Ɛpsilon

From William Farr   27 February 1868

General Register Office | Somerset House

1868 Feb 27

My dear Sir

Rutland is our smallest county—& the proportions fluctuate from accidental causes—the extent of fluctuation varying with the numbers in relations which are expressed by a formula— given by the writers on probability. I enclose the numbers for Rutland—& will shortly send you the proportions for all our counties.1

I am my dear Sir | yours very truly | W. Farr

P.S. The Registrar General to whom I mentioned your striking facts about the sexes of racehorses2—inquired whether Mr. Darwin is acquainted with any known method for determining? He was told by a breeder that he possessed such a secret.

C. Darwin Esq FRS

[Enclosure]

Number and Proportion of Male and Female Children born in the County of Rutland in each of the 10 Years 1857–1866.

Children born Males born to
Years Males Females every 100
Females born
1857 398 348 114.4
1858 372 377 98.7
1859 385 346 111.3
1860 388 390 99.5
1861 371 338 109.8
1862 352 363 97.0
1863 367 369 99.5
1864 407 355 114.6
1865 377 372 101.3
1866 353 357 98.9
3770 3615 104.5 average
Total 7385 Checked

CD annotations

Side of enclosed table: ‘All in Printed Table’ pencil

End of enclosed table:

‘377
362
739’
ink

1
See letter from William Farr, 17 February 1868. In Descent 1: 301, CD reported on the proportion of male to female births in the counties of Rutlandshire and Buckinghamshire, and in North Wales.
2
The registrar-general was George Graham. CD had received information on sex ratios in racehorses from William Bernhard Tegetmeier (see letter to W. B. Tegetmeier, 21 February [1868] and n. 2).

Please cite as “DCP-LETT-5947,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-5947