462 Analyses of Books. ~ (June, 
ArtTIcLE IX. 
Philosophical Transactions of ‘the Royal Society of London for 
the Year 1816, 
This volume contains the following papers :— 
1. On the Fire-Damp of Coal-Mines, and on Methods of light- 
ing the Mines so as to prevent Explosion. By Sir H. Davy, LL.D. 
F.R.S. V.P.R.I. 
The author confirmed the experiments of preceding chemists, 
who had considered fire-damp as carbureted hydrogen. He found 
it the least combustible of the gases. 
2. An Account of an Invention for giving Light in explosive 
Mixtures of Fire-Damp in Coal-Mines by consuming the Fire- 
Damp. By Sir H. Davy. 
This consists of the well-known lamp covered with a wire sieve, 
avery ingenious invention, which has contributed so much to ex- 
tend our ideas respecting the combustion of gases, and the explo- 
sion of gaseous mixtures. 
3. On the Developement of Exponential Functions, together with 
several new Theorems relating to Pinite Differences. By John Fre- 
derick W. Herschel, Esq. F.R.S. 
As it would be impossible to give an intelligible abridgment of 
this important paper, f must refer those who are desirous of under- 
standing it to the volume of the Transactions itself. 
4. On new Properties of Heat, as exhibited in its Propagation 
along Plates of Glass. By David Brewster, LL.D. F.R.S. Lond. 
and Edin. 
When a plate of glass is laid with its edge upon a bar of red-hot 
iron placed horizontally, and a ray of light polarized in a plane in- 
clined 45° to the horizon is transmitted through it, the light will 
be polarized in various degrees in different parts of the glass. The 
glass in fact acquires a crystalline structure, which changes its cha- 
racter with the temperature, and which vanishes when the heat is 
uniformly diffused over the plate. ‘The edge of the glass lying on 
the hot iron and the opposite. edge acquire the same structure as 
that class of doubly refracting erystals (quartz, selenite, &c.) in 
which the extraordinary ray is attracted to the axis, while the centre 
of the plate has the same structure as the other class of doubly re- 
fracting crystals (calcareous spar, beryl, &c.) in which the extraor- 
dinary ray is repelled from the axis. Between the centre and each 
of the edges there is an intermediate space, which has a structure 
similar to that of common salt, fluor spar, &c. bodies destitute of 
double refraction. These phenomena, and many others depending 
on them, which are described in this curious paper, are of the most 
fugitive nature. But Dr. Brewster has discovered a method of ren- 
dering them permanent, and consequently of subjecting the phe- 
