London, 4th. Dec. 1856
My dear Tom,
I promised to write to you today and now set about fulfilling that promise though I fear my doing so will be merely lost time as far as the subject of the promise is concerned. A gentleman1 called upon me today to know if I could recommend any one to a school of very high standing, and which contained some of the children of the nobility, merely for four hours a week, to prepare a class of 12 pupils for the public examinations for appointments in the Royal Artillery and Engineers.2 The salary would be £100 a year, only 9 months of the year being thus occupied, and it was said that more would be given sooner than miss a good man. I said I knew nobody but yourself, stated your peculiar situation but said at the same time that I would write to you, which the gentleman earnestly requested me to do. I have no doubt that were you in London you would soon have three or four things of this kind which would enable you to buy bread and cheese; in writing thus I simply fulfill my promise as you must judge whether the state of Anna’s3 health is such as to permit you to accept any thing of the kind. The school is kept by a Mr Hopkirk,4 Eltham Kent,5—not far from Blackheath,6 and I am assured it is an establishment of a superior order. Indeed the fees of the students, 100 guineas each yearly, insures this. Write to me when you receive this as I have promised to give an answer soon. Write so that I may forward your letter as the reply.
I have been working very hard at glaciers lately. I had no idea when I commenced the subject that it would open out so well. Forbes of Edinburgh7 will assuredly think that I have some design on him, although I have not, and have been led by the purest accident, if such there be, to tread in his footsteps. My object first was to examine the structure of glacial ice of which Forbes has given a most ingenious theory,8 and which has been the subject of most lively discussion between several men of great eminence. —Well I think I have so smashed up this theory; so utterly annihilated it, that its author will hardly acknowledge it. Of course this may be all self delusion—others must judge of the force of my arguments, but unless I labour under a hallucination altogether new, the theory is killed without the hope of recovery. It is therefore more than an Irish ‘killing’9 from which people recover sometimes. Well I have not been altogether destructive for I think I have made compensation for what I have pulled down by shewing that the structure of the ice of glaciers and the cleavage of slate rocks are to be attributed to one and the same cause. How we are led forward in this life. How little did I think as I expounded my little hypothesis of slaty cleavage10 to you on the summit of Broughton Hill11 two years ago that it would carry such fruit. Another subject which has caused much discussion are certain discoloured bands observed first by Forbes on the surface of the Mer de Glace.12 These I think I have also succeeded in explaining, and can produce them experimentally. The next point regarding which I did not intend to say anything, or to learn anything was the motion of the glaciers downwards. The so called viscous theory has been propounded by Forbes to account for the phenomena, and this theory commands the assent of almost all English geologists and others at the present day. Dr. Kame13 in his Arctic Voyage14 has even named certain places after Forbes in testimony of his being the only one to unravel the mystery of glacial motion: on this point I have also something to say. The glacier does certainly exhibit many phenomena which are exactly such as would be produced by a plastic mass, but I think I have succeeded in shewing15 that all the phenomena which it exhibits are perfectly reconcilable with those properties of ice which experiment reveals to us, and that it is not viscosity, but a property known to some for years, but wholly overlooked by glacial theorists that these phenomena are due. Give my love to Anna, and respect to Mr Martin—as ever—John
RI MS JT/1/T/634
RI MS JT/1/HTYP/484–4a
A gentleman: not identified.
Royal Artillery and Engineers: from 1856–7, Tyndall wrote and graded examinations in scientific topics for commissioned officers of the Royal Artillery and Royal Engineers at the Royal Military Academy at Woolwich. It appears he was recommending Hirst for a teaching position to prepare students for such examinations. Tyndall stopped being an examiner when the War Office decreased the pay in April 1857 (see letters 1375 and 1376). In January 1858, he again became an examiner for commissioned officers of the Royal Artillery and Royal Engineers at the Royal Military Academies at both Woolwich and Sandhurst for the newly-established Council of Military Education. For more on Tyndall’s and others’ role as examiners for military education, see J. Elwick, ‘Economies of Scales: Evolutionary Naturalists and the Victorian Examination System’, in G. Dawson and B. Lightman, eds., Victorian Scientific Naturalism: Community, Identity, Continuity (Chicago: University of Chicago Press, 2014), pp. 131–56.
Anna’s: Anna Hirst.
Hopkirk: Thomas Hopkirk (1819–81), principal of the preparatory Military Academy in Eltham, Kent. See ‘Obituary’, Monthly notices of the Royal Astronomical Society, 42 (1882), p. 145.
Eltham Kent: then a town southeast of London bordering the county of Kent.
Blackheath: an area of southeast London to the west of Eltham.
Forbes of Edinburgh: James Forbes.
a most ingenious theory: Forbes’s theory of viscous glacier motion that Tyndall and others disagreed with. Forbes published his theory in Travels through the Alps of Savoy and Other Parts of the Pennine Chain with Observations on the Phenomena of Glaciers (Edinburgh: Adam and Charles Black; London: Longman, Brown, Green, and Longmans, 1843); and in three papers for the RS: J. D. Forbes, ‘Illustrations of the Viscous Theory of Glacier Motion Part I. Containing Experiments on the Flow of Plastic Bodies, and Observations on the Phenomena of Lava’, Phil. Trans., 136 (1846), pp. 143–55; ‘Illustrations of the Viscous Theory of Glacier Motion Part II. An Attempt to Establish by Observation the Plasticity of Glacier Ice’, Phil. Trans., 136 (1846), pp. 157–75; and ‘Illustrations of the Viscous Theory of Glacier Motion Part III’, Phil. Trans., 136 (1846), pp. 177–210.
an Irish ‘killing’: not identified.
my little hypothesis of slaty cleavage… would carry such fruit: Tyndall explained glacier motion by the fracture of ice (similar to his theory of slaty cleavage, which he lectured on at the RI on 6 June 1856, ‘Comparative view of the Cleavage of Crystals and Slate Rocks’) and regelation (the refreezing of water between two pieces of ice). In Glaciers of the Alps, Tyndall described regelation as when ‘Two pieces of ice at 32º Fahr., with moist surfaces, when placed in contact freeze together to a rigid mass’. He continued, ‘When the attachments of pressed ice are broken, the continuity of the mass is restored by the regelation
of the new contiguous surfaces. Regelation also enables two tributary glaciers to weld themselves to form a continuous trunk; thus also the crevasses are mended, and the dislocations of the glacier consequent on descending cascades are repaired. This healing of ruptures extends to the smallest particles of the mass, and it enables us to account for the continued compactness of the ice during the descent of the glacier’ (p. 423).
summit of Broughton Hill: a hill near Queenwood College, Hampshire.
Mer de Glace: a large glacier on the north side of Mont Blanc, France.
Dr. Kame: Elisha Kent Kane (1820–57), an American explorer and naval medical officer who was present on two Arctic expeditions in search of Sir John Franklin (ANB).
Arctic Voyage: E. Kane, Arctic Explorations: The Second Grinnell Expedition in search of Sir John Franklin, 1853, ’54, ’55, 2 vols (Philadelphia: Childs & Peterson, 1856).
shewing: alternative spelling of showing.
Please cite as “Tyndall1306,” in Ɛpsilon: The John Tyndall Collection accessed on