The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1868-07-01

nearly at the point where the river Lena
crosses the Arctic circle, the other not so far
to the north--only few degrees north, in fact,
of Lake Superior. In the SOUTH in like man
ner, there are also two poles, one on the Ant
arctic circle about $50 degrees east longitude
in Adele Island the other not yet precisely de-
termined but supposed to lie on about the
24Oth degree of longitude, and south of the
Antarctic circle. Singularly enough there Is a
line of lower intensity running right round
the earth along the valleys of the two great
oceans, "passing through Behring's Straits
and bsecting the Pacific on one side of the
globe, and passing out of the Arctic Sea by
Spitzbergep and down the Atlantic on the
other"
Colonel Sabine discovered that the intensity
of the magnetic action varies during the course
of the year. 1t is greatest in December and
January in both hemispheres. 1t the intensity
had been greatest in winter one would have
been disposed to have assigned seasonal varia-
tion Of temperature as the cause OF
the change. But as the epoch is the
same for both hemispheres we must seek
another cause. Is there any astronomical
element which seems to correspond with the
law discovered by Sabine There is one very
important element. The position of the peri
helion of the earth's orbit is such that the
earth is nearest to the sun on about the 3lst
of December or the lst of January. There
seems nothing rashly speculative, then, in
concluding that the sun exercises magnetic
influence on the earth, varying according to
the distance of the earth from the sun. Nay,
Sabine results seem TO point very distinctly to
the law of variation. For, although the number
of observations is not as yet very great, and the
extreme delicacy of the variation renders the
determination of its amount very difficult,
enough has been done to show that in all pro-
liability the suns influence varies according
to the same law as gravity-that is, inversely
as the square of the distance.
That the sun, the source OF light and heat,
and the great gravitating centre of the solar
system, should exercise a magnetic influence
upon the earth. and that this influence should
vary according to the same law as gravity, or
as the distribution of light aud heat, will not
appear perhaps very surprising. But the
discovery by Sabine that the moon exercises
distinctly traceable effect upon the magnetic
needle seems to us very remarkable one. We
receive very little light from the moon, muchless
lin comparison with the suns light) than
most persons would suppose, and we get abso-
lutely no perceptible heat from her. There
fore, it would seem rather TO the influence of
mass and proximity that the magnetic dis
turbances caused by the moon must be
ascribed. But if the moon exercises an infu-
ence in this way, why should not the planets
We shall see that there is evidence of some
such influence being eXerted by these bodies.
More mysterious, if possible, than any of
the facts we have discussed is the phenomenon
of magnetic storms. The needle has been
exhibiting fol several weeks the most perfect
uniformity of oscillation. Day after day the
careful microscopic observation of the needles
progress, has revealed a steady swaying to
and fro, such as may be seen in the masls of
stately ship at anchor on the scarce-heaving
breast of ocean. Suddenly change
is noted irregular Jerking move. move
auU1a A mao
netic storm is in progress. But where is the
centre of disturbance, and what are the limits
of the storm The answer is remarkable. If
the jerking movements observed in places
spread over very large regions of the earth
and in some well-authenticated cases over the
whole earth-be compared with the local time,
it is found that (allowanGe being made for
difference of longitude) they occur precisely al
the same instant. The magnetic vibrations thrill
in one moment through the whole frame of our
earth
But a very singular circumstance is observed
to characterize these magnetic storms. They
are nearly always observed to be accompanied
by the exhibition of the aurora in high lati-
tudes, northern and southern. Probably they
never happen without such display; but num-
bers of auroras escape our notice. The con-
verse proposition, however, has been established
as universal one. No great display of the
aurora ever occurs without strongly marked
magnetic storm.
Magnetic storms sometimes last for several
hours or even days.
Remembering the influence which the sun
has been found to exercise upon the magnetic
needle, the question will naturally arise, has
the sun any thing to do with magnetic storms
We have clear evidence that he has.
On the lst of September, 1859, Messrs. Car
ringtOn and Hodgson were observing the sun,
one at Oxford and the other in London. Their
was directed tocertain large spotswhich, scrutiny
at that time, marked the suns face. Suddenly
bright light was seen by each observer to
break out on the suns surface and to travel,
slowly in appearance, but in reality at the
rate of about 1000 miles in minute, across
part of the solar disc. Now it was found
afterwards that the selfregistering magnetic
instruments at Kew had made at that very
instant strongly marked jerk. 1t was
learned that at that moment a magnetic storm
prevailed at the West Indies, in South Anne
rica, and in Australia. The signalmen in the
telegraph stations at Washington and Phila-
dephia received strong electric shocks; the pen
of Bain's telegraph was followed by a flame of
fire; and in Norway the telegraphic machinery
was set on fire. At night great auroras were
seen in both hemispheres. 1t is impossible
not to connect these startling magnetic indica-
tions with the remarkable appearance observed
upon the SUMS disc.
But there is other evidence. Magnetic
storms prevail more commonly in some years
than in others. In those years in which they
prevail most frequently, it is found that the
ordinary oscillations of the magnetic needle
are more extensive than usual. Now, when
these peculiarities ha / been noticed for many
years, it was found that there was an alternate
and systematic increase and diminution in
= the intensity of uapuatio action nd tbat ba