Search: Herschel, John in correspondent 
Dallmeyer, John Henry in correspondent 
1860-1869::1866 in date 
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Herschel6683

From:
John Henry Dallmeyer
To:
Sir John Herschel
Date:
[24 September 1866]
Source of text:
RS:HS 6.2
Summary:

Outlining phenomena in the refraction of light. Has been experimenting with wide angle lenses for cameras and gives some of their defects. Would like JH's opinion on how to get rid of the 'secondary focus.'

Contributor:
John Herschel Project

Herschel6684

From:
Sir John Herschel
To:
John Henry Dallmeyer
Date:
[30 September 1866]
Source of text:
RS:HS 24.167
Summary:

Provides a physical explanation for a white patch in the center of JD's photograph.

Contributor:
John Herschel Project
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