274 PROCEEDINGS OF THE SOCIETY OF 
Bibliotheque Universelle, published during the present year. Colonel Gautier 
also favored us with observations made by himself, particularly those relative 
to the solar eclipse of 1860; while Professor Plantamour has continued to insert 
in our Memoires the series of astronomical observations made at the observa- 
tory of Geneva. 
PHYSICS. 
Is it among cosmic phenomena, or those which fall within the province of 
terrestrial physics, that we should class the aurora borealis? This question is 
no longer an open one since our learned colleague, M. de la Rive, has made it 
the subject of his profound research. On different occasions, and especially in 
an extensive memoir now in course of publication in our collection, he has fur- 
nished the proof that the boreal and austral auroras are a phenomenon produced 
in the highest region of the atmosphere by the encounter of opposite elec- 
tricities. The higher region is habitually charged with positive electricity, 
while the earth is ordinarily negative, and the lower stratum of the air acts as 
an isolating medium. The winds drive the electric vapor towards the two 
poles where the discharges take place. M. de la Rive holds that, according to 
the laws of terrestrial magnetism, an equal conductibility of the maritime or 
wet surfaces being assumed, the manifestations ought to be simultaneous at 
both poles, and he insists that observation has in fact confirmed this simulta- 
neousness. In order still better to demonstrate his theory, our ingenious,col- 
league has had an apparatus constructed representing the terrestrial globe, and 
so arranged as to be capable of realizing all the conditions of magnetism; and 
with this, by the application of electricity, he has produced the different phe- 
nomena of the aurora, its glimmering light, its luminous jets surrounding the 
poles, &c., exciting the admiration even of those who take little interest in the 
theoretical question or the difficulties necessary to be surmounted in procuring 
so decisive an imitation. In this apparatus, constructed at Geneva, in the 
atelier of Professor Thury, and under the direction of M. Eugene Schwerd, a 
sphere of wood represents the terrestrial globe. It is so contrived as to pre- 
sent at the extremities of its horizontal axis two magnetic poles, around which 
the discharges of a Ruhmkorff apparatus produce luminous effects. The sur- 
face of the globe having been moistened, is covered here and there with small 
metallic plates, from which proceed wires terminating in a galvanometer at 
some distance. The deviations of the needle, when the polar discharges take 
place, are analogous, in their minutest phases, to those manifested in the com- 
mon telegraphic apparatus during an aurora borealis. A peculiar arrangement 
allows of the artificial reproduction of the perturbations of the magnetic. needle 
which accompany the auroral phenomenon. The memoir of M. de la Rive 
comprises a discussion on the nature of these perturbations and on the direction 
of the electric currents to which terrestrial magnetism is attributable. It is 
enough to announce these investigations to attract to them the attention of 
physicists. 
M. Wartmann, senior, being, in September last, at Cologny, and therefore at 
a certain elevation above the left bank of the lake, several times observed, half 
an hour after the setting of the sun, singular effects produced by mirage. On 
the other side of the lake, or rather towards the middle of it, an island would 
make its appearance, presenting ranges of trees in a reversed position, while 
beyond this isle the lake retained its usual liquid appearance. 
Professor Wartmann, junior, repeated before the Society the recent experi- 
ments of M. Plateau on bubbles of soap, of varied forms as well as much per- 
sistency, obtained by mixing with soapsuds a small quantity of glycerine, and 
causing the bubbles to attach themselves to iron wires arranged in different 
manners. At a subsequent session M. Wartmann exhibited an apparatus of 
the same kind, still more varied, so as to produce more perfectly than by former 
