My dear Father,

I send you the finale of my cousin paper— do you think it will do. I have summed up the result of my own job at the end of the last part. Norman is copying it, & so I shall have polished it off soon—thank goodness. I shall then write to Farr & offer it to him for Statist. Soc.¹

Have you seen some very curious papers by Prof. A. Mayer of the U.S on audition of insects, if not I will bring home the Phil. Mag. with it. He is going on to the Hemiptera & Homop.²

The cousin business & polit. Econ. have been keeping me away from the Squashy Solids,³ but I’ve read one long paper & have now a vol. of 400 or 500 pp. of quarto to read. It’s before the French Instit. so I do’nt know what I shall do in Xmas Vac.

I’ve sent off my defence of Jevons, (wh. he read & approved) to Fortnightly, but fear it may be too dull for them.⁴

Venn⁵ is picking my polit. Econ. to pieces now, but I’ve not heard what he has to say yet. He’s perhaps better than Sidgwick⁶ as being mathematical. I shall be much disappted if Contemp. thinks it too stiff as I think it worth something.⁷ At Glaisher’s request I’m just sending a little Mathematical paper to ‘the Messenger’ on a mechanical contrivance for finding an important function.⁸ I found it out for a problem at the lakes,⁹ but didnt think it worth anything, but G. rather likes it— I’ve had the thing made in the rough, but I don’t supp. anyone w^d. ever use it—but it’s the idea that’s curious.

Jevons is coming today & he & M^rs.¹⁰ dine with me on Tuesd. Fawcett is coming & so w^d. M^rs. F. but that she’s away.¹¹ So M^rs J. will be my only lady. The rest are Sidgwick, Venn (a friend of Eleanor Dicey’s),¹² Colvin¹³ & a friend of his. So we shall be quite small.

I’ve been very seedy for 4 or 5 days, & not in my usual way quite, & I do’nt know what to make of it unless it’s another cold coming on. Whether its these violent changes of temperature, I dont know,—but nothing agrees with me. I’ve been playing tennis every day all the same. If I’m very bad on Tuesd. I must write & put it off, but I fear it’ll be a grind, tho’ I must try to get thro’ without it somehow

Lady Rayleigh, asked me to visit them in Dec. when she was here the other day, in coming thro’ from Scotland;¹⁴ but I’ve not heard when it’ll be yet, but I expect I shall go straight from here, & prob. not come home till Xmas. I hope y^r. London visit is suiting you, & that mother & Uncle R. are both pretty fair.¹⁵

I’ve read hardly anything this term, as work of one sort or another has filled almost the whole time; but much of it has been merely tiresome e.g the cousins.

Mayer finds the fibres of a mosquito’s antennæ m. more sensitive to one note than to any other;¹⁶ I suspect it is the note of their own humming, I’m going to try to find out— If it is it’ll be a curious case of Sexual Selection

Y^r affec son | G H Darwin