1841.] ANALOGOUS STRUCTURE IN SLATY ROCKS. 9 



through strata whose planes of stratification, horizontal, ele- 

 vated, undulating, or contorted, offer no obstacle or modifica- 

 tion to the omnipotent energy which has rearranged every 

 particle in the mass subsequent to deposition. The supposition 

 of Professor Sedgwick, who has minutely described and con- 

 sidered this geological puzzle, that " crystalline or polar forces 

 acted on the whole mass simultaneously in given directions, 

 and with adequate power,"* can hardly be considered as a 

 solution of the difficulty, until it is shown that the forces in 

 question have so acted, and can so act. The experiment is 

 one which the boldest philosopher would be puzzled to repeat 

 in his laboratory ; it probably requires acres for its scope, and 

 years for its accomplishment. May it not be that Nature is 

 performing in her icy domain a repetition of the same mys- 

 terious process, and that in another view from the one which 

 has recently been taken, the Theory of Glaciers may lead to 

 the true solution of geological problems ? 



II. FIRST LETTER on GLACIERS, addressed to 

 PROFESSOR 



Account of the First Experiments, undertaken in June 1842, to determine the Laws 

 of Motion of the Mer de Glace of Chamouni. 



COURMAYEUR, PlEDMONT, 4th July 1842. 



My Dear Sir Knowing that you will be glad to hear of 

 my safe arrival amongst the Alps, and of my farther proceed- 

 ings, I hasten to give you an account, in a few words, of what 

 I have as yet done. Finding the season more than usually 

 advanced, I hastened to reach Chamouni, in order to ascertain 

 whether the Mer de Glace was as yet accessible in all its ex- 

 tent ; and I arrived at the Mon tan vert on the 24th June, and 



* Geological Transactions, Second Series, iii. 477. 

 f Edinburgh New Philosophical Journal, October 1842. 



