Work of our members

What is a bifilar sundial?
Around 1925, the German Hugo Michnik invented the principle.
Over a horizontal plane and parallel to it, two wires are stretched; one north-south, the other east-west, and in differing heights.
The time is read at the intersection of the two shadows on the dial plane.
(Instead of wires, the edges of two planes can be used as gnomons.)

It was not until 1980 before this sundial attracted some interest again, but many other types of bifilar sundial have been developed since.
One such development, and a simple one at that, is to rotate the wires about the vertical.
That in itself is a different subject; but after such a dial was calculated, the idea needed testing.

There was a need for a model of the sundial.
Rather than constructing a beautiful miniature, some ordinary objects, found in any house were gathered and assembled into the sundial shown in the photograph. It took about five minutes.

Two small blocks of wood, a ruler, a matchbox and a couple of beermats for height were used.
Together with a computer generated drawing, they were sufficient to test the model on a sunny day. The dial performed excellently.

Why all this attention for a model?
With the aid of very simple models like this, an idea can be put to the test quickly, or the operation of a sundial can be understood quickly.
I have made dozens of these to increase my insight into gnomonics. I would warmly recommend the practice to anyone.

When I showed this model to some American sundial friends, one response was:
"It's matchless to catch the sun with a matchbox."