Page:Cyclopaedia, Chambers - Volume 2.djvu/444

 PLU

( 839 )

PLU

This is in ancient Piece of Husbandry, Xemphm, Pindar, and Virgil recommend it : witnefs thofe Verlis of Ktrgit.

Altemis idem tonfas, ceffare Novaleis, Etfegnem paxiere fitu durefcere campum.

Georg. lib. 1.

PLOW, or Plow, in Navigation; an ancient Mathe- matical Inftrument, made of Box, or Pear-tree, ufed to take the Height of the Sun or Stars, in order to find the Lati- tude. See Height, Latitude, &c.

It admits of the Degrees to be very large, and is much efteemed by many Artifts ; tho' now generally difufed a- mongus. See Altitude.

P l o w-Land, orPiouc H-Land. See Carucata Terrs.

Plo w- Alms, a Duty anciently of a Penny, paid to the Church for every Plough-Land, or Hide of Land. See Hide.

De qualibetCarucatajuntta inter Pafcha& Pentecbo/tem unum denarium, qui dicitur Plou-Almes. Monajl. Ang.

PLUG, a large wooden Peg wherewith to flop the Bot- tom of a Ciftern, Cask, Pipe, or the like.

PLUMAGE, the Feathers, or Covering of Birds ; For the Mechanifm, &c. whereof, fee Feather.

In Falconry, Plumage is particularly underftood of the Feathers under a Hawk's Wing. See Hawk and Hawk- ing.

The Falconers alfo give their Hawks Parcels of fmall Fea- thers to make them caft ; and thefe they call Plumage. See Casting.

PLUMB, in Matters of Spicery. See Currants and Raisins.

PLUMB-Liot, a Term among Artificers for a Perpendi- cular Line. See Perpendicular.

It is thus call'd becaufe ufually defcribed by means of a Plummet. See Plummet.

PLUMBAGO, among the Ancients, was the Oar of the Black-Lead, ufed in making Pencils for defigning, r>c. See •Black-Lead.

Pomet adds, that Plumbago was the Sea-Lead of the An- cients -, who, he notes, took that Drug for a Production of the Sea, not a Mineral, as it really is ; but this is fcarce cre- dible.

PLUMBERY, the Art of calling, preparing, and work- king Lead ; and of ufing it in Buildings, r>c. See Lead.

The Word is form'd of the Latin Plumbum, Lead.

The Lead ufed in Plumbery is furnifh'd from the Lead- Works in large Ingots, or Blocks, call'd Pigs of Lead, or- dinarily weighing about an hundred Pounds a-piece.

As this Lead melts very eafily, 'tis eafy to caft Figures hereof, of any kind, by running it into Moulds of Brafs, Clay, Plafter, &c. See Foundery and Statue.

But the chief Article in Plumbery, is the Sheets and Pipes of Lead.— 'Tis thefe make the Bafis of the Plumbers Work in Building ; the Procefs of thefe, therefore, we fhall give a Defcription of:

Method of calling large Sheets of Lead.

The Lead deftined for this ufe is melted in a large Caul- dron or Furnace, ufually built with free-Stone and Earth, fortified on the out-fide with a Maffive of Shards and Pla- fter. At the bottom hereof is a Place funk lower than the reft, wherein is difpofed an Iron Pot, or Peel, to receive what may remain of the Metal after the Sheet is run. The Furnace is fo rais'd above the Area of the Floor as that the Iron Pot juft refts thereon.

To Ufe the Furnace they heat it with Wood laid within it -, that done they throw in the Lead, pell-mell with the burning Coals, to melt.— Near the Furnace is the Table,

or Mould, whereon the Lead is to be caft It confifts of

large pieces of Wood, well jointed, and bound with Bars of Iron at the ends. Around it runs a Frame, confifting of a Ledge or Border of Wood two or three Inches thick, and one or two high from the Table. The ordinary Width of the Tables is from three to four Foof, and their Length from 18 to 20 Foot.

The Table is cover'd with fine Sand ; prepared, bymoiften- ing it with a Watering-Pot, then working it with a Stick ; and at laft, to render it fmooth and even, beating it flat with a Mallet, and planing it with a Ruler or Slip of Brafs.

Over the Table is a kind of Rake of Wood, which bears and plays on the Edges of the Frame by means of a Notch cut in either End thereof ; and fo placed, as that between it and the Sand is a Space proportionable to the intended

Thicknefs of the Sheet. The Ufe of this Rake is to drive

the Matter, while yet liquid, to the Extremity of the Mould.

A-top of the Table is an Iron Pan, Peel, or Shovel, bear- ing, before, on the Edge of the Table itfelf, and behind

on a Treftle fomewhat lower than the Table Its Ufe is

in conveying the Metal into the Mould ; and the Defig.i of its oblique Difpofition is, that it may by that means be able to retain the Metal, and keep it from running off at the

lore-fide, where it has no Ledge Some of thefe Peels are

big enough to hold fifteen or fixteen hundred Weight of Lead, and even more.

Things being thus difpofed, with a large Iron Ladle they take out the melted Lead, Coals and all, out of the Furnace \

and with this, mix'd as it is, fill the Iron Peel When full, '

they take out the Coals, and clear the- Lead with another Iron Spoon pierced after the manner of a Scummer.

This done, they hoift up the- lower Part of the Peel by its Handle ; upon which the liquid Matter running off and fpreading it fclf on the Mould, the Plumber conduas and drives it to the Extremity of the Table by means of the Rake, which the Workman paffes along the Ledges, and thus renders the Sheet of an equal Thicknefs.— The Sheets thus caft there remains nothing but to edge them, i. e. to take off the two Sides with a Plane, in order to render them fmooth and ftrait.

Method of cafting thin Sheets of Lead.'

The Table or Mould here ufed is of a Length and Breadth at difcretion, only ledg'd on one fide.—Inftead of Sand they cover it with a Piece of woolen Stuff, nailed down at the two Ends to keep it tight, and over this lay a very fine lin- nen Cloth — The Feet of the Table are uneven, fo that it does not ftand horizontal, but moderately inclined.

Great Regard is had to the Lead while melting, that it have the juft Degree of Heat, fo as it may run well, yet not burn the Linnen.— This they judge of bv a Piece of Paper, for if the Paper take fire in the liquid Lead, 'tis too hot, and if it be not fhrunk and fcorch'd a little, 'tis not hot enough.

Being then in its juft degree, they have a Rake, but dif- ferent from that defcribed in the former Article ; as ferving both for Peel and Rake, to contain, and to conduft the li- quid Lead— 'Tis in effeit a wooden Box without any bot- tom, only clofed on three Sides. It is pretty high behind, but the two fides, like two acute Angles, ftill diminifh to the tip, from the Place where they are joined to the third or middle Piece where they are of the fame Height therewith, •viz.. 7 or 8 Inches high.— The Width of the middle makes that of the Rake, which again makes that of the Sheet to be caft.

The Rake is placed a-top of the Table, which is, before," cover'd in that Part, with a Pafte-board that ferves as a bot- tom to the Box, and prevents the Linnen from being burnt while the liquid Lead is pouring in.— The Rake is fo difpo- fed on the Table, as that the higheft Part looks to the lower end of the Table, and the two (loping Sides to the higher End.

The Rake is now fill'd with Lead according to the Quan- tity to be ufed; which done, two Men, one at each fids the Table, let the Rake defcend down the Table, or elfe draw it down with a Velocity greater or lefs, as the Sheet is to be more or lefs thick ', the Thicknefs of the Sheet ftill depending on the Promptitude wherewith the Rake Hides down the Inclining Mold.

Thefe fine fmooth Sheets of Lead are fometimei ufed be- tween the Joints of large Stones in great Buildings, &c.

Method of making Pipes without folder ing.

To make thefe Pipes they have a kind of Furnace, confi- fting of a large Iron Furnace or Cauldron, fupported on a pretty high Iron Stand. The Cauldron isencompaffed with a Maffive of Bricks and Loam ; only leaving a Mouth or Paffage for the Conveyance of Wood underneath, and light- ing the Fire; and another little Aperture behind, to ferve as a Vent-hole.

In this Furnace they melt the Lead, after firft heating it with a Fire underneath : To forward the Fufion they put in burning Faggots along with the Metal. — The Metal is skim- med and laden off with the Inflruments mentioned above.

Near the Furnace is a Bench, furnifh'd at one End with a little Mill, with Arms or Levers to turn it withal— A ftrong Girt, arm'd with an Iron Hook at one Extremity, is fattened by the other to the Axis of the Mill, around which it turns when in Motion. On this Bench the Moulds of the Pipes are placed horizontally ; and the Mill and the Girt ferve to draw out the Iron Core after the Pipe is caft.

The Moulds of thefe Tubes are of Brafs, and confifr of two Pieces which open and fhut by means of Hooks and Hin- ges their inner Calliber, or Diameter, is according to the Size of the Pipe to be made:, their Length is ufually two Foot and a half.

In the middle is placed a Cere, or round Piece of Brafs or Iron, fomewhat longer than the Mould, and of the Thick- nefs