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From: Brooke Clarke (no email)
Date: Sat Aug 09 2003 - 16:37:34 EDT
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:
http://www.pacificsites.com/~brooke/Sundial.shtml
http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=heliochronometers
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
>>obsolete.
>>
>>
>>
>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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