![Sir WIlliam Herschel's telescope or the Great Forty-Foot reflecting telescope built between 1785 and 1789 at Observatory House in Slough, England. Copperplate engraving by Wilson Lowry after a drawing by J. Farey Sir WIlliam Herschel's telescope or the Great Forty-Foot reflecting telescope built between 1785 and 1789 at Observatory House in Slough, England. Copperplate engraving by Wilson Lowry after a drawing by J. Farey](https://c8.alamy.com/comp/P6EFTN/sir-william-herschels-telescope-or-the-great-forty-foot-reflecting-telescope-built-between-1785-and-1789-at-observatory-house-in-slough-england-copperplate-engraving-by-wilson-lowry-after-a-drawing-by-j-farey-from-abraham-rees-cyclopedia-or-universal-dictionary-of-arts-sciences-and-literature-longman-hurst-rees-orme-and-brown-london-1820-P6EFTN.jpg)
Sir WIlliam Herschel's telescope or the Great Forty-Foot reflecting telescope built between 1785 and 1789 at Observatory House in Slough, England. Copperplate engraving by Wilson Lowry after a drawing by J. Farey
![Sir William Herschel Great 40 foot telescope reflecting telescopes 1785 1789 Observatory House Slough England primary mirror Stock Photo - Alamy Sir William Herschel Great 40 foot telescope reflecting telescopes 1785 1789 Observatory House Slough England primary mirror Stock Photo - Alamy](https://c8.alamy.com/comp/C8NAJN/sir-william-herschel-great-40-foot-telescope-reflecting-telescopes-C8NAJN.jpg)
Sir William Herschel Great 40 foot telescope reflecting telescopes 1785 1789 Observatory House Slough England primary mirror Stock Photo - Alamy
![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
![Sir William Herschel's Great Forty Foot telescope. Sir William Herschel's telescope or the Great..., Stock Photo, Picture And Rights Managed Image. Pic. MEV-10934710 | agefotostock Sir William Herschel's Great Forty Foot telescope. Sir William Herschel's telescope or the Great..., Stock Photo, Picture And Rights Managed Image. Pic. MEV-10934710 | agefotostock](https://previews.agefotostock.com/previewimage/medibigoff/4887fc467388661d73b8a18c01b08b1d/mev-10934710.jpg)