Will look for worm-castings in the cloisters,

and will send CD items from the Cambridge papers on the honorary degree.

Has hit on a possible fallacy in W. Thomson’s theory of secular cooling of the earth.

Asks CD if he would like to sign GHD’s Royal Society proposal for membership.

Has been reading Samuel Haughton on geological time ["Notes on physical geology, no. III", Proc. R. Soc. Lond. 26 (1877): 534–46]. It is utter rubbish. Asks whether CD thinks GHD should write a critical note on the subject [see Nature 17 (1878): 509–10].

Recounts some figures relating deaf-mutism and consanguineous marriages.

GHD has failed to be elected to the Royal Society.

Is frustrated to see, from a paragraph in Nature [18 (1878): 242], that Charles Lagrange has got hold of the same sort of ideas as he has.

Erasmus is unwell.

Refers to Charles Lagrange, who is working on the same subject as GHD, but in a fundamentally different way.

Sends drawings of specimens [of Thalia] CD requested.

Recounts the experiments on Fechner’s law he has found in Helmholz; they are on the smallest perceptible differences of illumination. Describes how to test whether plants’ responses to lights are in accordance with it.

Asks CD if he would screw himself up to inviting A. Newton to Down.

Thanks CD [for his increased allowance?].

Writes of his tour [in Algeria].

Encloses some references [missing] to information on Dr Erasmus Darwin.

Sends CD an article on Dr Erasmus Darwin [from Monthly Magazine, see 12028].

Tells of a "discovery" he has made about taking observations of the sun. Does not know yet whether it is new.

Sends abstracts of more articles [on Dr Erasmus Darwin] from Monthly Magazine.

Sends some papers on Erasmus Darwin for CD.

Sends results of his researches on the Darwin family at the Record Office.

Has written to Col. J. L. Chester [genealogist] to ask whether he would like to see the deeds [for Darwin genealogy, see Emma Darwin 2: 237].

Sorry to hear Henrietta’s opinion of the [Erasmus Darwin] proofs. GHD did not think it dull. He makes some suggestions.

Erasmus thinks CD should give a copy of Erasmus Darwin to Henry Parker.

Writes on family matters and researches.

Mentions construction of a pendulum

and completion of a paper he will send to the Royal Society.

Has sent off paper to the Royal Society

and begun work on a new problem which he feels contains the meaning of Bode’s Law, concerning the mean distances of the planets from the sun. There are mathematical difficulties, however, which he may be unable to surmount.

Will get to work on the pendulum next week.