The ancient Greeks are credited with inventing the armillary sphere, sometimes also known as the equatorial sundial. Today, garden armillary spheres, or “shadow-clocks” as they are sometimes known, are still beautiful instruments that demonstrate man’s great ability to conceive and craft.

Place the sundial on the base but do not secure it. Use the compass to locate true north and point the gnomen in that direction. For the greatest accuracy, the gnomon must point to magnetic north, not true north but to get a “ballpark” directional reading, a standard compass reading is fine.

An armillary sphere is basically a skeletal celestial sphere with a model of the Earth or, later, of the Sun placed in the center. It is useful as a teaching tool and as an analog computer for solving various astronomical problems to a crude degree of accuracy.

How does an armillary sphere work? Held stationary at the centre is a small brass sphere representing the Earth. About it rotate a set of rings representing the heavens – the celestial sphere – one complete revolution approximating to a day or 24 hours.

A sundial at a particular latitude in one hemisphere must be reversed for use at the opposite latitude in the other hemisphere. The gnomon, set to the correct latitude, has to point to the true South in the Southern hemisphere as in the Northern Hemisphere it has to point to the true North.

To use the gnomon, set it in the sun and rotate the base so that the shadow of the rod falls on the center line. The scale for reading the length of the shadow must be accurately horizontal, so use the spirit level to make sure of this, shimming the base as necessary with pieces of cardboard.

Gnomon is a really great school, the atmosphere is awesome and the location is great. Gnomon has quite a few traditional arts classes to suppliment their digital curriculum. Many of the instructors for those classes are graduates of Art Center in Pasadena and they’re very good at what they do.

To set up your sundial, find a place with as much exposure to the sun as possible. Mount the sundial on top of a post , use a level to make sure the face of the sundial is level. Fasten the dial in place (with one screw) with the gnomon facing north (The gnomon is the angled piece that casts the shadow).

Theodosius of Bithynia