ISO Proceedings of the Poyal Society of Edinburgh. 
prism in a retrograde direction from left to right. He detected 
a similar difference in fluids ; and he concluded, that the cause 
of the phenomena resided in the ultimate particles of silex and 
the fluids, and was entirely independent of their mode of aggre- 
gation. 
The principal object of Dr Brewster’s paper, was to describe the 
co-existence of the direct and retrograde structure in the same mi- 
neral, and the entire extinction of the circular polarisation in the 
stratum which intervened between the two opposite structures. 
He discovered traces of circular polarisation in crystals with two 
axes, and detected some new properties of this interesting species 
of polarisation. Several arguments were adduced to shew, in 
opposition to the opinion of M. Biot, that in ,the case of cry- 
stals, or of solid bodies dissolved in fluids, the property of cir- 
cular polarisation cannot belong to the ultimate particles. 
Nov. 29. — At a general meeting of the Society, the follow- 
ing gentlemen w^ere elected Office-Bearers and Counsellors : 
Sir James Hall, Baronet, President. 
Right Honourable I.ord Gray, 1 Vice-Presidents. 
Hon. Lord Glenlee, J ' 
Dr Brewster, General Secretary. 
James Bonar, Esq. Treasurer. 
Thomas Allan, Esq. Curator of the Museum. 
PHYSICAL CLASS. 
Sir G. S. Mackenzie, Bart. President. Professor Alexander Irving, Secretary. 
Counsellors from the Physical Class. 
Mr James Jardine. Gilbert Laing Meason, Esq. 
Honourable Captain Napier. Professor Russel. 
Dr A. Duncan jwTi. Dr Hope. 
LITERARY CLASS. 
Henry Mackenzie, Esq. President. Thomas Thomson, Esq. Secretary. 
Counsellors from the Literary Class. 
Reverend Dr Jamieson. Sir John Hay, Bart. 
Reverend John Thomson. Professor Christison. 
Reverend Dr Brunton. Hon. Baron Clerk Rattray. 
Dec. 6. — At this meeting, a paper was read, containing farther 
particulars respecting the slide at Alpnach, and a notice respect- 
ing its recent demolition. This paper is printed in our present 
number, p. 112. 
