ARMILLARY SPHERE
An Armillary Sphere is a model of the celestial sphere based on the Ptolemy theory of the universe with the earth being stationary at the centre. The celestial sphere is imagined as a sphere with the stars fixed onto its interior and the earth at its centre. Although we now know this to be inaccurate, it does not effect the working of the Armillary Sphere since to an observer on Earth the motion of the Sun and Stars appears the same.
The Armillary Sphere was an early stage in the history of horology (the science of time measurement) Since the rising and setting of the sun governs our day, a model of the motions of the sun and stars was an important step in the understanding of time.
It is a refinement of the earlier solid celestial spheres developed by Greek scientists such as Archimedes. Being solid made it difficult to imagine the position of the Earth at the centre, consequently these spheres developed a more skeletal appearance, consisting of a series of rings and becoming known as Armillary Spheres, presumably from the Latin word 'armilla' meaning bracelet. Although it is possible to use the Armillary for making observations (Eratosthenes 204BC catalogued more than 700 stars, and Hipparchus of Rhodes (150-125BD) determined distance from the Earth to the Sun and produced a complete star catalogue for his latitude) in practice this is difficult. However with the advent of stereographic projection the Armillary led to the development of the more accurate and useful anaphoric clock and the Astrolabe.
The Armillary Sphere as seen here was most commonly used in the 16th and 17th Centuries as a teaching instrument to explain the motion of the Sun and stars in relation to the Earth, hence illustrating the basic principles of astronomy and horology.
Specification:
Price....Non Uk $3000.00 incl. carriage....UK £1850 incl. carriage....Plinth £80.00 (Make: Haddonstone Elizabethan)