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.

Encloses William Thomson’s report on GHD’s paper. Some of it was written in Rayleigh’s hand.

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