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    Nautical Mile, was: Why is a sextant like it is?
    From: Trevor Kenchington
    Date: 2004 Nov 18, 19:30 -0400

    Alex wrote:
    > I am sorry, but is seems that "the mile is a minute"
    > is the DEFINITION of the (n)mile, which was made
    > just because people wanted to preserve this super-ancient
    > system of degrees and minutes. The nautical mile was introduced....
    > I don't know exactly when, but centuries if not millenia
    > after this Babylonian hexadecimal system.
    > (Let Herbert Prinz correct me here. I really don't know much
    > about history).
    The nautical mile is quite a recent unit, which seems to have arisen
    because the length on the ocean surface subtended by one minute of
    latitude proved to be conveniently close to one Roman mile -- itself the
    distance covered by 1,000 paces by a Roman soldier (the Romans counting
    a "pace"  from one foot lifting off to its touching down again, in
    contrast to the modern English notion of a "pace").
    The whole topic is apt to get confused because the length of a degree of
    latitude, the length of a foot, the numbers of feet per mile, miles per
    league and leagues per degree were all fluid. The earliest close
    approach (at least in English) to the modern version seems to have come
    with Norwood's "The Seaman's Practice" of 1637. At least, that is the
    best answer I can dig out of Waters' "The Art of Navigation" -- a
    comprehensive but sometimes confusing source.
    At the opposite end, the origins of the 360-degree circle and 60-minute
    degree may belong to Babylon but, along with much else of Mesopotamian
    culture, could be far, far older. Seafaring was at least 50,000 years
    old and perhaps 500,000 by the time that the Sumerian kings recorded the
    story of their progenitor escaping a catastrophic flood in his reed ship
    (complete with breeding pairs of his domesticated animals). Somewhere in
    that huge span of time, men capable of building seagoing vessels and
    crossing open water may have felt the need to divide the circle into
    convenient units, using as system that we know has survived about five
    millennia and could well have survived ten times longer.
    Trevor Kenchington
    Trevor J. Kenchington PhD                         Gadus{at}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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