308 
History. “found in Hereulaneum, that window. glass had. been 
introduced at amuch earlier period. St Jerome, A. D. 
422, Paulus Silentiarus, A. D. 534, Gregory of Tours, 
A.D. 571, and Johannes Philoponus, A.D, 630,* all 
‘speak in the most distinct manner of the use of gl 
in the formation of windows. : 
Italy was the first modern nation that employed glass 
in windows. The custom was afterwards introduced 
into France; and though the art of making glass was 
brought into England in A. D, 674, by foreign artists 
sent for by the Abbot Benedict, who glazed the church 
and monastery of Weremouth in Durham, yet this great 
invention was so much neglected, that private houses 
were not lighted through glass till the.end of the 10th 
century. The windows of houses, and even of. cathe- 
dral churches, were covered with fine linen cloths. 
Painting of |The application of painted glass to the decoration of 
church win- ghurch windows, was made before the commencement 
cove. of the 9th century, as we are informed. by. Anastasius, 
librarian to Pope Leo III. that painted’glass was used 
in his time. This art made rapid advances to perfec 
tion ; and all the ingenuity. of the art was exhausted in 
the production of those splendid windows which at pre- 
sent adorn the Gothic cathedrals of Europe. The. art 
of staining glass, though still known and. practised, is, 
however, to a certain extent lost ; and we admire, with- 
out being able to imitate, some of the rich productions 
of the middle ages. We have had occasion to see a 
specimen of glass, brought home by Dr Brewster from 
the abbey of Konigsfeld, in Switzerland, which con- 
sists of sia different layers of green and purple glass 
placed alternately. The thickness of the plate is only 
about the 7th part of an inch ; and the different layers 
have an equality of thickness, and a parallelism, which 
is truly surprising.. The compound colour is a light 
purple. <A section of this. plate is shewn in Plate 
CCLXXV. Fig. 5, the dark layer representing the pur- 
ple, and the light one the green glass, 
Glass made, Lhe art of making plate glass by blowing, was car- 
at Venice. vied on to a great extent,at the village of Murano, near 
Venice ; and Europe was long supplied from this quar- 
ter with the finest and largest mirrors. ; 
In England _ We are indebted, however, to the French, for the art 
and France. of casting large plates of glass, which was introduced in 
1688 by Abraham Thevenart. An account of this esta- 
blishment, and of the-glass manufactories in England, 
will be found in our articles Enexanp, vol. ix. p. 10, 
nd France, vol. ix. p. 718. 
Glass appears to have been first made in Scotland in 
the reign of James VI. and the exclusive right of ma- 
nufacturing it within the kingdom, was given to Lord 
George Hay for 31 years, from 1610. This right was 
canal in 1627 for a considerable sum, to ‘homas 
Robinson, merchant-tailor in London, who again trans- 
ferred it for £250 to Sir Robert Mansell, vice-admiral 
of England. A manufactory of glass’ was carried on 
for some time in a cave at Wemyss, in Fifeshire. Re- 
gular glass works were afterwards established at Pres- 
tonpans ; but the principal places where glass is now 
made in Scotland, are Leith, + Glasgow, and Dumbarton. 
In Scotland- 
Secr.I, On Glasshouses, Pots, Sc. 
PS Tue glasshouses now in use are commonly large 
houses. Cones, from 60 to 100. feet high, and from 50 to 80 
* Philoponus informs us that the glass was fastened in with plast 
GLASS. 
feet in diametersat the base. ..The furnace is evected in. 
the centre, over 2. large. vault, extends from one 
side of the cone to the other. . The vault or. cave is 
generally made of a sufficient height and width to Bio 
the workmen to wheel a barrow with, rubbish out 
and in. This; however, is not the only, 2 of 
this cave, as it is made to communicate with Sg ate 
nace by an aperture in the top of it, of such a size 
as the furnace above may require. Over this a 
ture a grating of strong) iron_is placed, so as to be in 
the centre of the furnace, and upon that. grating pe if 
fuel is laid. and ignition is maintair by the ‘air that 
issues into it through the caves or. vaults underneath, q 
The crucibles or pots are the most important article Cm 
about a glasswork. ‘The clay obtained at Stourbridge * 
is found to answer the purpose better than any oie 
After carefully picking and brushing the, clay, it is _ 
ground ina mill, and sifted through a sieve of about j 
20 passes in an ineh ; it is then wet. with warm wai " 
and well tramped in a large cistern, until it is bro z 
to the consistence of a thick paste. Some manufacturers 
make up a very large quantity of this paste, and bop 
it in that state for many months: others, again, work i 
immediately into pots or crucibles. It is also common 
‘to take old crucibles and grind them down toa fine pow- 
der, which they add to the crude clay in quantities 
seldom exceeding a fourth part, from an idea that the 
burnt clay renders the crucible more refractory, and 
of course more likely to resist the combined action of 
the fire and alkali required.in the composition for glass. 
This mixture contracts less than if the pots were made 
entirely of crude clay, and of course is less liable to. 
break while drying. - 
nee. 
Various methods have been tried for worki 
into pots, by using moulds, &e.; but the met 
has most generally practised, is to knead the 
clay, while in the state of a paste, till it is nearly as tough 
as the putty used by glaziers. It is then made into r 
and wrought one layer upon another, and pressed to- 
ther with the greatest care, so as to make a ont Le 
y>. ane eh of any vacuity, and generally into the _ 
shape of an inverted cone, or into a lindrical fora ». 
four inches thick ; and house pots from, 
three inches thick, After the pots are made, it requires 
a good deal of attention to bring them to that state of 
dryness requisite for their being taken to the annealing 
furnace. Before pots are set into the furnace, they are 
heated up with the greatest caution, in an arch or vault 
built for the purpose, to a perfect white heat. This — 
operation requires four or five days, or if they 
are not very dry previous to their being used; | 
when they are completely annealed, as it is termed, they — 
are carried with the utmost expedition from the 
ing arch, and set into the working furnace. The setting 
of pots is deemed the severest labour about a 
house, from the great heat attending it ; and bo 
bed as follows by M. Blancourt.. observes, that t 
roughest work in this art,.is the changing the pots 
when they are worn out or cracked, In this case, the 
great working hole must be uncovered, the faulty pot 
+ The Editor has been indebted to Mr James GenDES, of Leith, 
crown, and flint glass, centainedin Sects, I, II, I'V, and V, 
for the principal information respecting the manufacture of bottle, — 
' . a 
