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Darwin Correspondence Project

To George Gabriel Stokes   18 February [1868]1

Down. | Bromley. | Kent. S.E.

Feb 18th.

My dear Sir

I have ventured to send my son2 to you to obtain a little information for me, on one point, if in your power to give it, and by this means you will be saved the trouble of answering this note.

Have you ever attended to feathers, & can you tell me whether the splendid colours of the eye of a Peacock’s tail depends on colouring matter, or on reflection.3 If on the latter, as appears the case, I much want to know, whether any change of structure,—as the distance of a film, or the distance of fine lines or points from each other—gradually, but perhaps not equally, increasing or diminishing, would account for the series of colours, which surrounds the eye, & passes into the general tint of the barbs at the circumference of the feather. Will you be so kind as to look at the feather, & tell my son anything you can.—

Pray forgive me for troubling you & believe me | My dear Sir | Yours sincerely | Ch. Darwin


The year is established by the relationship between this letter and the letter from G. G. Stokes, 27 February 1868.
CD probably refers to George Howard Darwin.
On CD’s interest in the peacock’s plumage, see the letter to Roland Trimen, 16 January [1868] and n. 5.


Wants to know how the colour of the eye of the peacock’s tail is produced, whether it depends upon colouring matter in the feathers or reflection, and whether any varying structural change will account for the series of colours surrounding it.

Letter details

Letter no.
Charles Robert Darwin
George Gabriel Stokes, 1st baronet
Sent from
Source of text
CUL (Add 7656: D73)
Physical description
3pp & AdraftS 2pp

Please cite as

Darwin Correspondence Project, “Letter no. 5891,” accessed on 6 July 2020,

Also published in The Correspondence of Charles Darwin, vol. 16