The Story of Pittsburgh 
GLASS 
5 
HERE is scarcely a form of manufactured glass 
in which Pittsburgh does not take the lead, from 
window glass and lamp chimneys to optical glass 
and astronomical lenses. 
Very large is the city’s production of plate glass, win- 
dow glass, pressed table ware and lamp chimneys. The 
finer manufactures in glass are represented by establish- 
ments which make diffracting prisms, used in lighthouses, 
lenses for telescopes, opera glasses, microscopes and range- 
finders. Dr. John A. Brashear, who recently died, mourned 
by thousands who knew him personally, and to whom he 
was “Uncle John”, enjoyed an international reputation 
as an astronomer and a maker of the finest telescopic 
lenses made anywhere in the world. His establishment 
was known the world over for the excellence of the lenses 
it produced. 
The Encyclopedia Americana, the most recently pub- 
lished work of this character, speaking of Pittsburgh, says: 
“The total production of plate glass in the district in 1918 
was nearly 60,000,000 square feet, which, if made into one 
sheet, would cover an area of 1877 acres, or make a pane 
of plate glass three miles high by one mile wide; and the 
ordinary window glass made here, would, if in one piece, 
oe a pane nearly three times as large.” 
The invention of glass occurred at so early a date in 
:he history of the world, as to be lost in obscurity. The 
method of its discovery is a matter of surmise. Obsidian, 
which is found in volcanic discharges, was the earliest form 
of transparent matter. It was used by the ancient Egyp- 
tians in the manufacture of various objects. The Romans 
and the early Mexicans also fashioned articles from obsidian.