a journey in other worlds-第19节

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ratio　to　its　weight。　　There　was　constant　and　incessant　movement
among　the　individual　fragments；　but　it　was　not　rotary。　　Nothing
seemed　to　be　revolving　about　anything　else；　all　were　moving；
apparently　swinging　back　and　forth；　but　no　collisions　took　place。　
When　the　separate　particles　got　more　than　a　certain　distance
apart　they　reapproached　one　another；　but　when　seemingly　within
about　one　hundred　diameters　of　each　other　they　swung　off　in　some
other　direction。　　The　motion　was　like　that　of　innumerable
harp…strings；　which　may　approach　but　never　strike　one　another。　
After　a　time　the　Callisto　seemed　to　become　endowed　with　the　same
property　that　the　fragments　possessed；　for　it　and　they　repelled
one　another；　on　a　near　approach；　after　which　nothing　came　very
near。
　　　
Much　of　the　material　was　like　slag　from　a　furnace；　having
evidently　been　partly　fused。　　Whether　this　heat　was　the　result　of
collision　or　of　its　near　approach　to　the　sun　at　perihelion；　they
could　not　tell；　though　the　latter　explanation　seemed　most　simple
and　probable。　　When　at　about　the　centre　of　the　nucleus　they　were
in　semi…darknessnot　twilight；　for　any　ray　that　succeeded　in
penetrating　was　dazzlingly　brilliant；　and　the　shadows；　their　own
included；　were　inky　black。　　As　they　approached　the　farther　side
and　the　sunlight　decreased；　they　found　that　a　diffused　luminosity
pervaded　everything。　　It　was　sufficiently　bright　to　enable　them
to　see　the　dark　side　of　the　meteoric　masses；　and；　on　emerging
from　the　nucleus　in　total　darkness；　they　found　the　shadow
stretching　thousands　of　miles　before　them　into　space。
　　　
〃I　now　understand；〃　said　Bearwarden；　〃why　stars　of　the　sixth　and
seventh　magnitude　can　be　seen　through　thousands　of　miles　of　a
comet's　tail。　　It　is　simply　because　there　is　nothing　in　it。　　The
reason　ANY　stars　are　obscured　is　because　the　light　in　the　tail；
however　faint；　is　brighter　than　they；　and　that　light　is　all　that
the　caudal　appendage　consists　of；　though　what　produces　it　I
confess　I　am　unable　to　explain。　　I　also　see　why　the　tail　always
stretches　away　from　the　sun；　because　near　by　it　is　overwhelmed　by
the　more　powerful　light；　in　fact；　I　suspect　it　is　principally　in
the　comet's　shadow　that　the　tail　is　visible。　　It　is　strange　that
no　one　ever　thought　of　that　before；　or　that　any　one　feared　the
earth's　passing　through　the　tail　of　a　comet。　　It　is　obvious　to　me
now　that　if　there　were　any　material　substance；　any　gas；　however
rarefied；　in　this　hairlike＇1＇　accompaniment；　it　would　immediately
fall　to　the　comparatively　heavy　head；
and　surround　that　as　a　centre。〃

＇1＇　　Comet　means　literally　a　hair。

　　　
〃How；　then；〃　asked　Cortlandt；　〃do　you　account　for　the　spaces
between　those　stones？　　However　slight　gravitation　might　be
between　some　of　the　grains；　if　it　existed　at　all；　or　was
unopposed　by　some　other　force；　with　sufficient　timeand　they
have　eternityevery　comet　would　come　together　like　a　planet　into
one　solid　mass。　　Perhaps　some　similar　force　maintains　gases　in
the　distended　tail；　though　I　know　of　no　such；　or　even　any
analogous　manifestation　on　earth。　　If　the　law　on　which　we　have
been　brought　up；　that　'every　atom　in　the　universe　attracts　every
other　atom；'　were　without　exceptions　or　modifications；　that　comet
could　not　continue　to　exist　in　its　present　form。　　Until　we　get
some　additional　illustration；　however；　we　shall　be　short　of　data
with　which　to　formulate　any　iconoclastic　hypothesis。　　The　source
of　the　light；　I　must　admit；　also　puzzles　me　greatly。　　There　is
certainly　no　heat　to　which　we　can　attribute　it。〃
　　　
Having　gone　beyond　the　fragments；　they　applied　a　strong　repulsion
charge　to　the　comet；　creating　thereby　a　perfect　whirlpool　among
its　particles；　and　quickly　left　it。　　Half　an　hour　later　they
again　shut　off　the　current；　as　the　Callisto's　speed　was
sufficient。
　　　
For　some　time　they　had　been　in　the　belt　of　asteroids；　but　as　yet
they　had　seen　none　near。　　The　morning　following　their　experience
with　the　comet；　however；　they　went　to　their　observatory　after
breakfast　as　usual；　and；　on　pointing　their　glasses　forward；
espied　a　comparatively　large　body　before　them；　a　little　to　their
right。
　　　
〃That　must　be　Pallas；〃　said　Cortlandt；　scrutinizing　it　closely。　
〃It　was　discovered　by　Olbers；　in　1802；　and　was　the　second
asteroid　found；　Ceres　having　been　the　first；　in　1801。　　It　has　a
diameter　of　about　three　hundred　miles；　being　one　of　the　largest
of　these　small　planets。　　The　most　wonderful　thing　about　it　is　the
inclination　of　its　orbitthirty…five　degreesto　the　plane　of
the　ecliptic；　which　means　that　at　each　revolution　in　its　orbit；
it　swings　that　much　above　and　below　the　imaginary　plane　cutting
the　sun　at　its　equator；　from　which　the　earth　and　other　larger
planets　vary　but　little。　　This　no　doubt　is　due　to　the　near
approach　and　disturbing　attraction　of　some　large　comet；　or　else
it　was　flung　above　or　below　the　ordinary　plane　in　the　catastrophe
that　we　think　befell　the　large　planet　that　doubtless　formerly
existed　where　we　now　find　this　swarm。　　You　can　see　that　its　path
makes　a　considerable　angle　to　the　plane　of　the　ecliptic；　and　that
it　is　now　about　crossing　the　line。〃
　　　
It　soon　presented　the　phase　of　a　half　moon；　but　the　waviness　of
the　straight　line；　as　in　the　case　of　Venus　and　Mercury；　showed
that　the　size　of　the　mountains　must　be　tremendous　compared　with
the　mass　of　the　body；　some　of　them　being　obviously　fifteen　miles
high。　　The　intense　blackness　of　the　shadows；　as　on　the　moon；
convinced　them　there　was　no　trace　of　atmosphere。
　　　
〃There　being　no　air；〃　said　Cortlandt；　〃it　is　safe　to　assume　there
is　no　water；　which　helps　to　account　for　the　great　inequalities　on
the　body's　surface；　since　the　mountains　will　seem　higher　when
surrounded　by　dry　ocean…　bottom　than　they　would　if　water　came
halfway　up　their　sides。　　Undoubtedly；　however；　the　main　cause　of
their　height　is　the　slight　effect　of　gravitation　on　an　asteroid；
and　the　fact　that　the　shrinking　of　the　interior；　and　consequent
folding　of　the　crust　in　ridges；　may　have　continued　for　a　time
after　there　was　no　longer　water　on　the　surface　to　cut　them　down。
　　　
〃The　temperature　and　condition　of　a　body；〃　continued　Cortlandt；
〃seem　to　depend　entirely　on　its　size。　　In　the　sun　we　have　an
incandescent；　gaseous　star；　though　its　spots　and　the　colour　of
its　rays　show　that　it　is　becoming　aged；　or；　to　be　more　accurate；
advanced　in　its　evolutionary　development。　　Then　comes　a　great
jump；　for　Jupiter　has　but　about　one　fourteen…hundredth　of　the
mass　of　the　sun；　and　we　expect　to　find　on　it　a　firm　crust；　and
that　the　planet　itself　is　at　about　the　fourth　or　fifth　　period　of
development；　described　by　Moses　as　days。　　Saturn　is　doubtless
somewhat　more　advanced。　　The　earth　we　know　has　been　habitable
many　hundreds　of　thousands　or　millions　of　years；　though　three
fourths　of　its　surface　is　still　covered　by　water。　　In　Mars　we　see
a　further　step；　three　fourths　of　its　surface　being　land。　　In
Mercury；　could　we　study　it　better；　or　in　the　larger　satellites　of
Jupiter　or　Saturn；　we　might　find　a　stepping…stone　from　Mars　to
the　moon；　perhaps　with　no　water；　but　still　having　air；　and　being
habitable　in　all　other　respects。　　In　our　own　satellite　we　see　a
world　that　has　died；　though　its　death　from　an　astronomical　point
of　view　is　comparatively　recent；　while　this　little　Pallas　has
been　dead　longer；　being　probably　chilled　through　and　through。　
From　this　I　conclude　that　all　bodies　in　the　solar　system　had　one
genesis；　and　were　part　of　the　same　nebulous　mass。　　But　this　does
not　include　the　other　systems　and　nebulae；　for；　compared　with
them；　our　sun；　as　we　have　seen；　is　itself　advanced　and　small
beside　such　stars　as　Sirius　having　diameters　of　twelve　million
miles。〃
　　　　
As　they　left　Pallas　between　themselves　and　the　sun；　it　became　a
crescent　and　finally　disappeared。
　　　
Two　days　later　they　sighted　another　asteroid　exactly　ahead。　　They
examined　it　closely；　and　concluded　it　must　be　Hilda；　put　down　in
the　astronomies　as　No。　153；　and　having　almost　the　greatest　mean
distance　of　any　of　these　small　bodies　from　the　sun。
　　　
When　they　were　so　near　that　the　disk　was　plainly　visible　to　the
unaided　eye；　Hilda　passed　between　them　and　Jupiter；　eclipsing　it。　
To　their　surprise；　the　light　was　not　instantly　shut　off；　as　when
the　moon　occults　a　star；　but　there　was　evident　refraction。
　　　
〃By　George！〃　said　Bearwarden；　〃here　is　an　asteroid　that　HAS　an
atmosphere。〃
　　　
There　was　no　mistaking　it。　　They　soon　discovered　a　small　ice…cap
at　one　pole；　and　then　made　out　oceans　and　continents；　with
mountains；　forests；　rivers；　and　green　fields。　　The　sight　lasted
but　a　few　moments　before　they　swept　by；　but　they　secured　several
photographs；　and　carried　a　vivid　impression　in　their　minds。　
Hilda　appeared　to　be　about　two　hundred　miles　in　diameter。
　　　
〃How　do　you　account　for　that　living　world；〃　Bearwarden　asked
Cortlandt；　〃on　your　theory　of　size　and　longevity？〃
　　　
〃There　are　two　explanations；〃　replied　Cortlandt；　〃if　the　theory；
as　I　still　believe；　is　correct。　　Hilda　has　either　been　brought　to
this　system　from　some　other　less　matured；　in　the　train　of　a
comet；　and　been　captured　by　the　immense　power　of　〃Jupiter；　which
might　account　for　the　eccentricity　of　its　orbit；　or　some　acci