Page:Cyclopaedia, Chambers - Volume 1.djvu/905

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GLA

After they havedipp'd the fourth time, and there is now Matter enough on the Inftrument, the Operator begins to blow gently thro' the Iron ; by which he raifes or lenghtens it nearly a Foot; much as we do by blowing in a Bladder, or Giobe : And to give it a Polifh, he rolls it to and fro on a Stone, or Marble.

This done, he blows a fecond time, and thus forms the Bunch, or Belly of the Glafs. The Matter by this fecond Blaft affumes the Figure of a Gourd, or Callebafs, eighteen or twenty Inches in Diameter. As often as the Operator blows into the Iron (which muft be very often) he removes it haftily from his Mouth to his Cheek, left he mould draw the Flame into his Mouth, when he re-applies it to the Iron.

The Operator whirls his iron many times round his Head, to lengthen and cool the Glafs ; fometimes the Glafi thus blown round, is return'd to the Fire, where it flattens a little of itfelf: When flatted, it is taken out, and cooled; and if needful for the Defign, the Workman flats its Bottom, by preffing it on the Marble; .or moulds it in the Stamf-irons: And thus delivers it to the Mafter Workman, to break off the Collet.

The Collet, or Neck, is the narrow Part which clove to the Iron: To fet the Glafi at liberty, they lay a Drop of cold Water on the Collet ; which by its Coldnefs, cuts, or cracks about a Quarter of an Inch : After which, giving it a flight Blow, the Fracture is communicated all around the Collet. ThewaftPieceto be thrown by to make green Glafi.

This done, they dip an Iron Rod, or fonteglo in the Melt- ing Pots, and with the Matter that flicks thereto, they ap- ply and faften it to the Bottom of the Veffel, oppofite to the Collet.— The Veflel thus fuftained by the Iron Rod, is carried to the great Bocca to be heated, and fcalded ; and ■while another Perfon takes care thereof, the former Opera- tor refts and prepares himfelf for the branching.

To branch, or make the Bowl, they thruft in an Iron In- strument, call'd TaJfagO; and the Aperture, open'd there- by, they further augment, and widen with the 'Prccello : In turning this Inftrument about, to form the Bowl, the Edge becomes thickned ; the Glafi being, as it were, doubled in that Part : Whence the Hem obferved on the Circumference of our Glajfes.- — What is fuperfluous, they cut off with the Shears.

The Veflel thus open'd, is return'd to the great Bocca; where, being fufficiently heated a fecond time, the Work- man gives the Bowl its finifhing, by turning it about with a circular Motion ; which it increafes, in proportion as the Bowl opens, and enlarges by means of the Heat and Agitation.

The Glafi thus fini/h'd, they carry it from the Bocca, ftill turning it round, to a kind of earthen Bench, cover'd with Brands, or Coals extinguifh'd : Here they let it cool a little, and come to its Confiftence, having firft detach'd it from the Iron Rod, by a Stroak or two with the Hand.

Thus, with blowing, preffing, fcalding, amplifying, and cutting, the Glafi is framed into the Shape preconceived in the Workman's Mind. If need be, he proceeds to put on a Foot and Handle ; and with the Spici puts on Rigarincs, and Marblings.

When the Mafter has finifh'd a Number of them, an- other Servitor takes them with an Iron Fork, and fpeedily places them in the Tower, or Leer to anneal and harden. See Furnace, Annealing, $S>c.

What has been here faid of White, or Cryflal Glafi, holds equally of common, or Gteen Glafs ; the working being the fame in all ; and the Difference only in the Salt, or Polverine made ufe of.

So many Mafters as there are, fo many Pots, at the leaft, and fo many Bocca's there muft be ; each Man having his proper Station ; where, fays Dr. Merret, they receive thofe fcorching Heats fallying directly into their Faces, Mouths, and Lungs ; whence they are forc'd to work in their Shirts, like the Cyclopes, and Nudi-membra Tyrracmones, with a Straw broad-brimm'd Hat on their Heads, to defend their Eyes from the exceffive Heat and Light. — -They fit in large, wide, wooden Chairs, with two long Elbows, to which their Inftruments are hung. They work fix Hours at a time, meafur'd by a fingle Glafs ; after which they are relieved by others, for the like Time : So that the Furnaces are ne- ver idle.

Method of working, or blowing Window, or Table Glass.

The Method of making Crown Window Glafi, now pra- ftis'd in England, is faid to have been borrowed from the Trench. — An Englifh Glafs-maker went over, to work in France, on purpofe to get into the Secret; which, when he had attain'd to, he return'd, and fet up a Glafs-work, where- in he far outdid the French, his Teachers.

This Glafs is blown much after the manner of Looking Glafs. Some Writers, from wrong Intelligence, have faid that it was run, or call in Sand: But the real Procefs is as follows. — •

The Furnace, Melting-pots, Materials, and Fire : are the fame for Window, or Table Glafs, as for Round Glafs ; and the Difference in the" Operation only commences after the Servitor has dip'd his Blowing-iron the fourth time in the melted Metal.

The Glafs, then, being in this Condition, they blow it ; but inftead of rounding, or forming it into a Bunch ; the particular Motion the Workman gives it in the direft. ing and managing the Wind, and the way of rolling it on the Iron; make it extend in length two or three Foot, and form a Cylinder, which at firft is but two Inches in Diameter; but which, by being recommitted to the Fire, and blown a-frefh when taken out, becomes of the Extent required for the Table of Glafs to be form'd. With this Cir- cumftance however, that the Side which is faflen'd to the Iron, goes gradually diminifliing, and ends in a kind of Conej or Pyramid.

To render the two Ends nearly of the fame Diameter, after adding a little Glafi to that oppofite to the Iron, they draw it out with a Pair of Iron Pinchers. Then they incidej or cut off the fame End with a little Water ; and carrying the Cylinder back to the Bocca, they incide it likewife with Water in two other Places ; one, eight, or ten Inches from the Iron ; and the other, the whole Length.

The Glafs Cylinder thus abridg'd of both its Extremities, is, next, heated on a kind of earthen Table, fomewhat rais'd in the Middie, in order to promote its Opening at the Place incided longitudinally. The Workman, here, makes ufe of an Iron, wherewith he alternately lowers and raifes the two Sides, or Halves of the Cylinder, which now begin to open, and unfold like a Sheet of Paper, and at length grow perfectly flat. — The Table of Glafi is now in its laft Perfection, and needs nothing farther but to be heated over again. When taken out, they lay it on a Table of Copper ; whence, after it has cool'd and come to its Confi- ftence, they carry it on Forks to the Tower of the Furnace, where they leave it to anneal for 24 Hours.

The Number of Tables anneal'd at a time, which fometimes amount to an hundred, with the perpendicular Situation they are fet in, occafion'd, antiently, that thofe fet in firft, fuftaining in fome meafijre, the Preflure of all the laft, were bent ; and thus render'd inconvenient for Ufe 1 But this Inconvenience is now remedied, by feparating them into Tens, with an Iron Shiver ; which diminifliing the Weight, by dividing it, keep'* the Tables as flat, and even as they were put in.

Kinds of Table, f^tVindow Glass.

There are divers Sorts of this Glafi, made in divers* Places, for the ufe of Building : Thofe moft known among us, are given us, by the Author of the Builders Dictionary, as follows :

Octow-Glass, of which, fays that Author, there are two Kinds ; diftinguifh'd by the Places where they are wrought, viz. i° Ratcliff Crown Glafs, which is the beft and cleareftj and was firft made at the Bear Garden, on the Bank-fide, Southwark ; but fince at Ratcliff : Of this there are 24 ta- bles to the Cafe, the Tables being of a circular Form, about three Foot fix Inches in Diameter. See Table, and Case.

2 Lambeth CrownGlafi, which is of a darker Colour than the former, and more inclining to green.

French Glass, alfo call'd Normandy Glafs, and for- merly Lorrain Glafi, becaufe made in thofe Provinces. At prefent it is made wholly in the Nine Glafs Works ; five whereof are in the Foreft of Lyons ; four in the County of Eu ; the laft, at 'Beaumont, near Rouen. — -It is of a thinner Kind than our Crown Glafs ; and when laid on a Piece of white Paper, appears of a dirtyifh green Colour. There are but 2 5 Tables to the Cafe.

German Glass, is of two Kinds, White, and Green : The firft is of a whitifh Colour, but fubject to thofe fmall,curved Streaks, obferved in our New-Caftle Glafi ; tho' free from the Spots and Blemifhes thereof. The Green, befide its Colour, is liable to the fame Streaks as the White : But both of them are ftraighter, and lefs warped than our New-Cajlle Glafs.—

2)utcb Glass, is not much unlike our New-Caftle Glafi, either in Colour, or Price. 'Tis frequently much warped, like that, and the Tables are but fmall.—

New-Caftle Glass, is that moft ufed in England. 'Tis of an Afh Colour, and fubjefl to Specks, Streaks, and other Blemifhes ; and befide is frequently warp'd. Lcybourn fays, there are 45 Tables to the Cafe, each containing five fuperficial Feet : Some fay there are but 3 5 Tables, and fix Foot in each Table.

Method of working Plate-w Looking Glass.

The Materials whereof Looking Glafi is made, are much the fame as thofe of other Works of Glafi ; viz.nn Alkali Salt, and Sand. •

The