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Herschel's 40-foot telescope. Illustration of the 40-foot (12 metre) reflecting telescope built by astronomer William Herschel in 1787-9. Unlike other reflecting telescopes, the eyepiece was situated at the open end of the tube. This removed the need for a secondary mirror, reducing loss of light, but meant that astronomers had to climb some distance to make an observation. One visitor, the Italian astronomer Piazzi, fell from the structure and broke his arm. The telescope cost #4000 to build and #200 a year for upkeep, all of which was provided by King George III. On its first night of service Herschel discovered two new moons of Saturn. It was dismantled in 1839.
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