In 1905 the borough ranked fifth among the cities of the United States in the manufacture of glass (plateglass, lamp chimneys and bottles), its product (valued at $1,841,308) being 2.3% of that of the whole country.
In the original Whitwell stove, which lacks the chimneys shown at the top of fig.
On account of its transparency and its resistance to fire and sudden changes of temperature, mica has been much used for the windows of stoves and lanterns, for the peep-holes of furnaces, and the chimneys of lamps and gas-burners.
Among the many developments of the Jena Works, not the least important are the glasses made in the form of a tube, from which gas-chimneys, gauge-glasses and chemical apparatus are fashioned, specially adapted to resist sudden changes of temperature.
The furnaces are square and open in front, to allow the outlet ends of the retorts to project; they are grouped together by fours; and their several chimneys are within the same enclosure.