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    Telegraphic longitude
    From: Paul Hirose
    Date: 2003 Mar 24, 16:31 -0800

    Putting those words into a search engine produces many interesting
    hits. Take a look at this paper presented at an IEEE conference by
    Trudy Bell. She goes into the specific techniques in some detail.
    And this online version of the 1911 Encyclopaedia Britannica has an
    article with surprising technical depth. It's a bit rough due to
    misreads by the optical character reader used to transcribe the text.
    However, it's possible to make out the method used to cancel the
    effect of signal transit time over the telegraph link.
    Those two links are just from the first page of hits; there may be
    even better stuff out there. I haven't looked further yet.
    Coincidentally, I have "The Victorian Internet" (Tom Standage, 1998)
    checked out of a library. The high voltage telegraphy George is
    wondering about was the brainchild of Dr. Edward Whitehouse. Tycoon
    Cyrus Field hired him as chief electrician on the Atlantic cable
    project. Unfortunately, Whitehouse was a medical doctor who was merely
    a self-taught hobbyist when it came to telegraphy.
    Although the cable worked at first, it couldn't take the voltage from
    Whitehouse's big induction coils. After a month the gutta-percha
    insulation broke down.
    It was the great scientist William Thomson (later known as Lord
    Kelvin) who showed that low voltage and an extremely sensitive current
    detector were the right approach. Standage says: "The death blow was
    finally dealt to Whitehouse's high-voltage theories by the noted
    engineer Josiah Latimer Clark, who had the two cables connected
    back-to-back and successfully sent a signal around the whole circuit
    -- from Ireland to Newfoundland and back -- using a tiny battery and
    Thomson's mirror galvanometer as the detector."

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