NavList:

Patrick, you wrote:
"Looking for a nav guide contemporaneous with Cook, I found a copy Maskelyne's "British Mariner's Guide: Containing complete and easy instructions for the discovery of the longitude at sea and land". My question is, is Maskelyne's method similar to what Cook was using? The astronomer royal has not appeared so far in B's account except as a name. Did Cook know of his work and did he use it?"

The "British Mariner's Guide" published in 1763 was a stopgap with quite long and elaborate calculations which, while feasible with great effort, were not really a practical solution, and Maskelyne knew it. He campaigned in the next few years to have the calculations greatly reduced for practical navigation at sea by doing most of the computations on land. He made his case and got his funds; the longitude would be found by tabulating lunar distances in a little book, pre-computed in Britain, for use all around the globe. THIS was the origin of the original "Nautical Almanac and Astronomical Ephemeris" which is the ancestor of our modern "Nautical Almanac".

The first Nautical Almanacs were published with data for the year 1767, and they were cranked out rather quickly by Maskelyne's team of computers (a "computer" was a person). When James Cook and Joseph Banks and the others left for the Pacific to observe the transit of Venus, they had the Nautical Almanac available for several years ahead. I don't remember if they had enough editions for the whole duration of that first voyage.

Cook's expedition also had the "Tables Requisite" which included all the other details for accomplishing the job including instructions on clearing lunar distances and working all the other calculations of nautical astronomy. You can find two editions of the Tables Requisite (made available by Google Books) under the "Resources" section right on the main NavList page. Here's the short link to this list of books (which I try to maintain): http://www.fer3.com/arc/navbooks2.html

-FER

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