NavList:

Modris, Wolfgang, Frank, Murray,  Bill, and Robert,

Thank you all for the very thoughtful and valuable responses. I was indeed aware of the two articles that were attached to a previous Navlist interaction (Frank and Modris) but I re-visited them since it had been some time since I first reviewed them. The Whiteley article provides a good (and very readable) overview of Cook's time in Newfoundland but it was Andrew David's 2009 article in The Northern Marina that reminded me of the Burgeo Island's eclipse measurements and their later reduction to an estimate of longitude. A. David tells us: ". . on 5 August 1766, having now his own telescope, he observed an eclipse of the Sun on Burgeo Islands off the south coast of the Newfoundland. The longitude of these islands was subsequently calculated in England by an amateur astronomer, Dr John Bevis and later used by Cook in his printed sailing directions."

I do not attach any particular significance to the fact that Nevil Maskelyne hadn't published his lunar tables until after Cook’s time in Newfoundland. The ephemeral information Cook needed would have been available in the years leading up to the publication and/or (as some of you suggest) they could have been derived from other (then available) sources. At the end of each survey ‘season’ in Newfoundland, Cook make the long commute back to England and overwintered his survey schooner, The Grenville, in Deptford on the River Thames literally within a short walk of the Royal Observatory at Greenwich where Nevil Maskelyne laboured away on his upcoming publication of lunar tables.

I have nothing to suggest that the two men were aware of each other’s work but I would be thoroughly surprised to learn they weren’t. Cook’s survey work was a major part of an important British military mission. The islands of St. Pierre and Miquelon just off the south coast of Newfoundland were being ceded to France as part of the peace terms of the Seven Years War and Newfoundland’s Governor Hugh Palliser wanted them thoroughly charted along with all adjacent Newfoundland coastal areas in order to support British warship patrols.

Although St.Pierre and Miquelon were being given to France as a haven for French fishermen, the British strongly suspected that the French were going to use them as a secret military base and wanted to know more about them (than the French did) before handing them over. My point here is that Cook would have had (I believe) the necessary ‘security clearance’ and maybe even an explicit mandate to access whatever information he needed to have his charts provide the greatest degree of security and safety for the British warships that would be deployed to keep an eye on French activities. I am led to suspect (but do not know) that Cook had taken many, many more measurements with the intent of having them reduced eventually to longitude estimates.

Well now, you might ask, why did he publish his charts with only latitude. This is a great question and my response to this (actually, my poorly supported hypothesis) is based on the military mission mandate underlying Cook’s hydrographical activities. Charts published with longitudes would have easily fallen into French hands and thereby minimized any British military advantage realized by Cook’s surveying work. Ok. I’m now firmly in the area of wild speculation so I’ll stop there.

Thank you all for your knowledgeable responses. Again, I must apologize for my long-windedness.

Cheers,

Jim.