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    Re: No Lunars Era
    From: Henry Halboth
    Date: 2004 Dec 5, 22:01 -0500

    I certainly so not question the evidence produced by actual voyage log
    books, but do wish to remind all hands of Thomas Arnold's work both in
    publishing and in conducting a school intended to educate the mariner in
    working Lunar Distances. As I have previously noted on this List,
    Bowditch was not alone in the advocacy of Lunars in the USA - Arnold,
    certainly a commercial vessel navigator, states having utilized them over
    a 40-year period as Master of American vessels, and in the 1820s wrote
    rather prolifically on the subject and actually operated a school at
    Philadelphia.
    
    It would be of interest to consider whether all navigation calculations
    actually done aboard any particular vessel, aside from a notation of
    position, was actually spread out on the pages of the log book, as
    opposed to being calculated on scraps of paper or in a separate workbook
    which remained the possession of the individual - of course it involves
    an entirely different era, but I still retain volumes of navigation work,
    of which only the resultant position ever found its way into the logbook.
    As they say, however ..."Different ships, different longsplices".
    
    Henry
    
    On Sun, 5 Dec 2004 16:06:59 EST Frank Reed  writes:
    > From the 18th and 19th century logbooks I've studied (only a sample
    > of the
    > thousands out there), I've noticed a pattern. Lunars (lunar distance
    > sights)
    > were never a primary method of navigation for American commercial
    > vessels.
    > There  was no "lunars era" comparable to the "chronometer era".
    > Rather the primary
    >  method of determining longitude until the 1830s or so was dead
    > reckoning, as
    > it  had been for centuries. Around 1830, the primary method began to
    > switch
    > over to  chronometers. During the early period of lunars, from
    > c.1770 to
    > c.1830, lunars  were used as an occasional check on the dead
    > reckoning. In their
    > logbooks,  navigators only occasionally updated their dead reckoning
    > with results
    > from  their lunars observations. Rather, they continued their dead
    > reckoning
    > until  they were able to take a new departure from a point of land
    > with
    > results of  lunars listed marginally. The "mindset" was centered on
    > the dead
    > reckoning.  After c.1830 (and it is a decades long process of
    > transition), the
    > primary  longitude listed in the logbooks become "long by chrono"
    > with occasional
    > checks  by lunars.
    >
    > For an example of a late holdover, take a look at the logbook of the
    > bark
    > "Mary & Louisa" from 1858 in the collection of the library at Mystic
    > Seaport
    > (mysticseaport.org). The navigator on this voyage from the northeast
    > US to
    > Shanghai uses dead reckoning as his primary longitude and for him
    > the  chronometer
    > longitude is only a sanity check, listed once in a rare while (no
    > lunars
    > either).
    >
    > I think I ought to risk stating the obvious here. Every navigator
    > works in a
    > unique manner. Many navigators in the 19th century never used lunars
    >  at all
    > --except "in the classroom". Some others, unusual navigators,
    > apparently  did
    > treat lunars as their primary method of finding longitude. But the
    > only case
    > I'm aware of personally is Nathaniel Bowditch himself. Additionally,
    > I should
    > note that the comments above refer specifically to "American
    > commercial
    > vessels".
    >
    > Any thoughts?
    >
    > Frank R
    > [  ] Mystic, Connecticut
    > [X] Chicago, Illinois
    
    
    

       
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