Sundials - World's Oldest Clocks

North American Sundial Society

Sundial at School in Janowice Rybnickie just south of Rybnik
Photo: PL 664 Sundial at School in Janowice Janowice Rybnickie just south of Rybnik

The sundials working group of the Czech Astronomical Society in Hradec Králové organized a short study tour to Poland in June 2016 with a special emphasis on seeing sundials. This report is provided by Hohumil Landsman:

"The first stop was the Muzeum im. Przypkowskich, the world famous museum that began as the clock collection of the Przypkowski family. It is situated in the town square of Jędrzejów. As well as various fixed and portable sundials, the museum showed devices for the construction of sundials and several old books on astronomy and gnomonics."

"From there we visited the Planetarium and Observatory of Youth in Niepołomice. Among other things, there were commentaries available for blind visitors for whom the spoken word is a principal source of information.  Another interesting stop was the Silesian Planetarium and Astronomical Observatory of Nicolaus Copernicus in Chorzów.  In the courtyard of the planetarium there is a large sundial showing local solar time, and in the basement we found a seismological station containing two early 20th-century seismographs as well as their more modern equivalents. A meteorological station forms part of the same complex of buildings. As an additional diversion, we also visited the salt mines in Wieliczka."

Woodruff (Woody) T. Sullivan III hosted two NASS conferences, one in 1998 and a second in 2011, each time showing many new Seattle sundials...most of which he had a helping designer's hand.  Woody made T-shirts proclaiming "Seattle - sundial capital of North America". Now in the on-line University of Washington Today for December 1, 2016, Peter Kelley profiled Professor Emeritus Sullivan, noting the many worlds of interest by the UW astronomer and astrobiologist...including his passion for sundials.  In Kelley's interview Woody expounded "My sundial interest began very specifically in 1991.  I got interested because three years before we moved in to the new Physics-Astronomy building in 1994, the architects asked , what do you want?  I'm thinking of my interest in history of science and art and design, so I casualy said, 'A sundial would be nice'.  Since then, it's hard to believe - like getting married - that there's a phase in my life before that."

That UW sundial was a large vertical decliner, entered in the NASS Sundial Registry as Dial #117.  But now a new precision sundial...using an arm tattoo. Woody explained, "This started with a paleontologist graduate student in the astrobiology program.  She likes sundials and we got talking and over the last couple of years we designed [a tattoo sundial].  The idea was for her to have it, but she how has her degree and has since left town.  Meanwhile I said to myself, dammit -  that would be pretty neat.  In April I gave a talk to the British Sundial Society about the technical details and showed the decal I'd made for my inner forearm. I'm going to write it up for their publication.  The world's first working sundial tattoo!"

Read more at::

More than 25 years ago Robert diCurcio made a compound sundial.  A small round horizontal dial is surrounded by a larger gnomonic dial engraved with hour lines in the shape of analemmas. Careful inspection of the dial shows that the lines are offset from the longitude of 70 degrees to account for the sun at the eastern time meridian of 75 degrees west.  In "Yesterday's Island - Today's Nantucket" Katherine Brooks of the Maria Mitchell Association (MMA) takes a close look at the sundial in their front yard, sitting on the lawn of the Maria Mitchell Observatory on Vestal Street.

Here is a slight correction to the article's text: diCurcio set up the sundial perfectly level and oriented it so that the meridian-line is exactly north-south. [Hopefully aligned to true north, NOT magnetic north.] Once the dial is aligned the triangular gnomon will cast a shadow not only for the small horizontal dial telling east coast solar time, but the tip of the gnomon shadow points to the analemma, the “figure of eights”, which shows standard or daylight mean time (clock time). Installed by diCurcio, the sundial at the Maria Mitchell Association is accurate to this day. Brooks writes,"We hope you stop by the Maria Mitchell Vestal Street Observatory on Vestal Street to see the 1908 observatory built by the MMA and to test out the Sun d’Isle on the lawn in front. If reading shadows interests you, we encourage you to attend our Summer Speaker Series this Tuesday, August 30,[2016] to learn about the “Effects of Light at Night” with Dr. Mario E. Motta."

Compare the photo of the MMA sundial from Brook's article with the sundial photo above that appears in the NASS Sundial Registry at

Michael Lee's photograph of Central Park started it all.  Erika Owen ( wrote "If you think Central Park is only good for its slightly quieter reprieve from the hustle and bustle of the Big Apple, you're missing out. As it turns out, the park can actually be used as a giant sundial. Understandably, this isn't a universally accessible perk of the'd need to be in an airplane or helicopter to truly appreciate the functionality."

Any vertical ediface such as a tall building, a flagpole, or even the Washington Monument can become a gnomonic sundial measuring time by the tip of their shadow.  But seeing those shadows on the ground results in fuzzyness of the penumbral shadow.  The solution?  Step back, way back to a perspective of seeing the shadows from high in the air. From this view these giant sundials become visible.  Owen continues, "Billionaire's Row, the name given to the skyscrapers lining the two blocks south of the park between Fifth Avenue and Central Park West gives off plenty of shadows..."

To see the shadows in motion, Cube Cities presents a short video "Central Park Shadows". Cube Cities specializes in urban city representations and animation software to create them.  For example they visualize the growth of cities as Manhattan from the 1920s and the growth of San Franciso from 1977 to 2015 and Chicago from 1862 to 2014.

An analemmatic sundial was dedicated July 4th 2016 at noon in the Frontier Heritage Park at La Pine, Oregon.  The Daniel and Crystal Richer Family Foundation created a simple but accurate sundial where one's own shadow tells the time.  The sundial honors veterans and the unmentioned heros of our country.  The plaque sums it all: "Always Remember".

The video is from KTVZ, Channel 21:

News Item from the Wet Mountain Tribune on June 30th, 2016: Custer County courthouse is getting a new sundial.  Using a true north line surveyed by county commissioner Kit Shy, Charlie French is cementing a rod anchored in obsidian rock, whose shadow will align with that of the courhouse flagpole. "Taking advantage of the summer solstice on June 20, he literally nailed down the farthest reach of the flagpole shadow."

While French happily proclaims, “thanks to Harrison [whose clock allowed longitude determination in 1761], and knowing where the time zone meridian is, and how distant we are from it, we are accurate to one minute and 51 seconds of Mountain Time here in the visible solar time at the courthouse.”  Well, that's almost correct.  French's gnomon rod and courthouse flagpole shadows align at local solar time.  Mountain Time like other clock times do not match solar time due to the tilt of the earth's axis and eccentric orbit around the sun, shifting solar and clock time by +/- 15 minutes throughout the year.  Read more at:

Read more: New Courthouse Sundial

Japan Sundial House

As reported in Design Bloom architect Kikuma Watanabe has designed a beautiful modern house integrating asundial and solar design principles: "The internal spaces support a comfortable environment where in summer it is naturally cool and in the winter it is warm. This ecological technology aids this passive system using the sun and the wind for an effective air conditioner."

The interior of the house has two-story rooms and lots of natural wood.  But unlike other houses except perhaps for the Cosmic Room in Corregadora, Mexico, it has a built in equatorial sundial. Central stairs lead up to the equatorial dial projection area with the gnomon itself a glass slit window in the roof. But the most important aspects for solar comfort are the angles of the eve overhangs, preventing hot summer sun from entering the windows yet allowing warming sunlight to enter during the winter . Brighter areas such as the kitchen are situated in rooms with southern exposure while the living room faces east looking out upon ponds and hills. Upstairs surrounding the equatorial dial projection ring are two rooms: the Room of Sunrise and the Room of Sunset, and on the main floor facing north is the Room of Shadow.

Read more: Japan Sundial House

Andrewes Longitude Sundial

Example of an Andrewes Longitude Sundial

Texas Christian University (TCU) in Fort Worth Texas will unveil a new longitude sundial on May 5th, 2015. As William Andrewes, creator of the longitude dial explains, "The Longitude Dial is based on an idea proposed in 1607 by Franz Ritter of Nuremburg...Ritter devised and published a world map projected from Nuremburg, with its lines of longitude arrayed to serve also as hour lines. However, the difficulties of creating a new project for each location and the expense of producing it in durable materials were considerable. Ritter's gnomonic projection map does not appear to have been developed for use in sundials - until now."   See Andrewes website at:

One of Andrewes sundials will be unveiled in front of Walsh Performing Arts Center, situated in the middle of a circular stone plaza. Andrewes monumental sundial prices start at $50,000.  Read more at TCU-360 news

As an interesting side note, the gnomonic project map upon which Andrewes creates his sundials was extensively used during World War II and into the 1950's by high frequency (HF) direction finding (DF) sites.  On the gnomonic map not only are lines of longitude straight, but any great circle line of bearing is straight as well.  Using a pin on the DF site, the lines of bearing could be drawn with an extended piece of string.  Computer calculations eventually replaced the manual direction finding and geolocation method.