Page:Cyclopaedia, Chambers - Volume 1.djvu/944

 GUN

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GUN

For greater Quantities, Mills are ufually provided, by means of which, more Work may be perform d in one Day, than a Man can do in an hundred. Sec Mill.

Gun-Powder may alio be made of feveral Colours, but the Black is the moil ferviceable of any. To make Wbite-
 * Po<wder, proceed thus:

Take ten Pounds of Salt-Peter, one of Sulphur, and two of the Saw-dull of Elder or the like Wood powder'd fine; mix them together, and ufe the former Method — Or thus, with ten Pounds of Nitre, and a Pound and a half of Sulphur dried and finely powder'd, mix two Pounds of Saw- dull, &c. or inllead of that, rotten Wood dried and powder- ed, with two Pounds and three Ounces of Salt of Tartar; whereof make Powder to be kept clofe from the Air.

'Tis alio to be noted, that in making Pijlcl-Powder, if you would have it Wronger, it mould be ftirred up feveral Times while in the Mortar, and moiflen'd with Water di- fUll'd from Orange or Lemmon-peels in an Alembick, and then beat for 24 Hours, as aforefaid.

Corn-Powder is of fo much greater Force than when in Dufl or Meal, that 'tis concluded, the largei Grains are Wronger than the [mailer 5 for which Reafon Cannon-Pow- der is granulated larger than other Powders ; and therefore ^Powder in loading mould not be beat home into the Piece, fo as to bruife the Grains.

There are three Ways to prove the Goodnefs of Gun- f&wkr, 1. By Sight, for if it be too black, it is too moift, or has too much Charcoal in it ; fo alfo if rubbed upon white Paper, it blackens it more than good 'Powder does : but if it be a kind of Azure Colour, fomewhat inclining to Red, 'tis a fign of good Powder, 2. By Touching, for if in crufhing it with your Fingers-Ends, the Grains break eafily and turn into Dull without feeling hard, it has too much Coal in it; or if in prefung under your Fingers upon a fmooth hard Board, fome Grains feel harder than the reft, or as it were dent your Fingers-Ends, the Sulphur is not well mixed with the Nitre, and the Powder is naught. 3. By Burning, wherein little Heaps of Powder arc laid upon White Paper three Inches or more afunder, and one of them fired ; which if it only fires all away, and that fuddenly and almoll imperceptibly, without firing the reft, and make a fmall thundering Noife, and a white Smoke rifes in the Air almoft like a Circle, the Powder is good ; if it leaves black Marks, it has too much Coal, or is not well burnt : If it leaves a Greafinefs, the Sulphur or Nitre are not well cleanfed or ordered. Again, if two or three Corns be laid on Paper an Inch diflant, and Fire be put to one of them, and they all fire at once, leaving no Sign behind, but a white fmoaky Colour in the Place, and the Paper not touched ; the Pow- der is good. So alfo if fired in a Man's Hand and it burns not : but if black Knots appear which burn downwards in the Place where Proof was made after firing, 'tis not flrong enough, but was Nitre.

To recover damaged Powder, the Method of the Pow- <fe/--Mcrchants is to put part of the Powder on a Sailclorh, to which they add an equal Weight of what isequaily good ; and with a Shovel mingle it well together, dry it in the Sun, and barrel it up, keeping it in a dry and proper Place.

Others again, if it be very bad, reftore it by moift 'ning it with Vinegar, Water, Urine, or Brandy ; then they beat it fine, fearce it, and to every Pound of Powder, add an Ounce, an Ounce and half, or two Ounces (according as 'tis decay'd) of melted Salt-Peter ; afterwards thefc Ingre- dients are to be moiflen'd and mixed well, fo that nothing can be difcern'd in the Competition ; which may bs known by cutting the Mafs, and then they granulate as aforefaid.

In Cafe the Powder be in a manner quite fpoiled, the only way is to extract the Salt-Peter with Water according to the ufual manner, by boiling, filtrating, evaporating, and cryftallizing ; and then with frefh Sulphur and Charcoal, to make it up anew again.

GUNTERS-Line, call'd alio Line of Lines, and Line of Numbers, is a graduated Line ufually placed on Scales, Rules, Sectors, £$c. See Scale, Rule, igc.

This Line is only the Logarithms transfer'd upon a Ru- ler, from the Tables, fo as to anfwer much the fame Pur- pofes inflrumentally, as the Logarithms themfeves do arithmetically.— What the Logarithms do by Addition and Subftraction, is done in this Line by turning a Pair of Com- pafles this way and that. See Logarithm.

This Line has been conttived various Ways, for the Ad- vantage of having it as long as pofllblc— As, firil, on the two-foot Ruler, contrived by Edm. Gunter, and called Gun- ter's-Scale ; whence alio the Line itfelf took its popular Denomination Gunter\-Line. See GvNTEK's-Scale.

After this, Wingcite doubled the Line, or laid it toge- ther, fo as one might either work right on, or a-crofs. Then it was projeded in a Circle, by Ougbtrcd, and made to Aide by the lame Author : And laltly, projected in a kind of Spiral, by Brown.

The Method of ufing or applying it, is much the fame in all ; except that in Gguter'i and tVwgats'i way ; common

Compafles are ufed: In Ougbtred's and flroim's, flat Com- paffes, or an opening Index; and in the Sliding Rules no Compafles at all. See Sliding-Ruxe.

CDcfoription of Gvsr-EK's-Line, or the Line of Numbers. The Lines reprcfented, is ufually divided into an hundred Parts, whereof every Tenth is number'd, begin- ning with 1 and ending with to: So that if the firil great Divifion I, fignify one tenth of any whole Number or Integer, the next will fignify 2, two tenths; 3, three tenths, (Sc. and the intermediate Divifions fo many 100 Parts of the fame Integer, or Tenths of one of the former Tenths. For Numbers greater than jo, the Sub-divifions mud fig- nify Integers, and the greater Divifions 10 Integers, fo that the whole Line will exprefs 100, Integers ; and if you would have it flill more, then the Sub-divifions to be each 10 In- tegers, and each great Divifion 100, fo that the whole be 1000; and after the fame Manner, may it be extended to 10000, by making each Sub-divifion 100.

A whole Number under four Figures being given, to find, the Point on the Line of Numbers that reprefents the fame.

Look for the firfl Figure of the Number among the large figured Divifions ; this leads you to the firil Figure of your Number. For the fecond, count fo many Tenths from that Divifion forwards, as that fecond Figure amounts to. For the third Figure, count from the lafl Tenth fo many Cen- tefms as the third Figure contains : And fo for the fourth Figure, count from the lall Cemefm fo many Millions as the fourth Figure has Units, or is in Value ; that will be the Point where the Number propounded is, on the Line of Numbers.

For an Example— To find the Point rcprefenting the Number 1728— for 1000 take the firfl grand Divifion mark- ed 1 on the Line; then for 7 reckon feven Tenths for- wards, this is 700 ; for 2, reckon two Centefms from the feventh Tenth; and for 8, cltimatc the following Cen- tefm to be divided into 10 Parts, if it be not exprefled, which in Lines of ordinary Length cannot be done ; and 8 of that fuppofed 10 Parts, is the prccife Point for 1728, the Number propofed to be found; and the like of any other Number.

To find a Fraction, confider that the Line properly only expreffes decimal Fractions, as thus, fs-, or T ra, or -Ijj, and nearer the Rule cannot well come than as one Inch, one Tenth, one Hundred, or one Thoufand Part of an Inch: So that for other Fractions, as Quarters, Haif-Quarters, f$c. you mufl either eflimate them as near as you can reafbna- bly, or elfe reduce them into Decimals.

life o/Gunter'i-Line, or the Line of Numbers.

i° Two Numbers being given, to find a third geometri- cally proportional to them ; and to three a fourth Number, to four a fifth, ci?c— Extend the Compaffes on the Line from one Number to another ; then that Extent applied upwards or downwards, as you would either increafe or dU minifh the Number from either of the Numbers, the move- able Point will fall on the third proportional Number re- quired. Again, rhe fame Extent applied the fame way from the third, will give a fourth ; and from the fourth a fifth, ££?c.

For Example— Let the two Numbers 2 and 4 be propo- fed to find a third Proportional, &c. to them ; extend the Compafles on the firfl Part of the Line of Numbers, from 2 to 4 ; which done, and the fame Extent being applied up- wards from 4, the moveable Point will fall on 8, the third Proportional required; and from 8 it will reach to 16", the fourth Proportional; and from iff to 32 the fifth, (gc. Con- trariwife, if you would diminifh, as from 4 to 2, the move- able Point will fall on 1, and from I to \^ or .5 ; and from .5 to .25, £?<;.

But, generally, in this, and moll other Works, make ufe of the fmall Divifions in the middle of the Line ; that you, may the better eflimate the Fractions of the Numbers you. make ufe of; for how much you mifs in fetting the Com- pafles to the firfl and fecond Term, fo much the more you will err in the fourth ; therefore the middle Part will be mofl ufeful. For Exampls ; as 8 to it, fo is 12 to it, .50, if you imagine one Integer to be divided but into to Parts, as they are on the Line on a two foot Rule.

z c One Number being given to be multiplied by another, to find the Product— Extend the Compafles from j to the, Multiplicator; and the fame Extent applied the fame way from the Multiplicand, will make the moveable Point fall on the Product : Thus, if 6 be given to be multiplied by 5 • extending the Compaffes from 1 to 5, the fame Extent will reach, from « to 30, the Product fought.

3* One