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    Re: long lost lunars
    From: George Huxtable
    Date: 2003 Dec 10, 01:06 +0000

    Frank Reed wrote-
    >Now how about Slocum? Everyone mentions him when they talk about lunars, but
    >reading "Sailing Alone Around the World", it seems that he barely used the
    >technique. Is there other evidence (his log book) that he practiced lunars
    >his circum-navigation?
    And I think somewhere recently (but I can't locate it now) Frank implied
    that Slocum used lunars only once in his circumnavigation.
    All this is a vile calumny on my favourite voyager! I think Frank should
    re-read his Slocum, as I have just done: for the nth time (and a pleasure
    each time).
    Slocum mentions, early on, that although he owns a chronometer it would
    cost $15 to get it cleaned, so he decided to leave it behind. At Yarmouth
    he purchased his famous tin clock, the price of which was a dollar and a
    half "but on account of the face being smashed the merchant let me have it
    for a dollar".
    South of Rio, "Spray" exchanged positions with a steamship, and, with her
    tin clock, had exactly the same reckoning.
    43 days out from Juan Fernandez he says- "If I doubted my reckoning after a
    long time at sea I verified it by reading the clock aloft made by the Great
    Architect, and it was right."
    Nearing Nukahiva (Marquesas), he obtained a lunar longitude that was within
    5 miles of his dead reckoning, and when sighting it found that his
    longitude was halfway between those two reckonings. He said "even expert
    lunarians are acknowledged as doing clever work when they average within 8
    miles of the truth." Clever work indeed. But this was after discovering an
    error in a logarithmic table that otherwise would have put him many
    hundreds of miles out.
    Nearing Timor, he says "But the greatest science was in reckoning the
    longitude. My tin clock and only timepiece had by this time lost its
    minute-hand, but after I boiled her she told the hours, and that was near
    enough on a long stretch."
    These passages are written in such a way as to imply that the lunar
    observations were routine matters that were kept up at regular intervals.
    How, otherwise, could he have had lat and long readily at hand to exchange
    with that steamship?
    However, in mid-Indian Ocean, he does admit- "I hope I am making it clear
    that I do not lay claim to cleverness or to slavish calculation in my
    reckonings. I think I have already stated that I kept my longitude, at
    least, mostly by intuition."
    In taking a lunar, the angle changes so slowly that precise timing is
    unnecessary. The requirement for extreme precision is in the angle, not in
    the time. A clock with an hour hand only could probably be estimated to the
    nearest minute or two, which was close enough to relate a morning
    time-sight to a measured lunar distance. And it could give a rough measure
    of time (and therefore longitude) for a few days thereafter. Even if it had
    been boiled. So Slocum's claim isn't impossible.
    However, Slocum's son, Captain Victor Slocum, in his biography "Capt.
    Joshua Slocum" (1950), thought that the tin-clock business was Slocum's
    "joke". Here's what he says, about the days when Joshua was a merchant
    "On one of the Captain's runs in the Constitution between Honolulu and San
    Francisco, his chronometer broke down. But as it had always been rated by
    lunars, the mishap made no difference so far as navigation of the vessel
    was concerned. In fact, on arriving in San Francisco, it was found that the
    passage had been unusually short. Mr Bichard, the owner, who was waiting on
    the dock, was amazed, and without saying a word about the circumstances of
    the voyage, turned on his heel, and returned with the best chronometer
    watch, an E. Howard, that money could buy. This he presented to his
    Captain, both as a mark of appreciation and a guarantee that he would be
    protected against further accidents by having a second timepiece about.
    The chronometer breakdown episode throws a light on the navigation of the
    Spray which has never been very well understood, owing perhaps to the
    Captain's purposeful vagueness on this point. Even professional navigators
    have taken his tin clock joke seriously. The Captain meant that he emploted
    the same methods in navigating the Spray that he had on all of is former
    vessels. In the hands of skilful observers and patient computers the Lunar
    Method is reliable within a quarter of a degree longitude, which would be
    the distance of a high landfall..."
    As for me, I think that Joshua Slocum was a gifted teller of tales, and
    don't think we need to accept every word as gospel truth.
    contact George Huxtable by email at george@huxtable.u-net.com, by phone at
    01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
    Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.

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