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Darwin Correspondence Project

To L. C. Wedgwood   5 January [1872]1

Jan 5

My dear Lucy

Supposing that you have leisure during next 2 or 3 weeks, will you have a try with straight blunt knitting needle to ascertain, whether on steep slopes the worms come to surface at nearly right angles to the slope, or at nearly right angles to the horizon.—2

We have no steep grass-covered slopes here;—3 On nearly level surfaces the worms come up at all conceivable angles.— It wd be very important for me if I cd. ascertain that they generally come up at rt. ⁠⟨⁠s to the slope.— It is not easy to probe the holes.—

Yours affect | C. Darwin


The year is established by the relationship between this letter and the letter from L. C. Wedgwood, 20 January [1872].
CD thought that if earthworms dug burrows at right angles to the slope, denudation would be increased (see Earthworms, p. 270).
Wedgwood lived with her parents at Leith Hill Place, near Dorking, Surrey.


Earthworms: The formation of vegetable mould through the action of worms: with observations on their habits. By Charles Darwin. London: John Murray. 1881.


Asks her to probe worm-holes on grassy slopes with a knitting needle to ascertain whether they come out at right angles to the slope or to the horizon.

Letter details

Letter no.
Charles Robert Darwin
Lucy Caroline Wedgwood/Lucy Caroline Harrison
Sent from
Source of text
Cambridge University Library (Add 4251: 331)
Physical description
ALS 2pp

Please cite as

Darwin Correspondence Project, “Letter no. 8144,” accessed on 18 May 2024,

Also published in The Correspondence of Charles Darwin, vol. 20