585
* tlle opening in the
spreading furnace, for enabling the workmen to regulate the pro-
ft
x-
wmm,
- n 2
■<c
501
am? ’ ^ a ^ 00r ln the aane aling arch, for introducing the tools requisite for raising upremoving the tables.
jj] n forming glass-plates by the extension of a cylinder into a plane, the workman firsthe"? ^ le ^ um p of glass into the shape of an oblong pear, the length of which must be^ariy equ a ] to the length of the intended plate, and its diameter such, that the circum-bl 0 e ° ce> w **en developed, will be equal to the breadth of the plate. He now rests thej Wl hg i ron on a stool or iron bar, while an assistant, with a pointed iron, pierces a hole«nl° tlle extreme end of the pear, in the line of the blowing-pipe. This opening is thenar ;ed, by introducing the blade of a pair of spring-tongs, while the glass is turnedCV ]. a ®i and by skilful management, the end of the pear is eventually opened out into ar tndrical month. The workman next mounts upon a stool, and holds the blowing-ironprp Paiulic alaxly. - The blown cylinder is now cracked oflf, a punto rod of iron having beenjwtously stuck to its one end, to form a spindle for working the other by. This rod hasr. at fee « ' .
the
on its end, or three prongs, which being dipped in melted glass, are applied to
the 01011111 °f the cylinder. By this as a handle, the glass cone is carried to the fire, andop aar row end being heated, is next opened by spring tongs, and formed into a cylinder<W - same Slze as the other end. The cylinder, thus equalized, is next cracked or slitiron* 110 ‘ ts s ‘d e with a pair of shears, laid on a smooth copper plate, detached from thetfan r° J ’ s P rea£ I out by heat into a plane surface, and finally annealed. This series of^formations is represented in fig. 502, at A, b, c, o, e, f, g, h.
Slas 503 and 504 represent a Bohemian furnace in which excellent white windows ls founded. Fig. 503 is a longitudinal section of the glass and annealing furnace,fire i 04 ls tlle ground plan. a ls the ash-pit vaulted under the sole of the furnace ; thel„..'lVace itself is divided into three compartments; with a middle slab at d, which ishol-inthe centre, for collecting any split glass, and two hearth tiles or slabs b b. c c
are the draught or air holes; e e arearches upon which the bearing slabsf f partly rest. In the middle be-tween these arches, the flame strikesupwards upon the pots g g, placedas closely together as possible, foreconomy of room, h is the breastwall of the furnace; i,fig. 504, theopening through whicli the pots areintroduced; it is bricked up as soonas they are set. fc fc, is the base ofthe cone or dome of the furnace;l l l, the working orifices, whichare made larger or smaller accord-ing to the size of the glass articlesto be made, m is the flue whichleads to the annealing stove «, withan arched door. Exterior to this,there is usually a drying kiln notshown in the figure ; and there aredryi ao .adjoining stoves called arches, forT;,g ani * annealing the new pots before they are set.
Pur >>acp C • or annealln S arch; or leer, is often built independent of the glass-housebersi n , ’ '? t!lea heated by a separate fire-place, and constructed like a very long rever-The 1 Urnace ‘ See Copfek.
fiookn.i . r ' lans or trays sheet-iron, are laid upon its bottom in an oblong series, and3 _ 00 to each other.
"I'ere i—The crown-glass house with its furnace is represented in fig. 505,the oth 6 operation is shown on the one side of the figure, and the flashing on
si° 0s TJie furnace is usually constructed to receive 4 or 6 pots, of such dimen-10 make ab °ut a ton of glass each at a time. There are, however, several sub-
502 n