De la Rive on the Aurora Borealis. 361 
constantly condensed in the forming mists in the polar regions 
that the positive electricity should find its passage into the earth, 
and also therefore its discharge. This‘discharge when possessing 
acertain degree of intensity should be luminous, especially: if, as 
is almost always the case near the poles and sometimes in the 
upper regions of the atmosphere, it encounters in its course icy 
particles of extreme minuteness, which form the haze as well as 
the more elevated clouds. 
The formation of lunar halos which generally precede the 
appearance of an aurora, and the fall of rain or snow which also 
is often a prelude to it, are a proof of the presence in the atmos- 
phere of these fine needles of ice, and of the part they play in 
the phenomenon before us. 
balloon ascension which they recently made, suddenly found 
themselves,—although the sky was quite serene and the atmos- 
phere without a cloud—in the midst of a veil or mist, which 
Was perfectly transparent, consisting of a multitude of small icy 
needles so fine that they were hardly visible. Such are the nee- 
dles which become Inminous by the passage of the electricity, 
Which determine the formation of halos as has been rigorously 
demonstrated, and produce by condensation the aqueous vapors in 
their passage through the air towards the earth, the fall of snow 
or rain, or sometimes under peculiar circumstances, hail. 
ow if we inquire what should pass in the portion of the lu- 
minous mist nearest to the earth’s surface, we shall conclude 
that the vicinity of the magnetic pole must exert a decided influ- 
ence on this electrised matter,—for it is in fact a true mobile 
conductor traversed by an electric current. f 
0D order to obtain a correct idea of this action, I have, endeav- 
ored to imitate artificially the process of nature, and with this 
View, I contrived the following experiment. a 
nto a glass globe, 30 to 40 centimeters in diameter, I intro- 
duced through one of its two opposite tubulures, a piece of soft 
Iron wire, about 2 centimeters in diameter, making it to termi- 
hate at the inner end very near the centre of the globe, while 
the other end was exposed out of the globe. The wire was cov- 
ered through its whole length, excepting its extremities, by a very 
thick insulating bed formed first of shell-lac, then with a glass 
tube covered itself with shell-lac, then with a second tube of 
glass, and finally with a bed of carefully applied wax. The 
Skooyp Seriss, Vol. XVIII, No. 54.—Noyv., 1854. 46 
