The Stark County Democrat. [volume] (Canton, Ohio) 1833-1912, 1875-07-01
PEFINEMENTS IN MODERN AS7R0-
NOMICAL OBSERVATIONS.

NOAICAL OBSERVATIONS
The tools used by the modern astrono-
mer are clocks to measure time, gradua-
ted circles to measure degrees and their
subdivisions, telescopes to magnify dis.
tant objects, Photographic apparatus to
make permanent records of ephemeral
phenomena, photometers to measure the
comparative intensity of light, polari-
scopes to reveal the nature Of certain Luz
mipous rays, and spectroscopes to reveal
the chemical composition of the heayen-
ly bodies.
The invention of the clock is Of great
ahtiquity;'but it, is tothe wants of mod
ern astronomy and other sciences to
which it is applied navigation, for in
stance) that the perfection with which
they are now made is due. So with the
graduated Circlesy which are applied to
qnadrahts, aectantsj Octants, and aStro-
labes.
The telescope, invented by Jansen in
Holland, about 1909, was successfully inn
proved by Galileo, Herschel, Dollond,
Fraunhoier, and others, while lately
| Lord Rosse and our own Alvan Clark
have surpassed all former efforts. But
who can say what improvements the fu-
ture has in store for the telescope, espe-
cially as liberal monetary compensation
has become stimulus to the ablest opti-
clans, and the making of million dollar
instruments has been discussed2
Photography is now largely used in
astronomy, and the work done by it du-
ring the recent transit of Venus, in diff
erent parts of the earth, has enriched as
Economical science with records Of the
highest value and permanency. One
amateur astronomer, Mr. Rutherford Of
New York city, has for several years past
applied this science to making records of
| the position of the stars, so as ulti-
mately to obtain knowledge of their dis
tances from us, and their motions in
space and in connection with this branch
of the subject, he has invented instru-
ments of measurement, to be applied to
the Photographic impressions, which
have already given results superior in
precision to the measurement by direct
observation of the stars represented.
Photometric observations on heavenly
bodies, comparing their relative luminos-
ity and determining changes in their
nature or distance, have been brought to
a higher degree of perfection, especially
by Zollner, who used for this purpose
the following apparatus: The polariscope,
an ingenious tool invented by Malus in
France in 1908, is based on certain pecu-
liar properties of reflected light, by which
it may be ascertained what light or por-
tions of light belong to luminous body
itself, and which are borrowed from 9th
er sources; while it also shows the direc-
ton whence the borrowed light arrived
before it was reflected by the body under
investigation. Zollner applied to this in
strument several ingenious devices, max
ing it the most perfect measurer of the
intensity of light, and has thus founded
new branch of astronomical research
called astro-photometry.
The spectroscope, based on discovery
made 1890 by Fraunhofer, and in 1910
by John W. Draper of New York city, is
the invention of Bunsen in Germany,
and, next to telescope, is the greatest
gift astronomy has ever received. By
means of this instrument, Secchi, in
Rome, has 80 successfully investigated
the light of the stars that he has classi-
fed them by their temperatures, which
may be distinguished by the number of
dark lines or bands in their spectra; the
hottest stars show the least number, the
next class Ito which our sun belongs)
showing a greater number, and the third
class having so many dark lines, obsCur-
ing portions Of their spectra, that pc
culiar color prevails in them; while a
fourth class, of still lower temperature,
are still more obscure. Next come the
dark globes, so cool that they have no
light of their own, and cannot be seen
except when they are so near to lumi-
nous star as to shine by reflected light.
This is the case with most of our planets,
as we'll as with we do not know how
many, perhaps much larger, darker bod
les, floating in the lnfnity of space, and
to which the disappearance and reap
pearance or changes in luminosity Of
some stars are ascribed, these phenomena
taking place when their light is intercept
ted by aninterveni ng dark body.
SSecchi has just published somesof his
recent observations on Coggias asucomet.,
He combined the spectroscope and polar
iscope with his telescope; the spectre
scope showed that there are two spectra,
one continuous, and the other consisting
of luminous bands, agreeing with those
Of oxide, of carbon; while the Npolaris-
cope showed that the latter spectrum was
original light, while the continuous spec
trum was reflected light, also showing that
the latter came from direction of the sun:
consequently that the continuous spec
trum was reflected sunlight. He proved
thus that this comet shone not only
with reflected sunlight, but by its own
light also, thereby revealing the nature
of its original luminosity. This is an in
stance of the highest degree of refine
ment as yet obtained in modern astro-
nomical research.