![William Herschel's 40 foot telescope, also known as the Great Forty Foot telescope, was a reflecting telescope constructed between 1785 and 1789 at Observatory House in Slough, England. It used a 47 William Herschel's 40 foot telescope, also known as the Great Forty Foot telescope, was a reflecting telescope constructed between 1785 and 1789 at Observatory House in Slough, England. It used a 47](https://c8.alamy.com/comp/T964MB/william-herschels-40-foot-telescope-also-known-as-the-great-forty-foot-telescope-was-a-reflecting-telescope-constructed-between-1785-and-1789-at-observatory-house-in-slough-england-it-used-a-47-inch-diameter-primary-mirror-with-a-1200-cm-focal-length-it-was-the-largest-telescope-in-the-world-for-50-years-it-may-have-been-used-to-discover-enceladus-and-mimas-the-6th-and-7th-moons-of-saturn-it-was-dismantled-in-1840-today-the-original-mirror-and-a-10-foot-section-of-the-tube-remain-T964MB.jpg)
William Herschel's 40 foot telescope, also known as the Great Forty Foot telescope, was a reflecting telescope constructed between 1785 and 1789 at Observatory House in Slough, England. It used a 47
![40-foot Telescope Slough William Herschel Telescope, PNG, 2400x1889px, Slough, Astronomer, Black And White, Drawing, Herschel 40-foot Telescope Slough William Herschel Telescope, PNG, 2400x1889px, Slough, Astronomer, Black And White, Drawing, Herschel](https://img.favpng.com/4/10/3/40-foot-telescope-slough-william-herschel-telescope-png-favpng-XKPJY2YrPGyRnfhAQp1G4HtPJ.jpg)
40-foot Telescope Slough William Herschel Telescope, PNG, 2400x1889px, Slough, Astronomer, Black And White, Drawing, Herschel
![The great reflecting telescope of Wilhelm Herschel (1789), , (evolution history book, 1894), Das große Spiegelteleskop des Wilhelm Herschel (1789), Le grand télescope à miroir de Wilhelm Herschel (1789 Stock Photo - Alamy The great reflecting telescope of Wilhelm Herschel (1789), , (evolution history book, 1894), Das große Spiegelteleskop des Wilhelm Herschel (1789), Le grand télescope à miroir de Wilhelm Herschel (1789 Stock Photo - Alamy](https://c8.alamy.com/comp/2J0RKAH/the-great-reflecting-telescope-of-wilhelm-herschel-1789-evolution-history-book-1894-das-groe-spiegelteleskop-des-wilhelm-herschel-1789-le-grand-tlescope-miroir-de-wilhelm-herschel-1789-2J0RKAH.jpg)