To J. F. W. Herschel 7 May 
Down Farnborough Kent.
Dear Sir John Herschel
At last I send you my M.S. I have heard from the Post Office that it could discover no trace of the lost parcel;1 I have, therefore, this time sent it direct to you registered: I shd be much obliged for a single line to acknowledge its receipt.
I have done my best in these instructions, but I cannot say that I much like them; I shd be very grateful for any corrections or erasures on your part.— I want to beg a favour of you: M. E. de Beaumont2 has measured the inclination of many lava-streams & I have suggested the great advantage (in which Mr Lyell strongly concurs with me) of repeated observations on this head. At the back of p. 33 I have given a translation of the means employed by M. E. de Beaumont, which is applicable to the slope of Glaciers &c.. Now it appears to my Brother (who translated the passage, & understands such subject a very little better than I do,3 who am profoundly ignorant on such points) that the note is not very clear, as we do not see what errors the precautions are intended to prevent. We in our ignorance cannot see, why a white sheet thrown on the lava-stream could not be reflected in the artificial horizon, & the angle thus measured, like the sun or moon in the Heavens. Would you be so kind as just to give this point a thought, & either leave the note as it stands, or add one yourself.—4
I shd be glad to correct the press of my M.S, if there be no objection to it, as I often write very incorrectly.
I have added a Heading of the contents, for the chance of such being required.
As I have sometimes been applyed to for geological hints by travellers, I shd be glad to have a few copies of my part, in the same manner as each author has some copies of his paper in most Transactions: Prof. Owen, also, told me he should like the same. I shd, also, much like to have one copy of the whole volume.—5
I sincerely hope that the Influenza has long ere this left you & your family.6
Pray believe me dear Sir John Herschel | Yours sincerely | C. Darwin To | Sir J. Herschel Bart &c
Sends MS of "Geology" for Manual [Collected papers 1: 227–50]. First parcel lost. Asks JFWH to give advice on an unclear note, translated from Élie de Beaumont, on measuring incline of lava-flows.
Please cite as
Darwin Correspondence Project, “Letter no. 1173,” accessed on 20 February 2017, http://www.darwinproject.ac.uk/DCP-LETT-1173