created by Carl Sabanski
Pinwheel Equatorial Sundial Kit
Equatorial Sundial: a dial in which the dial plate is parallel to the equatorial plane and the polar-pointing gnomon is perpendicular to it.
The equatorial sundial and how to set it up is described in another kit and will not be repeated here.
This equatorial sundial is slightly different than one that uses a narrow gnomon and where the time is read at the centre of the shadow. The gnomon for this sundial is quite wide and the hour lines are laid out so the time is read using only one edge of the gnomon's shadow. The typical equatorial sundial has the hour lines originating from one point. The hour lines of this sundial are tangent to the circumference of the gnomon. Because of the way it appears, it is called a pinwheel equatorial sundial. Figure 1 shows the Kit you will use to make your own pinwheel equatorial sundial.
Figure 1: Pinwheel Equatorial Sundial Kit (CAD)
The sundial is designed so that you can build one for the Northern or Southern Hemisphere. All you need are scissors, cardboard, glue and a wood dowel. The dial is a lot of fun to make and would be a great science project. If you would like to download a PDF file of the "Pinwheel Equatorial Sundial Kit" just open the door.
When you have completed the sundial all you have to do is set up and it will tell you solar time.
Here's what the sundial will look like once you have finished making it. It is positioned for a latitude of 40° in the Northern Hemisphere. You can see the shadows of the equatorial sundial at different times of the year. Note that the time is read using the edge of the gnomon's shadow. This edge comes from a different part of the gnomon throughout the day.
Northern Hemisphere - June - 1:00 P.M.
Northern Hemisphere - December - 11:00 A.M.
This sundial is very easy to build and a lot of fun to use.