Labels:bulletin board | person | poster | reckoner | sky OCR: Orrery: Miniature planetarium designec B ma henma tical instrument -maker from Lichfield for Charles Boyle fourth Earl of Orrery who promoted the device and popu larized its use The mechanism was designed r illustrate Copernican principles, the diurnal and annua motions the earth. the motion f the moon and the heliocentric orbits af the planets. The demonstration knawn as the "Grand Orrery involved theatrical staging to the unini tiated of the clock <work accuracy f the solar system. The device was activated by turning crank attached set of gears which were surmounted by an armillary hemisphere com posed of elliptical I bands. The horizontal calendar ring fixed to the base represents the plane af the ecliptic through which the earth moves and on it are inscribed the Zodiacal signs and the ...
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