316 B. V. Marsh on the Aurora, 
rounded one of the terminals, whilst in others cloud-like masses 
of light were successively developed from one of the terminals, 
whence they ae 89 towards the other terminal and were thus 
arranged in a line between them—their development being 
tently promoted by the presence of a powerful magne 
With a water-battery of 8500 cells, these are represented as 
faint and cloudy in their appearance; and with Grove’s nitric- 
acid battery of 400 cells although the action was so intense that 
they became extremely bright they still retained their cloud-like 
form and motion. In describing experiments made with this 
battery, the exhausted receiver being placed between the poles 
of the large electro-magnet of the Royal Institution, Mr. G. says, 
“On now exciting the magnet with a battery of ten cells, effil- 
gent strata were drawn out from the positive pole and passing 
along the upper or under surface of the receiver, according to the 
direction of the current. On making the circuit of the magnet 
and breaking it immediately, the luminous strata rushed from 
‘the positive, and then retreated, cloud following cloud with a delib- « 
erate motion, and appearing as if swallowed up by the positive 
electrode.’ 
In another experiment with the nitric-acid battery Mr. G. 
says, “four or five cloud-like and remarkably clear strata came 
out from the positive.” These were large lens-shaped masses 
arranged at regular intervals between the terminal foul sg won 
flattened surfaces facing these terminals, as shown in 
pr V, which is copied from Gassiot’s figure Proskedings of 
og Eieeieets vol. x, No. 39, p. 401). 
if in this case we imagine — glass globe placed 
oe its centre directly between the wires, it is evident that 
each of these cloud-like discs as it ‘came: at from the positive” 
towards the negative terminal, must, while passing the glass 
gore be pierced by it, and be converted into a ring, (see fig. ,) 
as the auroral cloud was supposed to take the annular as 
in oping over the spherical surface of the non-conducting at 
mosphere. 
This part of the auroral display may therefore prove to be some 
modification of the ‘ stratified discharge” —the magnetic poles of the 
earth being the terminals, and the auroral arches being analogous to 
the cloud-like masses 0 BA hight or glow ramet by Gassiot, the mag- 
netism of the earth aiding in their development. 
_* The follow me another of reat Skane 
terminal, — = aaa light “a 
some sudden aC on, flashes 0 ight strati 7 ena 
be ened the mene) but by carefully atoning. ee contact breaker the dis- 
a hil gw on the eee lal 
without, to the eye feadog any appearance of an intermittent 
