Source:Dithridge-improved
From Pittsburgh Streets
Edward Dithridge and Edward D. Dithridge. "Improved lamp-chimney." U. S. patent 33,428, Oct. 8, 1861. http://pdfpiw.uspto.gov/.piw?Docid=00033428, https://patents.google.com/patent/US33428A. Reissue 4,182, Nov. 22, 1870: http://pdfpiw.uspto.gov/.piw?Docid=00004182, https://patents.google.com/patent/US4182A.
