Year: 1869

The true nature of the aurora bore
alis has long been a perplexing mys-
I terry to men of science. Careful OBJ
servatiOns and comparison of accom-
| panying phenomena have shown that
solar disturbances, manifested by the
| appearance of spots of unusual num-
| bers and dimensions, are followed or
accompanied by intense magnetic ac-
/ tiOn, affecting the whole electric sys-
/ tenn of the earth, and marked by bril-
liant displays of auroral streamers on
the night succeeding the solar disturb
ance. This showed that a relation
| exists between the aurora, terrestrial
magnetism and the sun, but it left the
precise way in which the sun excited
the electric luminosity of the auro-
Ta as much in doubt as ever. At what
elevation above the earth the auroral
light exists, and whether within or
beyond the regions of our atmosphere,


was also unknown, and the most em-
inent men of science were at variance
as to the possibility of aseertaining
the actual distance of the silently
shifting streamers of light in the
northern sky.


SpectorOscopic analysis, that has so
wonderfully expanded the limits of
scientific research, was sometime
since applied to the light Of an aurora
with unloOked-for results. Instead of
a parti-colOred band of light, which
might have been expected, showing
that the aurora was due to solid parti-
cles excited to luminosity by electric
action, it gave the single line of light
characteristic of incandeseent gas.
But the line produced by each gas
has its own proper position in the
spectrum, and the line of the aurora
does not correspond with that of any
gas with which chemists are acquaint-
ed Repeated observations by several
skillful experimenters give always
the same result. They can pronounce
only that the aurora is due to the in
eandescence of gas different from
any known to science.


But another discovery has been
made which, from its connection with
the former, is of great interest. The
zodiacal light, that faint gleam in the
sky which has hitherto been supposed
to be due to the light reflected from a
vast number of minute bodies travel
ing round the sun within the orbit Of
the earth, has been an object of great
interest to astronomers. 1t has, until
recently, never been subjected to spec
troscopic analysis, because its light is
so faint that it was thought its spec
tFum could hardly be made visible.
1t was presumed, however, that if
definite spectrum could be obtained,
it would present, as the accepted the
Ory of its origin required, a feeble
likeness of that of the sun. A Ger
man scientist has at last succeeded in
observing the spectrum of the zodical
light, and instead of being, as expect
ed, a faint copy of the ordinary pris-
matte spectrum, it presented only a
single line, and that identical with
the spectrum of the aurora. This
proves eonelusively that the previous
" received theories of the nature of
the ZOdical light were erroneous, and
that and the aurora are due to the
same electric influences operating in
the same medium.


1t is now believed by astronomers
that the same methods of inquiry will
show, when an opportunity occurs for
making the test, that the tails of COM
cts are of the same nature with the
aurora and the zOdical light; if so,
three of the most mysterious phenom-
ena of the heavens will be traced to q
common origin, and their nature par
TALLY explained.