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    Re: Persistence and demise of Lunars
    From: Frank Reed
    Date: 2017 Dec 7, 16:17 -0800

    "Tables of occultations (and “Moon Culminating Stars”) outlasted Lunar Distance tables."

    Yes, but in which resource? :) A big problem when looking at these tables in this period is that The Nautical Almanac is not the "nautical almanac". The volume that we read today that says "The Nautical Almanac" is descended from the "Abridged Nautical Almanac" (British) and the "American Nautical Almanac". If you went to a bookshelf in 1920 and grabbed a copy of "The Nautical Almanac" you would soon realize that you're looking at an astronomer's reference. If you're digging online and explore "The Nautical Almanac" from that period, you're not looking at marine navigation tables at all! And in fact, the modern "Astronomical Almanac" is the lineal descendant of "The Nautical Almanac" (British) and "The American Ephemeris & Nautical Almanac". Neither of these latter books were used by practical navigators at sea. They were the reference works for astronomers in observatories. I suppose Shackleton brought "The Nautical Almanac" because the expedition was early in the splitting of the branches of the family tree, and also because they expected to be taking observations on solid ground, or solid ice, working more like astronomers than ocean-going navigators much of the time. 

    The family trees of almanacs/ephemerides split by function on both sides of the Atlantic at the beginning of the 20th century and then merge by function but trans-Atlantic after the middle of the 20th century. That is, in the 19th century we have one combined ephemeris/almanac work used by both astronomers and "nautical astronomers" (as celestial navigators were sometimes known back then). But there are two of them, largely identical in coverage, in the English-speaking world after mid-century: one British, one American. At the end of the 19th century, both works have shorter, cheaper extracts in print for navigators at sea. Then early in the 20th century, there are major revisions to what are now four separate volumes: the big, fat, relatively technical astronomical volumes become bigger, fatter, and more technical on both sides of the Atlantic, while the slim nautical editions become more specialized and more practical, especially on the American side (the British Abridged Nautical Almanac is an "also ran" and few of its innovations lasted). During the Second World War and accelerating after 1950, negotiations began to share the workload and create consolidated English-language volumes, one for navigators, one for astronomers. One milestone was passed when the star lists and were combined in 1953. Alas, poor Benetnasch did not survive. Five years later, in 1958, the British and American almanacs for marine navigators were combined in a new nautical almanac nearly identical to what's still published now, 60 years later. After two years retaining their old names, finally the name Nautical Almanac is made logical again, and was transferred to the actual nautical almanac. That was 1960... And let's not forget, on top of all this, there were a number of commercial nautical almanacs which generally used the government data and even the printing plates but sometimes in quite distinct arrangements and approaches.

    Frank Reed

       
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