Overall view of the grand orrery by Benjamin Martin, London. It shows the drum holding the gea…

Images(28)

Detail of the planetary system, calendar ring, and divided colures.

This is a side view of the movement to the orrery, shown outside of its case and with the plane…

Detail showing the earth on its axis, with a crescent-shaped terminator marking the line betwee…

This is part of the central drive mechanism of the orrery. The shaft on the right is turned by…

This is a top view of the movement to the orrery, shown outside of its case and with the planet…

This is the movement to the orrery outside of its case and with the planetary cover rings remov…

Overall view of the grand orrery by Benjamin Martin, London.

This is a detail of a grand orrery by Thomas Heath. It was part of David P. Wheatland's person…

This is the gear assembly for the earth-moon system, showing the components disassembled. The …

This is the underside of the gear assembly for the earth-moon system, shown disassembled. See…

This is part of the central drive mechanism of the orrery. The shaft on the left is turned by …

The central coaxial gear cluster for the orrery.

grand orrery

Date1764-1767

Inventory Number0004

ClassificationOrrery

Subject

Maker Benjamin Martin 1704 - 1782

Cultural Region

Place of Origin

Place of Use

Dimensions79.5 x 56 x 63 cm (31 5/16 x 22 1/16 x 24 13/16 in.)
orrery diam.: 56 cm (22 1/16 in.)

Material

Bibliography

The Apparatus of Science at Harvard, 1765-1800

DescriptionThis orrery stands on three columns which meet three curved legs on ball feet. A compass is fixed between the legs, just above the ball feet. This stand supports a cylindrical brass case containing the weight-driven clockwork mechanism that drives a model of the solar system. The large weight is found on the side of the orrery. To the left of this case is a knob on a pull lever. It is presumed to be a brake to stop the orrery.

Six concentric brass rings (formerly silvered), which are fitted with model of planets on short brass posts, revolve around the central brass sphere representing the sun. Other brass spheres represent Mercury, Venus, Mars, Jupiter (with four moons) and Saturn (with a ring and four moons). The earth, made of ivory, automatically rotates on its axis. The lunar phases are indicated and the period of the moon's nodes are shown.

A colonnade of twelve brass posts around the edge of the case supports the ecliptic circle engraved with a calendar and the signs of the zodiac. Mounted above the ecliptic circle are five principal "Circles of the Sphere": "Arctic Circle," "Tropic of Cancer," and a portion of the "Equinoctial Circle" (or the celestial equator). These three circles are in turn supported by two meridian circles engraved with scales which intersect at right angles at the celestial North Pole.

In Collection(s)

Signedon case: Made & Improv'd by B: MARTIN in / Fleet Street LONDON

Inscribedon case, opposite to signature: The Gift of the / Hon.ble JAMES BOWDOIN Esq.r / To the Apparatus of HARVARD College / N.E. May 1764

FunctionThe orrery, named after the Earl of Orrery who commissioned one of the first examples in 1713, was designed as a representation of the solar system. Usually mechanized, it showed the relative motion of the planets around the sun. The most intricate of them also displayed the motion of the moons around the planets. It was a pedagogical tool, not a research instrument.

A video of the orrery being demonstrated by former CHSI curator Will Andrewes in a 1989 episode of the PBS series Nova can be seen on YouTube: https://www.youtube.com/watch?v=lTx4gqSTlmE

ProvenanceGift of James Bowdoin, Esq., commissioned May 1764 for Harvard College. Received at Harvard April 1767. Jefferson Physical Laboratory, Harvard University; transferred to CHSI April 1948.

Historical AttributesUnlike the small hand-cranked orreries that Benjamin Martin advertised as stock items from his shop, this larger clock-driven machine was built on special order. After the 1764 fire of Harvard Hall, James Bowdoin gave Harvard College £50 for a new orrery. He and the College authorities expected to buy a fairly good instrument at the price. Apparently Martin set out to devise one as well as he knew how and eventually the bill amounted to £90.8.6. This was a shock to the College and a lesson to Martin who promptly revised his own figures in his <i>Catalogue of Philosophical, Optical and Mathematical Instruments</i> (London, 1766). Orreries were then offered from £12.12.0 to £150, the latter price presumably representing the best clock-driven type. Martin was proud of this machine and stated "that an orrery proper for use of your College could not be made at near" the original agreed amount of £50. Fortunately, Bowdoin generously consented to make up the difference.