![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 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
![Sir Fw Herschel / Slough 1. Available as Framed Prints, Photos, Wall Art and other products #14281007 Sir Fw Herschel / Slough 1. Available as Framed Prints, Photos, Wall Art and other products #14281007](https://www.prints-online.com/p/164/sir-fw-herschel-slough-1-14281007.jpg.webp)
Sir Fw Herschel / Slough 1. Available as Framed Prints, Photos, Wall Art and other products #14281007
![21 William Hershel Stock Photos, Pictures & Royalty-Free Images - iStock | Johannes kepler, Ptolemy, Ptolemaic system 21 William Hershel Stock Photos, Pictures & Royalty-Free Images - iStock | Johannes kepler, Ptolemy, Ptolemaic system](https://media.istockphoto.com/id/458976133/photo/william-herschel-telescope-greenwich-royal-observatory.jpg?s=612x612&w=0&k=20&c=nqQngO6160sBC8PqhK-RQ7dOU9c0u2H9_Ze5eL2vBcs=)
21 William Hershel Stock Photos, Pictures & Royalty-Free Images - iStock | Johannes kepler, Ptolemy, Ptolemaic system
![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)