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    Re: No Lunars Era
    From: George Huxtable
    Date: 2004 Dec 6, 20:33 +0000

    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."
    
    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. For example, Robert Bishop's form, dated
    1768, can be seen copied into Howse's biography of Nevil Maskelyne (also in
    "The Quest for Longitude"). Later, around 1812, the English whaler William
    Scoresby the younger was using such forms, presumably pulled from a pad
    produced by Norie, which used a Mendoza method. Such observations would be
    taken at a particularly perilous point in his annual return journey South
    to Whitby, from the whale-fishery between Geenland and Spitzbergen, when it
    was essential to pass to one side or the other of the unlit skerries that
    surrounded Shetland.
    
    I think we need to recognise that otherwise well-found vessels were
    continuing to make ocean passages, well into the mid-1800s, without lunars
    or chronometers, still adhering to the old methods of latitude-sailing to
    find their way around the globe.
    
    George.
    
    ================================================================
    contact George Huxtable by email at george---.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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