Saturday, August 22, 2009

1898 Hummel's Telediagraph

The Telediagraph was one of several early fax-like devices sending pictures via telegraph lines. It was invented circa 1895 by Ernest A. Hummel, a watchmaker of St. Paul, Minnesota. The first machines were installed in the office of the New York Herald in 1898. By 1899, Hummel had improved the machine and the newspaper had machines in the offices ofthe Chicago Times Herald, the St. Louis Republic, the Boston Herald, and the Philadelphia Inquirer.The system used synchronised rotating 8-inch drums, with a platinum stylus used as an electrode in the transmitter. The original image was drawn on 8x6" tin-foil using a non-conducting ink made from shellac mixed with alcohol. The image was received on carbon paper wrapped between two sheets of blank paper. When the electrode touched the tin-foil in the transmitter the circuit was closed; when it touched the shellac the circuit was open.The signal controlled a moving stylus in the receiver, making it touch or move back from the paper. At the end of each rotation a synchronising signal was sent, and the styluses in both machines moved 1/56" to the left before scanning the next line.The first picture sent was "an accurate picture of the first gun fired at Manila." The machine took 20-30 minutes to send the picture

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