The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1900-11-04

can method" with unheard OF accuracy and
rapidity. and the figure OF our globe will
soon be well determined. One OF the striks
ing discoveries OF the century Is DR.. Chand-
ler's detection of minute regular change
OF the axis of rotation of the earth whose
effect is shown In a regular. though small.
variation OF the ATTITUDES of places. This
discovery is an excellent example of the
thoroughness with which all astronomical
worl-both observation and caiculation-is
now performed.
NEW DISCOVERIES.
At the beginning of the century. Sir Will
liam Herschel was in mid-career. He had
discovered the planet Uranus in ISL; its
two brighter satellites were discovered by
him in 1857; the two innermost satellites OF
Saturn in 1873. The satellite OF Neptune
was discovered by Lassell In 1876: two more
satellites TO Uranus, again by Lassell, in
1851; a satellite to Saturn by Bond in 1913;
two satellites to Mars By Hall in 1871;
satellite to Jupiter by Barnard in 1892; a
ninth satellite to Saturn by Pickering
ir 1888.
Newton's discovery of universal gravita-
ton reached no further than the outermost
planet known to hjm-Saturn The dis
covery of Uranus and Neptune extended the
scope, but Herschels detection Of systems
of binary stars revolving about each other
according TO this law made grayitation
truly universal; the law effective TO
the boundaries of the universe. Our knowl-
edge of double stars has been vastly ex-
tended by the discoveries of this century
Thousands of such systems have been dis
covered and many orbital motions are al
ready calculated.
TO Herschel a star was shining body
like the sun. both being of unknown con-
stitution. The spectroscope Invented by
Bunsen and Kirchhoff in 1889 brought
new engine TO bear on problems until then
utterly insolvable. The spectrum of the
sun, or of a star, compared with the spectra
Of terrestrial substances, proves the ex-
istence in the fiery envelopes of these bodies
OF incandescent clouds of metallic vapors.
Lead, iron, gold, copper and other metals
are there present.
COMPOSITION OF THE SUN.
The Nebular Hypothesis of Laplace pub
lished in 1856 had declared that the sun
and all the planets were but condensations
from single vast nebula that once filled
all space. The spectroscope proves that
the stars, the sun and the earth are made
up of the same elements. If the earth
were to be raised TO the temperature of
the sun, IL would be like it-a miniature
sun. The sun is in fact, a star. The stars
are, in general, composed of terrestrial
elements. This great generalization
strengthens the nebular hypothesis in its
larger acceptations, but the century has
brought forward many doubts as to its
minor details. With the discovery of the
spectroscope the science Of astronomical
physics was born. The most amazing single
result of spectroscopic observation is the
determination of the velocity with which
stars are approaching TO, or receding from,
the earth. All stars are in motion with
respect to the earth. AS they move away
from, or towards US, the pitch of their
spectral lines is altered by their velocity
precisely as the pitch of the bell of a
passing locomotive engine is altered by its
motion towards us, or from us. The mo-
ton of the sun and of the whole solar
system among the stars, in space. can be
determined in this fashion. We are APP
preaching some stars; we are receding
from others. The line of the motion of
our whole solar system can thus be drawn
in the universe and this problem is now
being worked out in all it's details at sew
eral places, notably at the Lick Observa-
tory.
In the foregoing paragraphs it has not
been possible TO note more than a few of
the greater achievements of the astronomy
OF the century. Only few of the greater
men are named. A full account of astron-
omical progress would require a volume,
and 1t would include a host of honored
names. In each and every department we
should find Americans in the highest
places. Nowhere has astronomy fiourished
better than upon our own soil, and we
may look forward to the next century with
confidence. EDWARD S. HOLDEN,
Formerly Director of Lick Observatory.