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Curiosities
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·Title ·21 ·48 ·75 ·102 ·129
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·iv ·23 ·50 ·77 ·104 §Plate 1
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§Contents ·26 ·53 §80 ·107 ·Plate 2
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·3 ·30 ·57 §84 ·111 ·Plate 3
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·14 ·41 ·68 ·95 ·122 §Index
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ANNEALING.
was formerly always under the lock and key of the Excise-man; often to the great injury, and always to the great inconvenience, of the manufacturer.
Goods for cutting, requiring extra care and time in the lear, are protected from cold draft under semi-cylindrical arched iron covers, technically called "omnibuses;" or, when very massive, the goods are immersed in hot sand. Kilns were formerly used for annealing almost universally to render the Glass fit for the severe friction of deep cutting. There is a great distinction between a kiln and a lear. The kiln, when in use, is closed at the further end; whereas the lear is open at both ends. The kiln, when filled with goods carefully placed in pans, is closed, with the burning fuel also; the openings, or interstices, in the event of the door not shutting accurately, are seal up with clay; and the time required to cool is usually about a week. This period seems very long in comparison with the short time allowed for the lears; but, as the Glass in the kiln is immured with the burning coke, which consequently parts with its caloric very slowly, it will require nearly that period to allow the Glass to become sufficiently cool to be handled, or to expose it to the ordinary temperature of the atmosphere. The lear admits the goods to be continually drawn more quickly, although by slow degrees, away from the burning coke; and the glass, therefore, more readily cools. Kilns are objectionable through causing so much delay; and dispatch being the order of the day, they have been superseded by the use of iron covers, or sand, in lears, as already stated: likewise by lengthening the lear fire-places, and not filling the pans with Glass too fast, as well as by great attention to the regularity and intensity of heat; it being the instruction