What's New Under The Sun

Tuesday, 10 June 2025 18:51

  Prosciutto di Portici (Ham) Sundial Photo: Getty Images The Prosciutto di Portici Sundial, more often called the Portici Ham Sundial, dates from the first century somewhere between  8 BCE to 79 CE.  This small silvered bronze dial was uncovered on 11 June, 1755 in the ruins of Herculaneum (current day Portici) in the "Villa of the Papyri", buried in...

Friday, 06 June 2025 21:01

  Sundial dedication May 31, 2025.  At left is Kathleen Stuckey Fox, with the City Proclamation presented by Mayor Pat Moeller and City Council on-lookers Carla Fiehrer and Susan Vaughn offering congratulations. On May 31, 2025 at 1pm, the Hamilton, Ohio, sundial (NASS Sundial Registry #1109) was re-dedicated in Monument Park. Originally dedicated in 1941 to the...

Monday, 24 March 2025 21:33

Several years ago Frans decided to write the course on sundials that included self assessment questions to force students not only to read the text, but to internalize the concepts. And a final submittal question "not necessarily a difficult question, but: no answer, no new lesson." Thus Frans Maes began writing lessons and sending them out to students. NASS has now used his material to create...

Monday, 24 March 2025 15:37

In a 24 March 2025 article from the on-line Science Advisor (American Association for the Advancement of Science) Phie Jacobs summarizes the "great debate" of the yearly shift from standard time to daylight savings time.  In January 2025 the US Senate introduced the Sunshine Protection Act to permanently have daylight savings time year round. Certainly 54% of Americans do not like the...

Friday, 21 March 2025 19:26

Perhaps the most famous alignment circle in the United States is the Cahokia Woodhenge near St. Louis constructed between 700-1400 CE by Cahokia Indigenous native Americans. But there were an estimated 10,000 other earthen mounds that once were scatter across the mid-west.. In an article from Atlas Obscura (https://www.atlasobscura.com/articles/octagon-earthworks-ohio) by Olivia Young on March...

Friday, 21 March 2025 18:37

The Hamilton dial is in the restorative care of Jarrett and Celene Hawkins (Hawkins & Hawkins Custom, LLC in Cincinnati Ohio https://www.studio-hawkins.com/) in preparation for the dial's dedication on Saturday, May 31, 2025. The face of the Hamilton Grand Army of the Republic (GAR) sundial has been cleaned and bead-blasted showing the dial as it was cast 84 years ago. In the process,...

Tuesday, 11 February 2025 00:27

We will celebrate our 30th annual NASS Sundial Conference in Ottawa, Ontario 7-10 August 2025.  But you need to register by April 15th to get theFull and Partial attendee rates at a discount. We will be staying at Le Germain Hotel Ottawa, 30 Daly Avenue, Ottawa ON Canada.  We have a block of rooms at a discount daily room rate of 284 CAD (approx. 216 USD) plus HST and MAT taxes. ...

Tuesday, 17 December 2024 23:47

In November 2024, a team consisting of members from SPL, TTDG and CMD of VSSC successfully designed and installed an accurate and fully functional sundial at the Rocket Garden of VSSC Space Museum, Thumba (8.53°N, 76.86°E). Following a space theme, the vertical gnomon is a 3-stage rocket that casts its daily and seasonal shadow on a dial face 1 1/2 meters by 1 meter.  The the sundial face...

Saturday, 16 November 2024 00:07

Esteban Martínez Almirón has published a new book Historical Sundials: Forgotten Andalusian Treasures (Relojes de Sol Históricos Tesoros Andaluces Olvidados) In it he reviews over 400 sundials from the Andalucian region of southern Spain Originally to celebrate the 25th year of the website https://relojandalusi.org/ Esteban Martínez Almirón began showing his sundial drawings on the site....

Wednesday, 13 November 2024 19:36

It isn't often that a sundial face is created before the gnomon is attached.  In Shelbyville IN a large, circular art piece in the form of a sundial, was created at the Blue River Trailhead early in 2024.  If they had chosen an analemmatic sundial, a walker of the trail could have simply stood on the appropriate date and used his or her own shadow to tell the local solar time. ...

Monday, 04 November 2024 18:38

The Sun Tower's shadow marks the passing of the seasons credit Jonathan Leijonhufvud For two years News Atlas (https://newatlas.com/architecture/) has reported on the progress of the construction of the Sun Tower in Yantai, China.  The 164-foot (50m) curved conical tower was designed by OPEN Architecture symbolized the watch towers of the Ming dynasty (1368 to 1644 CE)...

Monday, 04 November 2024 17:30

NASS Registered Sundial #1109 at https://sundials.org/index.php/sundial-registry/onedial/1109 is one of a series of bronze sundials presented by Daughters of Union Veterans of the Civil War, dedicated to the memory of the Grand Army of the Republic. Unfortunately the dial in Hamilton, Ohio, suffers from neglect and the gnomon has long been missing. With support, this dial has been designated...

equatorial-fig-7

This Sundials for Starters appeared in The Compendium in June, 2007

by Robert L. Kellogg, Ph.D.

 

In this day and age of computers, I began musing what is one the least complicated sundial to build.  In the last Compendium I showed the classical method of graphically constructing a horizontal dial, and the introductory NASS Sundial CD discs contain power point presentations for creating a variety of sundials.  Here is a simple equatorial dial that I’ve used in sundial demonstrations.  It requires several pieces of cardboard and a coffee stirrer.

Step #1.  We need a base to hold the coffee stirrer gnomon.  The front face is 3”, but the gnomon ridge of length L is a function of latitude. (See Table below).   For those who enjoy mathematics, the length L is given by

equatorial-eqn-1 inches

equatorial-fig-1

Step #2.  Fold the gnomon base along the dotted lines and glue the coffee stirrer into the top ridge of the gnomon base, letting the stirrer protrude by about 5”.  Be sure that the coffee stirrer is firmly against the fold.  An extra staple helps hold it while the glue dries or strengths it if you use a glue stick.

equatorial-fig-2

Step #3.  Next, we need a base to hold the equatorial band.  The equatorial base has a semi-circle cut out with radius of 2 3/8”.   The support sides can be cut fancifully, but the semi-circle needs to be 3/4” from the bottom fold line.  Past the fold line is a support tab that is S inches long.  (See Table above).  The value of S will place the equatorial base just far enough in front of the gnomon base so that the coffee stirrer goes through the center of the cut out semi-circle.  Using similar sides of triangles, we find that S, the distance between gnomon and equatorial base, is:

equatorial-eqn-2inches

equatorial-fig-3

Step #4.  Here we create the equatorial band itself, spanning 6am to 6pm local solar time.  The semi-circle radius of 2 3/8” allows the hour lines to be almost exactly 5/8” apart.  The total distance of the 6am to 6pm hour lines is therefore 7 1/2”.  I’ve allowed a little bit of extra length for the end to end measurement of equatorial band that allows for labeling the hour lines.   Along one side of the band, cut a series of tabs.  These will be used to glue the band to the equatorial base.

equatorial-fig-4

Step #5.  Glue the equatorial band to the equatorial base.  Make sure that the 12 o’clock hour line is on the center line of the equatorial base.  The 6am and 6pm hour lines should just make it to the top of the equatorial base semi-circle cut out.

equatorial-fig-5

Step #6.  On a piece of cardboard about 5”x7” draw a center line along the long axis.  Glue the gnomon base to the stand’s center line with the small end of the gnomon base about 1/2” from the end.  Next, glue the equatorial base tab to the stand, just touching the gnomon base with the fold line perpendicular to the stand center line.

equatorial-fig-6

Step #7. Tilt the equatorial base and band until it is perpendicular to the coffee stirrer gnomon.  You may have to make a small paper support to help stabilize the equatorial base and band position.  When properly angled, the coffee stirrer gnomon will pass through the center of the circle made by the equatorial base and band.

equatorial-fig-7

Step #8.  Take the dial outside and align it true north-south, with the gnomon base at the southern end.  Read the shadow of the coffee stirrer gnomon on the equatorial band.  This will be correct local solar time for every day of the year.  Of course, to match clock time, both longitude compensation and the equation of time must be added to the dial time.  Have fun.