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    0000 not 2400?
    From: Jim Thompson
    Date: 2004 Oct 18, 08:01 -0300

    I am revisting my understanding of how dates change around the world over
    time (George called time/dates "slithery" -- no better word for it!).
    
    I am learning that times and dates, an arbitrary measurement tool applied to
    our spinning earth for human convenience, must have a set of carefully
    defined, fixed, arbitrary conventions to work.  One example is using Time
    Zone Y on ships at sea, as agreed upon in 1917 at the Anglo-French
    Conference on Time-keeping at Sea. But I think it would be safe to say that
    another convention would be to avoid using the term "2400".
    
    Although we can think and write the term "2400", it has no practical
    meaning, is that right?  As soon as the time advances past 23:59:59, then
    from a navigator's perspective the date changes to the next day, at time
    00:00:00.  The term "2400" seems to refer to a non-entity, a purely
    abstract instant of time past 2359 when it is midnight, but the date is
    still the same day.
    
    To resolve that conundrum, I revised the time-date conversion table at
    http://jimthompson.net/boating/CelestialNav/TimeDateConversionTable.htm
    by changing the entries from 2400 to 0000, and shifting the date
    relationships accordingly.  But the original version that used 2400 was
    based on the old US Coast Guard manual, which used 2400.  I do not know the
    historical context of their use of "2400", but today I think 0000 makes more
    sense.
    
    Am I merely catching up with the obvious?
    
    Jim Thompson
    jim2{at}jimthompson.net
    www.jimthompson.net
    Outgoing mail scanned by Norton Antivirus
    -----------------------------------------
    
    
    

       
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