95 
of Edinburgh, Sessio7i 1862-63. 
University of G-lasgow conferred upon Dr G-reville the degree of 
Doctor of Laws, and many of the Natural History Societies in 
Europe and America have received him among their corresponding 
or honorary members. 
Though somewhat foreign to the present occasion, the Society 
will, I trust, excuse me for adding, that Dr G-reville has taken an 
active part in those interesting questions of philanthropy, on the 
solution of which the happiness and security of society depend, 
He has felt, as I am sure most of us here feel, that there is some- 
thing greater than science, and something higher and more endur- 
ing than fame ; and it is no slight ground of congratulation, that 
some of those who have been commissioned by their Maker to 
study His works, and to sound the depths of His wisdom and His 
power, have shunned the fatal course which others have pursued, 
of sapping the foundations of that faith and hope which science is 
so able to sustain. 
Dr Greville, In the name of the Council I now beg to present 
to you the Neill Medal, and to congratulate you on this honour, 
which you have so well merited. 
The following Communications were read : — 
1 . Letter from Sir D. Brewster relative to the specimens 
of Topaz with Pressure Cavities presented by him to 
the Museum of the Society. 
Dear Professor Balfour,— -In vol. xvi. of the “ Transactions of the 
Eoyal Society of Edinburgh,” I have described and given drawings 
of the pressure cavities which I discovered in topaz ; and in vol. 
xxiii., just published, I have pointed out the geological relations of 
these cavities. 
As the specimens of topaz containing them are so rare that I 
have found only^ve out of many hundreds which I have examined ; — 
as the existence of such cavities with a polarising structure around 
them, proving that the topaz was in a soft or plastic state, will 
hardly be admitted by those who believe that the topaz was formed 
by aqueous depositTon ; — and as it is quite possible that other speci- 
mens containing such very minute cavities may never be found. 
