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Newtonian primary mirror
A 7-inch Newtonian primary mirror of speculum metal with a focal length of 7ft.
In a Newtonian reflector telescope the eyepiece is at the side of the tube. Light comes in at one end, is reflected off the objective (or primary) mirror and onto a secondary mirror which directs the light towards the eyepiece.
William Herschel, with help from his brother Alexander and his sister Caroline made a number of these mirrors to go in the telescopes they made to use and to sell. A mirror of this size and focal length would have been used in one of their 7ft telescopes.
In a Newtonian reflector telescope the eyepiece is at the side of the tube. Light comes in at one end, is reflected off the objective (or primary) mirror and onto a secondary mirror which directs the light towards the eyepiece.
William Herschel, with help from his brother Alexander and his sister Caroline made a number of these mirrors to go in the telescopes they made to use and to sell. A mirror of this size and focal length would have been used in one of their 7ft telescopes.
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Object Details
| ID: | AST0960.1 |
|---|---|
| Type: | Newtonian primary mirror |
| Display location: | Not on display |
| Creator: | Herschel, William |
| Date made: | 1770-1790; 1770-90 |
| Credit: | National Maritime Museum, Greenwich, London, Herschel Collection |
| Measurements: | Diameter: 19 mm x 162 mm;Overall: 50 mm;Weight: 4.15 kg |
| Parts: |
7-foot Newtonian (reflector) telescope (Telescope)
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