Sends notes on volcanic islands for LH to read and return.

[Letter could be an inaccurate contemporary copy to which the copyist interpolated details, or a forgery. The address "Down House Orpington Kent" occurs nowhere else.]

Thanks Horner for his letter [about Volcanic islands].

Discusses craters of elevation with respect to the views of Leopold von Buch and Élie de Beaumont. Compares Lyell’s views to those of continental geologists. Mentions reading A. D. d’Orbigny [Voyage dans l’Amérique méridionale (1835–47)].

Encloses note from Emma to Mrs Horner, inviting the Horners to visit Down.

Discusses proposed survey of Glen Roy. Mentions Glen Roy theories of Agassiz and William Buckland. Includes a memorandum calling for a careful survey of the parallel roads of Glen Roy. Mentions M. A. Bravais ["On the lines of ancient level of the sea in Finmark", Q. J. Geol. Soc. Lond. 1 (1845): 534].

Thanks LH for memorandum [missing] by K. R. Lepsius.

Variations in nature arise from unknown causes, accidentally or spontaneously, and are preserved by natural selection if beneficial.