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    Re: No Lunars Era
    From: Fred Hebard
    Date: 2004 Dec 6, 22:41 -0500

    >> Frank Reed wrote-
    >>> 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.
    >> and Henry Halboth added-
    >> "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."
    > An George Huxtable added
    > I think Henry has a worthwhile point here. Right from the earliest
    > days of
    > lunars, in the 1760s, printed pro-formas existed to systematise the
    > calculations involved in a lunar....
    Unfortunately, I expect they sailors would have said in the log:
    "longitude by account," or "longitude by chronometer," or "longitude by
    lunar," depending upon the method used, even if the calculations were
    not recorded.

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