461 
formation of the impressed pebbles, it appears to me that it 
is not likely to be the only case to be met with in geological 
inquiries. I have indeed observed a number of facts con- 
nected with the structure of limestone rocks which cannot be 
explained in a satisfactory manner on any other principle. 
Striking examples are met with in the case of rocks affected 
with slaty cleavage. There certainly are some peculiarities 
in cleaved rocks which strongly point to the more or less 
chemical origin of that structure ; but these can now be 
completely reconciled with the mechanical theory which has 
so much to recommend it to our acceptance. Probably 
various other examples will be found, to which similar 
principles may be applied; but, at the same time, the 
mechanical equivalent of chemical changes is usually so 
great, that we can only expect them to apply to cases where 
the affinities are extremely feeble. 
Thanks were voted to the readers of the various Papers. 
The Chairman said it was a somewhat singular fact in 
connection with this meeting, that, although it was a 
Geological Society, not a single Paper bearing upon geology 
had been read, if they excepted the Paper forwarded by Mr. 
Sorby. He hoped that at their next meeting the members 
would have their attention directed to one or more geological 
subjects. He knew much more of antiquity than of geology ; 
but, at the same time, he should be glad to hear geological 
Papers read the next time the Society assembled. 
W. Chad wick, Esq., of Arksey, proposed a vote of thanks 
to Lord Houghton for presiding. 
The vote was unanimously agreed to. 
His Lordship, in acknowledging it, observed that it was to 
such Societies as this (over which he had had the pleasure 
that day to preside) they were indebted for much valuable 
