An edition of George A. Campbell, application filed March 5, 1900, serial no. 7281 v. Michael I. Pupin, patent issued June 19, 1900, no. 652, 230, application filed Dec. 14, 1899, serial no. 740, 238 (1902)

George A. Campbell, application filed March 5, 1900, serial no. 7281 v. Michael I. Pupin, patent issued June 19, 1900, no. 652, 230, application filed Dec. 14, 1899, serial no. 740, 238

interference declared Aug. 22, 1900 : record for George A. Campbell

By George A. Campbell,Michael Idvorsky Pupin,United States. Patent Office