Armillary spheres have been used since the 3rd century BC, when the Greek scholar, Eratosthenes, is credited with inventing the device. Before the invention of the telescope in the 17th century, an armillary sphere was the main instrument of astronomers to chart the motion of the celestial bodies around the earth.
Construction of armillary spheres vary, but they all have the same basic design: a series of rings that center around a central point. The central point is sometimes represented by a small orb but can also have no center element such as ours. The armillary is said to be Ptolemaic if the orb represents the earth; otherwise it is Copernican and revolves around the sun.
Our armillary sphere has been made with five rings of iron. The arrow-shaped gnomon is designed to be pointed towards the North Star. The ring that the gnomon runs through is the equinoctial colure known as the meridian circle. The ring that is perpendicular to this is the celestial equator that measures the sun’s ascension. The ring that lays relatively flat represents the horizon. The ring which runs perpendicular to this is known as the ecliptic, which is designed to trace the sun’s path during the year. The final ring which envelops all other rings is the solstitial colure that measures the declination of the sun, moon, and stars.
The sphere sits upon a stone pedestal with a cap that has stepped molding. The die has been hand-carved with geometric panels that have canted corners, while the base features volute ornamentation.
While armillary spheres are still used today, their main function is now to act as focal points in gardens or be displayed as artwork.
CONDITION: More information coming soon…