Page:Cyclopaedia, Chambers - Volume 1.djvu/942

 GUM

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GUN

It is efteem'd good to incraffate, to flop the Pores, blunt the Points of too pungent Medicines, and temper the Acri- mony of the Trachea in Coughs, £&:.

GvM-Gutla, or Gutta-Gamba, or Gutta-Gemon, or Ga- mandra, popularly Gamhocbe, is a resinous Gum brought from the Kingdom of Siam,!kc. in large Pieces fafliion not unlike Saucidges, hard, brittle, and very yellow.

It ouzes from Incifions made in a kind of prickly Shrub, which climbs up the neighbouring Trees. It purges violently both upwards and downwards ; and is particularly ufed in Dropsies, the Itch, (fie. but it is dangerous.

It ferves alfo to make a yellow Colour, for painting in Miniature. See Miniature.

Gum- Senegal, is the Gum ordinarily fold by the Druggifts for Gum-Arabic, which it refembles very nearly both as to Form and Virtue : It is either white bordering on .the yel- low, or of a deep Amber Colour, traniparcnt, £5f. It ouzeu out of a prickly Shrub common enough in Africa. The Gum is brought us trom Senegal, whence its Name. —

GuMMo-icc/5;/, or Gum-Rofin, is a hardtn'd Juice of a middle Nature between a Gum and a Refiu, being both diffolubic in aqueous Mcnftruums like a Guru ; and in olea- ginous ones like a Re/in.

Such are Mastic, Camphor, Storax, (fie. Some NaturalHls make a Clais of Irregular Gummo Re- fills,^ being fuch as diflblve, tho' with Difficulty, and not perfectly, both in aqueous and oleaginous Liquors; as Bdel- lium, Myrrh, &c.

Gum, among Gardeners, is a Difeafe incident to Fruit Trees, of the Stone kind, as Peaches, Plumbs, Apricots, Cherries, (fie. See Disease, g?c.

The Gum is a kind of Gangrene, ariiing from a Corrup- tion of the Sap, which cxrrav.tfates and hardens. It ufualiy^ begins on fome naked or broken Part, and fpreads it felf to the reft. To avoid its fpreading, M. S{uiminie directs to cut off the morbid Branch two or three Inches below the Part affected.

This Gum is no more than a thick, diltemper'd, vifcid Juice, which not being able to make its way through the Fibres of the Body of the Tree, to feed and fupply them, is obliged, by the Protmfion of other fuccecding Juice, to burft its Veffels, which lie between the Wood and Bark, and to ouze out upon the Bark.

When the Distemper furrounds the Graft, it admits of no Remedy : When it is only on one Side of a Bough, the Gum mall be taken off to the Quick of It ; fome Cow-dung clap'd on the Wound, and cover'd over with a linnen Cloth, and tied down. —

GUN, a Fire-Arm, or Weapon of Offence, which forci- bly diftharges a Ball, Shot, or other offenfivc Matter, thro' a Cylindrical Barrel, by means of Gun-powder. See Ball, Gdn-eowoek, Arm, (fie.

Gun is a general Name, under which are included di- vers, or even mod Species of Fire-Arms : They may be divided into great and /mail.

Great Guns, called by the general Name Cannon, make what we call Ordnance, or Artillery ; under which come the levcral Sorts of Cannon, as Cannon-Royal, Demi-Can- non, (fie. Culverins, 'Demi-Culvers, Sakers, Minions, Fal- cons, Sec. See Ordnance; fee alfo Cannon, Culverin,S?c. Small Arms include

Muskets, Muskcteous, Carabines, Slunderbufies, Fo-wl- ing-CP'ieces,&c. See Carabine, Musket, Fowling-Piece, (fie.

Tiftols and Mortars are almost the only Kinds of regular Weapons charged with Gun-powder, that are excepted from the Denomination of Guns. See Mortar and Pistol. For the History and Inven- - > _, _

tioriofffnsj, C t Cannon and Gun-

For the Ufe and Applica- C fc0 <* «WMR. tionofGsaj, J J CrUNNERY.

GUNNERS, Officers of the Tower, and other Garri- fons, whole Bufmefs is to manage and look after the Ord- nance mounted on the Lines and Batteries, which are all fix'd and ready with Cartouches and Ball, for Service on the ihortcft Warning.— One or more of them are on Duty Day and Night. Sec Ordnance and Tower.

Mafter-GvNNT.R of England, is an Officer appointed to teach and lnllrucT all fuch asdclire TO learn the Art of Gun- nery, and to administer to every Scholar an Oath ■ which, befide the Duty of Allegiance, obliges him not to serve any foreign Prince or State without Leave ; nor ro teach the Art of Gunnery to any, but luch as have taken the faid Oath ; and to certify to the Mailer of the Ordnance, the Sufficiency of any Perfon recommended to be one of his Majesty's Gun- ners.

The Gunner, Sir J. Moor obferves, fhould know his Pie- ces, and their Names, which are taken from the Heieht of the Eore, the Names of the feveral Tarts of a Piece of Ordnance, how to rertiate his Gun, and how to difpart it See Ordnance, Tertiate, Dispart,^

GUNNERY, the Art of ihooting with Guns and Mor- tars, i.e. of charging, directing, and exploding thole Fire-

Arms to the heft Advantage. See Gun and Mortar.

Gunnery is fometimes considered as a part of the mili- tary Arr, and fometimes of Pyrotechny. See War and Py- rotechny.

To the Art of Gunnery belongs the Knowledge of the Force, and Effect, of Gun-powder, the Dimensions of Pie- ces, and the Proportions of Powder and Ball they carry; with the Methods of Managing, Charging, Pointing, Spung- '.ngi ifie. Sec Gunpowder, Charge, Pointing, Spunge, (fie.

Some Parts of Gunnery arc brought under mathematical Consideration, which among Mathematicians are called ab- lolutely by the Name Gunnery, viz. the Method of eleva- ting or railing the Piece to any given Angle, and of compu- ting its Range; or of railing and directing it fo, as it may hit a Mark or Object propofed.

The Instruments chiefly ufed in this Part of Gunnery, are the Callipers or Gunners Compafles, Quadrant , and Level ; the Methods of applying which fee under the Articles Calliper, Level, and Quadrant.

The Line or Path in which the Bullet flies, whatever Di- rection or Elevation the Piece is in, is found to be the fame with that of all other Projectiles, viz. a Parabola. See Pa- rabola.

Hence, the particular Laws obferved in the Motion or Flight of the Ball, its Velocity, Extent, (fie. with the Rules for hitting Objects, are delivered under the Ar- ticle Projectile.

Malms, an Englifh Engineer, is mentioned as the Perfon who first taught any regular Ufe of Mortars, in the Year 1S34; but all his Knowledge was experimental and tenta- tive; he knew nothing of the Curve the Shot del'cribes in its Paflage, nor of the Difference of Range at different Ele- vations. And moll of the Gunners and Engineers employ 'd about Batteries, (fie. to this Day go by no better Rules : If the Range docs not hit right, they raife or lower the Piece, till they bring it to a Truth : And yet there arc certain Rules, founded on Geometry, for all thefe Things ; molt of which we owe to Galileo Engineer to the Grand Duke of j'ufiany, and his Difciple Torricellius.

A Ball or Bomb going out of a Piece, we find, never pro- ceeds in a ftreight Line towards the Place it is levelled at, but begins to rife from its Line of Direflion the Moment it is out of the Mouth of the Piece. — This fome account for thus: The Grains of Powder nigheft the Breech, taking Fire firfl, prefs forward, by their precipitated Motion, nor, only the Ball, but likewife thofe Grains which follow the Ball along the Bottom of the Piece ; where successively ta- king Fire, they strike, as it were, the Ball underneath, which because of a neceffary Vent, has nor the fame Diameter, as the Diameter of the Bore ; and fo infenfibly raife the Ball towards the upper Edge of the Mouth of the Piece, against, which it fo rubs in going out, that Pieces very much ufed, and whofe Metal is foft, are obferved to have a considerable Canal there, gradually dug by the Friction of Balls. Thus the Ball going from the Cannon, as from the Point of theParabola ^.;{T-ib. Fortification, Vig.i 3. raifes it felf, in its Progrefs, to the Vertex G ; after which it defcends by mix'd Motion.

Ranges made from the Elevation of 45 Deg. arc the great- eft ; andthofe made from Elevations equally diftant from 45 Deg. are equal; that is, a Piece of Cannon, or a Mortar, le- vell'd to the 43thDeg. will throw a Ball, or Bomb, the fame Diftance, as when they are elevated to the 50th Deg. and as many at 50 as 6a, and fo of others.

It has been fliewn, that to find the different Ranges of a Piece of Artillery in all Elevations, we muft, ifl. Make a very exift Experiment by firing off a Piece of Cannon, or Mortar, at an Angle well known, and measuring the Range made, with all the Exaflnefs poffible ; for by one Experi- ment well made, we may come at the Knowledge of all others, in the following Manner.

To find the Range of a Piece, at any other Elevation required, fay, as the Sine of double the Angle under which the Experiment is made, is to the Sine of double the Angle of an Elevation propofed, fo is the Range known by the Experiment, to the other required.

GUN-Powder, a Composition of Salt-Peter, Sulphur, and Charcoal, mixed together, and usually granulated; which cafily takes Fire, and ratifies or expands with great Vehemence, by means of its Elaftic Force. See Elasti- city, Rarefaction, (fie.

'Tis to this 'Powder we owe all the Aflion, and Effect of Cruns, Ordnance (fie. fo that the modern military Art, For- tification, lie. depend wholly thereon. See Gun, Ord- nance, Fortification, (fie.

The Inventiori lof Gun-powder is afiribed, by 'PoVvdoreVir- g:l, to a _Ghym.lt, who having accidentally put fome of this Competition in a Mortar, and cover'd it with a Stone ■ it happen d to take Fire, and blew up the Stone.

Thevet fays, the Perfon here fpoke of, was a Monk of Fryhwrg, named Conftantine Anelzen : But Sellefcret and other Authors, with more Probability, hold it to be Sartboldus Sdmartz, or the Black : At least it is affirm'd,

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