Discusses a specimen of Mexican obsidian with an unusual laminated structure.
Down near Bromley Kent
I venture to take the liberty of addressing you, knowing how much you are interested on
the subject of your discovery on the zoned structure of glacier-ice. I have a specimen (from M
It has occurred to me, that you possibly might like to see the specimen of obsidian
& some curious, most finely, laminated obsidians & trachytic rocks,
which I collected at Ascension island. You would not of course, I presume, think it
worth the expence of carriage to have the specimens sent to Edinburgh; but
I hope you will excuse, should you feel no interest in this subject, the liberty I take in writing to you, & I beg to remain, your obedient servant | Charles Darwin
- f1 781.f1Forbes argued that the zoned structure of glacier ice was produced by tension resulting from gravitational force acting on the viscous ice. See letter to Adolf von Morlot, 9 August , n. 4.
- f2 781.f2The specimen from Charles Stokes's collection is discussed in Volcanic islands, pp. 67, 69–70.
- f3 781.f3See Volcanic islands, pp. 70–1.
- f4 781.f4The Public Library of the University of Edinburgh, i.e., the collection belonging to the whole University and open to all its members.
- f5 781.f5Forbes had already made a comparison between glacier ice and lava, although coming to different conclusions from CD (J. D. Forbes 1844). See letter to J. D. Forbes, 13 [November 1844].
- f6 781.f6Forbes published parts of this letter with a paragraph from another letter from CD (see letter to J. D. Forbes, [November? 1844]) in the Proceedings of the Royal Society of Edinburgh 2 (1845): 17–18.