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    Re: Old Navigation Techniques
    From: Lu Abel
    Date: 1998 Jul 22, 3:22 PM

    I have not seen the article in Navigation, but I find it very hard to
    believe the assertion that Columbus might have used Lunars.
    Involvement in a Power Squadron project in celebration of the Colombian
    Quincentennial in 1992 allowed me to learn quite a bit about navigation in
    the time of Columbus.  The state of the art for celestial navigation in the
    late 15th century was determining latitude by Polaris using a backstaff,
    astrolabe, or quadrant (the latter was like a child's protractor; the
    navigator sighted along it while a crewman simultaneously read latitude from
    a plumb bob line).  Precision of even 1 degree was hard to achieve.  Ships
    typically sailed to the latitude of the destination point and then sailed
    along that latitude line until they bumped into the destination.  Longitude
    determination was impossible; accurate timepieces were far in the future.
    Many naval historians doubt Columbus used celestial at all, but there is
    general agreement he was a superb DR navigator.
    The history of Columbus's expedition with respect to navigation and
    geography is interesting.  In the early 15th century (Europe's) knowledge of
    world geography spanned from the Baltic to the Mediterranean, from the Black
    Sea to the Canaries.  People thought Scandinavia might be an island and they
    had no knowledge of the coast of Africa more than a few miles below the Med.
    Spain did not yet exist as a nation (that happened with the marriage of
    Ferdinand and Isabella in the last quarter of the century).
    The Portuguese, starting in the 1520s, endeavored to methodically explore
    the coast of Africa, with a strong belief they could pass below its southern
    tip and thereby get to the Orient by sea and cash in on the thousandfold
    markups typical of the overland spice trade controlled by the Arabs and the
    Italians.  Prince Henry, one of the younger sons of the King (and therefore
    having no career ahead of him unless his older brother died) became a patron
    for advancing the state of the navigational art and founded the first
    scientific institute for methodically dealing with a technical problem.  In
    what was probably the first nautical almanac, a couple of astronomers in
    Henry's employ worked out tables for the declination of the Sun over a
    year's time.  This allowed the Portuguese explorers to sail below the
    Equator and still determine longitude even without being able to see
    Polaris.  Columbus's thirst for exploration led him to Portugal.  He spent a
    large part of his life there doing everything from being a captain to
    running a chart store and married the daughter of a minor Portuguese
    Most educated people of the 15th century knew the world was round, and many
    even believed one might indeed be able to reach the Orient by sailing west.
    Only problem was that the range of a 15th century ship was only 3,000 to
    5,000 miles before it ran out of supplies and  nobody knew what the westward
    distance was to the Orient.
    Columbus was obsessed with the idea of sailing west to reach the Orient and
    like many visionaries before and after he bent the facts to support his
    point of view.  Determining longitude was impossible in the 15th century.
    Neither accurate timepieces nor almanacs with the sort of data which could
    be used for time determination existed.  The longitudinal separation or
    west-to-east distance to China was unknown.  Neither was the circumference
    of the earth -- estimates ranged from 20,000 miles to 28,000 miles.
    Columbus took the largest estimate of the breadth of Europe and Asia --
    17,000 miles -- and the smallest estimate of the circumference of the earth
    and used the difference as "proof" that his suggested voyage could be made.
    (It's no wonder that Columbus was a very happy man when he hit land 3,000
    miles west of Europe!).
    Columbus first tried to sell his idea to the Portuguese.  Their geography
    was a lot better than Columbus's -- they correctly figured the proposed trip
    was more likely a voyage of 10,000 miles than 3,000 -- and their king issued
    a polite "thanks, but no thanks" (besides their methodical exploration of
    the coast of Africa had gone very far south, they were but a few years from
    doubling the Cape of Good Hope).  Columbus then went to newly united Spain,
    figuring their political aspirations might support his proposed voyage.
    Spain's geographers and astronomers weren't as good as Portugal's, the Queen
    said yes, and the rest is history...
    > -----Original Message-----
    > From-	MMillard0@aol.com [SMTP:MMillard0@aol.com]
    > Sent:	Wednesday, July 22, 1998 6:25 AM
    > To:	navigation@gomoku.ronin.com
    > Subject:	[Nml] Old Navigation Techniques
    > In the recent past we have had discussions on older navigation techniques
    > which including the Lunar Distance method.
    > I want to call the attention, to those interested in these affairs, to an
    > article in "Navigation",  Winter 1997-1998, Volume 44, #4 by  Arne
    > Molander,
    > titled "The Celestial Navigation of Christopher Columbus." (Yes, its some
    > time
    > ago, but it takes a while for the library circulation to work its way
    > through
    > the subscribers in the company.)
    > The author suggests that Columbus could have used the Lunar Distance
    > technique
    > to establish his Longitude. Interesting!
    > Maurice Millard
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