Armillary sphere
Armillary sphere. The primary sphere of 15.5 cm diameter consists of two brass hemispheres fixed together at the equator to form a hollow sphere. Sections of the hemispheres have been cut away so that eight brass rings are left. Two of the rings are perpendicular to each other and these represent the colures. Five parallel rings are perpendicular to the colures and represent the polar circles, the tropics and the equator. The last ring represents the zodiacal band, and shows the symbols, pictures and the Latin names of the signs of the zodiac. In the centre there is a small gilt brass sphere , mounted on an equatorial polar axis. The primary sphere is mounted in a graduated brass meridian ring. On the top of the meridian ring, there is a graduated brass hour circle with a pointer. The meridian ring fits into a stand composed of four brass quarter circles, which support the hoizon ring and are fixed tot he short central column of a simple brass pedestal. The hollow base of the pedestal is filled with stone to make it satable. The horizon ring has a number of scales for the zodiac, degrees, the compass and for the Julian calendar. One of the fastenings, connecting the sphere to the meridina ring, is of metal and is obviously a later replacement. This instrument is unusual in that the '8' is seen with a flat top, unusual in English istruments. Also, the technique of forming the rings out of the sphere is unusual.
Object Details
ID: | AST0623 |
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Collection: | Astronomical and navigational instruments |
Type: | Armillary sphere |
Display location: | Not on display |
Creator: | Unknown |
Date made: | 17C |
Credit: | National Maritime Museum, Greenwich, London, Caird Collection |
Measurements: | Overall: 290 x 218 x 218 mm; Diameter of sphere: 154 mm |
Parts: | Armillary sphere |