Cambridge | Dec. 16 57
My dear Sir,
I returned your MSS1 by post about two days ago. You will find various comments in pencil. Some of them might perhaps have been modified had I been able to read successive portions of your paper in the order in which you intend to arrange them. I had not time to read them as they came and the discontinuity in the paging made it impossible for me to place them afterwards in their proper order.
I quite believe that ice has very little extensibility but I think you have carried your notions respecting it too far. I recommended some revision of that part of your paper. Forbes’s notion of the almost indefinite extensibility of ice, was always to me one of the great difficulties of his theory.2 Even without considering it all but inextensible, your views approximate much nearer to those which I entertained when I investigated the motion and internal action of glaciers, than they do to Forbes’s notion. Only after I had broken the ice by tension, I did not know well how to join it again. According to your notions a glacier must break in consequence of its motion. According to Forbes the breaking was an accidental rather than a necessary consequence of the motion.
I should like to have seen your paper on the Physical properties of ice,3 but as soon as I feel well enough (I have lately been laid up with bronchial affection) I am off to Manchester,4 and should have no time at present to read your paper.
I am satisfied that no partial observations will now be of any essential service as to glacial theories. A number of points on the surface of a glacier ought to be deter[mine]d by accurate ad- measurements, and these points watched and re-measured from time to time for a good many years. It is only in this manner we can really know how a glacier conducts itself during a length of time.
Yours truly | W. Hopkins.
RI MS JT/1/TYP/2/612
LT Typescript Only
your MSS: based on the discussion of ‘breaking’, this must be a draft of Tyndall’s paper received and read at the RS on 20 May 1858 and published as ‘On the Physical Phenomena of Glaciers–Part I. Observations on the Mer de Glace’, Phil. Trans., 148 (1859), pp. 261–78. An abstract, received on 10 June 1858, was published as ‘Observations on the Mer de Glace–Part I’, Roy. Soc. Proc., 9 (1857–9), pp. 245–7.
his theory: see letter 1306, n. 8.
your paper on the Physical properties of ice: J. Tyndall, ‘On Some Physical Properties of Ice’, Phil. Trans., 148 (1858), pp. 211–29, which Tyndall read to the RS on 17 December 1857, the day after Hopkins wrote this letter.
Manchester: see letter 1311, n. 8.
Please cite as “Tyndall1468,” in Ɛpsilon: The John Tyndall Collection accessed on