Newtonian secondary mirror

F3368

Newtonian secondary mirror Long Caption: An elliptical plane mirror made as a secondary mirror for a Newtonian reflector telescope. The diameter of the minor axis of this mirror is 13.97 mm. 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. Credit line: © National Maritime Museum, Greenwich, London, Herschel Collection Object: AST0827 Artist: Sir William Herschel Date: circa 1800 Medium: speculum metal Size: diameter: 137 mm Click here to buy a bespoke print of this image.