Source:Dithridge-molds
From Pittsburgh Streets
Edward Dithridge. "Improvement in molds for making lamp-chimneys." U. S. patent 124,343, Mar. 5, 1872. http://pdfpiw.uspto.gov/.piw?Docid=00124343, https://patents.google.com/patent/US124343A.
Edward Dithridge. "Improvement in molds for making lamp-chimneys." U. S. patent 124,343, Mar. 5, 1872. http://pdfpiw.uspto.gov/.piw?Docid=00124343, https://patents.google.com/patent/US124343A.