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    Re: 7 ways to determine longitude
    From: Fred Hebard
    Date: 2003 Dec 24, 16:18 -0500

    Just to nitpick, method 1, and, later, method 3 (substituting radio for
    telegraph), also are used at sea.
    Merry Christmas Everyone!
    Fred Hebard
    On Dec 24, 2003, at 4:12 PM, Frank Reed wrote:
    > Dan wrote:
    > "I have just started to read an old book called "Spherical and Nautical
    > Astronomy", a two volume set by William Chauvenet who was a professor
    > at Washington University in St. Louis.  My copy was printed in 1903 but
    > it appears that it is just a reprint of an 1863 edition."
    > Yes, that's the "Chauvenet" that you may have seen in a couple of
    > subject lines on the list. It's a classic.
    > "Chapter 7 is "Finding Longitude by Astronomical Observation" where it
    > lists seven different methods, which are:
    >   1st method - by portable chronometers
    >   2nd method - by signals
    >   3rd method - by the electric telegraph
    >   4th method - by moon culminations
    >   5th method - by azimuths of the moon, or transits of the moon
    >                and a star over the same vertical circle
    >   6th method - by altitudes of the moon
    >   7th method - by lunar distances"
    > One little thing to keep in mind is that Chauvenet was an astronomer
    > who was writing for other astronomers. Most of the methods were meant
    > to be used by astronomers at fixed positions on land. The only method
    > significant for ocean navigation is "by lunar distances". His method
    > was probably only used rarely at sea because it came along so late and
    > perhaps because so many other methods were already in place. His
    > analysis of the Earth's oblateness (polar flattening) is clever, and
    > his approach can be applied to other methods of clearing lunars
    > without much modification.
    > Frank E. Reed
    > [X] Mystic, Connecticut
    > [ ] Chicago, Illinois

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