Fellow gnomonicists:
The recent discussion on the analemma has been very interesting --
as a professional astronomer, I can testify that most of my colleagues have
no idea why the date of earliest sunrise does not coincide with the summer
solstice, etc. Even more interesting and puzzling without detailed
examination is the fact that the date of earliest sunrise depends on one's
latitude.
I would like to direct attention to 4 articles on the analemma:
(1) B.M. Oliver (1972), "Sky & Telescope", Vol. 44, 20-22 -- calculations
of the slowly changing shape of the analemma over several 100,000 years due
to changes in the earth's orbit and axis tilt.
(2) D.A. Harvey (1982), "Sky & Telescope", Vol. 60, 237-39 -- fascinating
diagrams showing the varied solar analemmmas that would be observed from
each of the nine planets!
(3) F.W. Sawyer, III (1994), "Compendium",Vol. 1, No. 4, 2-6 -- includes a
short history of the concept of the analemma and the differing meaning of
the word since ancient times.
(4) W.T. Sullivan, III (1995), "Compendium", Vol. 2, No. 4, 18-21 --
detailed description of a 4-meter long analemma created on a kitchen
ceiling by observing the reflection of the sun off a window-sill-mounted
mirror.
"Compendium" is the quarterly journal of the North American Sundial
Society, now in operation for about three years. Membership is only
US$25.00 per year (for overseas rates, inquire first at
[EMAIL PROTECTED]). Send your check to the treasurer, Mr. Harold
Brandmaier, 63 Florence Road, Harrington Park, NJ 07640, USA.
Happy dialling,
Woody Sullivan
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Prof. Woodruff T. Sullivan, III [EMAIL PROTECTED]
Dept. of Astronomy, Box 351580 tel. 206-543-7773
Univ. of Washington fax 206-685-0403
Seattle, WA 98195 USA
