40-foot telescope, Historical reflecting telescope in Slough, England
The 40-foot telescope contained a 48-inch diameter primary mirror and measured 12 meters in length, making it a remarkable astronomical instrument of its time.
William Herschel constructed this telescope between 1785 and 1789 with financial support of £4,000 from King George III for astronomical research and discoveries.
Caroline Herschel received payment of £50 per year as the first female astronomy assistant in England while operating this telescope with her brother William.
The telescope featured an altazimuth mount system that enabled complete rotation for tracking celestial objects across the night sky during observations.
The telescope remained the largest instrument of its kind for 50 years and contributed to the discovery of Saturn's moons Enceladus and Mimas.
Location: Slough
Creator: William Herschel
Diameter: 1.2 m
GPS coordinates: 51.50820,-0.59540
Latest update: September 16, 2025 17:29
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