A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Barrie
Date: 2016 Jun 27, 03:18 -0700
On the question of the accuracy of lunars in the early 19th century here is what Matthew Flinders had to say in 1814:
"...some sea officers who boast of their having never been out by more than 5', or at most 10', may deduce from the column of corrections in the different tables, that their lunar observations could not be entitled to so much confidence as they wish to suppose; since, allowing for every degree of perfection to themselves and their instruments, they would probably be 12', and might be more than 30' wrong".
He did however acknowledge that sixty sets of observation (!) using the latest tables would "probably give the longitude exact to 1' or 2' ". And as one of the finest hydrographers of his time Flinders had every right to make this comment. See my book 'Sextant' (chapter 13) for further details if you're interested.