From:
Sir John Herschel
To:
[William Whewell]
Date:
[28 August 1839]
Source of text:
RS:HS 25.5.16
Summary:
Wishes to have mentioned to the Physical Section of the B.A.A.S. that JH has discovered that the extreme red rays [infra-red?] of the sun do not darken photographic paper, but tend to whiten it.
Contributor:
John Herschel Project