a journey in other worlds-第37节

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account　for　its　size；　and　for　the　Nautical　Almanac's　statement
that　there　is　a　'small　and　variable'　inclination　to　its　orbit；
while　Io　and　Europa　revolve　exactly　in　the　plane　of　Jupiter's
equator。〃
　　　
They　had　about　as　long　a　journey　before　them　as　they　had　already
made　in　going　from　the　earth　to　Jupiter。　　The　great　planet　soon
appeared　as　a　huge　crescent；　since　it　was　between　them　and　the
sun；　its　moons　became　as　fifth…　and　sixth…magnitude　stars；　and　in
the　evening　of　the　next　day　Jupiter's　disk　became　invisible　to
the　unaided　eye。　　Since　there　were　no　way　stations；　in　the　shape
of　planets　or　asteroids；　between　Jupiter　and　Saturn；　they　kept
the　maximum　repulsion　on　Jupiter　as　long　as　possible；　and　moved
at　tremendous　speed。　　Saturn　was　somewhat　in　advance　of　Jupiter
in　its　orbit；　so　that　their　course　from　the　earth　had　been　along
two　sides　of　a　triangle　with　an　obtuse　angle　between。　　During　the
next　four　terrestrial　days　they　sighted　several　small　comets；　but
spent　most　of　their　time　writing　out　their　Jovian　experiences。　
During　the　sixth　day　Saturn's　rings；　although　not　as　much　tilted
as　they　would　be　later　in　the　planet's　season；　presented　a　most
superb　sight；　while　they　spun　in　the　sun's　rays。　　Soon　after　this
the　eight　moons　became　visible；　and；　while　slightly　reducing　the
Callisto's　speed；　they　crossed　the　orbits　of　Iapetus；　Hyperion；
and　Titan；　when　they　knew　they　were　but　seven　hundred　and　fifty
thousand　miles　from　Saturn。
　　　
〃I　am　anxious　to　ascertain；〃　said　Cortlandt；　〃whether　the
composition　of　yonder　rings　is　similar　to　that　of　the　comet
through　which　we　passed。　　I　am　sure　they　shine　with　more　than
reflected　light。〃
　　　
〃We　have　been　in　the　habit；〃　said　Ayrault；　〃of　associating　heat
with　light；　but　it　is　obvious　there　is　something　far　more　subtle
about　cometary　light　and　that　of　Saturn's　rings；　both　of　which
seem　to　have　their　birth　in　the　intense　cold　of　interplanetary
space。〃
　　　
Passing　close　to　Mimas；　Saturn's　nearest　moon；　they　supplemented
its　attraction；　after　swinging　by；　by　their　own　strong　pull；
bringing　their　speed　down　to　dead　slow　as　they　entered　the
outside　ring。　　At　distances　often　of　half　a　mile　they　found
meteoric　masses；　sometimes　lumps　the　size　of　a　house；　often　no
larger　than　apples；　while　small　particles　like　grains　of　sand
moved　between　them。　　There　were　two　motions。　　The　ring　revolved
about　Saturn；　and　the　particles　vibrated　among　themselves；
evidently　kept　apart　by　a　mutual　repulsion；　which　seemed　both　to
increase　and　decrease　faster　than　gravitation；　for　on　approaching
one　another　they　were　more　strongly　repelled　than　attracted；　but
when　they　separated　the　repulsion　decreased　faster　than　the
attraction；　so　that　after　a　time　divergence　ceased；　and　they
remained　at　fixed　distances。
　　　
The　Callisto　soon　became　imbued　with　motion　also；　but　nothing
ever　struck　it。　　When　any　large　mass　came　unusually　near；　both　it
and　their　car　emitted　light；　and　they　rapidly　separated。　　The
sunlight　was　not　as　strong　here　as　it　had　been　when　they　entered
the　comet；　and　as　they　penetrated　farther　they　were　better　able
to　observe　the　omnipresent　luminosity。　　They　were　somewhat
puzzled　by　the　approach　of　certain　light…centres；　which　seemed　to
contain　nothing　but　this　concentrated　brightness。　　Occasionally
one　of　these　centres　would　glow　very　brightly　near　them；　and
simultaneously　recede。　　At　such　times　the　Callisto　also　glowed；
and　itself　recoiled　slightly。　　At　first　the　travellers　could　not
account　for　this；　but　finally　they　concluded　that　the　centres
must　be　meteoric　masses　consisting　entirely　of　gases；　possessing
weight　though　invisible。
　　　
〃We　have　again　to　face；〃　said　Cortlandt；　〃that　singular　law　that
till　recently　we　did　not　suppose　existed　on　earth。　　All　kinds　of
suppositions　have　been　advanced　in　explanation　of　these　rings。　
Some　writers　have　their　thickness；　looked　at　from　the　thin　edge；
as　four　hundred　miles；　some　one　hundred；　and　some　but　forty。　　One
astronomer　of　the　nineteenth　century；　a　man　of　considerable
eminence；　was　convinced　that　they　consisted　of　sheets　of　liquid。　
Now；　it　should　be　obvious　that　no　liquid　could　maintain　itself
here　for　a　minute；　for　it　would　either　fall　upon　the　planet　as　a
crushing　hail；　or；　if　dependent　for　its　shape　on　its　own
tenacity；　it　would　break　if　formed　of　the　toughest　steel；　on
account　of　the　tremendous　weight。　　Any　number　of　theories　have
been　advanced　by　any　number　of　men；　but　in　weight　we　have　the
rub。　　No　one　has　ever　shown　how　these　innumerable　fragments
maintain　themselves　at　a　height　of　but　a　few　thousand　miles　above
Saturn；　withstanding　the　giant's　gravitation…pull。　　Their　rate　of
revolution；　though　rapid；　does　not　seem　fast　enough　to　sustain
them。　　Neither　have　I　ever　seen　it　explained　why　the　small
fragments　do　not　fall　upon　the　large　ones；　though　many
astronomers　have　pictured　the　composition　of　these　rings　as　we
find　they　exist。　　Nor　do　we　know　why　the　molecules　of　a　gas　are
driven　farther　apart　by　heat；　while　their　activity　is　also
increased；　though　if　this　activity　were　revolution　about　one
another　to　develop　the　centrifugal；　it　would　not　need　to　be　as
strong　then　as　when　they　are　cold　and　nearer　together。　　There　may
be　explanations；　but　I　have　found　none　in　any　of　the　literature　I
have　read。　　It　seems　to　me　that　all　this　leads　to　but　one
conclusion；　viz。：　apergy　is　the　constant　and　visible　companion　of
gravitation；　on　these　great　planets　Jupiter　and　Saturn；　perhaps
on　account　of　some　peculiar　influence　they　possess；　and　also　in
comets；　in　the　case　of　large　masses；　while　on　earth　it　appears
naturally　only　among　moleculesthose　of　gases　and　every　other
substance。〃
　　　
〃I　should　go　a　step　further；〃　said　Bearwarden；　〃and　say　our　earth
has　the　peculiarity；　since　it　does　not　possess　the　influence
necessary　to　generate　naturally　a　great　or　even　considerable
development　of　apergy。　　The　electricity　of　thunderstorms；
northern　lights；　and　other　forces　seems　to　be　produced　freely；
but　as　regards　apergy　our　planet's　natural　productiveness　appears
to　be　small。〃
　　　
The　omnipresent　luminosity　continued；　but　the　glow　was　scarcely
bright　enough　to　be　perceived　from　the　earth。
　　　
〃I　believe；　however；〃　said　Bearwarden；　referring　to　this；　〃that
whenever　a　satellite　passes　near　these　fragments；　preferably　when
it　enters　the　planet's　shadow；　since　that　will　remove　its　own
light；　it　will　create　such　activity　among　them　as　to　make　the
luminosity　visible　to　the　large　telescopes　or　gelatine　plates　on
earth。〃
　　　
〃Now；〃　said　Ayrault；　〃that　we　have　evolved　enough　theories　to
keep　astronomers　busy　for　some　time；　if　they　attempt　to　discuss
them；　I　suggest　that　we　alight　and　leave　the　abstract　for　the
concrete。〃
　　　
Whereupon　they　passed　through　the　inner　ring　and　rapidly　sank　to
the　ground。



　　　　　　　　　　　　　　　　　　　　　　　　　　　　BOOK　III。
　
　　　　　　　　　　　　　　　　　　　　　　　　　　　CHAPTER　I。

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　SATURN。

Landing　on　a　place　about　ten　degrees　north　of　the　equator；　so
that　they　might　obtain　a　good　view　of　the　great　ringssince　ON
the　line　only　the　thin　edge　would　be　visiblethey　opened　a
port…hole　with　the　same　caution　they　had　exercised　on　Jupiter。　
Again　there　was　a　rush　of　air；　showing　that　the　pressure　without
was　greater　than　that　within；　but　on　this　occasion　the　barometer
stopped　at　thirty…eight；　from　which　they　calculated　that　the
pressure　was　nineteen　pounds　to　the　square　inch　on　their　bodies；
instead　of　fifteen　as　at　sea…level　on　earth。　　This　difference　was
so　slight　that　they　scarcely　felt　it。　　They　also　discarded　the
apergetic　outfits　that　had　been　so　useful　on　Jupiter；　as
unnecessary　here。　　The　air　was　an　icy　blast；　and　though　they
quickly　closed　the　opening；　the　interior　of　the　Callisto　was
considerably　chilled。　
　　　
〃We　shall　want　our　winter　clothes；〃　said　Bearwarden；　〃it　might　be
more　comfortable　for　us　exactly　on　the　equator；　though　the　scene
at　night　will　be　far　finer　here；　if　we　can　stand　the　climate。　
Doubtless　it　will　also　be　warmer　soon；　for　the　sun　has　but　just
risen。〃
　　　
〃I　suspect　this　is　merely　one　of　the　cold　waves　that　rush　towards
the　equator　at　this　season；　which　corresponds　to　about　the　10th
of　our　September；〃　replied　Cortlandt。　　〃The　poles　of　Saturn　must
be　intensely　cold　during　its　long　winter　of　fourteen　and　three
quarter　years；　for；　the　axis　being　inclined　twenty…seven　degrees
from　the　perpendicular　of　its　orbit；　the　pole　turned　from　the　sun
is　more　shut　off　from　its　heat　than　ours；　and　in　addition　to　this
the　mean　distancemore　than　eight　hundred　and　eighty　million
milesis　very　great。　　Since　the　chemical　composition　of　the　air
we　have　inhaled　has　not　troubled　our　lungs；　it　is　fair　to　suppose
we　shall　have　no　difficulty　in　breathing。〃
　　　
Having　dressed　themselves　more　warmly；　and　seen　by　a　thermometer
they　had　placed　outside　that　the　temperature　was　thirty…eight
degrees　Fahrenheit；　which　had　seemed　very　cold　compared　with　the
warmth　inside　the　Callisto；　they　again　opened　the　port…hole；　this
time　leaving　it　open　longer。　　What　they　had　felt　before　was
evidently　merely　a　sudden　gust；　for　the　air　was　now　comparatively
calm。
　　　
Finding　that　the　doctor's　prediction　as　to　the　suitability