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Darwin Correspondence Project

From David Milne   28 March 1840

10 York Place, Edinburgh,

28th March 1840.


I have been so much occupied professionally till within the last few days, that I have not been able to read and duly study your paper on South American volcanic action to enable me to acknowledge it.1 I assure you that it is appreciated by me most highly, and I have perused it a second time with increasing benefit. There are views in it as well as facts most interesting to the subject of my own inquiries. There is one passage in your paper on which I would venture to offer a remark. On page 618 you observe that the disturbance appears to emanate not from one point, but from many points, ranged in a band, otherwise the fact of the linear and unequal extension of earthquakes would be unintelligible.2 The Scotch earthquakes are felt over a greater extent of country in a N.E. or S.W. direction than in any other direction. They all emanate from one point, which I have ascertained to be N.W. of Comrie village in Perthshire. Fraserburgh, in the N.E. point of Aberdeenshire, is about 150 miles from Comrie, and the shocks were more sensibly felt there than at Stirling, which is about 25 miles S.S.E. from Comrie. The reason of this, I consider to be, that a chain of hills runs across the country through Comrie to Fraserburgh, consisting chiefly of gneiss, granite, and mica slate; whilst between Comrie and Stirling there are various secondary formations. The former transmits the vibration with tenfold more facility than the latter.

Is it not possible that the linear and irregular extension of the shocks in South America may be owing to a similar cause? Von Hoff makes a similar remark with regard to the earthquakes of Germany, which follow the line of the basaltic hills that stretch across the country.3 In your most interesting volume, which forms part of the notes on the Beagle’s voyage, you speak of the connection subsisting between earthquakes and the atmospheric disturbances which follow, and you express your belief in these. But I am somewhat inclined to go further. I think there are strong reasons for suspecting a connection between earthquakes and meteoric change preceding them.4 One of these may be the diminished atmospheric pressure as noticed by you, and in support of my view I have some very remarkable proofs drawn from our own country. But another of these influences I suspect to be water, a circumstance which I see from your book is matter of belief also in South America.5

I am much obliged to you for warning me against too ready a belief in the connection between earthquakes felt on opposite sides of the equator, especially when the interjacent countries evince no indication of them; and on this account I am beginning to be sceptical as to any connection between our Scotch earthquakes and those in Italy, for both in Calabria and in Savoy the volcanic fires were raging when Perthshire was excited.6

Another phenomenon has lately come to my knowledge, which I am anxious to make known to you. On the 16th November jets of smoke or steam were observed to issue from the side of a hill in Glen Almond, eight miles north-east from the focus of the Comrie shocks, and stones were by these jets raised out of their beds. On the 15th January last, about 200 yards from the same place, a flame was seen by a different person, who had not heard of the former eruption, which alarmed him so—he was within 150 yards of it—that he ran away for two miles without stopping. I have caused precognition, to use a Scotch lawyer’s phrase, to be taken regarding this matter. The result is, that such a flame has been seen occasionally for the last twenty or thirty years arising from the same spot.

Do you know of any analogous cases where flames rise from the ground not connected with craters or any volcanic disturbance? The formation is clay or mica slate; the latter, I rather think.

I wrote to Dr Daubeny about it. He thinks it must be carburetted hydrogen, but can suggest no cause for it, or any instance precisely similar. However, he speaks of flames issuing from the calcareous mountains of Albania; and the rocks of Pietra Mala in Italy are also calcareous.7 These gases may arise from bituminous matter, but of which none can exist in Glen Almond. I should feel very much obliged if you could suggest to me any case analogous to this, and any points which should be specially attended to in my investigations.—

I am, dear Sir, yours very truly, David Milne.


Milne was an advocate at the Scottish bar and a fellow of the Royal Society. He had become interested in earthquakes as a result of earthquake shocks at Comrie, Perthshire, in 1839, and had written to CD in early 1840 (Milne Home 1891, p. 63; this letter has not been found). CD replied in a letter that should now be dated 20 [February 1840] (it was published in Correspondence vol. 2 with the date [19 March 1840] and in Milne Home 1891, pp. 67–9, with the date 20 March 1840). In the letter, CD offered to send Milne, in a week or ten days, a copy of his article ‘Volcanic phenomena and the formation of mountain chains’, which he was expecting to be published ‘immediately’ in the Transactions of the Geological Society of London. The paper appears in the third part of volume 5 (2d series) of the Transactions, and a page following the table of contents of the second part of the volume states: ‘The Third and concluding Part of the Volume being nearly ready, will be published in February’.
See ‘Volcanic phenomena and the formation of mountain chains’, p. 618 (Collected papers 1: 70).
The reference is to Karl Ernst Adolf von Hoff, and possibly to Hoff 1822–41 (see, for example, Hoff 1822–41, 4: 61).
Milne refers to Journal of researches, pp. 430–3. CD had reservations about the theory that earthquakes were caused by a lowering of atmospheric pressure, which also tended to bring rain, since the weather that accompanied some earthquakes was itself abnormal and thus seemed more likely to have been a consequence of the earthquake than vice versa. Milne referred to CD’s account of the mercury in the barometer falling before the Valparaiso earthquake, and quoted his conclusion that there must be some connection between subterranean and atmospheric disturbances, in Milne 1841–4 (see Edinburgh New Philosophical Journal 31 (1841): 299 and Journal of researches, p. 433).
Milne may be referring to his belief that water filtering into underground fissures and turning into steam could generate electricity, and thus account for the electrical phenomena associated with earthquakes (see Milne 1841–4, Edinburgh New Philosophical Journal 31 (1841): 307). CD noted in Journal of researches, p. 431, as part of a discussion of the association between earthquakes and the weather, that the inhabitants of northern Chile were firmly convinced of a connection between earthquakes and rain.
See Correspondence vol. 2, letter to David Milne, [19 March 1840], which should now be dated 20 [February 1840] (see n. 1, above). Milne discussed the evidence for the coincidence of earthquakes around the world in Milne 1841–4 (Edinburgh New Philosophical Journal 36 (1843–4): 362–373).
The letter from Milne to Charles Giles Bridle Daubeny, and Daubeny’s reply, are published in Milne Home 1891, pp. 63–7.


Comments on CD’s paper on South American volcanoes [Trans. of the Geol. Soc. of London, 2d ser., pt 3, 5 (1840): 601–31]. Jets of steam or flame issuing from the side of a hill in Glen Almond.

Letter details

Letter no.
David Milne Home
Charles Robert Darwin
Sent from
Edinburgh, York Place, 10
Source of text
Milne Home 1891, pp. 69–72

Please cite as

Darwin Correspondence Project, “Letter no. 562F,” accessed on 24 September 2021,

Also published in The Correspondence of Charles Darwin, vol. 13 (Supplement)