Sundial Stuff

I have recently started playing around with the idea of making sundials.  I have found them interesting for quite a while, but did nothing with that desire.  So I decided to start with some simple dials and work up from there.  I started by buying some reference books, which I can highly recommend.  They are:

• "Sundials" by R. Newton Mayall & Margaret W. Mayall
• "Sundials, Their Theory and Construction" by Albert E. Waugh
• "Easy-to-Make Wooden Sundials" by Milton Stoneman

There are also numerous good webpages that talk about sundials, such as:

• "The  Sundial Primer by Carl Sabanski" at http://www.mysundial.ca/tsp/tsp_index.html
• "The North American Sundial Society" (they have a good forum) at http://www.sundials.org/
• "Sundials on the Internet" at http://www.sundials.co.uk/

Then you may need some software to help you out with the drawing and construction (at least to begin with anyway).  Some that I've found:

• A great site with good software for designing sundials and calculating/drawing the Equation of Time.  Check out their "SONNE 2.1.3" program by Helmut Sonderegger (Windoze only) at http://web.utanet.at/sondereh/sun.htm
• Or check out the web site of the "Shadows"program.  There is a free version that will make the most popular styles of sundials, or upgraded pay version that can design almost any type under the sun (excuse the pun) (Windoze only).  You can find all the info you need at http://web.utanet.at/sondereh/sun.htm
• There are several really nice programs that can help you accurately align you sundial at the software page of Precision Sundials LLC (Windoze only) at http://www.precisionsundials.com/software.htm
• The is also a nice program that computes sun related info and draws the analemma from Analemma.  It runs on multiple platforms (Mac OS X / Mac Classic / Windoze ) http://www.analemma.com/SunGraph/index.html
• All of the above Windoze programs run nicely in Virtual PC.


Sundials I have stumbled across


Sundials I have made (or bought)
A Sheppards Dial

I decide to start off simply with a homemade "Sheppard's" or "Cylinder" or "Pillar" sundial (the name depends on your preference I guess).  I made mine out of simple easy to find materials since my building skills are currently a little rusty.  The parts are available at any hardware store, in this part of the world anyway.  I used 2" PVC pipe for the body with black PVC end caps (I couldn't find white ones).  The gnomon is made from a small metal ruler that reads to the hundrenth of an inch, which helps to set it's length properly (I may switch to a wooden gnomon later).  A hole was drilled in the top cap and a cotter pin was inserted to use as a loop (this allows it to be hung from a string, an easy way to make sure it's vertical).  The scale could have been inscribed onto the face of the cylinder as was done in the days of old, but in my case the time scale was calculated by the SONNE program and printed out on paper (already corrected for the Equation of Time).  The paper was then taped into a cylinder and pushed onto the PVC pipe.  This is so that it is replacable. I this way other scales can be printed out for use at other locations and latitudes.  Since the PVC pipe is hollow, other time scales for different locations and/or latitudes can be stored inside along with the gnomon.

So here is my first sundial (that would be my lovely wife's hand).





Checking the time on my Sheppard's Dial.

The scale is rotated around the tube until the current date is underneath the gnomon (pointer).  The dial is then hung vertically by the string and rotated until the shadow from the gnomon falls parallel to the day lines.  The Local Mean Time is then read at the bottom of the shadow, which is showing approximately 16:40 in this picture.  To correct this to Standard Time (what you read off your watch) we add 18 minutes and 16 seconds to correct for the longitude in Kansas City (=> 16:58:16) and one hour for Daylight Savings Time to end up with 17:58:16 at the time of the photo.  The photo was taken at 17:52:25, so the sundial was off by 5 minutes and 51 seconds.  In using it so far it has been within one to ten minutes after the corrections have been applied.  Not bad for 1,000 year old technology and an afternoon's work.
A commercial "Sunwatch" on my homemade leveling board

I purchased this Sunwatch (on eBay) after seeing one in a local Antique shop.  It was made in the early 1920s and was sold through, amongst other places, the Boy Scouts of America.  It is roughly the size of a pack of cards, being quite small in your hands.




This is photo was taken in Kansas City on 13 June 2005 where the location is N39.24°/W94.57°. The sunwatch has settings for 35°, 40°, and 45° so I used the 40° as it is the closest to Kansas City's latitude. The Sunwatch indicates 17:30 in this photo. The correction for the Equation of Time was plus 7 seconds. The correction for lonigtude (4.57° from the standard meridian) is plus 18 minutes and 18 seconds. The correction for Daylight Savings Time is plus one hour. Therefore the time would be 17:30 plus (1:00 + 0:18:18 + 0:00:07 or 1:18:25). This gives a corrected time of 18:48:25 hours. The photo was taken at 18:41:04 so this little tiny sundial was off by seven minutes.  If the gnomon was careful adjusted to 39.25° it might read a little closer.
An Equitorial Dial

The printed sundial, printed below, comes from the "Sunny Day U" area of the "Sundial Primer" website (http://www.mysundial.ca/tsp/tsp_index.html). They have many sundial kits that can be printed out and assembled.  I assembled it with paper taped to cardboard with a square brass tube as a gnomon. This is photo was taken in Kansas City on 13 June 2005 where the location is N39.24°/W94.57°. The dial indicates 17:41, as close as I can read it. The correction for the Equation of Time was plus 7 seconds. The correction for lonigtude (4.57° from the standard meridian) is plus 18 minutes and 18 seconds. The correction for Daylight Savings Time is plus one hour. Therefore the time would be 17:41 plus (1:00 + 0:18:18 + 0:00:07 or 1:18:25). This gives a corrected time of 18:59:25.  The photo was taken at 18:59:31, so this easy to build sundial indicates to within a few seconds. Not to bad at all!





What's Next?

Next I am going to make a simple universal ring dial out of embroidery loops (remember my rusty construction skills).  A how to article can be found at http://www.angelfire.com/my/zelime/sundials.html.  After that a wooden Heliochronometer that shows standard time (i.e. watch time) with no mental math or corrections.

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