The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1869-10-27

the incaudescence of some gas through which
the electric discharges in upper air take place
But this was not the circumstance which at
traeted surprise. Rather, this was to have
been looked for. II was the position of the line
which astonished our physicists. If the gas
had been one which chemists are acquainted
with the bright line would have occupied the
position proper to that gas. and would at once
have Indicated its nature But there is no
known element whose spectrum has bright
line where this one appeared. The observation
mas been repeated over and over again, by Ang-
strom, by Otto Struve, and recently by Mr..
Plummer, always with the same result; we can
not tell what the substance may be to whose in
candescence or luminosity the aurora owes It's
brilliancy.
But now most remarkable discovery has
been effected. Angstrom has found that the
mysterious line of the auroral spectrum exists in
the spectrum of another object which had been
thought to be wholly different in character.
Ever since its discovery by Cassini, the zodiacal
light has been an object Of interest to astrono-
mers. Gradually theory had been formed re-
spectng 1t which had been sanctioned by the
authority OF such men as Humboldt ana sir
John Herschel. IL was held that this appear
ance is due to the light reflected from multi
tude of minute cosmical bodies travelling around
the sun within the orbit of our earth.
This theory had never been tested by spectre
scopic analysis. Indeed, the zodacal light
shines so family that it was hardly hoped that
its spectrum could be rendered visible. But II
was confidently anticipated that, if the Zodlacal
light ever were thus anylyzed, its spectrum
would be that which the theory required-that
is, very faint production of the common solar
spectrum.
Now, at length, we hear from Angstrom that
the spectrum of the Zodiacal light has been OBJ
served, and instead of being, as had been eX-
pected, faint rainbow-colored streak, it pre-
sents but n single line. That line is the same
that we see in the spectrum of the aurora! In
other words the light of the zodiacal CLEAN and
that of the auroral streamers are due to the
same sort of electric discharge taking place in
the same medium.
Without pretending to further interpret this
startling result, we may indicate the promise it
affords OF explaining q number of phenomena
which have long seemed most perpleXtng.
When once we recognize the fact that electric
action is effective in producing any OF the celes-
Hal lights, we have resource available to re-
move many difficulties. Astronomers were
asking how comets, for example, could exhibit
the spectrum of the incandescent vapor of car
bon-that is a spectrum indicative of the most
intense heat when, as in the case of Wmnecke's
comet (whose spectrum was OF this nature),
they were farther from the sun than
the earth is The action of the sun in eX
citing electrical discharges would be quite
sufficient to account for this and similar pheno-
mena. Again, it has been long recognized that
the peculiarities of comets tails seem only eX-
plicable as due to electrical action; but astrono-
mers were unwilling to adopt such theory
without some positive evidence in its favor. We
now have such evidences and it is most probable
that the first lOnG-tailed comet which is sub
mitted to spectroscOpc analysis will establish
the view which Euler put forth more than a
century ago, that comets tails have something
in common with the aurora and the zodiacal
light. 1t would indeed be strange if three Of
the most mysterious phenomena with which men
OF science are acquainted should find their eX-
planatiOn simultaneously.