From:
Sir John Herschel
To:
Robert Ellis Dudgeon
Date:
[22 January 1871]
Source of text:
APS B.H435p.26 (C: RS:HS 24.348)
Summary:
Comments on use of 'air' lens rather than glass in some circumstances.
Contributor:
John Herschel Project
Comments on use of 'air' lens rather than glass in some circumstances.