Object glass for refracting telescope

1781-1791 in London
Jesse Ramsden

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Object glass of 3-inch aperture for refracting telescope on an English type equatorial mounting constructed for Sir George Shuckburgh by Jesse Ramsden in 1781-91.

This object glass belongs to a refracting telescope commissioned for Sir George Shuckburgh from Jesse Ramsden, the famous London instrument maker in 1781. The telescope was not completed until 1791. It is the world's first example of a large equatorial telescope, namely an instrument mounted for making accurate measurement of the position of the stars and planets. The telescope has a lens of 4.1-inch aperture and is carried on an equatorial mounting made of tapered brass tubing. After Shuckburgh's death in 1804, his heir donated the telescope to the Royal Observatory, Greenwich in 1811. Though designed for angular measurement the mounting of the telescope proved too flimsy and was little used despite improvements made at later dates. The instrument was finally dismantled and donated to the Science Museum in 1929.


Object Number:
1929-979/1 Pt3
brass (copper, zinc alloy) and glass
objective lens
  • component - object
Royal Observatory, Greenwich