created by Carl Sabanski
Universal Horizontal Sundial Kit
Horizontal Sundial: the common or garden sundial with a horizontal dial plate and polar-pointing gnomon.
It is possible to create many variations of the universal horizontal sundial. There are three presented here and they all look very interesting and are very easy to make. In all cases a gnomon is required that can be adjusted to any latitude. The sundials are limited to a latitude range of 25º to 65º. To cover this range there are two gnomons available. One is for latitudes between 25º and 45º and the other for latitudes between 45º and 65º. Choose the one that best suits your needs. Use a couple of paper clips to hold the gnomon in place.
The dial plate of these sundial is designed to fit on an 8-1/2" by 11" sheet of paper. They are made as large as possible to make reading the time easier.
Figure 1 shows the first universal horizontal sundial Kit consisting of hour lines and latitude lines that are straight lines. The hour lines are all vertical but are not equally spaced.
Figure 1: Universal Horizontal Sundial #1 Kit (CAD)
Figure 2 shows the second universal horizontal sundial Kit. The hour lines are still vertical but now they are equally spaced. As a result the latitude lines are now curves.
Figure 2: Universal Horizontal Sundial #2 Kit (CAD)
Figure 3 shows the third universal horizontal sundial Kit. In the first two kits the hour lines converge as the approach at 6 a.m. and 6 p.m. making them difficult to distinguish. In this sundial circles are used for the latitude lines and this results in a sundial that is easier to read. The hour lines are now curved.
Figure 3: Universal Horizontal Sundial #3 Kit (CAD)
have made up a total of 6 kits so you can build any of the universal
horizontal sundials for the Northern or Southern Hemisphere. All you need are
scissors and glue. If you would like to download a
PDF file of the "Universal Horizontal Sundial Kit" just open the door that
works for you.
When you have completed the sundial all you have to do is set up and it will tell you solar time. The sundials are oriented like any horizontal sundial and a directional guide is provided to help. The gnomon is designed to slide between its two side supports. Align the desired latitude marker line with the top edge of the support. A paper clip can be used to hold it in place or it can be glued if you plan to use it in only one location.
Find the line for your latitude. Solar time is read at the point the gnomon's shadow crosses the line.
As can be seen in the first two sundials, the latitude line spacing decreases as the latitude increases. You can have a little fun with your universal horizontal sundial and try out an interesting technique. The important fact to note is that a sundial built for a given latitude can be positioned so it will work at any other latitude in a given Hemisphere. The dial plate just needs to be tilted until the gnomon is at an angle equal to the local latitude. Figure 4 shows the adjustable sundial base used to do this manipulation. The slope of the base can be adjusted over the range of 0º to 40º.
Figure 4: Adjustable Sundial Base (CAD)
Build the sundial and adjust the gnomon for a suitable latitude that gives better spacing of the latitude lines. This will of course be a lower latitude. Calculate the angle the base is to be set to as follows:
Adjustable Sundial Base Angle Setting = Local Latitude - Latitude of Constructed Sundial
For example, let's say we want to use the universal horizontal sundial #1 at a latitude of 55º. The lines are pretty tight there but there's a lot more space at 30º, which would make reading the sundial easier. Build the sundial with the gnomon set at an angle of 30º. Set the angle of the adjustable sundial base to 25º (55 - 30). Use a couple of paper clips to hold the base at the desired angle.. Place the sundial on the base at it is ready to use once it is oriented correctly.
Adjustable Sundial Base
Here's what the sundials will look like once you have finished making them. These are located in the Northern Hemisphere.