652

•GUN

G IT N

armed with match, llis business is to lay the gun, to pass, and tohelp to load and traverse her.

Gunner, Master, a patent-officer of the ordnance, who is ap-pointed to teach all such as learn the art of gunnery, and to cer-tify to the master-general the ability of anv person recommendedto be one of the king’s gunners. To every scholar lie administersan oath not to serve, without leave, any other prince or state; orteach any one the art of gunnery but such as have taken the saidoath.

GUNNERA, in botany, a genus of the diandria order, andgynandria class of plants. The amentum consists of unitlorousscales; there is neither calyx nor corolla ; the germen is bidentut-ed with two styles and one seed. It has but one species.

GUNNERY is the art of charging, directing, and exploding,fire-arms, as cannons, mortars, muskets, Sec. to the best advan-tage ; and of determining the course, velocity, time of flight, mo-mentum, &c. of the projected body. This branch of science be-longs to the subject of Projectiles, since it treats of projectedbodies, and (lie means of projecting them ; we shall therefore referthe reader to that article.

GUNPOWDER, a composition of nitre, sulphur, and char-coal, mixed together, and usually granulated. Thiseasilv takes lire,and when fired it rarefies or expands with great vehemence, bvmeans of its elastic force. It is to this powder that we owe all theeffect and action of guns, and ordnance of all sorts, so that fortifi-cation, with the modern military ait, &c. in a great measure de-pends upon it. The invention of gunpowder is ascribed bv l’olv-dore Virgil to a chemist, who having accidentally put some of liiscomposition in a mortar, and covered it with a stone, it happenedto take fire, and blew up the stone. Thevet says, that the personhere spoken of was a monk of Eribourg, named Constantine Anel-zen ; but Belleforet, and other authors, with more probability,hold it to be Raitholdus Schwartz, or the black, who discoveredit, as some say, about the year 1326. The name mortars, givento a species of ancient artillery, and their application in tlirondngstone-bullets, strongly favours this account of the discovery, of atleast the application of gunpowder. Hut it appears that RogerBacon knew of gunpowder near one hundred years beforeSchwartz was born ; and M. Dutens carries the antiquity of gun-powder still much higher, and refers to the writings of the ancientsthemselves for the proof of it. It appears too, from many authors !and many circumstances, that this composition has been known Ito the Chinese and Indians for thousands of years. The modernproportion of the ingredients for gunpowder is sip: parts of nitre toone of eacli of the other two: though .Mr. Napier says, lie findsthe strength commonly to he the greate-t when the" proportionsare, nitre three pounds, charcoal about nine ounces, and sulphurabout three ounces. See his paper on gunpowder in the Trans-actions of the Royal Irish Academy , vol. ii. The cannon-powderwas in meal, and the musket-powder grained; and it is certain,that the graining of powder, which is a very considerable advan-tage, is a modern improvement. To make gunpowder due re-gard is to be had to the purity or goodness of the ingredients, aswell as the proportions of them, for the strength of the powder de-pends much on that circumstance, and also on the due working ormixing of them together. After the materials have been reducedto line dust, they are mixed togetlrer, and moistened with water, orvinegar, or urine, or spirit ot wine, &c. and then beaten togetherfor twenty-four hours, either by hand or by mills, and afterwardspressed into a hard, firm, solid, cake. When dry, it is grained orcorned, which is done by breaking the cake of powder into smallpieces, and so running it through a sieve; by which means thegrains may have any size given them, according to the nature ofthe sieve employed, either finer or coarser; and thus also the dustis separated from the grains, and again mixed with other manufac-turing powder, or worked up into takes again. Powder is smooth-ed or glazed, as it is called, for small arms, by the following ope-ration: a hollow cylinder or cask is mounted on an axis, turned bvawheel; this cask is half filled with powder, and turned for sixhours, and thus by the mutual friction of the grains of powder it issmoothed or glazed. The fine mealy part, thus separated or wornoff from the rest, is again granulated. The velocity ot expansionof the flame of gunpowder, when fired in a piece of artillery; w ith-out either bullet or other body before it, is prodigiously great,riz. seven thousand feet per second, or upwards, as appears from

the experiments of Mr. Robins. But M. Bernoulli and M. Eulersuspect it is still much greater; and Dr. Hutton supposes it maynot he less, at the moment of explosion, than four times as much.It is this prodigious celerity of expansion of the flame of gunpow-der which is its peculiar excellence, and the circumstance in whichit so eminently surpasses all other inventions, either ancient or mo-dern ; for as to the momentum of these projectiles only, many ofthe warlike machines of the ancients produced this in a degree farsurpassing that of our heaviest cannon-shot or shells; but the greatcelerity given to these bodies cannot be in the least approachedby any oilier means but the (lame of powder.

Gunpowder, Method op Recovering Damaged. Thepowder-merchants put part of the powder on a sail-cloth, to whichthey add an equal weight of what is really good; and with a shovelmingle it well together, dry it in the sun, and barrel it up, keepingit in a dry and proper place. Others again, if it lie very bad, re-store it by moistening it with vinegar, water, urine, or brandy: thenthey heat it line, scarce it, and to every pound of powder add loz.If or 2oz. according as it is decayed, of melted salt-pctre. After-wards, these ingredients are to he moistened and mixed well, sothat nothing can be discerned in the composition, which may heknown by cutting the mass; and then granulated as at first. Ifthe powder be in a manner quite spoiled, the only wav is to extractthe saltpetre with water by boiling, filtrating, evaporating, andcrystallizing; and then with fresh sulphur and charcoal to make itup anew.

Gunpowder, Methods of Trying. There are two generalmethods of examining gunpowder; 1st, with regard to its purity:2d, As to its strength. 1. Its purity is known by laving two or threelittle heaps near tach other upon white paper, and firing one ofthem, l-’or if this takes fire readily, and the smoke ri>es upright,without leaving any dross or feculent matter behind, and withoutburning the paper, or firing the other heaps, it is esteemed a signthat the sulphur and nitre were w ell purified, that the coal was good,anil'that the three ingredients were thoroughly incorporated toge-ther: hut if the other heaps also take fire at the same time, it ispresumed that cither common salt was mixed with the nitre, or thatthe coal was not well ground, or the whole mass not well beat andmixed together; and if either the nitre or sulphur be not well pu-rified, the.paper will he black or spotted. 2. Several instrumentshave been invented to try the strength of gunpowder; but theyhave-generally been complained of as inaccurate. Count Rum-ford in (he Ehilosoph. T rans. Vol. 71, gives an account of an ex-act method of trying the strength of it. “ As the force of thepowder (says he) arises from the action of an elastic fluid that isgenerated Irom it in its inflammation, the quicker the charge tak*slire, the more of this fluid will be generated in any given shortspace of time, and the greater of course will its effect be upon thebullet. But in the common method of proving gunpowder, llu‘weight bv which the powder is confined is so great in proportion tothe quantity of the charge, that there is time quite sullicicnt forthe charge lobe all inflamed, even when the powder is of thcslow-est composition, before live body to he put in motion can he sen-sibly removed from its place. The experiment therefore may shewwhich of the two kinds of powder is the strongest, w hen equalquantities of both are confined in equal spaces, and both completelyinflamed; but the degree of inflammability, which is a propertyessential to the goodne-s of the powder, cannot by these means beascertained. Hence it appears how powder may answer to theproof, such as is commonly required, and may nevertheless turnout very indifferent when it comes to he used in service. Butthough the common powder-triers, may shew powder to he b< lty rthan it really is, they eau never make it appear to be worse than Ais; it will therefore always he the interest of those who manufac-ture the commodity to adhere to the old method of proof, but thepurchaser will find'his account in having it examined in a methodby which its goodness may he ascertained with greater precision.To determine the goodness of powder bv Count Rmnford’s mu! hud,it is necessary to have a barrel suspended by two iron-rods, tin* 1it can easily move backward or forw ard by the vibration of therods; and the space it moves through ascertained by marking it 011a piece of ribbon. The barrel being then charged with powder,and fitted with a proper bullet, is to be tired, and the recoil n ark*ed upon the ribbon. The experiment is to be repeated three orfour times, or oftencr if there is any difference in the recoil; ln e

extreme*