From rxpgnews.com
Sundial enthusiasts help celebrate 100th birthday of Washington University sundial
By Washington University in St. Louis,
Aug 4, 2008 - 3:59:37 AM
While we are bombarded daily with gloomy stories about Earth going to a hot place in a handbasket, a group of roughly 45 enthusiasts from around the country are meeting in St. Louis August 7-10 to celebrate the beauty of the Earth moving around the sun.
These folks are attending the 2008 Annual Conference of the North American Sundial Society (NASS), based out of Glastonbury, Conn.
While meeting in St. Louis, they will take a one-day tour on Friday, August 8, of 15 area sundials, some of them of historical importance, including one on the campus of Washington University in St. Louis that is marking its centennial anniversary. Donated to Washington University by the class of 1908, one hundred years ago, the sundial faces south on the Cupples I building on the university's quadrangle. The motto on the sundial reads: I am a shadow/ So art thou/I mark time/Dost thou?
Sundials can be traced to antiquity, come in many designs, some elaborate and beautiful, others plain and practical, but all measure time by the position of the sun. Key components of sundials are a shadow-casting object called a gnomon and a surface with lines indicating the hours of the day and important dates. In a vertical one, for instance, such as Washington University's, the gnomon's shadow casting edge, called its style, has to be aligned with the axis of the Earth's rotation. To tell correct time, the style must point towards true north. The style's angle with the vertical surface has to equal the sundial's colatitude (90 degrees minus the latitude), which for the University's is 51.4 degrees.
That's only one type of sundial but the core of these objects is a stew of mathematics and physics, and that is what appeals to Donald L. Snyder, Ph.D., Washington University senior professor of electrical and systems engineering, a NASS member, who helped organize and arrange the tour for the conference.
Snyder sees sundials as physical realizations of mathematics.
I'm interested in sundials because of their mathematical relation to the position of the sun at any time, said Snyder, who has made a number of portable, wooden sundials of his own for family members. It's a thing of beauty to design an instrument on the basis of mathematics and the physics of solar and Earth motion and the effects of sunlight.
Another reason I'm drawn to sundials is aesthetics. There are lots of artistic choices in designing and building one. Some are quite beautiful, such as Washington University's.
Snyder describes NASS members as by and large technical people, scientists and engineers, and a few historians, especially of science. He is counting on several Junior Academy and Passport members of the Academy of Science of St. Louis to participate in the sundial tour.
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