Perrysburg journal. (Perrysburg, Wood Co., O. [Ohio]) 186?-1965, 1881-07-15
THE NATURE OF COMETS.

"Since have found tho daisies here"
-Mdrudrct Eutt,lgc, IN Hdrper's weekly.
go
THE NATURE OF COMETS.
Prof BcnJamin Picrce's Theory-Ful
Brothcrs of Planets and Metcors-Ths
Guesses of Aristotle and scncca-Thc Eicc
trihed Train-Tniliess Comet.-How They
Arc wciRhed-Thcir Orbits-Thc Ncbuinr
Hypethesis.
In the Lowell lectures of the late
Prof. Benjamin Pierce, of Harvard Col
lege, published in book form under the
title of "ldeality in the Physical
Sciences" is a chapter treating of the
nature of comets, from which the fol
lowing extracts are made as being OF
special interest at the present time:
The final stage of the nebular history
is the concealed star, of which planet,
satellite, comet and meteor are special
forms, and which is destined to become
again, at last, chaotic mass. They
are simultaneous in existence, and not
belonging to successive stages of the
history. Starting from a common ori-
gin. they have passed through process
of differentiation, and are iitted for diff
ferent functions. They may all be
regarded as bolides; and they fill the
celestial spaces with every conceivable
variety of magnitude, motion and ply
steal aspect.
The comet, from the strangeness of
its appearance in the inaccessible firma-
ment, has been the immemorial wonder
and dread of mankind. 1t has been the
beard or tail of some invisible monster.
II has been the sword of some angry
god. 1t has been the pen of the furies,
writing in the book of fate the death oi
Kings, the fall of empires, the speedy
coming of famines and pestilences and
destructive wars. 1t has been O
light which has filed the souls
of philosophers with darkness. Even
the great Aristotle, with his clear
belief in nature and his contempt
for superstition, could propose nc
theory which was not a tissue of gra.
tuitous and inconsequent hypothesis.
He thought the comet, with its regular
motions, to be u phenomenon like the
fitting and uncertain tgntS tatttuS, an
exhalaton from the earth.
Nevertheless, even in cometology,
where modern progress has been SO
essentially aided by the discovery OF
gravitation and the invention of the
telescope, the instinct of the ancient
T. thinkers achieved some memorable re-
: suits. Passing by the researches of the
Pythagoreans, we need only refer to the
writings of Seneca in the first century
of the Christian era. 81 KNOW" writes
) Seneca, "no nobler research, nor a
more useful science, than that which
undertakes the study of the stars; but
to perfect this science is it not expedi.
ent to examine whether the nature oil
comets differs from that of the Other
celestial bodiesp If we reflect On theil
motions, ON their vicissitudes of rising
and setting, on their light and bril-.
liancy, we shall be struck with the
analogy which we perceive between
them and these other bodies. We need
an exact history of the comets which
have hitherto appeared; for it is their
rarity of appearance which prevents oul
deciding upon the regularity of theil
movement We are ignorant whether
describing fixed orbits, they do not re.
appear at periodic and determinate
intervals of time" This was the pre-
i diction of thoughtful genius. Modern
astronomy, profiting by the ancient sug
gestion, has demonstrated this, like
many other truths. The dwarf of tc
day who stands on the shoulders of thu
giant OF yesterday can see q greater
distance than the giant.
The perfect comet combines nucleus
and train. The beauty belongs to tn,
z train, which is unsubstantal and TEN
porary; while the mass and density re
side in the almost invisible but perma
nent nucleus. The solid nucleus move
hn IN rnn n,.l,y III.
orbit, obedient to the same law of at
traction which governs the motions o
any one of the planets; whereas eacl
particle of the train moves in its OWL
hyperbolic orbit, in consequence of
repulsiOn from the sun often two O
three times as great as the ordinar,
solar attraction. These particles o
the train are electrified bodies, and hav
the same electricity as that of the sun
the particles which are most highl,
electrified Ndvance to the front edge O
the tail, while those that are the leas
electrified fall back to the rear Som,
of the particles are electrified jus
enough to balance the solar gravitation
so that, after separating from th
nucleus, they become neutral to tn,
SUMS action and move uniformly il
straight lines, but without ceasing TO b.
part of the tail. The particles whicl
are less highly electrified remain at
tracted by the sun, but move in hyper
bolic orbits in the opposite branch O
the hyperhola, however, to that il
which the repealed particles move.
This theory, in an imperfect state
was rudely applied by Bessel to the tai
of Halley's comet, in 1885. But tn
comet discovered by Donati, in 1858
? offered as fine an opportunity as can b.
desired for its full verilication. Ho,
grand was the beauty of that comet
All the world stopped in the street
when it became visible after twilight
and wondered at it with bated breath
few centuries ago it would hav
caused universal dismay, and mel
would have paled at the frightful por
tent. But the Christian of to-day be
holds it as the loveliest messenger O
divine wisdom. A multitude OF oh
seryations were made upon the trai
as well as the head. in all civiIize
countries, and the theory of the trai
was sustained in every detail. The ele
p gance of the shape strictly conforme
TO the ideal constructions of the geom
'eter.
If the nucleus of a comet were take
away, the train would continue to NOV
off through space, undisturbed by tn
loss of its head. Singular as this phe
nomenon may seem, it has been actu
ally observed. At midday on the 2St
Of February. 1S43, groups OF people i
. many of the towns of New England
especially at Portland, collected at Tn
corners of the streets, gazing up te
ward the sun. Protecting their eye
in the shadows of the houses. the
saw brilliant object few degree
from the sun. Such a marvellous spe,
tacle had never before been beheld.
few days later wonderfully brilliar
tail OF comet was seen skirting tn
horizon soon after sunset, and reacl
ing more than one-third of the wa
round the sky. What we now saw Wa
tail without head, as we had befoi
seen head almost destitute OF tail. Bl
head and tail were members of the sam