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Darwin Correspondence Project

From H. B. Brady   18 October 1871

Mosley St, | Newcastle-on-Tyne.

Oct: 18th. 1871

My dear Sir,

I have just returned from a little tour in the United States. Whilst at Boston—Prof Shaler1 shewed me much kindness and one day when talking after dinner at his home I elicited the fol⁠⟨⁠lowing⁠⟩⁠ circumstances which, unless they are already well known to you, will I think be of much interest— if known, no harm is done,— to me they were quite new, but that might easily be. ⁠⟨⁠    ⁠⟩⁠ I manifested some ⁠⟨⁠curi⁠⟩⁠osity as to what the rattle of the ⁠⟨⁠    ⁠⟩⁠ snake really sounded like— ⁠⟨⁠    ⁠⟩⁠ only by the shaking of the ⁠⟨⁠    ⁠⟩⁠ skins one sees in European museums. He replied—in reality it is such a sound as you might imagine the dried specimen to produce if hung or a tuning fork or if by any other means a musical rythm could be imparted to it— in fact (he added) knowing rattlesnakes as well as I do, I could ⁠⟨⁠    ⁠⟩⁠ now, distinguish their ⁠⟨⁠    ⁠⟩⁠ from the whirr of the g⁠⟨⁠  ⁠⟩⁠ so common in the west.2 I suggested that there was wonderful significance in this fact from a Natural Selection point of view & to this he not only assented but said it had long appeared to him to be the real explanation.— I don’t know how far this observation may be original—but I told Prof. Shaler I shd. transmit it to you on my return on the chance of its being of value—, the rattle snake having been regarded by many as a difficulty in the way of the natural selection doctrine.3

I met my friend Mr. Pryor4 of Trin. College at Philadelphia again a little more than a fortnight ago at the 5th Ave. Hotel at New York.— Your sons were with him & well;5 but as chance had it, though a good deal with Mr Pryor I never met them personally.

Yours very truly | Henry B. Brady.

Charles Darwin Esq MA. F.R.S. | &c. &c. &c.

CD annotations

End of letter: ‘Dog & [Hybridism] | [quote] Flower’


In Expression, p. 107, CD cited an 1872 publication by Shaler for the information that the rattlesnake sounded like a cicada in the same district; however, he disagreed with Shaler’s theory that the rattling served to attract birds, believing rather that it was a warning to predators (ibid., n. 27).
Some authors thought that the rattlesnake was furnished with a rattle in order to warn its prey: see Origin, p. 201.
George Howard and Francis Darwin were travelling in the United States (see letter to Asa Gray, 16 July [1871]).


Expression: The expression of the emotions in man and animals. By Charles Darwin. London: John Murray. 1872.

Origin: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. By Charles Darwin. London: John Murray. 1859.


On visit to Boston was told by N. S. Shaler how habits of rattlesnake are consistent with natural selection. Informs CD, as rattlesnake is considered by some a difficult case for his theory.

Letter details

Letter no.
Henry Bowman Brady
Charles Robert Darwin
Sent from
Source of text
DAR 160: 277
Physical description
ALS 4pp damaged †, 2 CD notes damaged

Please cite as

Darwin Correspondence Project, “Letter no. 8015,” accessed on 16 August 2022,

Also published in The Correspondence of Charles Darwin, vol. 19