manufactured goods, which travel upon a miniature railroad gradually
downward from the heated to the cooler end, a distance of about sixty
feet; one-fourth of the length of this distance is arched, and leads
into an air-tight receiving or sorting room, from which the goods are
ultimately removed. If there be two or more lears, or arches, in one
house, there should be various degrees of heat in each; the highest being
intended for strong goods for cutting, the medium for the ordinary run
of table Glass, and the lowest for vials or light lamp glasses.
The time for annealing varies from six
to sixty hours, the weighty articles requiring the most heat and time.
The best arrangements for annealing may be foiled, should the Glass-blower
unnecessarily lose time after finishing the work;
as the hotter the goods enter the arch, the better; on this account,
the large goods receive a final reheating at the mouth of a pot heated
by beech-wood, and called the Glory Hole.
Successful annealing depends much upon the proper direction of the wind:
the best aspect for this purpose is when it passes over the fuel of the
lear toward the lear chimney, so that the hot air is always radiating in
the downward current upon the goods. Great losses accrue from breakage,
when an upward or contrary current of wind drives back the heated air from
the cool or chimney end, toward the fuel at he upper end. While annealing,
the lower, or discharging end of the lear,