in the Ice of Glaciers. 91 
rock undergoing metamorphic change, as this pervades the 
mass of the crystallizing glacier. In the former case, we 
have cleavage planes perfectly parallel, almost indefinitely 
extending with unaltered features over vast surfaces of the 
most rugged country, changing neither direction, dip, nor 
interval, with hill or valley, cliff or scar, and passing alike 
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 swbseguent to deposition. The supposi- 
tion of Professor Sedgwick, who has minutely described and 
considered this geological puzzle, that “crystalline or polar 
forces acted on the whole mass simultaneously in given direc- 
tions, and with adequate power,’* can hardly be considered 
as a solution of the difficulty, until it is shewn that the forces 
in question have so acted, and can so act. The experiment 
is one which the boldest philosopher would be puzzled to re- 
peat 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 ? 
Experiments on the Production and Transmission of Sound in 
Water, made in the Lake of Geneva. By M. Daniex Cor- 
tavon. In a Letter to M. Araco.t 
Sir,—I beg of you to have the goodness to communicate 
to the Academy of Sciences the results of some experiments 
which I have made in the Lake of Geneva. 
When I made my first experiments on the velocity with 
which sounds are propagated under water, at the close of the 
year 1826, you engaged me to try whether a sound reverbe- 
rated by the bottom of a lake or of the sea could be heard, 
in order to measure the depth of the water by the interval 
that elapsed between the primitive and reverberated sound. 
* Geological Transactions, Second Series, ili, 477. 
+ Bibliothéque Universelle de Geneve, No. 68, p. 364, aes Hily 
