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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Flinders' Survey of Australia.
From: George Huxtable
Date: 2008 Mar 3, 10:59 -0000
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@huxtable.u-net.com or at +44 1865 820222 (from UK, 01865 820222) or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---