they set upright under the five blowing-pipes to support them while
the rollers are reheating in the necks of the pots. The blowers blow
in the pipes with all their might, then clap their thumbs over the
holes to prevent the air from rushing out again; in the mean while the
end of the roller is softened, so that at last the air, forced in and
expanded by the heat, bursts it outwards. The glass is then a cylinder,
open at one end. It is whirled in the heat until the edges become true,
then brought away,-- the five iron supports dropping to the ground with
a simultaneous clang. The cylinders are laid on tables, where the
imperfect spherical end about the blowing-pipe is cracked off from the
rest by a stripe of melted glass drawn around it. The cylinder is then
cracked from end to end on one side by means of a red-hot iron passed
through it.
"In an adjoining building is what is called the
flattening oven. The cylinders brought there are lifted on the end of
a lever, passed in through a circular opening just large enough to
admit them, and laid on flattening stones on the oven bottom, with the
crack uppermost. The oven bottom is circular, and it revolves horizontally.
As the glass softens, it separates at the crack, and lays itself down gently
and gradually on the stone. The long cylinder is then a flat sheet, three
feet wide and nearly five feet in length. There are four openings around
the sides of the oven; at one the glass is put in, through another a workman
sweeps the stone for it, a third workman smooths it
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