From:
Sir John Herschel
To:
James David Forbes
Date:
[2 June 1842]
Source of text:
St. Andrews 55 (C: RS:HS 22.122)
Summary:
Compares actinometric measurements of radiation. Explains interest in total eclipse relative to actinometry. Discusses the possibility of making actinometric measurements by photographic means.
Contributor:
John Herschel Project