From:
Sir John Herschel
To:
George Biddell Airy
Date:
[8 March 1849]
Source of text:
RGO 6.160.78
Summary:
Tells GA about the internal counterpoise system in use in some German telescope mountings, and includes a diagram; JH knows nothing about chilling speculum metal [see GA's 1849-3-7].
Contributor:
John Herschel Project