Tour o9f the Library at the University of Pennsylvania

Masonic Library & Museum Association - MLMA

An International Organization of Librarians, Archivists, Curators, & Directors

Tour of the Library at the University of Pennsylvania

Pictured here is the Henry Charles Lea Library removed from his house and transplanted to the 6^th floor Inside the Van Pelt-Dietrich Library Center at the University of Pennsylvania

Pictured below is an Orrery at the University of Penn Library

An Orrery is a mechanical model of the solar system that illustrates the relative positions and motions of the planets and moons in the solar system in heliocentric model. They are typically driven by a large clockwork mechanism with a globe representing the Sun at the centre, and with a planet at the end of each of the arms. This orrery was built by David Rittenhouse.

A normal mechanical clock could be used to produce an extremely simple Orrery with the Sun in the centre, Earth on the minute hand and Jupiter on the hour hand; Earth would make 12 revolutions around the Sun for every 1 revolution of Jupiter. Note however that Jupiter's actual year is 11.86 Earth years long, so this particular example would lose accuracy rapidly. A real Orrery would be more accurate and include more planets, and would perhaps make the planets rotate as well.

Orreries are sometimes referred to as planetariums, although generally, planetariums are hemispherical theatres in which images of the night sky are projected onto an overhead surface. Orreries can range widely in size from hand-held to room-sized.

The first Orrery was built in 1713 by George Graham. He was supported (as a patron) by Charles Boyle, 4th Earl of Orrery, and thus the name. Orreries are usually not built to scale.

Similar to a Tellurion which is a mechanical device that depicts how day, night and the seasons are caused by the movement of the Earth on its axis and around the sun. An outer ring shows the signs of the zodiac and the months.