and　the　good…tempered　fellow　did　not　explain。　　Now　and　then　he
  climbed　up　by　cramp…irons　riveted　to　the　walls；　but　kept　the
  inspection　to　himself。　　He　arranged　and　rearranged；　he　plunged
  his　hand　rapidly　into　certain　mysterious　boxes；　singing　in　one
  of　the　falsest　of　voices　an　old　French　refrain　to　enliven
  the　situation。
  Barbicane　observed　with　some　interest　that　his　guns　and　other
  arms　had　not　been　damaged。　　These　were　important；　because；
  heavily　loaded；　they　were　to　help　lessen　the　fall　of　the
  projectile；　when　drawn　by　the　lunar　attraction　（after　having
  passed　the　point　of　neutral　attraction）　on　to　the　moon's
  surface；　a　fall　which　ought　to　be　six　times　less　rapid　than　it
  would　have　been　on　the　earth's　surface；　thanks　to　the　difference
  of　bulk。　　The　inspection　ended　with　general　satisfaction；　when
  each　returned　to　watch　space　through　the　side　windows　and　the
  lower　glass　coverlid。
  There　was　the　same　view。　　The　whole　extent　of　the　celestial
  sphere　swarmed　with　stars　and　constellations　of　wonderful
  purity；　enough　to　drive　an　astronomer　out　of　his　mind！　　On　one
  side　the　sun；　like　the　mouth　of　a　lighted　oven；　a　dazzling　disc
  without　a　halo；　standing　out　on　the　dark　background　of　the　sky！
  On　the　other；　the　moon　returning　its　fire　by　reflection；　and
  apparently　motionless　in　the　midst　of　the　starry　world。　　Then；　a
  large　spot　seemingly　nailed　to　the　firmament；　bordered　by　a
  silvery　cord；　it　was　the　earth！　　Here　and　there　nebulous　masses
  like　large　flakes　of　starry　snow；　and　from　the　zenith　to　the　nadir；
  an　immense　ring　formed　by　an　impalpable　dust　of　stars；　the　〃Milky
  Way；〃　in　the　midst　of　which　the　sun　ranks　only　as　a　star　of　the
  fourth　magnitude。　　The　observers　could　not　take　their　eyes　from
  this　novel　spectacle；　of　which　no　description　could　give　an
  adequate　idea。　　What　reflections　it　suggested！　　What　emotions
  hitherto　unknown　awoke　in　their　souls！　　Barbicane　wished　to　begin
  the　relation　of　his　journey　while　under　its　first　impressions；
  and　hour　after　hour　took　notes　of　all　facts　happening　in　the
  beginning　of　the　enterprise。　　He　wrote　quietly；　with　his　large
  square　writing；　in　a　business…like　style。
  During　this　time　Nicholl；　the　calculator；　looked　over　the
  minutes　of　their　passage；　and　worked　out　figures　with
  unparalleled　dexterity。　　Michel　Ardan　chatted　first　with
  Barbicane；　who　did　not　answer　him；　and　then　with　Nicholl；　who
  did　not　hear　him；　with　Diana；　who　understood　none　of　his
  theories；　and　lastly　with　himself；　questioning　and　answering；
  going　and　coming；　busy　with　a　thousand　details；　at　one　time　bent
  over　the　lower　glass；　at　another　roosting　in　the　heights　of　the
  projectile；　and　always　singing。　　In　this　microcosm　he
  represented　French　loquacity　and　excitability；　and　we　beg　you　to
  believe　that　they　were　well　represented。　　The　day；　or　rather
  （for　the　expression　is　not　correct）　the　lapse　of　twelve　hours；
  which　forms　a　day　upon　the　earth；　closed　with　a　plentiful　supper
  carefully　prepared。　　No　accident　of　any　nature　had　yet　happened
  to　shake　the　travelers'　confidence；　so；　full　of　hope；　already
  sure　of　success；　they　slept　peacefully；　while　the　projectile
  under　an　uniformly　decreasing　speed　was　crossing　the　sky。
  CHAPTER　IV
  A　LITTLE　ALGEBRA
  The　night　passed　without　incident。　　The　word　〃night；〃　however；
  is　scarcely　applicable。
  The　position　of　the　projectile　with　regard　to　the　sun　did
  not　change。　　Astronomically；　it　was　daylight　on　the　lower　part；
  and　night　on　the　upper；　so　when　during　this　narrative　these
  words　are　used；　they　represent　the　lapse　of　time　between　rising
  and　setting　of　the　sun　upon　the　earth。
  The　travelers'　sleep　was　rendered　more　peaceful　by　the
  projectile's　excessive　speed；　for　it　seemed　absolutely　motionless。
  Not　a　motion　betrayed　its　onward　course　through　space。　　The　rate
  of　progress；　however　rapid　it　might　be；　cannot　produce　any
  sensible　effect　on　the　human　frame　when　it　takes　place　in　a
  vacuum；　or　when　the　mass　of　air　circulates　with　the　body　which
  is　carried　with　it。　　What　inhabitant　of　the　earth　perceives　its
  speed；　which；　however；　is　at　the　rate　of　68；000　miles　per　hour？
  Motion　under　such　conditions　is　〃felt〃　no　more　than　repose；　and
  when　a　body　is　in　repose　it　will　remain　so　as　long　as　no　strange
  force　displaces　it；　if　moving；　it　will　not　stop　unless　an
  obstacle　comes　in　its　way。　　This　indifference　to　motion　or
  repose　is　called　inertia。
  Barbicane　and　his　companions　might　have　believed　themselves
  perfectly　stationary；　being　shut　up　in　the　projectile；　indeed；
  the　effect　would　have　been　the　same　if　they　had　been　on　the
  outside　of　it。　　Had　it　not　been　for　the　moon；　which　was
  increasing　above　them；　they　might　have　sworn　that　they　were
  floating　in　complete　stagnation。
  That　morning；　the　3rd　of　December；　the　travelers　were　awakened　by
  a　joyous　but　unexpected　noise；　it　was　the　crowing　of　a　cock
  which　sounded　through　the　car。　　Michel　Ardan；　who　was　the　first
  on　his　feet；　climbed　to　the　top　of　the　projectile；　and　shutting
  a　box；　the　lid　of　which　was　partly　open；　said　in　a　low　voice；
  〃Will　you　hold　your　tongue？　　That　creature　will　spoil　my　design！〃
  But　Nicholl　and　Barbicane　were　awake。
  〃A　cock！〃　said　Nicholl。
  〃Why　no；　my　friends；〃　Michel　answered　quickly；　〃it　was　I　who
  wished　to　awake　you　by　this　rural　sound。〃　　So　saying；　he　gave
  vent　to　a　splendid　cock…a…doodledoo；　which　would　have　done　honor
  to　the　proudest　of　poultry…yards。
  The　two　Americans　could　not　help　laughing。
  〃Fine　talent　that；〃　said　Nicholl；　looking　suspiciously　at　his　companion。
  〃Yes；〃　said　Michel；　〃a　joke　in　my　country。　　It　is　very　Gallic；
  they　play　the　cock　so　in　the　best　society。〃
  Then　turning　the　conversation：
  〃Barbicane；　do　you　know　what　I　have　been　thinking　of　all　night？〃
  〃No；〃　answered　the　president。
  〃Of　our　Cambridge　friends。　　You　have　already　remarked　that　I　am
  an　ignoramus　in　mathematical　subjects；　and　it　is　impossible　for
  me　to　find　out　how　the　savants　of　the　observatory　were　able　to
  calculate　what　initiatory　speed　the　projectile　ought　to　have　on
  leaving　the　Columbiad　in　order　to　attain　the　moon。〃
  〃You　mean　to　say；〃　replied　Barbicane；　〃to　attain　that　neutral
  point　where　the　terrestrial　and　lunar　attractions　are　equal；
  for；　starting　from　that　point；　situated　about　nine…tenths　of　the
  distance　traveled　over；　the　projectile　would　simply　fall　upon
  the　moon；　on　account　of　its　weight。〃
  〃So　be　it；〃　said　Michel；　〃but；　once　more；　how　could　they
  calculate　the　initiatory　speed？〃
  〃Nothing　can　be　easier；〃　replied　Barbicane。
  〃And　you　knew　how　to　make　that　calculation？〃　asked　Michel　Ardan。
  〃Perfectly。　　Nicholl　and　I　would　have　made　it；　if　the
  observatory　had　not　saved　us　the　trouble。〃
  〃Very　well；　old　Barbicane；〃　replied　Michel；　〃they　might　have　cut
  off　my　head；　beginning　at　my　feet；　before　they　could　have　made
  me　solve　that　problem。〃
  〃Because　you　do　not　know　algebra；〃　answered　Barbicane　quietly。
  〃Ah；　there　you　are；　you　eaters　of　_x_^1；　you　think　you　have　said
  all　when　you　have　said　‘Algebra。'〃
  〃Michel；〃　said　Barbicane；　〃can　you　use　a　forge　without　a　hammer；
  or　a　plow　without　a　plowshare？〃
  〃Hardly。〃
  〃Well；　algebra　is　a　tool；　like　the　plow　or　the　hammer；　and　a
  good　tool　to　those　who　know　how　to　use　it。〃
  〃Seriously？〃
  〃Quite　seriously。〃
  〃And　can　you　use　that　tool　in　my　presence？〃
  〃If　it　will　interest　you。〃
  〃And　show　me　how　they　calculated　the　initiatory　speed　of　our　car？〃
  〃Yes；　my　worthy　friend；　taking　into　consideration　all　the
  elements　of　the　problem；　the　distance　from　the　center　of　the
  earth　to　the　center　of　the　moon；　of　the　radius　of　the　earth；　of
  its　bulk；　and　of　the　bulk　of　the　moon；　I　can　tell　exactly　what
  ought　to　be　the　initiatory　speed　of　the　projectile；　and　that　by
  a　simple　formula。〃
  〃Let　us　see。〃
  〃You　shall　see　it；　only　I　shall　not　give　you　the　real　course
  drawn　by　the　projectile　between　the　moon　and　the　earth　in
  considering　their　motion　round　the　sun。　　No；　I　shall　consider
  these　two　orbs　as　perfectly　motionless；　which　will　answer　all
  our　purpose。〃
  〃And　why？〃
  〃Because　it　will　be　trying　to　solve　the　problem　called　‘the
  problem　of　the　three　bodies；'　for　which　the　integral　calculus　is
  not　yet　far　enough　advanced。〃
  〃Then；〃　said　Michel　Ardan；　in　his　sly　tone；　〃mathematics　have
  not　said　their　last　word？〃
  〃Certainly　not；〃　replied　Barbicane。
  〃Well；　perhaps　the　Selenites　have　carried　the　integral　calculus
  farther　than　you　have；　and；　by　the　bye；　what　is　this
  ‘integral　calculus？'〃
  〃It　is　a　calculation　the　converse　of　the　differential；〃　replied
  Barbicane　seriously。
  〃Much　obliged；　it　is　all　very　clear；　no　doubt。〃
  〃And　now；〃　continued　Barbicane；　〃a　slip　of　paper　and　a　bit　of
  pencil；　and　before　a　half…hour　is　over　I　will　have　found　the
  required　formula。〃
  Half　an　hour　had　not　elapsed　before　Barbicane；　raising　his　head；
  showed　Michel　Ardan　a　page　covered　with　algebraical　signs；　in
  which　the　general　formula　for　the　solution　was　contained。
  〃Well；　and　does　Nicholl　understand　what　that　means？〃
  〃Of　course；　Michel；〃　replied　the　captain。　　〃All　these　signs；
  which　seem　cabalistic　to　you；　form　the　plainest；　the　clearest；
  and　the　most　logical　language　to　those　who　know　how　to　read　it。〃
  〃And　you　pretend；　Nicholl；〃　asked　Mi