Source:Dithridge-annealing
From Pittsburgh Streets
Edward Dithridge. "Improvement in annealing glassware." U. S. patent 38,930, June 16, 1863. http://pdfpiw.uspto.gov/.piw?Docid=00038930, https://patents.google.com/patent/US38930A.
Edward Dithridge. "Improvement in annealing glassware." U. S. patent 38,930, June 16, 1863. http://pdfpiw.uspto.gov/.piw?Docid=00038930, https://patents.google.com/patent/US38930A.