either iron, or, which is more common, a mixture of copper, tin and brafs; the tin being added to the copper to make the metal more dense and compact; fo that the better and heavier the copper is, the lefs tin is required. Some to an hundred pounds of copper add ten of tin, five of brafs, and ten of lead."

VOL. XLVI. Sept. 1778,

Brav

• Braudius defcribes a method of making cannon of leather, and it is certain the Swedes made ufe of fuch in the long war in the last century; but they were too apt to burft to be of much fervice. Iron cannon are not capable of fo much resistance as thofe of brass, but as they are lefs expenfive they are often used aboard fhips, and in feveral fortified places.

The parts and proportions of cannon about eleven feet long are, the barrel or cavity nine feet; its fulcrum or support fourteen; and its axis feven; the diameter of the bore at the mouth fix inches two lines; the plug of the ball two lines; the diameter of the ball therefore fix inches, and its weight thirty-three pounds and one-third; the thickness of the metal about the mouth two inches, and at the breech fix; the charge of powder from eighteen to twenty pounds. It will carry a point black fix hundred paces, and may be loaded ten times in an hour, and often more. Cannon often fired must be carefully cooled, or elfe they will burft.

⚫ Cannons are diftinguished by the diameters of the balls they carry. The rule for their length, &c. is that it be fuch that the whole charge of powder be on fire before the ball quit the piece. If it be made too long, the quantity of air to be driven out before the ball, will give too much refiftance to the impulse; and that impulfe ceafing, the friction of the ball against the furface of the piece will leffen its velocity.

Formerly cannon were made much longer than they are at prefent; but fome being by chance made two feet and a half fhorter than ordinary, it was found that they threw a ball with greater force through a lefs space than the larger. This was confirmed by experience in 1624, by Guftavus Adolphus of Sweden; an iron ball of forty-eight pounds weight being found to go further from a fhort cannon, than another ball of ninetyfix pounds out of a longer piece; whereas in other respects it is certain the larger the bore and ball the greater the range.

• The greatest range of a cannon is ordinarily fixed at fortyfive degrees, but Dr. Halley fhews it to be at forty-four and a half. M. S. Julien adjufts the ranges of the feveral pieces of cannon, from the weight of the ball they bear, the charge of powder being always fuppofed to be in a fubduplicate ratio to the weight of the ball'.

In this article are many mistakes; for guns are now ufually made of iron, because found to be much stronger and more durable, as well as cheaper than the compofition with brafs; for guns of this latter metal foon become unferviceable by running and melting into a large hole at the vent; by being foon fpoiled in the chafe by the friction of the balls; and becoming bent, with hot fervice, like a ftick of fealing-wax when warm; fo that now only one fhip in the navy has brafs guns. Neither is the greatest range at an elevation of 45 degrees, nor even near it, unless the initial velocity be very small; every

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different velocity and ball requiring a different elevation to produce the greateft range; from 45 degrees downwards gradually to 30, or even lefs in very great velocities.

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Under the fame article of Cannon, he obferves, the new cannon, that are made after the Spanish manner, have a cavity or chamber at the bottom of the barrel, which helps their effect.' But this is not the cafe at present, the cannon being now made with a plain cylindrical bore, without any chamber at the top.

The article Gunpowder is well drawn up, and is as follows:

Gunpowder, a compofition made of faltpetre, fulphur, and charcoal, incorporated and granulated, which readily takes fire and expands with incredible force.

⚫ Bartholdus Schwartz, or the Black, was the firft who taught the ufe of gunpowder to the Venetians in 1380; but what fhews gunpowder to be of an older æra is, that the Moors, being befieged in 1343, by Alphonfus, difcharged a fort of iron mortars that made a noife like thunder. There is mention made of gunpowder in the registers of the chambers of accounts in France, as early as 1338. In fhort, our countrymen Roger Bacon knew of gunpowder one hundred and fifty years before Schwartz was born: for that friar exprefly mentions the compofition in his treatife De Nullitate Magia.

In order to reduce the nitre to powder, they diffolve a large quantity of it in as fmall a proportion of water as poffible; the keeping it continually ftirring over the fire, till the water exhales, a white dry powder is left behind.

In order to purify the brimstone employed, they diffolve it with a very gentle heat; then fcum and pass it through a double ftrainer. If the brimstone should happen to take fire in the melting, they have an iron cover that fits on close to the melting veffel, and damps the flame. The brimftone is judged to be fufficiently refined if it melts without yielding any fœtid odour, between two hot iron plates, into a kind of red subftance.

• The coal for making of gunpowder is either of the willow or hazel, well charred in the usual manner, and reduced to powder and thus the ingredients are prepared for making this commodity; but as thefe ingredients require to be intimately mixed; and as there would be danger of their firing, if beat in a dry form, the method is to keep them continually moist either with water, urine, or a folution of fal ammoniac; and to continue thus ftamping them together for twenty-four hours; after which the mafs is fit for corning, and drying in the fun, or otherwife, fo as fedulously to prevent its firing.

The explosive force of gunpowder is now a thing commonly known; but the phyfical reafon thereof may not, perhaps, be hitherto fufficiently underftood. In order to explain it, let us

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obferve, 1. That falt-petre, of itself, is not inflammable; and though it melts in the fire, and grows red hot, yet does not explode, unless it comes in immediate contact with the coals. 2. That brimftone eafily melts at the fire, and eafily catches flame. 3. That powdered charcoal readily takes fire, even from the fparks yielded by a flint and fteel. 4. That if nitre be mixed with powered charcoal, and brought in contact with the fire, it burns and flames. 5. That if fulphur be mixed with powdered charcoal, and applied to the fire, part of the fulphur burns flowly away, but not much of the charcoal. And, 6. That if a lighted coal be applied to a mixture of nitre and fulphur, the the fulphur presently takes fire, with fome degree of explofion, leaving a part of the nitre behind; as we fee in making the fal prunelle and fal polycreflum.

Thefe experiments, duly confidered, may give us the chemical caufe of the ftrange explofive force of gunpowder: for each grain of this powder, confifting of a certain proportion of fulphur, nitre, and coal, the coal prefently takes fire, upon contact of the fame fpark; at which time both the fulphur and the nitre immediately melt, and, by means of the coal interpofed between them, burft into flame, which fpreading from grain to grain propagates the fame effect almoft inftantaneously; whence the whole mafs of powder comes to be fired and as nitre contains a large proportion both of air and water, which are now violently rarified by the heat, a kind of fiery explosive blaft is thus produced; wherein the nitre feems, by its aqueous and ærial parts, to act as bellows to the other inflammable bodies, fulphur and coal, blow them into a flame, and carry off their whole fubftance in fmoke and vapour.

The discovery of this compofition was accidental, and per haps owing to the common operation of fulminating nitre with fulphur, for making of fal-prunella: it appears to have been known long before the time of Schwartz, as being particularly mentioned by friar Bacon, as we have before obferved.

The three ingredients of gunpowder are mixed in various proportions, according as the powder is intended for mufquets, great guns, or mortars; though thofe proportions feem hitherto not perfectly adjufted, or fettled by competent experience.

There are two general methods of examining gunpowder: one with regard to its purity, the other with regard to its strength: its purity is known by laying two or three little heaps near each other upon white paper, and firing one of them; for if this takes fires readily, and the fmoke rifes upright, without leaving any drofs, or feculent matter behind, and without burning the paper, or firing the other heaps, it is esteemed a fign that the fulphur and nitre were well purified; and the coal was good; and all the three ingredients were thoroughly incorporated together but, if the other heaps alfo take fire at the fame time, It is prefumed, that either common falt was mixed with the nitre, or that the coal was not well ground, or the whole mafs

not:

not well beat and mixed together; and, if the nitre or fulphur was not well purified, the paper will be black or spotted. In order to try the ftrength of gunpowder, there are two kinds of inftruments in ufe; but neither of them appear more exact than the common method of trying to what distance a certain weight of powder will throw a ball from a mufquet.

To increase the ftrength of powder, it feems proper to make the grains confiderably large, and to have it well fifted. from the fmalleft duft. We fee that gunpowder reduced to duft has but little explofive force; but, when the grains are large, the flame of one grain has a ready paffage to another, fo that the whole parcel may thus take fire near the fame time; otherwife much force may be loft, or many of the grains go away, as fhot unfired.

** It should also seem that there are other ways of increafing the ftrength of powder, particularly by the mixture of falt of tartar but perhaps it were improper to divulge any thing of this kind, as gunpowder feems already fufficiently deftructive.'

Of the huffars we have this short account:

Huffars. Hungarian horfemen. Their habit is a furr'd bonnet, adorned with a cock's feather, (the officers either an eagle's or a heron's) a doublet with a pair of breeches, to which their ftockings are faftened, and boots. Their arms are a fabre, carbines, and piftols. Before they begin an attack, they lay themselves fo flat on the necks of their horses, that it is hardly poffible to discover their force; but being come within piftol hot of the enemy, they raife themselves with fuch furprising quicknefs, and fall on with fuch vivacity on every fide, that, unless the enemy is accustomed to them, it is very difficult for troops to preferve their order. When a retreat is neceffary, their horfes have fo much fire, and are fo indefatigable, their equipage fo light, and themselves fuch excellent horfemen, that no other cavalry can pretend to follow them; they leap over ditches, and swim over rivers with great facility. They are retained in the fervice of moft princes on the continent. They are refolute partifans, and are far better in an invafion or hafty expedition, than in a fet battle.'

An Introduction is prefixed to the work, containing fome pertinent obfervations on fortification; accompanied with two copper-plates, containing a general plan of fortification, and the manner of carrying on a fiege; and a reprefentation of the several military utenfils defcribed in the Dictionary.-At the end is fubjoined a translation of The New Method of Fortification, by the late Marshal Saxe, explained; with fome Obfervations on the prefent Method of fortifying Towns, and the Reasons why they are fo liable to be reduced.'

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