The times. [volume] (Richmond, Va.) 1890-1903, 1900-12-09
some MARVELLOUS
ACHIEVEMENTS
A Famous Scientist Tells About Some
of the Astronomical Wonders
of the Century.
by PROF. EDWARD S. HOLDEN
astronomer OF Smithsonian institution.

astronomer OF Smithsonian Institutions
TT BE achievements of astronomy
during the nineteenth century
have been little short of marvel
Gus. Not only have the classic
methods OF research been expanded and
developed; but in the latter half of the
century new instruments OF unexpected
power have been perfected and results
obtained by their use in fields utterly
closed to the astronomers of hundred
years ago.
Mathematical analysis reached a high
state of perfection in the researches of
I.aplace and Lagrange at the century's
beginning: the labors of profound anal
,sfs like Gauss, Adams LIE Nefrier, CYL
den. Hill, Newcomb and many others.
have placed mathematical astronomy on
an entirely new footing. 1t is lmpossi-
BILE, in q popular paper, TO give an ac-
count for the triumphs Of methematlc'ans.
1t must suffice to say that the advances
in the theory of the motions of the heaV-
en1y bodies are as important by the spec
torscope, the photometer and the photo
graphic plate. One signal result stands
out as a brilliant type Of the power of
analysis.
NEPTUNE.
The planet Neptune was discovered With
the telescope in 1916 in consequence of
laborious calculations by lie Nercler (and
Adams upon the materials of the planet
Uranus Uranus had been discovered by
chance. by Sir William Herschel in 1IS1.
A body of unusual appearance was seen
in this telescope. Examination showed
that it was a major planet revolving
about the sun in eighty-four years. Care
full observations gave the shape and size
of it's orbit Calculations of the perturb-
ing forces exerted by the other known
major planets-Mercury, Venus, the
earth, Mars, Jupiter, Saturl-shoNed
that its course in space would De along
a certain line if these planets, and only
these. affected its motion Renewed OBJ
servations showed very slight, yet OBJ
vious deviations from the predicted
course 1t occurred to several astrono-
mers-to Arago, BeSScl, Strive, lie YER
rier Adams-that these deviauons were
produced by the attraction OF q major
planet as yet unknown. Sir John Hers
chel wrote of the new planet a few weeks
before it's discovery in memorable words:
1--WE see it as Columbus saw America
from the shores Of Spain. Its movements
have been felt trembling along the far
reaching line OF our analysis with Ger
tainty hardly inferior to ocular demon
stration." The extraordinary complex
problem of inverse perturbations was
worked out by lie Nerrier and by Adams,
and the place where the new planet
would be found was foretold When the
telescope was directed to the predicted
place the unknown planet was there; the
mathematician, in his study, had dlrect-
ed the observers telescope Other
achievements of the same order of merit,
though far less striking, have distin-
guished the present century.
GRE.Ar ADVANCES.
In the mathematical processes relating
to spherical and to practical astronomy
also, this century has made its mark
in history. Bessel, Strive and their
successors in Europe and Ill America
have reconstructed these branches OF the
science from the foundations. Every
pupil in our colleges is now familiar with
the highest retinements of observation
and calculations: and the principles Of
irstruuent-m king have been carried
well-nign to perfection. In some depart
,nents the Instruments furnished are so
perfect that the outstanding errors OF
observation are due chiefly to the human
being who uses the apparatus, not to
the apparatus itself. The distances of
the sun and Of many of the stars have
been fixed With eXactness. The heavens
are assiduously watched by professionals
and by amateurs. in ali the length and
breadth Of the globe, and no change OF
Importance can take place without being
detected-perhaps by photosraphy-and
reported by the electric telegraph Co
every interested watcher in all the con-
tinents.
HANDNIAID OF ASTRONOMY.
The advent of photography as the
handmade of astronomy marks q distinct
advance in the processes Of observation
The sensitive plate partially records all
rays OF light that fall upon its surface.
Such a plate directed at the heavens
shows thousands upon thousands OF stars,
each registered in its proper position
and Of its proper brightness. a second
plate taken upon a succeeding night
records ali changes, either Of position or
of brilliancy 1t is in this way that
new minor planets are discovered (by their
change Of positionl. new variable star;
detected Cby their change of brilliancy).
Maps of the whole sky are now made by
photography, and they record millions
upon millions of stars. The inventory
Of the stellar universe will soon be COM
pleted. d magnificent gift Of this century
to the next. Photography has proved
TO be of immense Importance in the study
OF the moon y satisfactory picture
of the full moon can be made in less
than a second of time which will show
more than in contained in the best lunar
maps that renIired a lifetime to construct
by the old l..ethods.
too is depicted by means of photography
with extraordinary faithfulness the work
of years of observation being compressed
into hours. Up to this time little sue
cess has been attained, however, in the
study of planetary features by photog-
raphy and the old methods of telescope
examination and pictorial representa- on
by drawings are still employed. 1t is
partly for this reasos that so much
remained doubtful in the accounts of the
surface details OF Mars. Jupiter, &c.
COMETS.
In the study of the physical character
istics of comets. also. photography has
proved to be of the very first Importance.
Features quite impossible to see with
the eye are distinctly shown on the mega
live plate; and in this field we are on
the Very verge of great discoveries. The
connection of comets with meteor swarrns
is a fact of capital Importance
The electric telescope has revoutioniZed
certain parts OF astronomy and geodesy.
All long!tudeS are now fixed by the
method" with unheard-of accu-
racy and rapidity, and the figure Of our
globe will soon be well determined. One
of the striking discoveries of the century
is DIR. Chambers detection of minute
regular change OF the axis of rotation
of the earth whose effec, is shown in