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    Re: Definition of term
    From: Herbert Prinz
    Date: 2003 Feb 4, 18:31 +0000

    "Trevor J. Kenchington" wrote:
    
    > Since all of Earth's great civilizations (aside from ancient Zimbabwe,
    > the Incas and the latter's precursors) had their roots astride or north
    > of that Tropic, what we have come to regard as the proper way for clocks
    > to rotate is the direction that shadows move on northern sundials.
    
    I have heard this argument many times, but I am not convinced. Nearly all
    mechanical clocks have the dial mounted in the vertical plane. The majority of
    public sun dials were mounted on vertical walls of churches or other official
    buildings. The shadow on those rotates anti-clockwise in the northern hemisphere.
    Clocks hands do, in general, not simulate the movement of the shadow on a sun
    dial. (Not to mention the double speed of rotation.)
    
    > In short, "clockwise" is synonymous with "with the Sun" in the Northern
    > Hemisphere because "clockwise" is defined to be the way that the Sun
    > appears to move when seen from that Hemisphere (north of the Tropic anyway).
    
    This sounds more plausible, but is a different explanation from the previous one.
    
    Isn't it a question of which kind of projection seems more natural to the
    observer? In higher latitudes, the sun remains close enough to the horizon, so
    that we are willing to consider the whole picture  from "above". But when we read
    local apparent time with a nocturnal using some circumpolar stars, we readily
    admit that the "hands of the celestial" clock" turn anti-clockwise. And yet,
    nobody denies that the daily revolution is the same for sun and stars. Of course?
    
    Best regards
    
    Herbert Prinz
    
    
    

       
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