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From:
Michael Faraday
To:
Thomas Davidson
Date:
15 October 1835
Source of text:
Uppsala University Handskriftsavdelningen ì Erik Waller's Collection of Autographs
Summary:

No summary available.

Contributor:
Faraday Project
From:
Charles Robert Darwin
To:
Thomas Davidson
Date:
23 Dec [1856]
Source of text:
American Philosophical Society (Mss.B.D25.142)
Summary:

Asks TD about variation among brachiopods.

Contributor:
Darwin Correspondence Project
From:
Thomas Davidson
To:
Charles Robert Darwin
Date:
29 Dec 1856
Source of text:
DAR 162: 116
Summary:

His experience confirms CD’s view that some species and even some genera of Brachiopoda are consistently more variable than others, and that such variable forms are variable in all localities and at all periods. Similarly a species that shows a lack of variability does so at all points in time and space. Discusses the causes of variability. [See Natural selection, p. 106.]

Contributor:
Darwin Correspondence Project
From:
Charles Robert Darwin
To:
Thomas Davidson
Date:
26 Apr 1861
Source of text:
DAR 143: 372
Summary:

Asks TD to carry out research on brachiopods to see whether the forms in one formation are intermediate between those above and below.

Describes unpublished study of spirifers by J. W. Salter.

Contributor:
Darwin Correspondence Project
From:
Charles Robert Darwin
To:
Thomas Davidson
Date:
30 Apr 1861
Source of text:
DAR 143: 373
Summary:

Thanks TD for his letter. Difficulties with CD’s theory are many and great, but CD thinks the reason is that we underestimate our ignorance. The imperfection of the geological record counts heavily for CD. His greatest trouble is weighing "the direct effects … of changed conditions of life without any selection, with the action of selection on mere accidental (so to speak) variability. I oscillate much on this head, but generally return to my belief that the direct [effects] … have not been great."

Is surprised that any one, like W. B. Carpenter, can go as far as to believe all birds may have descended from one parent, but will not go further and include all the members of the same great division. Such beliefs make "Divine mockeries" of morphology and embryology, the most important of all subjects.

Contributor:
Darwin Correspondence Project
From:
Thomas Davidson
To:
Charles Robert Darwin
Date:
3 May 1861
Source of text:
DAR 99: 1–2
Summary:

Sends three tables on the known geological distribution of genera and subgenera of Brachiopoda. Has been continually puzzled by intermediate forms, and is convinced that the greater number of species can be linked together. "Natura non facit saltum."

Contributor:
Darwin Correspondence Project
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From:
Thomas Davidson
To:
Sir John Herschel
Date:
[6 February 1862]
Source of text:
RS:HS 6.35
Summary:

Many years ago he read a paper to the Royal Scottish Society of Arts on the merits of JH's telescope compared with that of William Parsons (3rd Earl of Rosse); this paper has never been printed. Gives details of his own optical work.

Contributor:
John Herschel Project
From:
Sir John Herschel
To:
Thomas Davidson
Date:
[9 February 1862]
Source of text:
RS:HS 6.36 (C: RS:HS 23.361)
Summary:

Outlines the differences between the telescope of his own father and that of Lord Oxmantown [William Parsons]. Comments on various lenses. Sends him a little work of his own on telescopes.

Contributor:
John Herschel Project
From:
Thomas Davidson
To:
Sir John Herschel
Date:
[12 February 1862]
Source of text:
RS:HS 6.37
Summary:

Is grateful for JH's letter and pamphlet. Worked on portraiture before Mr. Baird and assisted him later. Outlines the various lenses he used and made for other people. Is pleased JH has a good opinion of the work of [W. B.?] Rogers. Is he familiar with the works of [Thomas?] Dicks in astronomy?

Contributor:
John Herschel Project
From:
Thomas Davidson
To:
Sir John Herschel
Date:
[29 February 1862]
Source of text:
RS:HS 6.38
Summary:

Has now had ample time in which to study JH's pamphlet. Comments on various points. Has constructed a 4 1/2" aperture achromatic telescope, but the buyer went bankrupt. Would welcome assistance from JH.

Contributor:
John Herschel Project
From:
Charles Robert Darwin
To:
Thomas Davidson
Date:
7 Apr 1873
Source of text:
American Philosophical Society (Mss.B.D25.426)
Summary:

Thanks TD for catalogue of his Cretacean fossils.

Regrets he cannot visit Brighton.

Contributor:
Darwin Correspondence Project