134 Proceedings of Philosophical Societies. [Fex. 
The deaths since last anniversary, including two foreign members, 
have been 23; the elections about 30. The number of the Society 
at present is 594, to which must be added 45 foreign members, 
making a total of 639 members. 
On Thursday, Dec. 7, a paper by Dr. Reid Clanny was read, 
giving a further account of his lamp for the security of colliers 
against the fire-damp. He has now constructed it of such a size 
that it may be put into the great coat pocket. It may be made of 
copper for 1/, 14s., and of block tin for 17s. A piece of mecha- 
nism at a low price is attached to the bellows, capable of supplying 
the lamp with air for an hour. Dr. Clanny relates a set of trials 
made in an apartment filled with carbureted hydrogen gas to the 
exploding point, and in a coal-mine the air of which was in the 
same state. In both cases the air within the lamp exploded, and 
the lamp was extinguished, but the external air was not in the 
least affected. 
He showed by a set of experiments that by attending to the 
proper mode of supplying the lamp with air, the candle will con- 
tinue to burn even when the carbureted hydrogen within the lamp 
explodes. Dr. Clanny states in this paper that the expense for steel 
mills in many collieries is much greater than would be requisite to 
light the mine by’ means of his lamp. In one mine he says it 
amounts to 30/. a week. Dr. Clanny likewise gave.an account of 
the numerous explosions that have taken place in the neighbourhood 
of Newcastle, and of the opposition which he has encountered in 
attempting to introduce his lamp into the coal-mines in the district 
in which he resides. | 
On Thursday, Dec. 15, a paper by Mr. Herschel on the fune- 
tions of exponential quantities was announced; but, from the 
nature of the subject, could not be read. 
At the same meeting part of a paper by Dr. Brewster on the 
properties of heat as modifying the nature of glass was read. He 
showed that, by heat, plates of glass acquire the properties of all the 
different kinds of crystallized bodies. One portion depolarizes the 
ray of light in the same manner as those crystals which attract the 
extraordinary ray towards the axis ; another part in the same manner 
as those crystals which repel the extraordinary ray from the axis. 
On Thursday, Dec. 21, Dr. Brewster’s paper was continued. A 
great number of curious facts were detailed ; but from the nature 
of the paper, and the constant reference to figures, it is scarcely 
possible to form an accurate idea of it merely from hearing it read. 
He found that by heating glass red hot, and cooling it upon cold 
iron, it acquired a permanently crystallized texture. Of all the 
minerals tried, obsidian was the only one whose texture was altered 
by a moderate heat. This points out a further analogy between 
obsidian and glass, and renders the opinion of those who consider 
this mineral as of volcanic origin still more probable. 
On Thursday, Jan. 11, Dr. Brewster’s paper was concluded. 
He pointed out the analogy between magnetism and heated glass, 
