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    Re: Sumner's Line (Navigation question)
    From: George Huxtable
    Date: 2006 Feb 14, 21:38 -0000

    Bill wrote-
    
    | For George, I still find the Bowditch editors' recounting ambiguous as is.
    | I stand by my statement.
    
    As long as Bill makes it clear that he is describing what he found in Bowditch, rather than in
    Sumner's own text, I have no quibble.
    
    | For the reader, rather than refer to it as "tinkering" with the original,
    | let me be specific. I was able to read through Sumner's book online Sunday.
    | Unfortunately, many pages at the end were listed as "n/a."  Perhaps these
    | are the plates.
    
    If those web pages omit the plates, that is indeed unfortunate, and detracts considerably from their
    value. I wonder, though, why Bill is still so unwilling to splash out $14 on the paperback, which
    will tell him all he wants to know.
    
    | As to my observations:
    |
    | 1. Tusker in Bowditch vs. Tasker in Sumner.
    |
    | 2. The Bowditch account omits the last paragraph which relates actual
    | position to DR position.
    
     Bowditch, in condensing Sumner's account to a single page, omits a lot more than that.  For
    example, Sumner provides a full page of numerical calculation on page 15.
    
    | 3. The Bowditch account omits the DR latitude.  This is the major sin of
    | omission, as if covers up (IMHO) that fact that latitude scale in the
    | Bowditch figure is off by approx. 5 degrees.
    
    Does Bill mean 5 minutes?
    
    Bill's persistence has pushed me into investigating, however. Yes, there are indeed discrepancies. I
    am not sure where the precise truth lies.
    
    Under protest, I have reluctantly done as Bill asked, and loaded Sumner's Plate III to the list's
    dedicated blackboard site, at navl@fisheriestrust.org  To me this classes as spoon-feeding,
    pandering to Bill's unwillingness to invest in that book. I hope it's arrived there in one piece,
    labelled-
    Sumner plate III 001.jpg (288 KB).
    
    Please let me know if there's any problem.
    
    My Times World Atlas, dating back to the 1950s, in its gazetteer, puts Smalls Lt. Ho. at 51deg 43'
    N, 5deg 30' W. That's about 6 miles SE of where Sumner shows it on his Plate III which I estimate to
    be about 51deg 48' N, 5deg 34' W. We really need an Admiralty chart of the 1830s to resolve that
    one, and I have no charts of that area to hand; it's away from my usual cruising-ground.
    
    The diagram in Bowditch puts the Smalls light at about 51deg 44' N, 5deg 30' W, some 6 miles W of
    its atlas position.
    
    I suppose it's possible, but doubtful, that the lighthouse has migrated, from one rock to another,
    over the years. By the 1830s, longitudes of the more important headlands and lights around the
    British coast had been rather precisely surveyed, but really detailed surveys did not happen in the
    Irish sea until the 1840s, with small steam paddlers. Of course, charts were not always updated
    tquickly to correspond, and Sumner might well have been using an old chart anyway.
    
    Anyway, there seems to be some confusion about the matter, and if anyone has access to old chart
    information, they might be able to resolve it. I'll take a look in the Bodleian Library, next visit
    to Oxford.
    
    The gazetteer of my Times Atlas gives the modern position of Tusker Rock Lt.Ho at 52deg 12' N, 6deg
    12' W.
    
    I wonder if that information helps Bill to put together his jigsaw.
    
    George.
    
    contact George Huxtable at george@huxtable.u-net.com
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    
    
    

       
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