This is the remaining section of a 40-foot (12m) reflecting telescope, built for the astronomer William Herschel, who became famous for his discovery of the planet Uranus in 1781. the telescope was the largest in the world and cost over £4000, paid for by King George III. Completed in 1789 and erected at Herschel's home near Slough, about 30 miles (48km) West of Greenwich, it soon became a tourist attraction. Some people likened it to the Colossus of Rhodes, and it was even marked on the 1830 Ordnance Survey map of the area. Sadly, the Herschels did not use the great telescope for much serious astronomy, since it was difficult to set up and maintain. William's son had it dismantled in 1840. Most of the tube was destroyed when a tree fell on it 30 years later. You can find out more about William Herschel's work in the Weller Astronomy Galleries in the Astronomy Centre on this site.