GLASS. 



furnace to the stool, fig. 9, and rolls the 

 lump of glass upon it to bring 1 it to a round 

 forin,after which IK blows through the 

 pipe, resting the glass upon the iron plate 

 /behind the stool, as in the figure, and 

 rolling it backwards and forwards. The 

 blowing makes the glass hollow, and he 

 has several methods of bringing it to a 

 proper shape to be worked ; by simply 

 blowing, it would assume a figure nearly 

 globular; if he wants it any bigger, in the 

 equatorial diameter^, fig. 11, he lays the 

 pipe on a hook driven in the side of the 

 stool, and turns it round very quickly ; 

 the centrifugal force soon enlarges it in 

 the equator. If, on the other hand, he 

 wishes to lengthen its polar diameter, he 

 holds the pipe perpendicular, the glass 

 hanging downwards, its weight lengthen- 

 ing it, and to shorten the polar diameter, 

 he holds the pipe upright, the glass at the 

 top by blowing through the pipe the ca- 

 pacity is increased, and the thickness of 

 the glass ot the vessel diminished. 



We now suppose, that by a very dex- 

 terous application of the above methods 

 the workman has brought it to the shape 

 of fig. 11; he now carries it to the mouth 

 of the furnace, and holds it in to get a 

 fresh heat, (for by this time it is become 

 too stiff" to work easily) taking care to turn 

 it round slowly, that it may not alter its 

 figure. The vessel in this stage is deli- 

 vered to the second, or principal work- 

 man, the other two being only assistants ; 

 he is seated upon the stool, figs. 1 and 2, 

 and lays the blowing pipe, with the glass 

 at its end, across its arm a b y and with his 

 left hand rolls the pipe along the arms, 

 turning the glass and pipe round at the 

 same time ; in his right hand he holds the 

 pliers, fig. 3, whose blades are rubbed 

 over with a small piece of bees'- wax, and 

 as the glass turns round presses the blade 

 of the shears against it, following it with 

 the shears as it rolls, at the end or side, as 

 occasion requires, until he has brought it 

 to the proper size, which he determines 

 by the compasses, fig. 4, though not ma- 

 terially altering its figure, the first work- 

 man kneeling on the ground and blowing 

 with his mouth at the end of the pipe, 

 which hangs over the arm , when di- 

 rected by his principal. The third work- 

 man now produces the small rod, fig. 8, 

 which is dipped into the melting pot, to 

 take up a small piece of metal to serve as 

 cement ; the end of this rod he applies to 

 the centre of the glass, just opposite the 

 blowing pipe, the principal workman di- 

 recting it, by holding its end between his 

 pliers, the rod by the small piece of glass 

 on its end immediately sticks to the glass 



vessel, and the third workman draws it 

 away, both workmen turning their rods 

 round,' but in contrary directions ; this 

 operation forms a short tube on the end, 

 as in fig 12. The principal workman then 

 takes the short tube at i, between the 

 blades of a pair of pliers, exactly like the 

 others, but which are not covered with 

 bees'-wax; the cold of these pliers in- 

 stantly cracks the glass all round, and a 

 very slight jerk struck upon the rod 8 

 breaks it off. A hole is now made in the 

 end of the glass, which is enlarged by the 

 pliers while the glass is turned, as in fig. 

 13, until the neck is brought to the pro- 

 per size and length to fit the brass cap, as 

 before described, and the inferior half of 

 the lamp is brought to its shape and size 

 in the same manner. 



In order to form the upper half, the 

 third workman has in the meantime been 

 preparing a round lump of glass K, 

 fig. 14, on the end of one of the rods, fig. 

 8, this he applies hot to the end of the 

 neck, it being guided by the principal 

 workman, and it immediately holds tight, 

 he then breaks off the other neck at 7, by 

 the cold pliers, and thus separates it from 

 the blowing pipe. 



The glass is now heated a third time, 

 and brought from the furnace in the state, 

 fig. 15, to the principal workman, who 

 enlarges the small orifice at the end by 

 turning it round, and holding the pliers 

 against it, until he enlarges it, as in fig. 16, 

 to the shape of fig. 10 ; it is now finished, 

 and the third workman takes it to a stool 

 strewed over with small coals, he rests the 

 rod upon the edge of the stool, and with 

 the file, fig. 6, files the joint at the bot- 

 tom neck, which soon breaks oft', and the 

 lamp falls upon the coals, the distance be- 

 ing so very small, as to be in no danger 

 of breaking; a boy now puts the end of 

 a long stick into the open mouth of the 

 glass, and thus carries it up the steps be- 

 fore described, places it in the annealing 1 

 oven, where it remains some hours ; 

 when taken out it must be cooled gradu- 

 ally, and is fit for sale. 



In the history of glass, there is a fact 

 deserving record ; it is related by Pliny, 

 that the discovery was owing to the 

 following accident. Some merchants, with 

 soda as part of their freight, had cast an- 

 chor at the mouth of the river Belus, in 

 Phoenicia, and were dressingtheir dinner 

 on the sand, making use of large lumps 

 of the soda as supports for their kettles. 

 The heat of the fire melted the soda, and 

 the siliceous earth together ; the result 

 was glass. The hint was not lost, and a 

 manufacture in that trading country was 



