Monday, 24 August 2009

Tuesday August 21, 1894

AST0800 Eye-piece for a measuring micrometer head, signed Troughton & Simms, c. 1850 © NMMA man called from Messrs Troughton & Simms about the Position of the 28 Inch Micrometer. I shewed him the method of illumination used in the Astrographic Telescope. He had been unable to obtain a dark field and illuminated wires in the way suggested by the Astronomer Royal, and wished to use some prisms to reflect the light. Mr Lewis & I discussed the matter with him and agreed that Mr Simms should do it as he liked & alter it subsequently, if necessary.

Frank Dyson, Chief Assistant

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