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XV. On the Structure and Motion of Glaciers. 
By John Tyndall, F.B.S., Professor of Natural Philosophy, Royal Institution; and 
Thomas H. Huxley, F.R.S., Fullerian Professor of Physiology, Royal Institution. 
Received and Read, January 15, 1857. 
§ 1 - 
In a lecture given at the Royal Institution on the 6th of June, by Mr. Tyndall, 1866, 
certain views regarding the origin of slaty cleavage were brought forward, and afterwards 
reported in the ‘ Proceedings’ of the Institution. A short time subsequently, the atten- 
tion of the lecturer was drawn by Mr. Huxley to the observations of Professor J. D. Foebes 
on the veined or laminar structure of glacier ice, and the surmise was expressed, that the 
same explanation might apply to it as to slaty cleavage. On consulting the observations 
referred to, the probability of the surmise seemed apparent, and the result was a mutual 
arrangement to visit some of the Swiss glaciers, for the purpose of observing the struc- 
ture of the ice. This arrangement was carried out, the field of observation comprising 
tlie glaciers of Grindelwald, tire Aar, and the Rhone. After returning to England, the 
one in whose department it more immediately lay, followed up the inquiry, which gra- 
dually expanded, until at length it touched the main divisions of the problem of glacier 
structm’e and motion. An account of the experiments and observations, and our joint 
reflections on them, are embodied in the memoir now submitted to the Royal Society. 
§ 2. On the Viscous Theory of Glaciers. 
A glacier is a mass of ice which, connected at its upper extremity with the snow 
which fills vast mountam basins, thrusts its lower extremity into the warm air which 
lies behnv the snow-line. The glacier moves. It yields in conformity with the sinu- 
osities of its walls, and otherwise accommodates itself to tlie inequalities of the 
valley which it fills. It is not therefore sm-prising that the glacier should have been 
regarded as an ice-river by those who dwelt in its vicinity, or that this notion 
should have found a place in the speculations of writers upon the subject. The state- 
[ ments of M. Rendu in connexion with this point are particularly distinct : — “ There are,” 
I he writes, “ a multitude of facts which seem to necessitate the behef that the substance 
I of glaciers enjoys a kind of ductility which permits it to model itself on the locality 
\ which it occupies, to become thin and narrow, and to elongate itself like a soft paste*.” 
But this obserr^er put forward his speculations with great caution, and often in the 
form of questions which he confessed his inability to answer. “ M. Rendu,” says Pro- 
* Theorie des Glaciers de la Savoie, p. 84. 
