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    Re: why 360 ?
    From: Glendon
    Date: 2001 Dec 02, 3:07 PM

    Without being knowledgable on the subject, I too have some doubts about the
    definitiveness of the segment quoted below by Eric.
    
    >From earliest recorded times (Sumerian cuneiform script, circa 2500 BC) the
    Sumerians and Bablyonians after them, used a number system based on 60. My
    uninformed belief has been that the division of the circle into 360 degrees
    emerged during those civilisations, probably for some of the reasons noted
    below. My Britannica CD does not put a date on its adoption, leaving the
    inference that it emerged at some unknown point. Possibly the segment quoted
    below refers to some formalisation of 360 degrees, linking it to the
    calendar. I also have a vague idea that the Egyptians used the concept of
    360 degrees from around 1000BC.
    
    Lee Martin
    
    PS As an example of how errors in history are created, see Bowditch 1995 p3
    where it states the magnetic compass was developed about 1000 years ago,
    with reference to the vikings...when in fact it was invented about 1400
    years ago by the chinese, and adopted by the persians for navigation use
    (first recorded in 1127), with the vikings following suit very quickly,
    about 1134. (The vikings located in what is now Sweden, were in regular
    trade with the persians, moving up and down the great inland rivers running
    into the Black and Caspian seas)
    ----- Original Message -----
    From  "Eric Haberfellner" 
    To: 
    Sent: Sunday, December 02, 2001 12:22 PM
    Subject: Re: why 360 ?
    
    
    > It was during the reign of Nebuchadnezzar (605-562 BC) in the Chaldean
    > dynasty in Babylon that the circle was divided into 360 degrees. This was
    > because the Chaldeans had calculated by observation and inference that a
    > complete year numbered 360 days. The basis of angular measure for the
    > mathematicians of Babylon was the angle at each of the corners of an
    > equilateral triangle. They did not have decimal fractions and thus found
    it
    > difficult to deal with remainders when doing division. So they agreed to
    > divide the corner of an equilateral triangle into 60 degrees, because 60
    > could be divided by 2, 3, 4, 5 and 6 without remainder. Each degree was
    > divided into 60 minutes and each minute into 60 seconds. If the angles at
    > the corners of six equilateral triangles are placed together they form the
    > angle formed by a complete circle (see diagram). It is for this reason
    that
    > there are six times 60 degrees of arc in the complete circle.
    >
    > I found this information at the following website:
    >
    > http://www.studentscount.com/impressive/360.shtml
    >
    > By the way, you might want to try registering with the list again. I doubt
    > that your parrents actually named you "Your Name Here".
    >
    >
    > -----Original Message-----
    > From- Navigation Mailing List
    > [mailto:NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM]On Behalf Of Yourname Here
    > Sent: Saturday, December 01, 2001 7:19 PM
    > To: NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM
    > Subject: why 360 ?
    >
    >
    > Why does a circle have 360 degrees ?
    >
    

       
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