This Sundials for Starters appeared in The Compendium in December, 2005
by Robert Kellogg, Ph.D.
This is the start of a regular column to review the basics of Sundials. Of course NASS provides an introductory CD disk on sundials and there is always the classic reference Sundials, Their Theory and Construction by A.E. Waugh.
For this article, let’s consider some basics in buying a sundial for the garden. Or perhpas you want to make one. There are magazine catalogs and websites that offer “fine English dials”. But are they for you? Consider the latitude of an English dial. London is at about 51º north latitude, while most of the populated area of North America is below 45º. Take a look at the gnomon of your potential purchase. The gnomon should be approximately the same angle as you latitude. Here we’ll illustrate a dial (Figure 1) from the Naval Medical Center in Bethesda, Maryland with latitude of approximately 38º.
One of the more interesting news items over the last several months has been the “Manhattan Henge” craze. Neil deGrasse Tyson, director of the Hayden Planetarium in New York, calculated the alignment of the sundown the street corridors of Manhattan (Fig. 1). For New Yorkers, two opportunities for alignment occur. The streets are aligned 28.9o east from North, and the sun sets near this at this azimuth on May 30-31 and July 11-12.
These alignments are just a small part of “shadow planes” where the shadow of the sun aligns with a building wall or other object. The best description of shadow planes comes from the NASS expert, Mac Oglesby and his compatriots William Maddux and Fer deVries in a series of three articles in The Compendium.
By Robert L. Kellogg, Ph. D.
Benjamin Banneker, 1731-1806 , is one of the nation's best-known African American inventors. He was born in Maryland and in 1791 played an important part in surveying the newly designed Federal Territory, now called the District of Columbia. In his youth, Banneker was inspired to build his own clock after an acquaintance gave him a watch. He took the watch apart to find out how it worked and made drawings of each component, and based on his drawings, he carved larger versions of the components out of wood and constructed a clock that kept accurate time for more than 50 years. As mathematician, he designed an Almanac that was a rival of Benjamin Franklin’s famous publication.
As astronomer, clockmaker, and mathematician, he was expected to know how to design sundials, although none exist bearing his mark. In an age before pocket calculators, how would Banneker design a sundial? The graphical method is available in modern texts such as Waugh’s 1973 classic “Sundials: Theory and Construction”. Want to lay out a horizontal sundial without sines, cosines, and tangents? Then this “Sundials for Starters” is for you.
From paper sundials to street side sundials, NASS celebrated its annual conference in Burlington, VT. Kate Pond’s “Come Light, Visit Me” sundial, in collaboration with Bill Gottesman, was dedicated at Champlain College. The sundial uses the properties of an equatorial ring, casting the shadows of time upon itself.
Fred Sawyer talked about Antique Hour Lines, showing finally that the lines are amazingly complex, but come very close, but not exactly to the traditional notion of a straight line. André Bouchard discussed Le Gnomoniste, a review of the Quebec sundial society 1993-2010. Roger Bailey gave a short presentation on the solstice points on analemmatic sundials that can be used as sight lines for summer and winter solstice. Roger Bailey gave a detailed talk on the Ibn Al-Shatir Sundial, whose design he studied in detail to produce the Ottoman Garden dial in Missouri.
Bert Willard, the Springfield Telescope makers Historian and Curator described the sundials and sunclocks from James Hartness and Russell Porter. Porter is also know for his leadership in amateur astronomy. Jack Aubert probed into the question of who was first to describe the Equation of Time and the figure “8” analemma. Finding that the first to draw it with reference to a mean time meridian was Grandjean de Fouchy at the Palace de Petit Luxembourg in Paris sometime before 1741.
The Portland tour of sundials included Colby Lamb’s Sundial and workshop, a patio sundial of Rob and Julie Brown that also served as a water sprinkler, a vertical mosaic dial at Stephenson Elementary School, the analemmatic sundial at Marylhurst University designed by John Schilke of NASS and Jan Dabrowski, and across the Willamette River to Reed College and a 1912 vertical sundial designed by Dr. F. L. Griffin. Then more sundials at the National History Site, Fort Vancouver, and ending with the Clark College Equatorial Sundial with a new analemmic gnomon. Roger Bailey outlined how he helped Soap Lake’s monumental sculpture become a summertime sundial. Bill Gottesman showed a realization of Fred Sawyer’s Horizontal Equant Dial that adjusts by simple rotation for the Equation of Time. And most interesting was Silvio Magnani’s presentation on an interactive reflecting heliochronometer in Milan, Italy. Read about this and much, much more by downloading the PDF.
Don Snyder was a superb host for the St. Louis conference. He organized an interesting tour that included the Jefferson Barracks 1817 sundial (now part of the National Geospatial Intelligence Agency), the angel holding a vertical sundial on the wall of the St. Louis University Hospital, and the several dials at the Jewel Box in Forest Park. At the Missouri History Museum, conferees saw the “Forgotten Sundial” designed by Thomas Jefferson. At Danforth Campus of Washington University was the 1908 Cupples Dial, and finally at the Missouri Botanical Gardens two dials were dedicated: Ron Rhinehart’s cross-gnomon equatorial and Roger Bailey’s “Ottoman Garden” sundial, based on Ibn Al-Shatir’s dial carved at the Great Mosque in Damascus in 1371. At the conference, the major talk was on the Cahokia Woodhenge, presented by Michael Friedlander, professor of physics and astronomy at Washington University.” And of course there were NASS speakers in abundance talking of dials, dialing scales, and new approaches to the Equation of Time.
In McLean, Virginia close to Washington, D.C. NASS held its 13th annual conference. At the Analemma Society’s site in Observatory Park, Tony Moss’ dial, the “Jamestown Commemorative Dial,” was dedicated in front of over 50 school children and twice as many adults. This is the first sundial installation in what is planned to be an International Sundial Garden. Other highlights of the sundial tour included the Lyman Briggs Memorial Dial at the National Institute of Science and Technology, the Latitude Observatory (once used to study the daily variation in the earth’s wobble and rotation rate), the Vernon Walker Education Center dial, and the vertical dial on the wall of Jack and Kate Aubert. The conference talks included Roger Bailey on “God’s Longitude and the Lost Colony,” Woody Sullivan’s “Ten Tons of Basalt and Tenths of Degrees,” Fred Sawyer’s discussion on the 17th century battle over the priority of inventing the stereographic quadrant dial, Kevin Karney’s “Variability in the Equation of Time” over geological epoch periods (well, for at least 500 years), and much more. Most impressive was Julian Chen’s “Omnidirectional Lens in Sundials and Solar Compasses” using spheres filled with solution of copper sulfate to focus the sunlight onto a dial.
Sundials for Starters
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Sawyer Dialing Prize
Fred Sawyer, in cooperation with the North American Sundial Society, established a continuing yearly award, the Sawyer Dialing Prize to be presented by NASS to an individual for accomplishments in or contributions to dialing and the dialing community.
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In these pages is the famous tub sundial created by Robert Terwilliger using his laser trigon to lay out hour lines on a very irregular surface to create a working sundial.
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Who are today's sundial artisans? Here are several bioghraphies of several artisans that show the unique combination of talents in art, engineering, and mathematics.
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