Search: Herschel, John in correspondent 
Dallmeyer, John Henry in correspondent 
1860-1869 in date 
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Showing 1–8 of 8 items

Herschel6682

From:
John Henry Dallmeyer
To:
Sir John Herschel
Date:
[13 August 1861]
Source of text:
RS:HS 6.1
Summary:

Thanks for his note on the performance of the telescope. Gives suggested reasons for faults. Sends a print of a photograph of a map recently taken by one of his achromatic lenses.

Contributor:
John Herschel Project

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

Herschel6685

From:
John Henry Dallmeyer
To:
Sir John Herschel
Date:
[14 February 1867]
Source of text:
RS:HS 6.3
Summary:

Has not had time until now to carry out experiments on 'the central spot' as seen in photographs as related in JH's last letter. His recent trials with various lenses have verified JH's theories.

Contributor:
John Herschel Project

Herschel6686

From:
Sir John Herschel
To:
John Henry Dallmeyer
Date:
[16 February 1867]
Source of text:
RS:HS 6.4 & 24.188
Summary:

Is he acquainted with his ordinary reading glass? Gives details. Always carries a small one around with him for reading small print; thinks there would be a good market for them.

Contributor:
John Herschel Project

Herschel6687

From:
John Henry Dallmeyer
To:
Sir John Herschel
Date:
[18 February 1867]
Source of text:
RS:HS 6.5
Summary:

Regarding various types of glass for lenses. Will make two of JH's reading glasses if he will send details.

Contributor:
John Herschel Project

Herschel6688

From:
Sir John Herschel
To:
John Henry Dallmeyer
Date:
[19 February 1867]
Source of text:
RS:HS 6.6 & 24.189
Summary:

Outlining suitability of various types of glass for optical work. Gives details of theories of his reading lenses and calls attention to one of his own papers in the R.S.P.T. for 1821.

Contributor:
John Herschel Project

Herschel6689

From:
John Henry Dallmeyer
To:
Sir John Herschel
Date:
[21 February 1867]
Source of text:
RS:HS 6.7
Summary:

Thanks for letter and details of his paper in the R.S.P.T. Wishes there was an index of authors and subjects for students. Theories regarding the action of light on glass. Has interested Messrs. Chance in his theories. Gives reasons why he wants a reading glass of 3 1/2 inches.

Contributor:
John Herschel Project
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