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Modris

Following your suggestions I tried to find out more about the letter by Green, so I ordered Beaglehole’s biography of Cook from our University library. Unfortunately Beaglehole doesn’t give a source for his quotation as you can see from the page I am attaching (Beaglehole, The Life of Captain James Cook, Stanford 1974, 154). But he was obviously thinking that Cook was only introduced to lunars by Green at the beginning of the First Voyage. As Frank has already explained Green’s letter may well be interpreted to refer to the beginning of the first voyage. That is plausible because the letter was written in Rio de Janeiro – after more than 3 months at sea – so Green had ample time for instructions and the log only records one lunar observation that may have been made by Cook.

If you want to follow this up I suppose that the letter may be in the Public Record Office in the UK National Archives, Kew among other letters to the Royal Society sent during the First Voyage – held under the signature PRO Adm 2/541.

So considering that the log of Cook’s passages to Newfoundland does not show determinations of longitude by lunars and that his only attempt to fix longitude in North America astronomically was by an eclipse of the sun in 1766 it should be considered as a fact that he did not use lunars during his surveys in North America.

And by the way, it would be helpful if you would give an indication of the origin of your images (in the case of your picture from the Flinders logbook: https://cudl.lib.cam.ac.uk/view/MS-RGO-00014-00064/1)

Cheers
Wolfgang