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Eyepiece
This eyepiece has a focal length of 2.95mm. It has a shallow and broad mount with a fairly large thread and milled edge.
William Herschel's eyepieces, made for him by his younger brother Alexander are outstanding because of their magnifying power which was exceptionally high for the time.
In his 'Account of a Comet', read to the Royal Society in April 1781 (the comet in question was later confirmed to be Uranus) he referred to having 'ready at hand the several magnifiers of 227, 932, 1536, 2010, &c'.
At the time a power of 270 was considered excellent, and his audiences disbelief at his claims of magnification was a serious hurdle in getting his discovery recognised.
William Herschel's eyepieces, made for him by his younger brother Alexander are outstanding because of their magnifying power which was exceptionally high for the time.
In his 'Account of a Comet', read to the Royal Society in April 1781 (the comet in question was later confirmed to be Uranus) he referred to having 'ready at hand the several magnifiers of 227, 932, 1536, 2010, &c'.
At the time a power of 270 was considered excellent, and his audiences disbelief at his claims of magnification was a serious hurdle in getting his discovery recognised.
For more information about using images from our Collection, please contact RMG Images.
Object Details
| ID: | AST0847 |
|---|---|
| Collection: | Astronomical and navigational instruments |
| Type: | Eyepiece |
| Display location: | Not on display |
| Creator: | Johann Alexander Herschel |
| Date made: | circa 1800 |
| People: | Herschel, William |
| Credit: | National Maritime Museum, Greenwich, London, Herschel Collection |
| Measurements: | Overall: 6 mm; Diameter: 35 mm |