Speculum metal
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Speculum metal is a mixture of around two-thirds copper and one-third tin, making a white brittle alloy that can be polished to make a highly reflective surface. It was used historically to make diffe
The speculum metal mirror from William Herschel's 1.2-meter (49.5-inch) diameter "40-foot telescope" at the Science Museum in London
Modern replica of Herschel's 6.2"-aperture Newtonian telescope which had a speculum metal main mirror
Leviathan telescope. Telescopes with speculum metal mirrors were a large breakthrough in aperture, but their drawbacks fueled competition from refractors
The metal mirror of the Leviathan, the largest telescope mirror until the 100-inch Hooker telescope of 1917 (a metal-on-glass mirror)
William Herschel
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Frederick William Herschel was a German–British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline Herschel. Born in the Electorate of Hanover,
Speculum metal
…for its use in the metal mirrors of reflecting telescopes, and famous examples of its use were Newton's telescope, the Leviathan of Parsonstown, and William Herschel's telescope used to discover the planet Uranus. A major difficulty with its use in telescopes is that the mirrors could not reflect as much light as…
Portrait of William Herschel (1785)
Original manuscript of Symphony No. 15 in E-flat major (1762)
Plaque at the Herschel Museum of Astronomy, which was the family home at 19 New King Street, Bath
Replica in the William Herschel Museum of a telescope similar to that with which Herschel discovered Uranus