326 
REPORTS OF MEETINGS. 
examination of the volcanic region of California, and the results 
obtained by him seem so far to support this theory. Other 
researches also lend weight to it. 
In November, two papers were contributed : the one by Mr. 
H. S. H. Shaw on “ The Methods of Wind Measurement,” 
which appears in full in the Proceedings of the Society ; the 
other by Professor S. P. Thompson, D.Sc., B.A., F.R.A.S., on 
“Faure’s Battery and Swan’s Lamps.” Professor Thompson 
commenced by alluding to the attempts which had recently been 
made by various experimentors to produce small electric lights 
of less intensity than that of the electric arc, referring more 
especially to Swan’s lamps, specimens of which were shown. 
The first attempts in this direction were made with platinum 
wire, but as in this case the resistance increases with the temper- 
ature, the wire soon becomes fused. Carbon filaments were next 
resorted to, both by Swan and Edison, and for the present they 
furnish the best means of producing incandescent light, as in 
their case the resistance instead of being increased is diminished 
as the temperature rises. However, the durability of these 
lamps is merely a question of time, seeing it is impossible to 
produce a perfect vacuum in the glass envelopes in which they 
are enclosed, so that eventually oxidation sets in. The filaments 
used by Swan are made from cardboard, while Edison employs a 
particular kind of bamboo. These, after being in use for some 
time, become almost metallic in appearance and hardness. The 
resistance of each is equal to about five miles of ordinary 
telegraph wire, and a current of a half to one weber per second 
is sufficient. Professor Thompson then passed to the consider- 
ation of accumulation of electricity by means of secondary 
batteries. In 1804 Plante made the first of these, the principle 
of which depends on the fact that if an electric current is passed 
through a liquid capable of being decomposed by it, and in 
which two metallic plates are immersed, we find after the current 
