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    Flinders' Survey of Australia.
    From: George Huxtable
    Date: 2008 Mar 3, 10:59 -0000

    I've just been reading "The Voyage of the Investigator", by K A Austin,
    written in 1964. This is the story of Matthew Flinders' cicumnavigation and
    survey of the continent of Australia from 1801 to 1803.
    
    It's rather short on the technical detail that I like to go for, but
    nevertheless a good account of an important voyage, by a skilled and
    enterprising (if unfortunate) navigator.
    
    Flinders died at only 40, in 1814, and the last few years of his life were
    spent in writing "A Voyage to Terra Australis", in two volumes and a folio
    Atlas, which appeared in the year he died.
    
    On page 202, Austin writes-
    
    "A major setback occurred when the lunar tables that had been used during
    the voyage were found tohave been erroneous. As a result, all observations
    made for longitude had to be corrected, and all charts altered accordingly.
    This revision took up most of 1813".
    
    [Unfortunately, no reference is given for that interesting bit of
    information. Perhaps it's mentioned within the journal itself, which I
    haven't read. Can anyone tell me if an accessible digitised version of
    Flinders' "A Voyage to Terra Australis" exists? All I have is an edition
    (2000) by Tim Flannery, titled "Terra Australis", purporting to be of
    Flinders' book, but so thoroughly filleted that little remains.]
    
    It's a bit of a surprise, in that Austin also tells us, on page 44, that the
    Board of Longitude provided Investigator with "astronomical telescopes and
    five timekeepers". The chronometers of that era were not always robust, and
    it's likely that not all the five remained in action over the whole two
    years.
    
    However, the problem with chronometers in those days (and later) was their
    gradual drift. Fine for on ocean voyage of a couple of months, but providing
    unacceptably degraded longitudes when used over much longer periods than
    that, unless some known headland, with known longitude, had been sighted en
    route. Flinders had left civilisation (if Port Jackson, later known as
    Sydney, could be described that way) in May 1802,. From what Austin tells
    us, it appears that from then on he must have relied on his lunars to find
    any drift. That was exactly what Cook had had to do in his second voyage,
    using an early chronometer, 30 years before. Neither Cook nor Flinders could
    expect to do any better than the precision of the lunar predictions in their
    current Almanacs.
    
    I have read comments elsewhere about inaccuracies in the Nautical Almanac,
    which appears not to have progressed much in prediction accuracy since its
    inception in 1767, and grown complacent about it. I wonder how big were
    those almanac errors in 1801-03, and who or what had brought them to light
    by 1813? It's an interesting thought, that if those discovered Almanac
    errors were large enough to call for significant corrections to Flinders'
    observed longitudes, they were affecting every other lunar navigator,
    elsewhere in the World, in exactly the same way.
    
    George.
    
    contact George Huxtable at george---.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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