Component of refracting telescope of 4.1-inch aperture, on an English type equatorial mounting, commissioned by Sir George Shuckburgh from Jesse Ramsden in 1781, though not completed until 1791

This is a component of 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.