The Democratic advocate. [volume] (Westminster, Md.) 1865-1972, 1878-07-13
How Common Wiaa0v aIass ! Made.


IT ever you visit Pittsbnrg, in Pennsyl-
Fania. you must 60 into the window glass
factories there; you viii fnd them very
curious. Their furnace, in the first place,
is built in the ancient style, it has no
chimney, and the smoke from the bitumi-
mons coal they burn pours out in a cloud
into the room. There are openings in the
roof fOriit to escape through, and con
tinual draught of air from the door carries
it upward, so that it is not as bad for the
workmen as one would think, Besides,
they do not begin to blow until the smoke
is all burnt of. as 7'a'i,i a.io
There are five pots on each side of the
furnace; and you win see FIVE men in a
row, blowing all at once, with the Tegulari-
ty Of fle of soldiers exercising. Each
gathers 80 or 40 pounds Of metal on his
pipe, which is very long and strong. They
stand on platforms to get room to swing
the glass as they blow it. The five men
begin to blow aud swing all together.
Each blows great globe Of glass, which
is stretched out gradually BY the swinging
motion into cylinder or roller, as it is
called, FIVE feet long. Then the FIVE roll
lers are swung up towards the furnace
holes, and five other soldiers spring forward
with their guns-which in this case are
iron bars, that they set upright under the
five blowing pipes to support them while
the rollers are being reheated in the neeks
of the pots. The blowers blow in the
necks of the pipes with all their might,
then clap their thumbs over the holes to
prevent the air from rushing ont again; in
the meanwhile the end Of the roller is
softened, SO that at last the air, forced in
and expanded by the heat, bursts it out
ward. The glass is then cylinder, open
at one end. It is then 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 were laid on tables where
the imperfect spherical end about the
blowing pipe is cracked off the rest by
strip Of melted glass drawn around it.
The cylinderis then cracked from end to
end on one side by means of red hot iron
passed through il.
In the adjoining building is what is
called the fatteuing oven. The cylinders
brought there are lifted on the end of
lever, passed in through circular opening
just large enough to admit them, and laid
on fattened stones on the oven bottom,
with the crack uppermost. The oven
bottom is circular, and it revolyes hori-
zOntally.a As the glass softens it separates
at the crack, and lays itself gently and
gradually on the stone The long cylin-
der Is then fat sheet three feet wide and
nearly five feet in legth. There are four
openings around the sides of the oven, at
one the glass IS put in, through another
workman sweeps the stone for it, a third
workman smooths it down with a block as
it comes round to him, and fourth, at
the last opening, which is close to the one
at which it was put in, lifts the sheet
partly cooled by this time-upon a ear
riage in the oven. This he does BY means
of lever furnished with sharp, broad
blades at the end, which he works in under
the glass. When the carriage is full it is
Fnn through an annealing oven beyond.
The opposite end of the apnoalipg oven
opens into the cutting room. There the
carriages are pushed along a central track,
and unloaded at the stalls of the cutters.
The cutter has a table before him with
measure marks on its edges He lifts one
of the sheets, lays it on a table, and CON-
mences ruling it faster than school boy
rules his slate. His ruler is wooden rod,
five feet long and his pencil point Is a di.
amond. Every stroke is a cut. Not that
he cuts the glass quite apart; indeed he
seems scarcely to make a scratch. Yet
that scratch has the effect of cracking the
glass quite through, so that it breaks clean
off at the slightest pressure. In this way
the sheets are cut up into panes of the
requisite size.
| remember one workman told me that
asingie diamond would last him two or three
years. 1t has Is or 16 different edges,
and when one is worn out he uses another.
South American diamonds, such as he
uses, cost he told me, from six to thirty
dollars each; and when they are worn out
for his purpose, he sells them for Jewels to
be put into watches.-J. T. Tro,cbridge.