To Leonard Horner [January 1847]1
Down. Farnborough. Kent.
Sunday.
My dear Mr Horner.
Your most agreeable praise of my Book2 is enough to turn my head; I am really surprised at it, but shall swallow it with very much gusto.
With respect to the inclination of the lava-streams, it would indeed as you say be utterly impossible to measure them with any clinometer. The river was carefully mapped, so that the distance between any two points was known: then I measured at (A) the height of lava-stream above the river & the fall of the river having been ascertained the height above the sea could be approximately known.
Then the same operation being done at B, the difference in height made a triangle & the angle is most easily calculated by trigonometry. Being out of practise my Brother calculated them.3 As I say, these measurements though not absolutely correct, from the data not being so, cannot be far wrong.
E. de Beaumont measured the inclination with a sextant & artificial horizon, just as you take the height of the sun for latitude.—4
With respect to my Journal,5 I think the sketches in the second edition are pretty accurate; but in the first they are not so, for I foolishly trusted to my memory, & was much annoyed to find how hasty & inaccurate many of my remarks were, when I went over my huge pile of descriptions of each locality.—
If you ever meet anyone circumstanced as I was advise them not on any account to give any sketches until his materials are fully worked out.
With many thanks for the pleasure your commendations have given me, believe me | Dear Mr Horner | Yours very truly | C. Darwin.
What labour you must be undergoing now; I have wondered at your patience in having written to me two such long notes. How glad Mrs. Horner will be when your address is completed.6
I must say that I am much pleased that you will notice my volume in your address, for former presidents took no notice of my two former volumes.7
I am exceedingly glad that Bunbury is going on well.—8
Footnotes
Bibliography
Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.
Horner, Leonard. 1847. Anniversary address of the president. Quarterly Journal of the Geological Society of London 3: xxii-xc.
Journal of researches 2d ed.: Journal of researches into the natural history and geology of the countries visited during the voyage of HMS Beagle round the world, under the command of Capt. FitzRoy RN. 2d edition, corrected, with additions. By Charles Darwin. London: John Murray. 1845.
South America: Geological observations on South America. Being the third part of the geology of the voyage of the Beagle, under the command of Capt. FitzRoy RN, during the years 1832 to 1836. By Charles Darwin. London: Smith, Elder & Co. 1846.
Summary
Responds to LH’s comments on South America.
Discusses inclination of lava stream.
Sketches in second edition of Journal of researches more accurate than in first.
Letter details
- Letter no.
- DCP-LETT-1048
- From
- Charles Robert Darwin
- To
- Leonard Horner
- Sent from
- Down
- Source of text
- DAR 145: 139
- Physical description
- C 2pp
Please cite as
Darwin Correspondence Project, “Letter no. 1048,” accessed on 19 April 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-1048.xml
Also published in The Correspondence of Charles Darwin, vol. 4