Thanks GHD for clear lecture on heat.

Will keep paper on proportion of sexes, in case GHD wants it again.

Wants him to translate some pages of Swedish or Norwegian sent by A. W. Malm, "a good man".

Glad to see the statistical paper ["Theory of exchange value", Fortn. Rev. n.s. 17 (1875): 243–53].

GHD has been using E. Norman [CD’s copyist], and he apologises if this has caused delays to CD’s work.

Likes GHD’s article ["Professor Whitney on the origin of language", Contemp. Rev. (1874): 894]. "You have defended me nobly."

Mainly family news.

Eager to read GHD’s political economy MS "though Heaven knows whether I shall understand it".

Sends Murray’s report of November sales of CD’s books. "I am well content."

CD thinks better of "cousin paper" than GHD does.

With respect to GHD’s "viscous work", remembers endless discussions of movement of viscous matter 20 years back, apropos of movement of glaciers.

Appleton will bring out the new edition of Descent in the U. S., so GHD’s work will now be in three editions.

Has finished the "cousin paper" and will offer it to W. Farr for the Statistical Society.

Describes other work in progress.

Has CD heard of A. M. Mayer’s curious work on audition of insects [Am. J. Sci. 3d ser. 8 (1874): 89–103?]

Returns historical sketch [of GHD’s "cousin paper"?] with comments. "For Heavens sake put a sentence in some conspicuous place that your results seem to indicate that consanguineous marriage, as far as insanity is concerned, cannot be injurious in any very high degree."