New Insights into Ancient Sundials Print
Posted: Saturday, 09 August 2014 19:28

Larisa N. Vodolazhskaya of the Department of Space Physics at Southern Federal University (SFU), Rostov, has brought two ancient time keepers together with a new and startling result.  The story starts at the turn of the end of the 19th century with the discovery of an L-shaped bar found in the tomb of Thutmose III (1479-1425 BCE). that appeared to be a sundial. In the 1930's a "user manual" of sort was found carved on the tomb ceiling of Seti I (1290-1279 BCE) at Abydos. The ideal L-shaped bar had lines engraved with distances from a starting mark of  3, 6, 9, and 12 units. The Seti I text describes these spacings as "an established procedure".  But what is the procedure?

Then in March 2013 during the excavation of rubble associated with worker huts of Ramesses II (1279-1213) in the Valley of the Kings, Professor Dr. Susanne Bickel and her student archeological team from the University of Basel found one of the oldest sundials in the world.  It is a vertical dial of limestone with what appear to be crudely drawn hour lines. The Basel team found a poor fit using hour lines with15o spacing expected of a traditional “unequal hour” sundial with horizontal gnomon.

Dr. Vodolazhskaya of Department of Space Physics at Southern Federal University (SFU), Rostov,
shows relation between tradition L-shaped Egyptian solar indicators and Egyptian vertical dial discovered
in the Valley of the Kings by the University of Basel in March 2013

Dr. Vodolazhskaya analyzes the use of these two sundial objects together, showing that the Valley of the King dial has accurately drawn hour lines that can be constructed by the L-shaped bar. The simple spacing distances of marks on the bar (ideally 1, 3, 6, 9 and 12) are measured for two L-shaped solar indicators held in the Berlin Museum.  The ratios are close to ideal, but not exact. Vodolazhskaya argues that these differences of L-shaped solar markings are intentional: one for marking (or interpreting) the morning hours of a vertical dial, and another for marking the afternoon hours where the lines are offset by half an hour. Vodolazhskaya speculates,"we associate the half-hour shift in the markup with the need for ...midday rest for workers - the traditional siesta ..."

 Dr Vodolazhskaya shows that Egyptian time telling was far more advanced than previously credited, but done in such a way that only the cognoscenti, the priesthood who held the L-shaped bar, could draw the lines of a sundial to create sundials with astounding accuracy of time. Her analysis is significant, showing that the Valley of the King dial using "equal hours" implies a gnomon pointed to the north celestial pole.  This Egyptian feat would not be replicated again for nearly 3000 years until the Arab Ibn al Shatir constructed the first "modern" sundial at the Great Mosque in Damascus in 1371 CE.

Read more:

Westminster Dial with Analemma Print
Posted: Thursday, 26 June 2014 21:56
Westminster Dial with Analemma Casting Mirror on Top
Photo Credit: Robert Clark

How do you get the people of your town interested in astronomy?  Robert (Bob) L. Clark a retired professor of mathematics and computer science and member of the Westminster Astronomical Society had the obvious answer: Build a unique sundial.

In the grassy field next to Hoffman’s Ice Cream in Westminster, the Westminster Astronomical Society dedicated a simple horizontal dial attached to a pole with a unique “ornament” … a vertical south facing mirror.  At the dedication on May 24th 2014 Jim Reynolds, director of the Bear Branch Nature Center Planetarium, demonstrated what will become a weekly noontime ritual of catching sunlight from the first-surface mirror as it hits the ground and marking the spot with a brick at precisely 12:12 Eastern Standard Time.

The sun of course keeps local solar time, not Eastern Standard Time and that extra 12 minutes past noon accounts for the correction to mean solar time as seen from Westminster Maryland.

The resulting difference between local solar time and mean solar time throughout the year is know as the Equation of Time and the path the sun will follow is the analemma. The sun’s excursion during the year travels not only north and south of the celestial equator by 23o ½  degrees, but performs a double east-west swing of  about +/- 15 minutes during the year … exceeding or lagging mean solar time, resulting in a figure 8.

The Westminster Astronomical Society intends to place a brick into the ground at the sunspot mark each week, resulting in a giant path of bricks that trace out the figure 8 of the analemma as cast as 12:12pm onto the grassy field.  Read more of Jon Kelvey's article at: carroll_county_times

While helping a friend with a camera obscura project, the idea for a mirror to trace the analemma came quickly to Bob who wants to popularize astronomy and get his town behind their Astronomical Society and Science, Technology, Engineering, and Mathematics (STEM).

As the Westminster Astronomical Society looks for a permanent site to house their telescopes, they’re looking for a way to make their presence known.  And perhaps what a better way than to create an analemmatic sundial?  Manchester, you too may have a sundial in your midst.

Cranmer Sundial Restoration Print
Posted: Tuesday, 24 June 2014 22:42
Damage to Erickson Equatorial Sundial in Cranmer Park, Denver, CO.  Photo Credit: Save Our Sundial


What happens to old sundials?  In Denver, citizens of Cranmer Park are taking matters into their own hands.  The City of Denver has generously committed $545,000 to the restoration of the Cranmer sundial and plaza through the Parks and Recreation and the Arts and Venues departments... but the citizens must raise another million dollars.

The whole plaza is sinking and a complete overhaul is required.  And the centerpiece is the 6-foot diameter Erickson equatorial disk sundial dedicated to the Park in 1966 and now shows signs of wear and damage.  Read about its unique history as it replaced a 1941 dial that was dynamited by vandals.

Donations for the plaza and sundial restoration can be made through Save Our Sundial Fund partner, The Park People [of Denver], a 501(c)3 organization. nass_news_2014_jun_SaveOurSundial_LogoSave Our Sundial has been instrumental in hosting fund raising events such as the June 8th benefit concert aptly named “Here Comes the Sundial”. For more information or to make a donation, go to

al Biruni's Cosmos Print
Posted: Friday, 20 June 2014 20:54
Al-Biruni's diagram of the moon's phases. 
Credit: photo reproduction from Seyyed Hossein Nasr, Islamic Social Science: An Illustrated Study (World of Islam Festival Publishing Co., 1976). 
Photo use for non-profit educational purposes only.

Ibn al-Shatir, whom we give credit for inventing the first modern sundial with gnomon pointing to the celestial pole in 1371 C.E., is but one of many scientific scholars of Central Asia during the “Eastern Renaissance” that lasted from about 800 to 1500 C.E. In this week’s issue of Science, [20 June 2014] Richard Stone reviews the accomplishments of Abu Rayhan al-Biruni (born 973 C.E.) and the possibility that he "discovered" the American continent.

Situated at the crossroads of cultures from China, India, the Middle East, and Europe, al-Biruni was an acomplished astronomer at an early age.  At 16 he measured the height of the midday sun and calculated the latitude of his hometown, now in present day Khiva, Uzbekistan.

The Science article reviews work by S. Frederick Starr, chair of the Central-Asia-Caucasus Institute of Johns Hopkins School of Advanced International Studies: “[al-Biruni] traveled widely as an adult, and at a hilltop fortress near present-day Islamabad he devised a technique for measuring Earth's circumference using an astrolabe, spherical trigonometry, and the law of sines. (Like the ancient Greeks, Biruni was aware that Earth is round.) His calculation was a mere 16.8 kilometers off the modern value…”

“In a massive tome called the Masudic Canon completed in 1037 C.E., Biruni analyzed classical Greek, Indian, and Islamic astronomy and used ‘bold hypothesizing’ to sort out credible claims from fantasy, Starr says.” …. “Most sensational of all may be Biruni's ‘discovery’ of America. For the purpose of precisely determining the qiblah—the direction of Mecca during Islamic prayers—Biruni meticulously recorded coordinates of the places he visited, and compiled data on thousands of other Eurasian settlements from other sources. After plotting out the known world—possibly on a 5-meter-tall globe he is said to have constructed—he found that three-fifths of Earth's surface was unaccounted for … [al-Biruni] concluded that one or more landmasses must lie between Europe and Asia, writing, ‘There is nothing to prohibit the existence of inhabited lands.’”

Sundial Outreach Success Print
Posted: Monday, 28 April 2014 22:50

This year nearly 300,000 students, parents and teachers attended the 3rd USA Science and Engineering Festival in Washington DC during 25-27 April 2014.   The Analemma Society and the North American Sundial Society jointly featured a very successful booth to encourage science, technology, engineering and mathematics (STEM) through sundials. The Analemma Society and NASS were among hundreds of exhibits from universities, scientific organizations, government agencies, and companies in the defense and educational industries.

Volunteers from the Analemma Society and NASS demonstrated a number of sundial types and provided paper sundial cut-outs that were enjoyed by children, students, parents and teachers alike. They handed out over 1400 of the sundial cut-outs, with the classic horizontal sundial and Briggs polar dial being the most popular.  Especially important were the numerous contacts made with teachers who will now enhance their science classes with sundials.

Volunteers from the Analemma Society and NASS who made this outreach possible were Ken Clark, Jeff Kretsch, Bob Kellogg and Dru Anne Neil.  They did a terrific job explaining that indeed, sundials are the world’s oldest clocks.

In the photo at left NASS member Ken Clark and Analemma Society member Jeff Kretsch show how sundials work while you dialists cut out their sundials.

Digital Cube Beams Time Print
Posted: Friday, 28 March 2014 17:28
Voshart's Digital Cube

Chindōgu is the Japanese art of inventing ingenious things that are, well, Rube Goldberg.  Daniel Voshart from Toronto has designed a solar time-telling cube from 59 stacked millboard plates. [See: Voshart Cube ] The result is a digital sundial, though not as universal as those patented by Scharstein [USP 5,590,093] or Kellogg [USP 05,596,553] but still, it is an interesting dial.

The cube creates light tunnels, an extension of an idea perhaps from Jiyeon Song’s “One Day Poem Pavilion” [].  Voshart’s cube gives the digital hours from 8am to 6pm [the animated illustration above shows the concept from 10am-2pm] but only for about 15 days centered around a specific date, in the case of the prototype, designed around the birthday of his father.  According to Voshart, it only works within 100 miles of the designated location, and even then, only for a limited number of days when the sun’s declination track across the sky matches the computed tunnel angles within the cube. Voshart commented on his website, “I gave myself a month [to design the cube] and then I had to stop, otherwise it would have continued for the whole summer. I have a plan to do a giant one for Burning Man next year.”

The statement that the cube works only within 100 miles is slightly incorrect.  The cube works within a latitudinal band of +/- 50 miles, but the cube vs clock time can be replicated within each time zone around the earth.

The cube, if designed correctly, accounts for the longitude offset from the center of the time zone (4 minutes of time per degree of longitude) and the solar variation of meridian passage called the “equation of time” that can be calculated for a father’s birthday or any other day of the year.  We shall assume that Vorshart was clever enough to include both these corrections for his father’s birthday thus creating a sun clock that for a brief two weeks will tell quite accurate clock time.

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