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Darwin Correspondence Project

To T. H. Huxley   7 May [1860]1

Down Bromley Kent

May 7th

My dear Huxley

As you seemed somewhat interested about changes in proportions of Pigeons, I will tell you the general results after reworking the whole subject in every possible manner & by the aid of about (more or less) ten thousands rule of three sums.—2

Sternum, scapulæ & furcula invariably reduced in size. Feet & tarsi generally reduced, in size, but are more plainly governed by correlation with length of Beak.—

Wings, measured from end to end of radius, generally reduced in length—viz in 17 Birds (of different races); but in 8 other birds rather increased in length, but then 5 of these 8 are long-beaked birds. But the wings if measured from extreme tip to tip are generally much increased in length—viz in 21 birds longer & in only 5 shorter.—

So that the proportion of birds with longer or shorter wings proportionally with the wild rock-pigeon are reversed, according as the measurement is made from tip to tip of wing or from end to end of radius.—

The increased length of wing, when measured from tip to tip, seems wholly due to greater length of the primary wing feathers, & may not be more related to use & disuse than the quicker or slower growth of nails on our fingers.—

Have you seen last Saturday Review?3 I am very glad of the defence of you & of myself.—   I wish the Reviewer had noticed Hooker.—4 The Reviewer, whoever he is, is a jolly good fellow, as this Review & the last on me, showed. He writes capitally & understands well his subject.—   I wish he had slapped Owen a little bit harder5

Ever yours | C. Darwin

Do not answer this.—


Dated by the reference to the Saturday Review (see n. 3, below).
CD was writing up the results of his study of pigeons for his larger work on species (‘Journal’; Appendix II). He refers to the measurements he made comparing the bone dimensions of wild birds and domestic breeds. In most cases he used the common arithmetical ‘rule of three’ to find the quotient, against which he assessed the actual measurements of domestic breeds. The measurements are given in Variation 1: 162–79.
An anonymous review of Richard Owen’s Palæontology (R. Owen 1860b) appeared in the Saturday Review, 5 May 1860, pp. 573–4. The reviewer suggested that Owen was the author of the unsigned, critical review of Origin in the Edinburgh Review ([R. Owen] 1860a), as in fact he was. See also letter to Asa Gray, 22 May [1860].
CD refers to Hooker 1859.
The review defended CD’s right to propose hypotheses and criticised Owen’s anonymous attack on Huxley’s Royal Institution lecture ([R. Owen] 1860a, pp. 521–3).


Observations on changes in physical proportions of pigeons.

The Saturday Review of 5 May has a defence of CD and THH by "a jolly good fellow".

Letter details

Letter no.
Charles Robert Darwin
Thomas Henry Huxley
Sent from
Source of text
Imperial College of Science, Technology and Medicine Archives (Huxley 5: 117)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 2786,” accessed on 20 January 2018,

Also published in The Correspondence of Charles Darwin, vol. 8