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Darwin Correspondence Project

To William Ogle   18 March [1871]

Down. | Beckenham | Kent. S.E.

March 18th

My dear Dr Ogle

There is not the most remote danger of my finding any letter of yours too long. Many thanks for the last.1 Since writing I have found old notes of my own, on the jaw falling from concentrated attention, & I agree that this may apply to the Deaf— I suspect various causes come into play.2 I am convinced that in startled surprise the mouth is opened suddenly & the chest filled with air.3 It is odd that so simple a movement as opening the mouth under surprise, & this holds good in all parts of the world, shd. be so perplexing to understand. I shall consider all that you say with my best attention.

Believe me | Yours very sincerely | Ch. Darwin


Ogle’s letter has not been found, but was evidently a reply to the letter to William Ogle, 12 March [1871].
See letter to William Ogle, 12 March [1871]. In Expression, pp. 283–4, CD noted that when attention is concentrated for a length of time many facial muscles relax and the jaw drops.
In Expression, p. 284, CD observed that the mouth opened when one was astonished or startled.


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


Agrees that in a deaf person the jaw may fall because of concentrated attention.

In surprise, mouth is opened suddenly and chest filled with air. This expression occurs in all parts of the world. Odd that so simple a movement is so perplexing to understand.

Letter details

Letter no.
Charles Robert Darwin
William Ogle
Sent from
MR 19 71
Source of text
DAR 261.5: 8 (EH 88205906)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 7596,” accessed on 16 October 2021,

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