Discusses loan of cirripede specimens from the British Museum and problems of classification. Encloses a note of thanks to be laid before the Trustees [see 1153].

CD cannot find the lagoon-island mud that WCW asked about, but he sends other geological specimens he hopes will be interesting.

Asks for the reference in which JP states that some erratic boulders came from a lower to a higher level. CD is writing a paper ["Transportal of erratic boulders", Collected papers 1: 218–26] in which he believes he has the true explanation. Would like as many instances, with details, as possible.

Though correspondence has never ebbed so low, CD is constantly in his thoughts.

Observations on cheetahs used as domesticated hunting animals.

Finds geographical barriers sometimes separate species, but also finds species that remain separate where there are no barriers to migration.

Colour "individuates" isolated animal species.

Plains and alpine animal distribution show altitude not strictly analogous to latitude.

Impact of timber cutting on climate has led to extinction of crocodiles.

Will discuss coal formation in letter to Edward Forbes.

CD often asked whether isolated mountains in southern latitudes had closely allied representatives of Arctic and north temperate plants; JDH has found a representative barberry.

Making for Darjeeling via Calcutta.

Thanks for sending cirripedes. Cannot make out the label, so can JCR tell him the bank and the depth. Hopes to keep the specimens for 6 or 8 weeks before returning them.

Arranges to pay subscription on 15 Feb and 16 Aug as requested by Mr Mason.

Thanks RC for information on hand-level; he has recommended it in his "Instructions" ["Geology", Collected papers 1: 227–50].

Agrees to pay Mr Mason as requested.

JP’s reference was clear, but seems to be different from the case cited by W. Hopkins about erratic conglomerate boulders. Asks for more details on the latter. CD does not think much of Hopkins’ paper ["Elevation and denudation of the district of the lakes of Cumberland and Westmorland", Q. J. Geol. Soc. Lond. 4 (1848): 70–98].

Thanks JP for his note and reference. CD’s paper will not deal with the general question of erratics but only their transportal from a lower to a higher level ["The transportal of erratic boulders", Collected papers 1: 218–27]. His notion is that the boulders were transported by coast-ice, not drifting icebergs, and that during the period of transportal the land was subsiding. Can JP tell him whether the raised conglomerate boulders he observed were rounded or angular?

Sends MS of his chapter on geology for Manual [Collected papers 1: 227–50]. Fears it may be too long. Does not much like it but can do no better. After hesitation, has recommended books. Defends his point that mere collection of rock specimens is "of hardly any use to Geology".

Cannot give information about hook. Fuegian women fish without hooks.

Robert Mallet’s suggestion about space for specimens on board men-of-war forwarded to Sir J. Herschel.

Describes his new microscope and its advantages for dissecting. Suggests RO might discuss topic [in his contribution to J. F. W. Herschel, ed., Manual of scientific enquiry (1849)].

Sir John Herschel has not received the parcel of "Scientific Instructions", which was posted on the 15th. He requests an accurate search at the Admiralty.

Thanks JSH for his address [Address delivered in the Ipswich Museum on 9th March 1848]. Questions a sentence which implies that only the practical use of a scientific discovery makes it worth while. The instinct for truth justifies science without any practical results. Cites his work on cirripedes.

Apologises for length of notes of advice for microscopic work.

Asks ACR to establish height of Moel Tryfan in Caernarvonshire; "in my notice on this hill [""Ancient glaciers of Caernarvonshire"" (1842), Collected papers 1: 163–71] I give a very much less height than others". [See also another mention of the elevation of Moel Tryfan in "On the transportal of erratic boulders" (1848), Collected papers 1: 218–27.]

CD discusses questions about his coral reef theory that were raised by HTDlaB [in his Geol. Soc. Anniversary Address (1848)].

Some geologists (especially H. T. De la Beche) doubt boulders have really been carried above their parent rock, but rather thought they were left behind as a result of denudation. Asks JP’s view of this, which he can quote. Supposes he will be well abused for his paper, but is resolved "not to show a white feather".

May go to Paris next summer about barnacles.

Unable to appreciate second volume of Alexander von Humboldt’s Cosmos [1848].

Recommends review by Sir John Herschel [Edinburgh Rev. 87 (1848): 170–229].

Recommends book by Mary Somerville [Physical geography (1848)].

Mentions article [on species] by M. E. Chevreul [Ann. Sci. Nat. (Bot.) 3d ser. 6 (1846): 142–214].