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Cassegrain secondary mirror
A 3-inch diameter convex secondary mirror for Cassegrain reflector telescope. It has a polish poor, with large corroded patches. The mirror is made of speculum metal in brass mount.
The mirror was found in the Herschel family home in the 1920s and is made of speculum metal. It is therefore assumed to have been made by William Herschel though there is no supporting evidence to suggest that he made cassegrain telescopes. In the early 1770s however, when William Herschel was starting out in telescope making he did experiment with different designs so it is possible that one of the designs he tried was the Cassegrain before eventually opting for the Newtonian.
The mirror was found in the Herschel family home in the 1920s and is made of speculum metal. It is therefore assumed to have been made by William Herschel though there is no supporting evidence to suggest that he made cassegrain telescopes. In the early 1770s however, when William Herschel was starting out in telescope making he did experiment with different designs so it is possible that one of the designs he tried was the Cassegrain before eventually opting for the Newtonian.
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Object Details
| ID: | AST0864 |
|---|---|
| Collection: | Astronomical and navigational instruments |
| Type: | Cassegrain secondary mirror |
| Display location: | Not on display |
| Creator: | Herschel, William |
| Date made: | 1773-1822 |
| Credit: | National Maritime Museum, Greenwich, London, Herschel Collection |
| Measurements: | Overall: 64 mm; Diameter: 88 mm |