created by Carl Sabanski
Universal Bifilar Sundial Kit
Bifilar Sundial: invented in 1922 by Hugo Michnik in its horizontal form, although it can be on any plane. The time is indicated by the intersection on the dial plate, of the shadows of two wires (or other lines in space) stretched above and parallel to it. The wires often run E-W and N-S, with their (different) heights above the plane being a function of of the location of the dial. It may have equiangular hour markings, and hence can be delineated to show many kings of hours.
This sundial is a bit out of the ordinary and not too difficult to make. It is a bifilar sundial with equiangular hour markings.
Figure 1 shows the Kit that you will use to make your own universal solar time bifilar sundial.
Figure 1: Universal Bifilar Sundial Kit (CAD)
is designed so that you can build one for the
Northern or Southern Hemisphere. All you need are scissors, styrofoam, glue and
some string. 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 "Universal Bifilar 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. Just set it on a level surface and align the arrows with your local meridian. i.e. the true north-south line. If you are comparing the time to a clock remember to adjust the time for the Equation of Time and longitude correction. The "Correct-A-Dial" or "Correct-A-Dial II" will help you here. And if the clocks are set to summer time don't forget about the one hour (or whatever) difference.
Here's what the sundial will look like once you have finished making it. The "wires" in this model are made from thin string and are attached to the latitude scales and north-south plates using clear tape. Note that the latitude scale marks are spaced for every 2 degrees to avoid having too many lines in such a short distance.
Universal Bifilar Sundial - Front View
Universal Bifilar Sundial - Rear View
(Note the latitude scales on the east and west sides.)
Universal Bifilar Sundial - Side View