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Dallmeyer, John Henry in correspondent 
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From:
John Henry Dallmeyer
To:
Sir John Herschel
Date:
[28 November 1859]
Source of text:
Harvard: Houghton AAH 67m-67 (48)
Summary:

Answers JH's inquiry concerning JD's telescope manufacturing process.

Contributor:
John Herschel Project
From:
John Henry Dallmeyer
To:
Sir John Herschel
Date:
[1 December 1859]
Source of text:
Harvard: Houghton AAH 67m-67 (48)
Summary:

Informs JH that he is taking over the optical workshop of his late father-in-law, Andrew Ross.

Contributor:
John Herschel Project
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
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
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
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
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
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
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
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
From:
John Henry Dallmeyer
To:
Sir John Herschel
Date:
[23 December 1870]
Source of text:
RS:HS 6.8
Summary:

Has made a trial of JH's lens but it was too large to be satisfactory. Regarding the 'graphoscope,' a new toy. Has been concerned with the manufacture of an improved form of opera glass. Present forms have many imperfections. Gives details of his own theories and sends one for JH's notice.

Contributor:
John Herschel Project
From:
Sir John Herschel
To:
John Henry Dallmeyer
Date:
[25 December 1870]
Source of text:
RS:HS 24.340
Summary:

Thanks and a detailed description of the functioning of a pair of binoculars sent by JD to JH.

Contributor:
John Herschel Project
From:
John Henry Dallmeyer
To:
Sir John Herschel
Date:
[27 December 1870]
Source of text:
RS:HS 6.9
Summary:

Thanks for his letter. Is glad the binoculars give a satisfactory performance, but regrets the width between the tubes does not suit JH's eyes. Will alter this and send a new pair later.

Contributor:
John Herschel Project