In the NASA Photograph of the Day for 27 June 2019 is a beautiful photograph by Gianluca Belgrado using a pinhole camera. https://apod.nasa.gov/apod/ap190627.html As explained by NASA, "This persistent six month long exposure compresses the time from solstice to solstice (December 21, 2018 to June 16, 2019) into a single point of view....Fixed to a single spot at Casarano, Italy for the entire exposure, the simple [pinhole] camera continuously records the Sun's daily path as a glowing trail burned into the photosensitive paper. Breaks and gaps in the trails are caused by cloud cover. At the end of the exposure, the paper was scanned to create the digital image...."
In 2011 Art Paque explained the art of solargraphy to members of the North American Sundial Society at their annual conference in Seattle. The construction steps involve creating a pinhole in thin foil, then taping the foil onto a tin can that has photographic paper inside and opposite the pinhole. The lid on the can is sealed and most important, pointed at the sky with firm support to prevent moving. The rest is up to nature as the sun crosses the sky each day. Beautiful solargaphs such as from Gianluca can be obtained with patience tracking the sun for three to six months. In the end your solargarph will be a day by day time capsule of solar observation.
Type "solagraphy" into your web search engine and you will discover a host of sites showing the details of making your pinhole camera. For example: http://www2.uiah.fi/%7ettrygg/camera.html and http://www.pinholephotography.org/Solargraph%20instructions%202.htm
Students at the University of Waterloo School of Architecture in Cambridge, Ontario are experimenting with the benefits of 3D design and printing. In particular Joanne Yau created a set of hexagonal hollow bricks called sundial arches that lets in sunlight from different portions of the arch as the sun travels across the sky. We expect that the length to width ratio of the bricks can tailor sunlight for specific times of the year (summer, spring/fall, or winter).
Joanne Yau was one of three teams challenged to learn how to operate a new industrial 3D printer capable of squirting out clay. Professor Correa, interviewed by 3Dprint.com said “There is no other way to make these kinds of façades without enormous cost and time,” said Correa, who has been involved in 3D printed research on an even more advanced level, studying how such objects respond when exposed to varying degrees of moisture and temperature. “They are completely unique.” “The printer allows us to make much more complex geometry,” said Joanne Yau, part of the team that 3D printed bricks for the ambitious arch/sundial. “To make this by hand or to extrude it would be virtually impossible.”
See a video of how the 3D clay bricks are created in an article by Bridget O'Neal June 5, 2019: https://3dprint.com/245698/whistling-walls-sundial-arches-ontario-architecture-students-3d-print-clay/
Even if your dial includes the longitude correction, its timekeeping will vary throughout the year due to a phenomenon called The Equation of Time. Simply put, the apparent motion of the sun compared to your watch will cause your dial to appear as much as 16 minutes" fast" or "slow" at various times of the year.
The Equation of Time is caused by the combination of two effects: (a) by the earth's elliptical orbit where the laws of Kepler tell the earth to speed faster near the sun than away...that is, at perihelion in December the earth's orbital change is faster that during the June aphelion, and (b) the 23.44° tilt of the earth's axis from the elciptic plane of its orbit.
Grimm & Parker Architects sponsored a "Green Apple Day" on October 15, 2016 to help two Baltimore City Schools - Graceland Park ES/MS and Holabird Academy ES/MS - receive analemmatic sundials on their front sidewalks. The weather was perfect as teachers and volunteers from G&P chalked out and then painted simple 16 x 5 foot analemmatic sundials.
The sidwalks were aligned true North-South, making dial lay-out easy. With tape measures in hand, they marked out the focal points and north point of the analemmatic ellipse. Then, using the time-honored principle of constant distance they used a chalk line between those 3 points to maneuver a piece of chalk following the shape of an ellipse. For the sundial, the ellipse stretched from 5am to 7pm. The hour marks were made using two tape measure to check positions that were quickly followed by drawing of the hour circles with a plastic lid. While volunteers painted the hour circles others chalked out the walkway whose monthly lines and solstices were quickly painted as well. The final touch was the inclusion of the East and West Bailey points that determine the direction of the rising and setting sun. With a lot of support and good organization, both dials were finished in 3 hours!
You can layout a sundial using only a compass and straight edge (and yes, a ruler and book of tangents so that you can set out the gnomon lines for your latitude). Clem Rutter has created a graphical set of instructions to make horizontal sundials taken from the challenge of Fred Sawyer of the North American Sundial Society to find how many different ways can you graphically lay out the lines of a sundial.
Here's where the fun begins. Clem Rutter in short order presents eleven different approaches. Do you want to follow the method of Dürer (1525), Benendetti (1574), Clavius (1586) or the more modern methods of Leybourn (1660) or Ozanam (1673)? All these methods are graphical shown. Join the centuries of gnomonists and begin your own Art of Dialing at https://en.wikipedia.org/wiki/Schema_for_horizontal_dials
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.
Eagle Scout Project by
Parker Middle School, Howell, MI
The "Human Sundial", technically called an analemmatic sundial, allows one's own shadow to cast the time of day. The sundial works with students of any height, where all they have to do is stand on the current day of year mark of a central walkway. The analemmatic sundial can be painted onto concrete or asphalt playgrounds or, using markers and a brick or paver-stone walkway, be designed for a flat, grassy area.
An armillary sundial also called an armillary sphere is a representation of both the terrestrial globe and celestial sphere. Often highly decorated, these are beautiful sundials.
This Sundials for Starters appeared in The Compendium in March 2014
Robert L. Kellogg, Ph.D.
In 1902 Alice More Earle in her book Sun-Dials and Roses of Yesterday commented:
“Of course, there are in the United States many houses that manufacture optical and mathematical instruments and also make sun-dials. There are also those who make and sell very pretty brass dials, made to look well … regardless of the shape of the gnomon or drawing of the hour lines. I know no individual, however, save Captain Bailey, who makes accurate sun-dials for all latitudes.” [Fig. 1 of Captain John S. Bailey, 19th century dial maker - Earle].