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Darwin Correspondence Project

From William Aitchison to George Cupples   16 June 1869


16th June | 1869


I regret my absence from here should have left yours of the 12th so long without an answer.—1

I am no stranger to Mr Darwin’s scientific fame & shall be glad to extend to him, through you, any information in my power about sheep— We sheep Farmers always count the number of our Lambs someway about the 20th or 25th May when we castrate the Tup Lambs, but I suspect none of us know the exact proportional deaths of the sexes previous to that period, but there is no doubt the males are most liable to die after birth—2 notwithstanding I have always been of opinion that the balance upon the whole is in numbers with the female sex—

In evidence of this I shall give you a statement of the number of Lambs I had on one of my largest Farms during the last two years at the time of castration about the 20th May—3

1867 Ewe Lambs — — 57.14
Tup Lambs — — 55.17
1868 Ewe Lambs — — 62.17
Tup Lambs — — 52. 1
1869 Ewe Lambs — — 57.9
Tup Lambs — — 49.13

You are at perfect liberty to further communicate with me about these matters—

I am Sir | Your obdt. Servt. | Wm Aitchison

CD annotations

2.3 the 20th … know the 2.4] scored blue crayon
2.5 but there … always 2.6] scored blue crayon
Top of table: ‘(Scores)’ pencil
End of table: ‘Cheviot Breed at period of castration’ pencil


Aitchison had been suggested to Cupples by Robert Elliot as a breeder worth contacting for information about the proportions of the sexes (see letter from Robert Elliot to George Cupples, 4 June 1869). This letter was enclosed in the letter from George Cupples, 20 June 1869.
CD cited Aitchison for this information and for returns on sheep in Descent 1: 305.
In the table, the first column (before the point) represents groups of twenty, the second (after the point) units up to nineteen. See letter from William Aitchison to George Cupples, 30 June 1869. Sheep were traditionally counted in a vigesimal counting system. Cupples added conventionally written figures at the side of the table.


Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.


Statistics on proportion of sexes in lambs.

Letter details

Letter no.
William Aitchison
George Cupples
Sent from
Source of text
DAR 86: A54–5
Physical description
4pp †(by CD)

Please cite as

Darwin Correspondence Project, “Letter no. 6784,” accessed on 2 August 2021,

Also published in The Correspondence of Charles Darwin, vol. 17