Orreries in the Ceiling

Orreries in the Ceiling

One of the most unusual orreries was that built by Eise Eisinga, a woolcomber of Franeker, near Leeuwarde, in West Friesland. Its construction, begun about 1774, took seven years. The mechanism, weight-driven and regulated by a pendulum, consists largely of cog-wheels in the form of oak disks and hoops fitted with iron pegs. It is all concealed. The pendulum moves inside a cupboard-bed, the weight hangs in an adjoining wardrobe, the main cog-wheel assembly is built into an attic, and the working parts of the model solar system are mounted in the double ceiling of a living room. Visitors in the living room therefore see the face of the orrery, about 12 feet in diameter, above their heads. The model planets move in eccentric slots in periods equal to those of their natural counter-parts. Each slot or orbit carries the symbols of the zodiacal signs, and each sign is subdivided, thus enabling the zodiacal positions of the earth and any naked-eye planet to be read off quite easily. Outside the orbit of Saturn a pointer, moving in another slot, indicates the date and the sun`s position in the zodiac.

On the south side of the ceiling Eisinga arranged dials for showing the day, the months, and year, the moon`s phase and position, and the times of its rising and setting. In a panel over the cupboard-bed is the face of an ingenious moving sky-chart from which one can see at a glance what stars are above the horizon at Franeker at the time of observation.

Ceiling Orrery. Source: object.com

In 1787, only six years after completing the planetarium, Eisinga had to leave his home and family and seek safety abroad. Against his will he had become involved in political differences and civil strife. His exile lasted eight years, during which time his wife died, his house was rented to strangers, and the planetarium became neglected. In 1796, however, he had it going again and was able to remain with it until his death in 1828. After his death the house was presented to the community of Franeker by King William III and the planetarium has been kept in working order ever since.

Another large ceiling orrery was constructed in the early 1920`s for the Deutsches Museum, Munich. Designed by Franz Meyer, chief engineer of the firm of Carl Zeiss, it occupied a circular room 37 feet in diameter. In the centre a sun globe, nine inches in diameter and suspended from the ceiling, contained a 300-watt light-bulb which provided illumination for the entire room. Smaller globes for the planets, suspended from electrically driven carriages, moved on elliptical rails with speed proportional to their natural velocities. The spectator went round the model sun on a moving platform located directly beneath the earth globe, and by using a periscope could watch the planets as they moved against a background of constellations painted on the walls of the room. Unfortunately, the orrery was destroyed during World War II, but modern versions of the ceiling orrery can be seen at the American Museum-Hayden Planetarium, New York, and the Morehead Planetarium, Chapel Hill.