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Darwin Correspondence Project

To W. D. Fox    [29 July 1828]



Dear Fox

What excuse have you to offer for not having answered my letter long before this? I hope it is nothing worse than idleness; or what would be still better, I hope it arises from your being 10 fathoms deep in the Mathematics, & if you are God help you, for so am I, only with this difference I stick fast in the mud at the bottom & there I shall remain in statu quo.—1

But you see I can afford time to write a single letter.— but I will not mention, how long I have been hoping in vain to receive a letter from my old master; more especially at this present time, when, if you remember; we talked of meeting on the top of some Welch mountain between Barmouth & Tenby. I will not flatter you, by saying how much I wish to hear what you yourself are doing & how entomology & your 101 other pursuits are going on? After this aweful Philippic I hope I shall soon receive a letter.—

I have been at Barmouth ever since the first of July, & like it very much; the scenery & therefore the walks are quite delightful. I only wish you would make a trip here, & I would Cicerone you up & down the mountains, untill you had not a particle of wind left in your lungs.— I go on very badly with Mathematics; neither have I succeeded so well as I expected in entomology: but I must mention a few of the most conspicuous insects or rather those which I can at all describe. Amongst the Lepidoptera, the Pterophorus Pentadactylus (Lamarck), a most extraordinary moth,—several large moths, one of which is figured in Samouelle; brown with a white band & spots; a beautiful small copper coloured butterfly, with a little tail like the Machæon: allso a sphinx Zigena (Lam:).

Inter Coleoptera—. A carabus, larger than the Violaceus, jet black & smooth.— Of the Carabidæ, one very odd one; black polished; very long; thorax, orbicular, & sep⁠⟨⁠arate⁠⟩⁠ from the abdomen, of this length diagram caught near sea side.— A Donacia, with calves as big as mine; several large Cimices, one most beautiful, scarlet & black;— a red & black Ptinus, with a thorax like a night-cap; et multa alia.— How go on the Chrysalises If you answer this letter, tell me of your success in the science, (of names, I am afraid).—

We have heard several times from Erasmus, he has changed his plans so often; that to follow him in his course would be to pursue a Machæon on a windy day. I have nothing more to write about, but I hope soon to write again.— Heaven knows this effusion will not tempt you to write again: but I must take my chance.—

My dear old Fox I long to see you again, but I suppose it will not be before Term begins | Believe me your most sincere & loving

cousin —– n2

| Charles Darwin

(n, being an unknown quantity, this formula will exactly express our relationship)


In the Autobiography, p. 58, CD comments on his weakness in mathematics: ‘I attempted mathematics, and even went during the summer of 1828 with a private tutor (a very dull man) to Barmouth, but I got on very slowly. The work was repugnant to me, chiefly from my not being able to see any meaning in the early steps in algebra. This impatience was very foolish, and in after years I have deeply regretted that I did not proceed far enough at least to understand something of the great leading principles of mathematics; for men thus endowed seem to have an extra sense.’


Autobiography: The autobiography of Charles Darwin 1809–1882. With original omissions restored. Edited with appendix and notes by Nora Barlow. London: Collins. 1958.


CD on a reading party at Barmouth, Wales;

difficulty with mathematics.

Reports on his entomological collecting.

Letter details

Letter no.
Charles Robert Darwin
William Darwin Fox
Sent from
Source of text
Christ’s College Library, Cambridge (MS 53 Fox 3)
Physical description
ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 45,” accessed on 7 June 2023,

Also published in The Correspondence of Charles Darwin, vol. 1