The sun., 1893-02-12
..THE sgN. suNpAY. FEBRUARY 4, 1893.

more solid though less brilliant man. and N q
impossible to apbortion the respective share
oil credit between these two men. the creates
scientists that France has produced. Betwcer
them they explained the libration or oscila
ton OF the moon which had been discovered
by dalileo Just before his blindness-the Ions
inequality OF Jupiter and Saturn. tho formeI
tagging behind it's true place. while the motion
OF saturn is being accelerated. the rstturba-
lions OF Jupfter's satellites and OF omets-and
inc acceleration OF the m oon's mean notion
inc same two scientists improved tho lunar
theory and the theory OF the tldos &C.
counted Tor the periodic changes In the
lorm and obl1uity Of the eArtb's orbits.
ana demonstrated the stability OF tho solar
system considered rs an assemb!ngs OF rigid
Dodies subject to gravity. 1t is obvious that
the question whether the solar system ia attn.
Die was one OF stupendous moment. II any
one planet OF the solar system were to fall into
.he sun. especially ~ 1t were big one. like
Jupiter or Saturn. the heat produced would he
SO terrific that life on this earth would be de-
stroved. even at its present distance We owe
10 Lagrange and Laplace tho proof that tho
changes OF the solar system are not cumu-
'atiVe. but periodic: that is. thoy repeat the M
selves Mt regular int ervals. and never exceed n
| certain moderate amount. The period, to bo
sure. is something enormous The members of
our solnr system will not have gone through all
their changes OF position until period OF two
miiiion years has elapsed. This is the term OF
the planetary oscillation. "a great pondulum
| OF eternity which beats out ages rs our pendu
lunis bent seconds"
The nebular hypothesis was thrown out by
Laplncc, not as the outcome OF profound cal
| cu'htion. like the demonstration OF the sta
biity OF the soar systom. nor ms following cer-
talnly from the theory Of Crnvitation, and
therefore 1t is not to be accepted as more than
| priiliant speculation. to be confirmed or re.
lected. rs our knowledge extends. Since the
| ume of Lanlace the nebulnr hypothesis has
had ups and downs OF crcdence. but at the
present time it holds the field with apparently
greater probability Of ultimate triumph than
has ever before seemed to belong to It.
With the help OF Prof. Lodge. let us try to
state the nebuar hypothesis in a compact and
intelligible form. We should. In the first
place. recapituate tho data on which It is
founded. They arc these: Every motion in
the solar system known in Laplace's time took
place In one direction. and in one direction
only Thus the planets revolved around tho
sun. all going the same way round; moons
revolved round the planets. still maintaining
the same direction OF rotation. and all the
bodies that were then known to rotate on
their own axes did 30 with the samo kind OF
spin. Moreover. all those lotions take place
~ VI hSuk - elHIlo DlHu6. nc anclont9 Knew
that sun. moon. and planets all keep near to
tho plane OF tho ecliptlc within a beltknown "a
the zodiac; none strays away into other parts
OF the aky. Satellites. also. and rings are ar
ranged in or near the same plane. and the
plane OF diurnal spin or equator OF tho difYer-
ont bodies is but slightly tilted. .--;3'..,t..
Maniiestly. all this could not be the result of
chance. What could have causedit? Is there
any connection or common ancestry to ac-
count for this strange family likeness? There
Is no connection now. but may there not have
been ona once9 Must there not have been
one. We should rather say 1t seems as though
they had once been parts OF one great mass
rotating as q whole. for. IL such o rotating
mass broke np. its parts would retain its di.
rection OF rotation. But such mass filling
all SPACE as far as or beyond Saturn, although.
containing the materials OF the whole solar
system in ITSELF must have been OF very rare-
fled consistency Occupying SO much bulk, IL
could not have been solid. nor yet LIQUID, but
1t might have been gaseous. Are there any
such gigantic rotating masses OF gas in the
heavens now3 Certainly there are: there are
the nebulir. Some Of the nebulR are now
known to be gaseous and some Of them. at
least, "are in state OF rotation. Lapiaee
could not have known this for certain. but he
suspected it The first distinctly spiral nebua
WAS discovered by the telescope of Lord
Rose: and quite recently n photograph of
the great Andromeda nebula, made by Mr.
Isaac Roberts. demonstrates that this pro.
digious mass is in a state OF extensive and
majestic whir.
The problem presented by the data ia the |
following: A vast mass Of rotating gas is left |
to itsolf to cool for ages and to condense as It
cools: how will it behave? Laplaoe pictured |
to himself this mass shrinking. and thereby
xrh hrlI md
body shrinking in size and retaining its original
amount OF rotation rs it will unless a brake is
applied. must spin more and more RAPIDLY as it |
shrinks. 1t has what mathemat icians call n a
constant momentum. and what it loses in lev |
erage as it shrinks 1t gains in speed. The mass |
is held together by Gravntion. every particle |
attracting every other particle. but, since all |
the PARTICLES are describing curved paths, they
will tend to fly Off tangentially. and only a |
small excess Of the gravitation force over |
the centrifugal is loft to pull tho particles |
In and slowly to concentrate tho nebula. |
The mutual Gravitation OF the parts
is opposed by tho centrifugal force OF |
the whirl. At length a point is reached
where tho two forces balance. portion out
side certain line will be In equilibrium. It
will be left behind. and the rest must contract |
without it. A ring is formed. and away GOES
the inner nucleus. contracting further and
further toward tho centre After d time an.
other ring will be left behind in the sane way
and so on. What happens to those rings?
They rotate with the motion they po.sess
when thrown or shrunk of. but will they re-
main rings? II perfectly regular they may;
II there be any irregularity they are liable to
break up They will break into one or two
or more large masses. which are ultima ately
very likely to collide and become one The
revolving body So formed is still a rotating.
gaseous mass. and 1t will 60 on shrinking
and cooling and throwing off rings like the
nucleus by which 1t has been sbandoned. AS
any nucleus gets smaller. its rate OF rotation
increases. and 80 the rings last thrown or
will be splnning faster than those thrown Off
Earlier. Tho final nucleus or residual central
body will be rotating fastest OF all.
Tho nucleus OF tine whole original mass
which once contained all the materials of our
solar system we now sec shrunk up into what
We call the sun. which is spinning on Its axis
'nce every twenty-five days. The rings suo.
h. H. m tN,o