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cember 1841, and published in the Edinburgh New Philosophical Journal for 1842*. 
He was undoubtedly the first to give the phenomenon a theoretic significance. 
While engaged in the Lower Grindelwald glacier, we separated plates of ice perpen- 
dicular to the lamination of the glacier. The appearance presented on looking through 
them, was that sketched in fig. 6. The layers of transparent ice 
seemed imbedded in a general milky mass ; through the former 
the light reached the eyes, while it was intercepted by the latter. 
Some of the transparent portions were sharply defined, and ex- 
hibited elongated oval sections, resembling that of a double con- 
vex lens, and we therefore called this disposition of the veins 
“ the lenticular structure In other cases, however, the sharp- 
ness of outline did not exist, but still the tendency to the lenticu- 
lar form could be discerned, the veins in some cases terminating 
in washy streaks of blue. This structure is probably the same as 
that observed by Professor Foebes on the Glacier des Bossons, 
and described in the following words : — “ The veins and bands are not formed 
in this glacier by a simple alternation of parallel layers, but the icy bands have all the 
appearance of posterior infiltration, occasioned by fissures, thinning off loth icays^T 
In 1842 Professor Foebes undertook the survey and examination of the Mer de Glace, 
and finally arrived at a theory of glacier lamination, which both in his ‘Travels’ and in a 
series of letters, extending over a period of several years, he has expounded and illus- 
trated with great skill. The theory is summed up in the following words: — “The 
whole phenomena in the case of any of the semifiuids I have mentioned (treacle, tar, 
&c.), are such as, combined with the evidence which I have given, that the motion of a 
glacier is actually such as I have described that of a viscid fluid to be, can leave, I 
think, no reasonable doubt, that the crevices formed hy the forced separation of a half 
rigid mass, whose parts are compelled to move with different velocities, becoming infltrated 
with water, and frozen during winter, produce the lands which ive have descHled J.” 
This theory has been opposed by Mr. Hopkins, whose excellent papers, published in 
the 26th volume of the Philosophical Magazine, are replete -with insti-uction as to the 
mechanical conditions of glaciers. On the other hand, the theory of Professor Foebes 
is defended in the same journal by Dr. Whewell^. We will leave the points discussed 
* This communication gave rise to a discussion as to priority between Professor Eoebes and M. Aoassiz, 
for the details of which we must refer to the original papers on the subject. 
t Travels, p. 181. 
X Ibid. p. 377. M. Agassiz also seems disposed to regard the blue bands as the result of the freezing 
up of fissures, which, however, are supposed to be formed in a maimer different fi’om that assumed by Pro- 
fessor Eokbes. But M. Agassiz calls the attention of future observers to some of the related phenomena ; 
and gives it as his opinion, “ qu’il n’est aucune phenomene dont I’explication offre plus des difficultes.” 
See his important work, ‘ Systeme G-lacike,’ which, imtil quite recently, we had not the oppoi-tunity of 
examining. 
§ Philosophical Magazine, S. 3. vol. xxvi. pp. 171, 217. 
