The Republican. [volume] (Oakland, Md.) 1877-current, 1882-11-11

photographing them, is decisive, making
IL absolutely certain that part of the
comet light is reflected sunlight. There
must be matter like meteoric dust in the
mead and nucleus and probably in the
tail also OF comet to enable it to shine
IN tins way by rejecting the light of the
sun.
But the latest comet which has vet
been observed with the spectroscope has
brought fresh news. l refer to Wells
comet, sometimes called, rather affect
eddy, Comet Wells. The spectrum of
this comet did not at first show the car
bon bands to which have referred above.
line cyanogen groups" says DR.. Hug
gins, care not SEEM and he does not
seem to have looked for them later. But
IN May, 1881, Vogel found that the car
Don bands were present, though faint.
lie noticed no other bright bands or
ms. Still later, however, an unex-
pectoi change took place. DIR. B. Has
selberg, of the Observatory of Pulkowa,
found that the nucleus of the comet gave
very strong and extended continuous
Si'CStl ulllf WIFI an CACtSSlNtll SlEOuO
bright line in the orange yellow, which
he was able to identify by microscopical
measurement with the well known ID
line of the solar spectrum-a line due to
the presence of sodium in the atmosphere
of the sun. So soon as the news was an
nounced, Duner, Bredichim and Vogel
observed the spectrum of the comet, and
were able fully to confirm DIR. HaSsel-
berg's observation.
Mr.. Hind, Superintendent of the En-
glish Nautical Almanac, remarks on this
that 1T is necessary to conclude that
during the last fortnight of May the
spectrum of Wells comet changed in a
manner of which the history of science
furnishes no precedent Since he so
wrote has been observed by DR.. Muller,
of the Astrophysical Observatory at Pots
dam, that the light of Wells comet in
creased more rapidly during the second
half of May than had been predicted,
"indicating an unexpected development
of proper or inherent light in the comet
itself" This increase" he adds, "was
most marked just about the very time
when the sodium line was first observed
in the spectrum; wherefore we must con-
clude that important changes occurred
about that time in the physical condition
of the comet"
1t appears to me that these observa-
tons are full of promise. Astronomers
had begun to suppose that no comets
were likely to give more information
than had been already obtained from
Brorsen's and Winnecke' comets. But
now it seems as though the appearance
of the carbon bands belongs to one stage
of the comets progress through the
changes which occur as the comet ap-
proaches the sun. With nearer approach
sodium vapor is first formed and then
caused to glow with its own inherent
light, What further changes might be
observed in the case of a comet observed
under such favorable conditions as exist
ed in the case of Donati's comet QS5S)
who shall say? 1t seems as though there
were chance that, after all, these mys-
FERROUS bodies will one day be interpreted.
For SO soon as we have learned how the
physical changes which the spectroscope
may detect are associated with the
changes of form, the development of en-
velopes, the outward sweep of the tail,
the formation of secondary tails, etc,
which still remain among the mysteries
of cometic existence, we may believe that
science will soon be able to decide be-
tween the various theories which have
been advanced, or perhaps to show that
while none OF these are sound some otl-
er theory hitherto unthought of will
alone account for the observed phenom-
ena. 1t seems not unlikely that the the
DRY may be admitted to which many
American men of science, and DIR. Hug
gins IN England, seem to have given to
their adhesion-the theory that great
electrical disturbances are set up by the
suns action in connection with the va
porization of some of the matter of the
comets nucleus, and that the tail is
probably matter carried away with cleo
trio discharges, under an electrical infu-
ence of repulsion eXerted by the sun.
RICHARD A. Proctor.