9th Feb. 1857
My dear Clausius
At length I have time to write you a line to thank you for your last friendly letter1 and for the book on glaciers2 which you sent to me. I found both very useful. The book is highly interesting and written by a man who has evidently taken pains to make himself acquainted with the phen[omena]. Since my return to England I have been at work upon the question. It opened out to a degree beyond my expectations, and finally embraced the viscous theory of Forbes,3 the veined structure of the ice, and the ‘Dirt Bands’ upon the surface of the glacier. On all three points I have been obliged to differ from Forbes. A few evenings ago I read a paper4 before the Royal Society [on the] subject, and I find that a short account of the communication has got into the weekly newspapers. I send you an extract from one of these which will give you some idea of the nature of the enquiry. As far as I can see at present the theory which I have ventured to propose is in accordance with all the phenomena <1 word missing> seems to meet all the cases adduced by [M.] Mousson at page 17 of his book5 in proof of the viscosity of the ice. I am still at work upon the subject and hope before I give it up to [clear] away much of the obscurity which has hitherto surrounded it.
I think the structure of the glacier [ice] as revealed by the infiltration experiments of Agassiz is more in accordance with [the] theory which I have given than with the [viscous] theory. In connexion with this point I took a piece of common ice dug a cavity in it, and filled the cavity with a strong infusion of cochineal.6 The ice was perfectly impervious to the liquid. The same ice was placed beneath a press and squeesed gently on takeing7 it out and making the same experiment the coloured liquid freely diffused itself through the capillary fissures and presented an appearance exactly resembling that figured by Agassiz in the Atlas which accompanies his important work.8
In communicating the paper to the Royal Society I took the liberty of reading before the Fellows that portion of your letter9 to <1 word missing> which referred to your own observations. Indeed Forbes himself expressly and repeatedly states that the veined structure is at right angles to the [lines] of maximum pressure. It is surprising how fruitful Forbes was in observation before he formed his theory, but having pledged himself to it he made facts bend to harmonize with it and I believe fell into great error.
With best wishes my dear Clausius | Ever sincerely yours | John Tyndall
I may go to the Mer de Glace10 this year.
Herrn Professor Clausius | Zurich11 | Switzerland12
RI MS JT/1/T/172
your last friendly letter: see letter 1305.
book on glaciers: A. Mousson, Die Gletscher der Jetztzeit (Zürich: Druck und Verlag von Fr. Schulthess, 1854).
viscous theory of Forbes: see letter 1306, n. 8.
I read a paper: on 15 January 1857, Tyndall lectured at the RS on ‘Observations on Glaciers’, published as J. Tyndall, ‘Observations on Glaciers’, Roy. Soc. Proc., 8 (1856), pp. 331–8; and J. Tyndall and T. H. Huxley, ‘On the Structure and Motion of Glaciers’, Phil. Trans., 147 (1857), pp. 327–46. He lectured on the same topic at the RI on 23 January 1857.
his book: see n. 2.
cochineal: a dye-stuff consisting of the dried bodies of the insect Coccus cacti (OED).
takeing: misspelled by Tyndall.
the Atlas which accompanies his important work: L. Agassiz, A. Guyot, and E. Desor, Système glaciaire ou recherches sur les glaciers (Paris: Victor Masson, 1847).
your letter: see n. 1.
Mer de Glace: see letter 1306 n. 12.
Zurich: a city in north central Switzerland.
Herrn Professor Clausius | Zurich | Switzerland: written as the address on the envelope.
Please cite as “Tyndall1333,” in Ɛpsilon: The John Tyndall Collection accessed on