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From: Brooke Clarke (no email)
Date: Sun Aug 10 2003 - 22:41:20 EDT
Hi Richard:
It's about 15 feel long and a few feet wide as far as I can remember.
Where the hole is at the base of the skylight might be above the floor
by 12 -15 feet.
In the winter when the slant distance is long the image is dim so the
white 3x5 card makes it visible.
I tried a number of different hole sizes. It's like a f-100 lens and
you get an image of the sun on the floor. As the hole gets larger the
image gets brighter and fuzzier.
Have Fun,
Brooke Clarke, N6GCE
Richard M. Pisko wrote:
>On Sat, 9 Aug 2003 22:52:32 -0700, Brooke Clarke wrote:
>
>
>
>>I did not file down the tacks. The heads are a little less than 1/8"
>>diameter and were seated so only a tiny fraction of an inch was sticking
>>up. You can feel the head with you fingers. No problem to walk on them
>>bare foot.
>>
>>
>>
>That was my first thought; yes. I'm glad it's not a problem, and I
>read the description so it seems as though it would be rather nice. I
>couldn't quite make out the drawings on your ... calculations, I think
>it was.
>
>
>
>>>>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.
>>>>
>>>>
>I see the reasoning behind the series of ellipses on the (much
>handled) 3x5 card; to more closely match the sun's shape on the
>horizontal floor. What are the rough dimensions of your analem...
>figure "8"?
>
>I guess I could calculate that, given the difference in elevation
>between the skylight aperture and the floor, as well as your latitude,
>but I thought a reality check might be a break from the theory. :-)
>
>
>--
>Richard ...
>
>
>
>
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