The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1869-10-27
The Secret of the Aurora.
From tie London Spectator.


Men of science have long felt that a strange
secret lay hidden in the brilliant folds of the
Aurora. The magic arch, with its pointed
srcamers, shifting silently but swiftly across the
Illuminated by the fitfully changing glow of
some concealed furnace, and rendered sur
passingly beautiful by the brlliancy of its
cOloTs had always had strange charms for men
laboriOus researches had revealed the
laws which associate this beautiful
apparitiOn with disturbances affecting the
economy of our whole earth, and not indis-
tinctly connected with the habitudes of the solar
system itself. But recently discovery has been
made which is even more remarkable than any
which had before rewarded the labors of physi-
cists-a discovery at once instructive and per-
picking, revealing n bond of union between the
aurora and phenomenon hitherto thought to be
quite different in character, but leaving us still
to learn what the exact nature of that bond of
union may be. Let us consider what had been
learned respecting aurOral displays and their re-
latiOn to the earth's economy.
We had occasion recently to point out that
sudden disturbance in the sun in 1859 had been
presently followed by intense magnetic action,
the whole electric system OF the earth quiyering,
so to speak, under the influence of the solar
forces educed by the disturbance. And we men
toned that amongst the signs OF this magnetic
action brilliant displays of the auroral streamers
had been witnessed in both hemispheres on the
night following the solar disturbance. This cir
cumstance teaches us the true character OF the
| aurora as strikingly as any which astronomers
and physicists had patiently been gathering to-
! gethcr during the past hali-century. We learn
! AT once that q relation subsists between the au-
rora terrestrial magnetism, and the central lumi-
| nary of our scheme.
And even if we were to paVse here, we should
! have learned enough to indicate the significance
| of the aurora. Our earth, we may be sure, is not
the only recipient OF that mystic influence which
rOuses into activity the phenomena we term
magnetic. Over the whole realm which it rules
the central orb sends forth the strange electric
! impulses. When our skies arc Illuminated by
| the magic stleamerS, we may be sure that those
of Venus and of Mars, OF Jupiter and of Saturn,
| nay, even the skies OF those unseen orbs which
travel far out in space beyond the paths Of
! Uranus and Neptune, are lit up with aurOral
displays. When once il has been shown that we
owe our auroras TO solar action, we recognize
| the COsmieal character of the display, and that
in a sense, the terrestrial magnetism on which
| il depends is a bond of affinity between our
earth and its sister orbs.
But while we were thus taught the true Sig
nifcance of the aurora, we were left in doubt as
| to the way in which the solar action aroused the
electric luminosity in the upper regions of our
air. We could not even tell at what elevation
the light was suspended above our earth. The
most eminent physicists differed in their views
as to the possibility of learning where the magic
streamers really wave, when we see them most
distinctly. While Arago had held that to at
tempt TO measure the height of the aurora was
as futile as TO attempt to measure the height of
a rainbow, Sir John Herschel considered that
precisely the same laws of measurement might
be applied to the aurora as to any object raised
high above the earth
One point, however, was well determined.
The aurOral lights arc undoubtedly to be ascribed
10 electric action taking place at a very con-
siderable height, where the air is very rare
indeed. 1t became, therefore, question whether
anything could be learned by analyzing the
auroral light as to the condition of that par
ticular part of our atmosphere in which the
electric action takes place
pin
ertul mode of research which has revealed so
many unlooked-for facts was accordingly APP
pied to the light of brilliant aurora. The
result was rather surprising Instead of a rain
bow-colored streak OF light, such as would have
appeared If the aurora were due to the exist
ence of particles excited to luminosity by cleo
trio action, single hue of cOlored light APP
peared. This indicated that the light is due 10