English: A diagram of the operating mechanism of a syphon recorder, an antique device used in telegraph stations during the late 1800s to the early 1900s to record incoming telegraph messages on paper tape. It functions on the principle of a D'Arsonval galvanometer. The telegraph signal current passes through a coil of wire suspended between the poles of a permanent magnet. The pulses of current representing "dots" and "dashes" of Morse code create a torque that causes the coil to rotate slightly about its vertical suspension. It is attached by two wires to the metal plate syphon support, which causes the metal plate to pivot about its horizontal axis suspension of thread. This swings the glass syphon tube which hangs down from the plate across the paper tape, making a pulse representing the Morse code "dot" or "dash" on the tape. A transcriber later reads the tape, translating the Morse code dots and dashes into characters spelling out the text message.