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    Re: The Nautical Day
    From: Trevor Kenchington
    Date: 2004 Feb 7, 20:12 +0000

    You wrote:
     > The next question is- when did the noon-to-noon nautical day drop out of
     > use? We know that the noon-to-noon astronomical day remained the
    basis for
     > nautical tables until 1925.
     > The Admiralty may have directed that it should be dropped by the
    Royal Navy
     > in 1805, but it was certainly still alive-and-kicking in the Arctic
     > fleet in 1813, and a reference quoted by Chuck Taylor states that it
     > persisted into the 1820's in the East India Company..
    I have already pointed to Smyth's entries for "Day" and "Nautical Day".
    To quote them in full:
    "DAY. The astronomical day is reckoned from noon to noon, continuously
    through the twenty-four hours, like the other days. It commences at
    noon, twelve hours after the civil day, which itself begins twelve hours
    after the nautical day, so that the noon of the civil day, the beginning
    of the astronomical day, and the end of the nautical day, occur at the
    same moment. (See the words SOLAR and SIDEREAL.)"
    "NAUTICAL DAY. This day commences at noon, twelve hours before the civil
    day, and ends at noon of the day following. (See DAY.)"
    No hints there that the old system was fading from use. However, Smyth
    sometimes quoted (almost) verbatim from earlier nautical dictionaries
    (as in 200 years earlier for at least one entry). He also sometimes
    noted changing usage within his lifetime. I'd guess from the above
    entries in his book that the use of the nautical day was still
    widespread in English merchant and warships circa 1860. (His
    book was first published in 1867.) Since other contributions to this
    thread have noted that official records were required to be kept in
    civil days from much earlier, I would venture to suggest that ships
    maintained multiple calendars just as they did multiple times: GMT for
    celestial navigation but local apparent time for setting watches, for
    It seems bizarre to us, though we are all familiar with financial years
    which do not follow calendar years and everybody copes with the (quite
    unnecessary) extra complication.
    George also wrote:
     > Trevor Kenchington says-
     >>The Nautical Day, 24 hours early than the Astronomical Day, was long
     >>established and of general application -- at least in the
     >>English-speaking world. (Smyth, for example, treated it as an
     >>established fact, without reservations or caveats.) I'm not sure when it
     >>entirely ended. I have a vague memory that it was still used in the
     >>grain trade (under sail) in the 1930s, though I would be pushed to find
     >>a reference to that.
     > I wish only to question that last sentence. If the nautical day was
     > being used so late as the 1930's, I would expect to see some
    references to
     > it in my collection of textbooks and tables dating from the mid
    1800s, and
     > (from indexes only, not cover-to-cover scanning) I can find no such
     > references. Not that such lack-of-evidence is in any way conclusive. It
     > would be interesting to learn more, if only to avoid errors when
     > old logs.
    I'm not sure where I got that notion from, so it is hard to check it .
    There are many memoirs of the grain "races" but mostly written by young
    middle-class Englishmen who shipped before the mast for the adventure.
    They would not have been involved in navigation. The ship's officers
    were mostly Swedish-speaking Finnish nationals from the Aland Islands
    and they have not left us readily-accessible accounts.
    I do have Greenhill & Hackman's "Herzogin Cecilie" (1991), which
    includes some quotations from that ship's logbook in the hours leading
    up to her stranding in 1936. Those clearly used the civil day (changing
    24 to 25 April at midnight). Thus, I would tend to agree with George's
    scepticism. Before withdrawing any suggestion of such a late use of the
    nautical day, however, I would note that the same logbook says that they
    "Changed the ship's time to land time at 2100 hours" of the day that
    they arrived off Falmouth for orders. Most likely, that was either a
    matter of correcting their reckoning for small accumulated errors in
    their chronometer time or perhaps an adjustment of the watch schedule to
    match GMT rather than local apparent time. However, it remains possible
    from this limited evidence that the ship had been using the nautical day
    during her blue-water voyage from Australia and changed to the civil day
    on arriving in coastal waters.
    That is all that I can contribute on this topic.
    Trevor Kenchington
    Trevor J. Kenchington PhD                         Gadus@iStar.ca
    Gadus Associates,                                 Office(902) 889-9250
    R.R.#1, Musquodoboit Harbour,                     Fax   (902) 889-9251
    Nova Scotia  B0J 2L0, CANADA                      Home  (902) 889-3555
                          Science Serving the Fisheries

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