Loss of water from leaf surfaces; action of a still air layer.

Proposal for CD’s LL.D.

Writes again about arrangements for the honorary degree ceremony.

Has been working on tides, which he is almost certain have altered the obliquity of the ecliptic.

Has given dates [for the Cambridge University honorary degree] to the Vice-Chancellor.

Asks GHD to determine whether there are worm-castings in cloisters of [Neville?] Court.

Enjoyed his visit to Cambridge. Asks for newspaper account of the LL.D.

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.

Thinks he had better not sign GHD’s paper [as a candidate for F.R.S.], since he obviously is no judge of the quality of his work.

Asks if Thomson did not overlook heat generated by the crushing and folding of strata during the refrigeration of the globe.

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].

CD at first thought GHD should not answer Haughton [see 10689], but Hooker thinks if no correction is made Haughton’s error will be quoted for 20 years. CD is now inclined to agree.

Recounts some figures relating deaf-mutism and consanguineous marriages.

GHD has failed to be elected to the Royal Society.

CD believes few or none have attributed deaf-mutism to consanguineous marriages.

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.

Asks for sketches of [Thalia] pistil, in which he is much interested.

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

Rejoices that "Lagrange’s case does not seem very bad".

CD is working hard at dissecting Thalia. Has recovered some handiness with microscope.

Sends drawings of specimens [of Thalia] CD requested.

Thanks GHD for his drawings [of Thalia]. Some parts need attention.

Writes to say that the point on which he thought GHD’s drawings were mistaken proves to be an error in his own observation.

He and Emma rejoice that GHD’s mathematical troubles are at an end. It is miraculous that he unconsciously followed the right course – like composing a sonata by a fluke.

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.