Sundials - World's Oldest Clocks

North American Sundial Society


2011_UnivPrepAcademyPillarDialSeattle: Sundial Capital of the United States?  The 2011 North American Sundial Society had perfect blue-sky weather for its annual conference held in August 2011.  Professor Woodruff “Woody” Sullivan, conference host at University of Washington started the fest by showing off the large vertical sundial built in 1994 on the side of the Physics and Astronomy Building.

The conference covered a wide range of topics including two presentations on stained glass sundials, the 17th work of La Hire and his successful "La Gnomonique ou L'art de tracer Des Cadrans" ("Gnomonicks or The Art of Shadows of Sundials") and dialist-surveyor and one of the founding members of the Acadamie Royale,  Jean Picard. The methods of taking photos of the sun over months of time, called Solargraphy, was presented by Art Paque, and then there were talks on the operation of cylindrical sundials, sundials that can show standard time, an update on the Mars sundial, and discussions on solar alignments, heliodons and stair shadows.

Helmut Sonderegger, this year’s recipient of the Sawyer Dialing Prize discussed the Rheticus Memorial sundial designed for Georg Joachim Rheticus, the first Copernican. 

Download the PDF and read about the conference in detail, including the bus tour of Seattle dials visiting the Pillar Dial of University Prep Academy, Epiphany School Vertical Dial, and Rebecca Cummins analemma and colored skylights in the ceiling of the Montrose Public Library.

Download this file (2011 NASS Conference Seattle.pdf)2011 NASS Conference Seattle.pdf[NASS Annual Conference]1005 kB

Dear Friends,

A great loss has hit our gnomonic community in Italy. Our friend Giacomo Agnelli died about a week ago.  Giacomo was one of the great gnomonists of the past. He had written dozens of articles in engineering and horology, also dealing with mechatronics [mechanical] sundials. He had worked at the European space project, and had frequent ...articles for our magazines [on] gnomonics. He had participated in all meetings of horology in Italy and was known for his satirical cartoons and gnomonic caricatures ...

Nicola Severino                      Visit A Tribute to Giacomo Agnelli

[from the Sundial Mailing List, sundial Digest, Vol 71, Issue 3  ]

NASS_2011_SondereggerThis year's Sawyer Dialing Prize awarded at the 2011 NASS Conference in Seattle Washington was given to Helmut Sonderegger, "In recognition of his ongoing development and support of the dialing software Sonne, and his many years of leadership in his national society." His acceptance talk was on one of the first Copernican followers, Rheticus.

 For many years Helmut Sonderegger has been active in the German Sundial Association and was chairman of a team of dialist to produce the 3rd Editiion of the Austrian Sundial Catalogue.  His most famous free sundial software, „Sonne“ calculates about 20 different sundial types and his program „Alemma“ is devoted to the calculation of analemmatic sundials.  The software is available at his website,  He endeavors to help people who make sundials through his software and through articles in the NASS Compendium and the German Rundschreiben, and for local groups.

Helmut was presented with a cash prize of $200 and a custom made Spectra Sundial by Jim Tallman of Artisan Industrials.

Along with her husband, Mrs. Webster spent much of her life and fortune combing auction catalogs and antiquarian shops to create a collection of early scientific instruments so renowned, it is considered in the same company as the Museum of the History of Science at Oxford University and the National Maritime Museum in Greenwich, England, according to Bolt, Adler planetarium vice president for collections.  The Websters are primarily responsible for the world-class collection of scientific instruments at the Adler.

NASS is supporting the Adler to catalog their sundial collection enhanced over the years by Marjorie Kelly and her husband.

This Sundials for Starters appeared in The Compendium in December, 2005

by Robert Kellogg, Ph.D.

Dial and Gnomon Set to Correct Site Latitude of 38 Degrees

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.

Download this file (SerlesRuler.jpg)Serle's Ruler[Ruler to Measure or Make a Sundial]37 kB

Read more: Sundial Latitude

This Sundials for Starters appeared in The Compendium in September, 2009
by Robert L. Kellogg, Ph.D.


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.[1]

Read more: Manhattan Henge

This Sundials for Starters appeared in The Compendium in March 2007
(Updated January 2017)

By Robert L. Kellogg, Ph. D.

Benjamin Bannekar

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.

Download this file (Bannaker- Dial Construction.pdf)Bannaker- Dial Construction.pdf[ ]2019 kB

Read more: Bannekar - Drawing a Dial


  • Sundials for Starters
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  • Conferences
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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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  • Terwilliger Sundials
    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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  • Biographies

    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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  • Sunquest Sundial

    This section is dedicated to Richard Schmoyer who invented the Sunquest sundial.  Please visit as well.

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