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    Re: I couldn't resist!
    From: Brad Morris
    Date: 2012 Oct 19, 13:48 -0700

    In my current employment, I use a device known as an Ultradex for metrology and calibration.  The device is mechanically accurate to 1/20th of 1 arc-second and reproducibly is 1/5th of one arc second.  An arc second is 1/3600 of a degree.  The one I use is no longer state of the art, there are better.  The type I use is so accurate, it was used for bomb sight calibration by the US military.

    Discussion of angular construction and claims of estimated accuracy need be taken with a degree of skepticism.  To what known standard can you trace that?  What methodology did you use in that determination?

    I use NMTBA standard methods of the determination of accuracy and repeatability, three sigma, using NIST trace-able tools that are within calibration and with recent certifications.  I think I may know a little about angular measurement!  


    Why bring this up?  There is a perception that angular construction in Columbus' day can use methods that we know today.  Just as I assumed that he sailed latitude lines (error), assumptions about the accuracy and repeatability of the meridian measurement used to create the declination table and the astrolabe's scale are just that, broad assumptions.


    On Oct 19, 2012 4:24 PM, "Lu Abel" <luabel@ymail.com> wrote:
    And let's not forget all the "knowledge" handed down by the Church, like the mythical kingdom in Africa of Presbyter John.  I'm not surprised that some of that "knowledge" included the earthly paradise he describes.

    From: Apache Runner <apacherunner@gmail.com>
    To: NavList@fer3.com
    Sent: Friday, October 19, 2012 12:37 PM
    Subject: [NavList] Re: I couldn't resist!

    Pretty, amazing huh?   One bad shot of Polaris and he thinks the world is shaped like a pear. 

    To be fair, there are other pieces of evidence that he was slowly losing his mind around that time.   

    On the other hand, there's the amazing forecast of a hurricane hitting Hispanola.   It's like he drifted between  some high functioning state and insanity. 

    On Fri, Oct 19, 2012 at 2:58 PM, G Becker <george@gwbeckerpls.com> wrote:
    I was hesitant to post this, but here is it. The following is a quote from a paper on the theory of a Roman World Survey in 44BC. ;/
    "A letter written by Columbus to the Spanish Royal Family during his third voyage in the Caribbean revealed his surprising belief: "I have always maintained that the world-land and water-was a sphere, but now I have seen so many irregularities that I am induced to form another idea of the World. Land that Their Majesties have discovered (America) are part of a sphere, but on the other hand, the earth is shaped like a pear to whose summit is the Earthly Paradise from which descend the four rivers, as written in the holy scriptures..."" (4) Columbus had come to this conclusion after having arrived at the mouth of the Rio Orinoco River
    (4) L. Lavonto "Los primeros italianos en America" Caracas. 2001
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