With all the discussion of discs and holes I thought members might be
interested in some photos I took of tests we made when we were deciding
on the Gnomon for the Swensen Sundial. I have put them up on the web
page http://www.uwrf.edu/sundial/design2.html . I had hoped to have
them up a week agao but there were problems withthe server.
As you can see the within a couple of hours of solar noon the disc
shadow (and the hole just) is quite visible but it soon becomes quite
blurred. The third photo shows a test with a cross piece whose shadow
was almost invisible convinced us to use the double gnomon structure.
Cheers,
John
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