skip to content
Home

Darwin Correspondence Project

To George Howard Darwin   [1866]

Dear George

Can you or any of your friends answer me this.1 In a family of 10 5 of the children squinted & 5 did not & they came alternately—.2 But you must understand it is indifferent whether a squinter or a non squinter comes first. What I want to know is what are the chances against their coming alternately.3

Yours affec | Ch. Darwin | Ch. Darwin | Ch. Darwin4

P.S This case of the squinting & other such cases are real.

Footnotes

1
George Darwin was studying mathematics at Cambridge University (Alum. Cantab.).
2
A case of squinting in five of ten siblings was reported in Streatfield 1857–9, and was referred to in Sedgwick 1861, which CD cited (in relation to a different subject) in Variation 2: 328 n. However, Streatfield stated that squinting affected only the boys among ten siblings, not that alternate children squinted. CD briefly discussed squinting in Variation 2: 9, in the chapter on inheritance, but relied exclusively on evidence provided by William Bowman.
3
At the top of the letter, George calculated a 1:126 chance of squinters and non-squinters being born alternately in a family of ten, by dividing twice the square of the factorial of five by the factorial of ten. At the end of his working, he multiplied 126 by two; the reason for this is unclear. George’s reply to CD has not been found.
4
The letter is in the hand of CD’s daughter Elizabeth. The signatures are copied from CD’s own.

Bibliography

Alum. Cantab.: Alumni Cantabrigienses. A biographical list of all known students, graduates and holders of office at the University of Cambridge, from the earliest times to 1900. Compiled by John Venn and J. A. Venn. 10 vols. Cambridge: Cambridge University Press. 1922–54.

Sedgwick, William. 1861. On sexual limitation in hereditary disease. British and Foreign Medico-Chirurgical Review n.s. 27: 477–89; 28: 198–214.

Streatfield, J. F. 1857–9. Seven cases of strabismus in one family. Ophthalmic Hospital Reports and Journal of the Royal London Ophthalmic Hospital 1: 260–2.

Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.

Summary

Asks GHD what the chances are against squinting and non-squinting children coming alternately in a family of ten.

Letter details

Letter no.
DCP-LETT-4961
From
Charles Robert Darwin
To
George Howard Darwin
Sent from
unstated
Source of text
DAR 210.1: 1
Physical description
L(S) 3pp †

Please cite as

Darwin Correspondence Project, “Letter no. 4961,” accessed on 19 April 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-4961.xml

Also published in The Correspondence of Charles Darwin, vol. 14

letter

Darwin Correspondence Project
darwin@lib.cam.ac.uk

© University of Cambridge 2022

Copyright declaration

Privacy policy

Website by Surface Impression

 

Study at Cambridge

About the University

Research at Cambridge