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    Re: leap seconds a navigational hazard, says expert
    From: Brooke Clarke
    Date: 2003 Aug 9, 13:37 -0700
    Hi Richard:

    There are a lot of ways of making heliochronometers.  For many years sundials were sued to set watches and clocks.  These typically were in the form of noon marks.  You mount a disk with a hole in the center and when the Sun crosses a figure eight line at the current date set your watch.
    I made one of these by placing a metal plate at the lower end of a South facing skylight and using a 3x5 card with a number of concentric ellipses and a small hole at their center.  I just tracked the Sun's image with the card and at exactly noon stopped and drive a small brad nail into the hardwood floor.  After many years there would be more than one nail for the same date because as we go through the 4 years of the leap year cycle the timing is a little different.

    For more on this and other precision sundials see:

    Have Fun,

    Brooke Clarke

    Richard M. Pisko wrote:
    On Sat, 9 Aug 2003 09:29:56 -0700, Brooke Clarke wrote:
    There's another problem for me and that's Sundials.  There are many
    dials that are accurate to 15 seconds and changing to a new time format
    where the time no longer matches the Earth's rotation will make them
    A spot of light in a room?  A fixed mirror onto a shaded wall?  Please
    tell me more.  And how do you correct for the daily changes?
    Richard ...
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