Hello George, What you described is a simple armillary sphere. It can be used as a sundial but if it does not have markings, it does not serve that function well. Mount it with the arrow facing north at an angle to the horizontal equal to your latitude.
Most armillary spheres made these days are symbolic representations of our place in the universe. They have a proud history going back to the ancient Greek astronomers of Alexandria where were used to represent the celestial sphere. In Ptolmey's great book on astronomy "Almagest", he describes at least four types and uses of armillary spheres. With appropriate markings, rotating rings and sighting devices, they were used to measure the position of the stars and planets. They were also used as a mechanical computer to solve the spherical geometry to predict rising and setting times and positions of the sun, moon, planets and stars. They were used for similar purposes by Tycho and Kepler for their observations and calculations. They soon abandoned them as being too cumbersome and inaccurate compared to a quadrant. What you received is a symbol of this remarkable historical scientific instrument, an excellent work of art representing our place in the universe. Treat it this way as its functional parts are missing: the movable parts are fixed; there are no markings to allow it to be used as a sundial. Yours has three rings. The first vertical ring is the meridian ring. It is pierced by the gnomon arrow representing the polar axis. The equatorial ring is at right angles to polar axis. Hour marks could be inscribed on this ring for use as a sundial. The zodiac ring is at 23.5 degrees to the equatorial ring. This represents the tilt of the earth's axis from the ecliptic, the path of the sun and planets on the celestial sphere. This is often marked by the constellations of stars along the path, Aries (the ram), Pisces (the fish) etc. The ecliptic ring intersects the eqatorial ring on the east west axis. This intersection marks the first day of spring when the sun is above the equator. More elaborate designs include a horizon ring, tropic rings and polar rings. They can get quite complex. This year I am giving as Christmas gifts, simple armillary spheres to be used as Christmas tree decorations. I call mine "Rings of the Magi". I will forward to you a note describing the connection between armillary spheres, precession of the ecliptic and the Magi. Roger Bailey Walking Shadow Designs N 51 W 115 At 11:44 AM 12/5/99 +0100, G.F.G. Willegers wrote: >Hello, > >I am completely new to this list. Recently someone gave me a sundial as a >birthday present. Unfortunately it came without any instructions to placing it >correctly. Can someone tell me how to place it? I am living in the centre of >the Netherlands, at 52 degrees N, 5 degrees 30 E. The sundial has three rings, >forming some kind of globe (all without marks), and an arrow. > >Thanks, > >George Willegers > >
