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Description: | 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.
AUDIT - case needs two part numbers
caption: Primary objective mirror | Publisher: | "http://collections.rmg.co.uk/" | Rights holder: | "Royal Museums Greenwich" | Source: | Royal Museums Greenwich | Identifier: | http://collections.rmg.co.uk/collections... | Go to resource |
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