Broomfield, Sheffield | Feb. 26/57.
My dear Sir,
I have just received your paper on the ice of glaciers,1 and I am sure you will believe that I have read it with the greatest pleasure, and take the deepest interest in the subject. What makes me the more pleased is the fact that, what you have proved so completely, corresponds to what I had concluded would turn out to be the case.2 Since, in the course of a few weeks, I hope to have the pleasure of seeing you in London, and explaining my views more completely, I will not say much now. I shall bring with me a number of my notions, and will show you a structure, that very often occurs in mica schist,3 that agrees most remarkably with the structure you have described in the ice of glaciers, only that the material is mica and quartz. The theory I had formed was that, when the rock was of such a nature as not to give way as a plastic substance, it had been broken up by the weather, and in this manner there is produced a structure thus4 when the lines in the direction E F are those of the stratification foliation—the rock having been metamorphosed before pressure occurred. Then, when compressed, not being able to give way as a plastic substance, it becomes fractured in the lines A B, C D. In some cases, as at A B, there is a layer, composed altogether of mica, whilst the rest contains much quartz. There is thus as it were a band, somewhat as in the ice; whereas at C D is only a simple fracture. The distance of such joints from one another varies from 1/1000 of an inch upwards.
You will remember that in my last note5 I said that there was such a structure in these rocks, and that I fancied that of glacier ice would turn out to be similar, little knowing that you had so clearly proved it to be so.
I am sure you will be much surprised to see some of my thin sections; for they show these things in so clear a manner, and I hope we shall be able to arrange to go over them carefully.
Trusting you are well, and thanking you for your most excellent paper. I remain
Yours very truly | Henry Clifton Sorby.
P.S. I have been working at the structure of cleaved wax, and find that, when so cleaved after pressure, it has exactly the same kind of structure as in fine grained slates which have yielded as plastic substances.
RI MS JT/1/TYP/4/1347–8
LT Typescript Only
your paper on the ice of glaciers: J. Tyndall, ‘Observations on Glaciers’, Roy. Soc. Proc., 8 (1856), pp. 331–8.
what I had concluded would turn out to be the case: that the mechanical theory of slaty cleavage in rocks also applies to glacial ice. See letter 1295, n. 3 and n. 4, and letter 1306, n. 10.
mica schist: a foliated, crystalline, metamorphic rock composed of alternate layers of mica and quartz and easily split (OED).
a structure thus: at this point in the typescript LT noted there was a diagram in the original letter, but the original letter is missing.
my last note: letter missing.
Please cite as “Tyndall1344,” in Ɛpsilon: The John Tyndall Collection accessed on