From Pirotechnia by Vannoccio Biringuccio. First edition 1540.
The "glory hole," the opening in the furnace for accessing the glass inside to begin to work. It is here where furnace-wound beads are made.
From L.M. Angus-Butterworth, "Glass", pp. 358-78 in Charles Singer, et al. 1958 A History of Technology, Volume !V: The Industrial Revolution, Oxford U. Press, New York/London.
One way of drawing glass tubes.
From Harper's Magazine 1871Glass-Blowing as a Fine Art 42(249): 337-54.