,,! ,,e>?',s ,,beg9n+ ---------------------------------------- -------------------------------- ,,works ,,by ,,sir ,,rob]t ,s4 ,,ball1 ,m4,a41 ,,ll4,d41 ,f4,r4,s4 ,,! ,,/ory ,,( ,,! ,,heav5s4 ,) #bd ,col\r$ ,plates & ,num]\s ,illu/rations4 ,new ,edition4 #ajs4 #f;d4 ,,! ,,e>?',s ,,beg9n+4 ,) #d ,col\r$ ,plates & ,num]\s ,illu/rations4 ,new ,edition4 #gs4 #f;d4 ,,! ,,/ory ,,( ,,! ,,sun4 ,) #aa ,full ,page ,col\r$ & o!r ,plates & ,num]\s ,illu/rations4 #gs4 #f;d4 ,,/>-,,l&4 ,be+ ,talks ) ,"y ,p ab\t ! ,wond]s ( ! ,heav5s ,) ,rembr&t ,frontispiece & #id ,illu/rations 9 ,text4 #gs4 #f;d4 ,,cassell ,,company1 ,,limit$1 ,london1 ,new ,york1 ,toronto ,melb\rne4 ---------------------------------------- -------------------------------- ,illu/ration3 ,,an ,,engli% ,,sunset ,,t+$ ,,by ,,krakatoa4 7,f a ,draw+ made at ,*elsea at #d4dj p4m4 on ,nov4 #bf?1 #ahhc1 by ,mr4 ,w4 ,ascr(t47 ---------------------------------------- -------------------------------- ,,! ,,e>?',s ,,beg9n+ ,,by ,,sir ,,rob]t ,s4 ,,ball1 ,m4,a41 ,,ll4,d41 ,f4,r4,s4 ,l[ndean ,pr(essor ( ,a/ronomy & ,geometry 9 ! ,univ]sity ( ,cambridge1 ,au?or ( 8,/>-,l&10 8,! ,/ory ( ! ,heav5s10 etc4 etc4 ,,) ,,f\r ,,col\r$ ,,plates ,,& ,,num]\s ,,illu/rations ,,new ,,edition ,,cassell ,,& ,,company1 ,,limit$ ,,london1 ,,new ,,york1 ,,toronto ,,& ,,melb\rne ,,mcmix ---------------------------------------- -------------------------------- ,fir/ ,edition ,octob] #aija4 ,repr9t$ ,decemb] #aija1 #aijc4 ,enl>g$ ,edition #aiji4 ,,all ,,rights ,,res]v$ ---------------------------------------- -------------------------------- ,,=eword ,,s9ce ^! lectures 7 deliv]$ 9 ! ,royal ,in/itution ( ,great ,brita9 !re has be5 mu* advance 9 our k ( a/ronomy4 ,! simultane\s advance 9 o!r sci5ces alli$ ) a/ronomy has be51 p]haps1 ev5 m rem>kable4 ,i am glad to avail myself ( ! opportunity af=d$ by a new issue ( 8,! ,e>?'s ,beg9n+0 to draw att5tion to c]ta9 rec5t developm5ts ( sci5ce :i* relate 9 a v /rik+ way to ! subject ( ?is volume1 namely1 ! fam\s ,nebul> ,!ory ( ! orig9 ( ! sol> sy/em4 ,x appe>s to me t ^! rec5t developm5ts t5d to r$uce greatly1 ev5 if !y d n altoge!r remove1 ! *ief out/&+ difficulty :i* has hi!rto ret>d$ ! acceptance ( ! ,nebul> ,!ory4 ,i h expla9$ 9 ,*apt] ,,vi4 ^? views ( ,helmholtz :i* h = s long provid$ ! receiv$ explanation ( ! ma9t5ance ( sol> heat4 ,calculation %[s t if ! sun's heat has be5 ma9ta9$ by ! contraction ( ! primval nebula--& ?is 0 ! supposition ( ,helmholtz--! orb ( day _c h radiat$ ) its pres5t int5sity = a p]iod mu* long] ?an tw5ty million ye>s4 ,b f ! evid5ce ( geology x mu/ n[ be admitt$ t ! exi/5ce ( our e>?1 inde$ ev5 t "p ( its exi/5ce dur+ :i* x has be5 ! abode ( life1 has endur$ = a p]iod f> 9 excess ( t :i* ?is calculation w\ld all[4 ,x !re=e seems to foll[ t ! !ory ( ,helmholtz does n provide an adequate explanation ( su* an amaz+ ph5om5on z ! cont9uance ( a suffici5t supply ( sunbeams ?r\gh\t ! va/ p]iods dem&$ by geological ph5om5a4 ,!re is ano!r entirely diff]5t l9e ( reason+ by :i* ,pr(essor ,john ,joly has rec5tly taught u ! imm5se antiquity ( our e>?4 ,8 argum5t is bas$ ^u an e/imate ( ! "t t mu/ h elaps$ s9ce ! wat]s ( ! ocean1 :i* _h previ\sly be5 su/a9$ 9 ! great vap\rs ( ! atmosph]e1 7 deposit$ 9 ! ocean b$s4 ,:5 ! e>? _h become suffici5tly cool to p]mit ( ! vap\rs n[ =m+ ! ocean pass+ f ! gase\s to ! liquid =m1 ! oceans desc5d$ f ! heav5s above to ! e>? b5ea? 9 ! =m ( fre% wat]4 ,9 ! lapse ( subsequ5t ages ! sea has become salt because ord9>y riv] wat]1 :i* always conta9s "s small quantity ( salt 9 solution1 is cont9ually be>+ salt d[n to ! sea4 ,no d\bt wat] is con/antly be+ ab/ract$ f ! sea by evaporation1 b only fre% wat] is ?us remov$1 s 9 ?is cycle ( *ange ! salt 9 ! sea mu/ be gradually accumulat+4 ,?us1 day by day1 ?\gh no d\bt extremely sl[ly1 ! sea has be5 gr[+ m & m salt4 ,pr(essor ,joly has made an e/imate ( ! quantity ( salt daily add$ to ! sea by all ! riv]s ( ! globe4 ,he has also made an e/imate ( ! total quantity ( salt :i* is at pres5t conta9$ 9 ! sea4 ,he has ?us ! means ( =m+ an e/imate ( ! numb] ( ye>s necess>y = ! sea to h become conv]t$ f its primval fre%ness to its pres5t saltness4 ,8 result is n a little a/oni%+4 ,! saltness ( ! sea c\ld n be acc\nt$ = unless ! riv]s _h be5 runn+ into ! sea = at lea/ a hundr$ million ye>s4 ,?is p]iod is five times z long z ! total p]iod dur+ :i* ! sun c\ld h be5 %9+ if ! ,helmholtzian view 7 correct4 ,( c\rse1 !re are _m elem5ts ( unc]ta9ty 9 su* a calculation4 ,we h assum$ t ! total fl[ ( ! riv]s is practically con/ant1 & t our e/imate fairly repres5ts ! av]age sal9ity ( riv] wat]4 ,we h also made a l>ge assumption 9 suppos+ t we h accurately e/imat$ ! total volume ( salt 9 ! oceans4 ,b tak5 9 conjunction ) ! geological evid5ce already ref]r$ to1 tak5 9 conjunction ) ! imm5se p]iods ( "t t h be5 requir$ = ! evolution ( life on ! globe by ! process ( natural selection1 ! conclusion arriv$ at is inevitable4 ,x seems impossible to d\bt t ! sun mu/ h be5 %9+ & t our sol> sy/em mu/ h exi/$ 9 practically ! same =m z x is at pres5t = p]iods enorm\sly great] ?an w\ld h be5 possible if ! heat ( ! sun _h be5 su/a9$ by ! sol> contraction only4 ,! difficulty "h indicat$ has be5 n unju/ly consid]$ ! mo/ s]i\s difficulty ) :i* ! developm5t ( mod]n physical & a/ronomical sci5ce has be5 confront$4 ,! "t dur+ :i* ! sun mu/ h la/$1 accord+ to ! receiv$ explanation ( ! s\rce ( its heat & ! "t dur+ :i* ! sun has actually la/$1 z %[n by ! facts ( geology1 pres5t a wide discrepancy4 ,sci5ce dem&s t "s reconciliation mu/ be effect$1 yet h[ is t to be accompli%$8 ,!re is only "o possible solution ( ! problem4 ,x is obvi\s t !re mu/ h be5 "s va/ res]ve ( heat 9 ! sun 9 comp>ison ) :i* ! quantity ( heat yield$ by ! contraction may be deem$ insignificant4 ,until ?is new s\rce ( sol> en]gy _h be5 discov]$1 our k ( ! physics ( ! sol> sy/em lay "u a reproa*1 :i* x 0 ! b\nd5 duty ( m5 ( sci5ce to endeav\r to remove4 ,dur+ ! la/ few ye>s l9es ( rese>* c>ri$ on 9 v>i\s directions h1 9 a mo/ unexpect$ mann]1 ?r[n mu* light on ! orig9 ( ! sun's heat1 &1 inde$1 we may n[ say t ! great difficulty :i* has = s long tr\bl$ u no long] exi/s 9 a s]i\s =m4 ,rec5t discov]ies %[ t matt] possesses /ores ( en]gy :i*1 if n actually b\ndless1 are enorm\sly 9 excess ( :at _h be5 previ\sly deem$ possible4 ,^! /ores ( en]gy are available = supply+ ! heat ( ! sun1 & x is easy to %[ t !y are amply suffici5t to furni% ! necess>y sunbeams = ev5 ! longe/ p]iods dur+ :i* ! claims ( geology ma9ta9 t ! sun mu/ h be5 %9+4 ,! rese>*es ( ,pr(essor ,sir ,j4 ,j4 ,?omson h %[n h[ corpuscles ( matt] are sometimes mov+ ) velocities enorm\sly great] ?an ^? ( any cele/ial body ) :i* a/ronomy _h made u acqua9t$4 ,! case ( high corpuscul> velocity :i* is mo/ g5]ally kn[n is t pres5t$ by radium1 ! p>ticles f :i* are be+ cont9ually %ot =? 9 myriads4 ,x is q true t ea* ( ^! corpuscles is excessively small1 & x may be useful to give ! foll[+ illu/ration be>+ on ! subject4 ,?9k ( a numb] repres5t$ by unity foll[$ by eighte5 cyph]s1 or m concisely z #ajah1 & ?9k ( a l9e a kilometre long4 ,if t l9e 7 divid$ into #ajah p>ts1 ea* ( ^? p>ts w\ld repres5t ! diamet] ( a corpuscle ( radium4 ,if t l9e 7 multipli$ by #ajah1 ! result w\ld be a l9e s long t a ray ( light w\ld require a p]iod ( no less ?an #ajj1jjj ye>s to pass f "o end to ! o!r4 ,^! corpuscles ( radium are1 no d\bt1 excessively small1 b ! velocity ) :i* !y are mov+ is comp>able ) ! velocity ( light4 ,:5 a mat]ial object is mov+ ) a velocity ( t magnitude ! en]gy x conta9s 9 virtue ( t velocity is inde$ />tl+4 ,a v small gra9 ( s& w\ld1 if mov+ ) ! velocity ( light1 conta91 9 virtue ( t motion1 ! equival5t ( m heat ?an c\ld be produc$ by ! combu/ion ( a ton ( ! be/ coal4 ,! late ,dr4 ,w4 ,e4 ,wilson %[$ t if an excessively m9ute p]c5tage ( radium %\ld be f\nd to exi/ 9 ! sun1 x w\ld completely acc\nt = ! su/5tation ( ! sol> heat1 & ! ,hon4 ,r4 ,/rutt has %[n t ! m9ute quantities ( radium :i* he has prov$ to exi/ 9 t]re/rial rocks w\ld enorm\sly protract ! e>?'s cool+4 ,^! discov]ies h1 9 fact1 completely *ang$ ! outlook on ! problem ( ! sun's heat1 &1 ?\gh no d\bt mu* has yet to be done be=e ! :ole subject is cle>$ up1 ! great difficulty may be reg>d$ z vanqui%$4 ,?us1 ! discov]y ( radium1 & ! wond]ful ph5om5a associat$ !re)1 has po9t$ out a possible escape f "o ( ! grave/ difficulties 9 sci5ce4 ,! mo/ notable fact :i* em]ges f ! mod]n /udy ( ! /ructure ( ! heav5s is ! ev]-increas+ significance & importance ( ! spiral nebul4 ,! foll[+ pages w h fail$ 9 _! object if !y h n succe$$ 9 emphasis+ ! fact t ! spiral nebula is1 next to a fix$ /> itself1 ! mo/ *>act]i/ic type ( object 9 ! mat]ial univ]se4 ,) e increase 9 ! p[] ( ! telescope1 & ) e developm5t ( ! application ( photography to cele/ial portraiture1 ! importance ( ! spiral /ructure 9 nebul becomes ( ev]-increas+ int]e/4 ,b ,i rev]t to ?is subject "h = ! purpose ( tak+ notice ( a sugge/ive pap] by ,mr4 ,c4 ,ea/on 9 ! 8,a/rophysical ,j\rnal10 ,vol4 ,,xii41 ,no4 #b1 ,septemb]1 #aijj1 entitl$ 8,a ,new ,!ory ( ! ,milky ,way40 ,?is pap] advances ! /rik+ view t ! ,milky ,way is itself a spiral nebula1 & c]ta9ly ! consid]ations adduc$ by ,mr4 ,ea/on seem to ju/ify 8 rem>kable conclusion4 ,x is fir/ to be notic$ t ! ,milky ,way ext5ds z an irregul> b& completely r\nd ! heav5s1 & t x foll[s v ne>ly ! c\rse ( a great circle4 ,! curi\s convolutions ( ! ,milky ,way1 ! v>y+ /> d5sities ( its diff]5t p>ts1 w\ld1 z %[n by ,mr4 ,ea/on1 be completely acc\nt$ = if ! ,milky ,way 7 a mighty spiral4 ,we view ! ord9>y cele/ial spirals f ! outside at an imm5se di/ance 9 space4 ,we view ! ,milky ,way f a position )9 ! circuit ( ! nebula4 ,x has1 h[ev]1 be5 %[n by ,mr4 ,ea/on t ! c5tre ( ! ,spiral ,nebula is n exactly at ! sun4 ,! c5tre ( ! ,milky ,way is ne> t sup]b region ( ! galaxy :i* lies 9 ,cygnus4 ,?us1 ! significance ( ! spiral /ructure 9 ! univ]se becomes greatly enhanc$4 ,! spirals ab\nd 9 e "p ( ! heav5s2 !y are plac$ 9 e conceivable position & 9 e possible plane2 !y h e range 9 size f comp>atively small objects1 ^: de/9y is to evolve into a sy/em l our sol> sy/em1 up to /up5d\s objects :i* include a myriad ( su* sy/ems4 ,!re is n[ ! fur!r int]e/ t z ! sun & ! sol> sy/em are includ$ )9 ! ,milky ,way1 & z ! ,milky ,way is a spiral1 ?is e>? ( ours is itself at ?is mom5t a con/itu5t "p ( a great spiral4 ,f9ally1 ,i w\ld say t1 s f> z ,i h be5 able to und]/& ! subject1 x appe>s to me t e advance 9 our k ( ! heav5s t5ds m & m to support ! gr& outl9es ( ! ,nebul> ,!ory z imag9$ by ,kant & ,laplace4 ,r4 ,s4 ,b4 ,may #a1 #aiji4 ---------------------------------------- -------------------------------- ,,cont5ts ,,*apt] ,,page ,i4 --,,introduction #a ,,ii4 --,,! ,,problem ,,/at$ #ba ,,iii4 --,,! ,,fire-,,mi/ #ci ,,iv4 --,,nebul--,,app>5t ,,& ,,real #eb ,v4 --,,! ,,heat ,,( ,,! ,,sun #ge ,,vi4 --,,h[ ,,! ,,sun',s ,,heat ,,is ,,ma9ta9$ #ie ,,vii4 --,,! ,,hi/ory ,,( ,,! ,,sun #aab ,,viii4 --,,! ,,e>?',s ,,beg9n+ #abb ,,ix4 --,,e>?quakes ,,& ,,volcanoes #aeh ,x4 --,,spiral ,,& ,,planet>y ,,nebul #aia ,,xi4 --,,! ,,un]r+ ,,guide #bjg ,,xii4 --,,! ,,evolution ,,( ,,! ,,sol> ,,sy/em #bdf ,,xiii4 --,,! ,,unity ,,( ,,mat]ial ,,9 ,,! ,,heav5s #bfa ,,& ,,! ,,e>? ,,xiv4 --,,! ,,fir/ ,,concord #bid ,,xv4 --,,! ,,second ,,concord #cjh ,,xvi4 --,,! ,,?ird ,,concord #cbd ,,xvii4 --,,objections ,,to ,,! ,,nebul> ,,!ory #ccg ,,xviii4 --,,! ,,beg9n+ ,,( ,,! ,,nebula #cdh ,,xix4 --,,conclud+ ,,*apt] #cfa ,,app5dices #cfi ,,index #chb ---------------------------------------- -------------------------------- ,,li/ ,,( ,,illu/rations ,,fig4 ,,page ,an ,engli% ,sunset t+$ by ,krakatoa ,frontispiece 7col\r7 #a4 ,immanuel ,kant 7f an old pr9t7 #g #b4 ,a ,fa9t ,diffus$ ,nebulosity #ag #c4 ,! ,crab ,nebula #ai #d4 ,jupit] #be #e4 ,nebul\s ,region & ,/>-clu/] #cc #f4 ,! ,great ,nebula 9 ,orion #da #g4 ,! ,dumb-bell ,nebula #de #h4 ,! ,crossley ,reflector #di #i4 ,! ,clu/] 9 ,h]cules #ec #aj4 ,spectra ( ! ,sun & ,capella #fb #aa4 ,spectrum ( ,nebula 9 ,orion & ,spectrum #fd ( ,:ite ,/> #ab4 ,sol> ,spectra ) ,bright ,l9es & ,d>k #fi ,l9es dur+ ,eclipse #ac4 ,! ,nebul 9 ! ,pleiades #ga #ad4 ,! ,sun #ha #ae4 ,i4 ,spectrum ( ! ,sun4 ,,ii4 ,spectrum ( #he ,arcturus #af4 ,brooks' ,comet & ,meteor ,trail #hi #ag4 ,argus & ! surr\nd+ ,/>s & #ajc ,nebulosity #ah4 ,trifid ,nebula 9 ,sagitt>ius #aje #ai4 ,to illu/rate ! ,hi/ory ( ! ,sun #aac #bj4 ,sol> ,corona #aag #ba4 ,! ,great ,comet ( #ahhb #aai #bb4 ,special ,!rmomet] = use 9 ,deep #abi ,bor+s #bc4 ,at ! ,bottom ( ! ,great ,bore #adj #bd4 ,?ree consecutive ,%ells ( ! ,e>?'s #ade ,cru/ #be4 ,e>?quake ,r\tes f ,japan to ! ,isle #aga ( ,wight ,%[+ ,localities ( ,e>?quakes #age 7col\r7 #bf4 ,%[+ ,coa/s invad$ by ! ,great #agi ,sea-waves f ,krakatoa ,! ,e>ly ,/age ( ! ,eruption ( #ahj ,krakatoa 7col\r7 #bg4 ,spread ( ! ,air-wave f ,krakatoa to #ahc ! ,antipodes #bh4 ,! great ,spiral ,nebula #aic #bi4 ,h[ to f9d ! great ,spiral ,nebula #aif #cj4 ,a gr\p ( ,nebul #aii #ca4 ,a ,ray ,nebula #bja #cb4 ,portion ( ! ,milky ,way #bje #cc4 ,a ,spiral ,nebula se5 ,edgewise #baa #cd4 ,a =e%ort5$ ,spiral #bab #ce4 ,edge-view ( a ,spiral boldly %[n #bac #cf4 ,to illu/rate ,mom5t ( ,mom5tum #bbc #cg4 ,saturn #bcc #ch4 ,! ,r+ ,nebula 9 ,lyra #bdi #ci4 ,lun> ,crat]s3 ,hyg9us & ,albategnius #bee #dj4 ,a rem>kable ,spiral #beg #da4 ,a cle>ly-cut ,spiral #bei #db4 ,! ,h & ,k ,l9es 9 ! ,photographic #bgf ,sol> ,spectrum #dc4 ,spectrum ( ,comet %[+ ,c>bon ,l9es #bij ,! ,sol> ,spectrum 7col\r7 #bij #dd4 ,spectrum ( ! ,sun dur+ ,eclipse #bia #de4 ,a ,spiral pres5t$ ,edgewise #bif #df4 ,! ,plane ( a ,planet's ,orbit #bih #dg4 ,a ,"r ,angle divid$ into ,t5 ,p>ts #cja #dh4 ,illu/ration ( ! ,second ,concord #cji #di4 ,orbits ( ! ,e>?1 ,eros & ,m>s #cac #ej4 ,i4 ,a ,natural ,sy/em4 ,,ii4 ,an ,unnatural #cah ,sy/em #ea4 ,an elongat$ irregul> ,nebula #cbi #eb4 ,two-bran*$ ,spiral #cde #ec4 ,clu/] ) ,/>s ( ! #ag? ,magnitude #cec #ed4 ,spectrum ( ,nova ,p]sei 7#aija7 #cei #ee4 ,! ,apt]yx3 a ,w+less ,bird ( ,new #cfe ,zeal& #ef4 ,skeleton ( ! ,apt]yx1 %[+ #cff ,rudim5t>y ,w+s #eg4 ,spirals 9 o!r ,dep>tm5ts ( ,nature3 #cfg ,=am9if] #eh4 ,ditto ditto ,nautilus #cfg #ei4 ,to illu/rate a ,!orem 9 ! #cfi ,attraction ( ,gravitation #fj4 ,fir/ ,law ( ,motion exemplifies ,con/ant #cge ,mom5t ( ,mom5tum #fa4 ,a useful ,geometrical ,proposition #cgf #fb4 ,accel]ation ( ,mom5t ( ,mom5tum #cgf equals ,mom5t ( ,=ce #fc4 ,mom5t ( ,mom5tum unalt]$ by #chj ,collision ---------------------------------------- -------------------------------- ,,! ,,e>?',s ,,beg9n+4 ,,*apt] ,i4 ,,introduction4 ,! ,e>?'s ,beg9n+--,! ,nebul> ,!ory--,_m ,applications ( ! ,!ory--,! ,f\nd]s ( ! ,doctr9e--,kant1 ,laplace1 ,william ,h]s*el3 ,_! ,diff]5t ,me?ods ( ,"w--,! ,va/ness ( ! ,problem--,voltaire's ,fable--,! ,oak-,tree--,! ,me?od ( ,/udy+ ! ,subject--,inadequacy ( our ,"t ,conceptions4 ,i ,,try 9 ^! lectures to give "s acc\nt ( an exceptionally great subject--a subject1 ,i ought r to say1 ( sublime magnific5ce4 ,x may1 ,i believe1 be affirm$ )\t exagg]ation t ! !me :i* is to occupy our att5tion repres5ts ! mo/ d>+ height to :i* ! human intellect has ev] v5tur$ to so> 9 its ef=ts to und]/& ! great op]ations ( ,nature4 ,! e>?'s beg9n+ relates to ph5om5a ( su* magnitude & importance t ! tempor>y conc]ns :i* usually engage our ?\ghts mu/ be =gott5 9 its pres5ce4 ,our p]sonal affairs1 ! affairs ( ! nation1 & ( ! empire--inde$1 ( all nations & ( all empires--nay1 ev5 all human affairs1 pa/1 pres5t1 & to come1 %r9k into utt] insignificance :5 we are to consid] ! maje/ic subject ( ! evolution ( t sol> sy/em ( :i* our e>? =ms a "p4 ,we %all obta9 a glimpse ( :at t evolution has be5 9 ! mighty *apt] ( ! book ( ,nature on :i* we are n[ to ent]4 ,! nebul> !ory discloses ! beg9n+ ( ?is e>? itself4 ,x po9ts out ! m>vell\s process by :i* f orig9al *aos ! firm globe on :i* we /& 0 gradually evolv$4 ,x %[s h[ ! f\ndations ( ?is solid e>? h be5 laid1 & h[ x is t we h l& to tread on & air to brea!4 ,b ! subject has a scope f> wid] ?an m]ely 9 its relation to our e>?4 ,! nebul> !ory acc\nts = ! beg9n+ ( t great & glori\s orb ! sun1 :i* presides ov] ! sy/em ( revolv+ planets1 guides !m 9 _! pa?s1 illum9ates !m ) its light1 & /imulates ! activities ( _! inhabitants ) its g5ial w>m?4 ,! nebul> !ory expla9s h[ x comes ab\t t ! sun /ill cont9ues 9 ^! latt] days to %9e ) ! brilliance & w>m? t x _h ?r\gh\t ! pa/ ages ( human hi/ory & ! va/ly great] p]iods ( geological "t4 ,!n1 z ano!r supreme a*ievem5t1 x discloses ! orig9 ( ! planets :i* accompany ! sun1 & %[s h[ !y h come to run _! mighty c\rses2 & x tells u h[ revolv+ satellites h be5 associat$ ) ! planets4 ,! nebul> !ory has1 inde$1 a rem>kable relation to all objects belong+ to t wond]ful s*eme :i* we call ! sol> sy/em4 ,x %\ld also be notic$ t ! nebul> !ory (t5 br+s facts ( ! mo/ div]se "* into /rik+ apposition4 ,z x acc\nts = ! cont9u$ ma9t5ance ( ! sol> radiation1 s x also acc\nts = t b5efic5t rotation by :i* ea* cont95t1 aft] ! enjoym5t ( a day "u ! invigorat+ rays ( ! sun1 passes 9 due alt]nation into ! repose ( night4 ,! nebul> !ory is ready ) an explanation ( ! m>vell\s /ructure reveal$ 9 ! r+s ( ,saturn1 & x %[s at ! same "t h[ ! volcanoes ( ! moon acquir$ _! pa/ ph5om5al activity1 & :y1 aft] ages ( activity1 !y h n[ at la/ become ext9ct4 ,) equal v]satility ! nebul> !ory w expla9 :y a colli] exp]i5ces increas+ heat z he desc5ds ! coalpit1 & :y ! planet ,jupit] is m>k$ ) ^? belts :i* h s mu* int]e/ = ! a/ronom]4 ,! nebul> !ory (f]s an imm$iate explanation ( ! e>?quake :i* wr\ght su* awful de/ruction at ,lisbon1 :ile x also po9ts out ! cause ( t heal+ w>m? ( ! wat]s at ,ba?4 ,above all1 ! nebul> !ory expla9s t pe]less discov]y ( cosmical *emi/ry :i* decl>es t ^? p>ticul> elem5ts ( :i* ! sun is compos$ are no o!r ?an ! elem5ts :i* =m ! e>? b5ea? our feet4 ,:5 a doctr9e ( su* transc5d5t importance is propos$ = our acceptance1 x is fitt+ t we %\ld look1 9 ! fir/ in/ance1 to ! s\rce f :i* ! doctr9e has emanat$4 ,x w\ld already h made good its claim to mo/ c>eful he>+1 ?\gh n p]haps to necess>y acceptance1 if x came to u be>+ cr$5tials :i* prove x to be ! outcome ( ! ?\ght & rese>* ( "o end[$ ) ! highe/ ord] ( intellect4 ,if ! nebul> !ory _h be5 prop\nd$ by only a s+le great lead] ( ?\ght1 ! sublimity ( ! subject ) :i* x deals w\ld h compell$ ! att5tion ( ^? :o love to /udy ! book ( ,nature4 ,if x _h appe>$ t a second inve/igator1 also fam\s = ! l(tie/ intellectual a*ievem5t1 _h giv5 to ! nebul> !ory ! sanction ( 8 "n1 a v mu* /rong] claim = its consid]ation w\ld at once h be5 e/abli%$4 ,if x %\ld fur!r appe> t yet a ?ird philosoph]1 a man :o 0 also an intellectual giant1 _h be5 conduct$ to some:at simil> conclusions1 we %\ld admit1 ,i ne$ h>dly say1 t ! argum5t _h be5 pres5t$ ) /ill fur!r =ce4 ,x may also be obs]v$ t !re might ev5 be c]ta9 conditions 9 ! "w ( ! ?ree philosoph]s :i* w\ld make = additional /r5g? 9 ! cause advocat$2 if x %\ld be f\nd t ea* ( ! great m5 ( sci5ce _h arriv$ at ! same conclusion irrespective ( ! o!rs1 &1 inde$1 9 total ignorance ( ! l9e ( ?\ght :i* 8 illu/ri\s compe]s 7 pursu+1 ?is w\ld1 ( c\rse1 be 9 itself a corroboration4 ,if1 f9ally1 ! me?ods ( rese>* adopt$ by ^! inve/igators _h be5 :olly diff]5t1 al?\gh conv]g+ to ! e/abli%m5t ( ! !ory1 !n ev5 ! mo/ sceptical might be dispos$ to conc$e ! />tl+ claim :i* ! !ory made ^u 8 reason & 8 imag9ation4 ,all ! conditions t ,i h assum$ h be5 fulfill$ 9 ! pres5tation ( ! nebul> !ory to ! sci5tific _w4 ,x w\ld n be possible to po9t to ?ree names m em95t 9 _! respective bran*es ( k ?an ^? ( ,kant1 ,laplace1 & ,william ,h]s*el4 ,kant occupies a unique position by ! pr(undity & bread? ( 8 philosophical /udies2 ,laplace appli$ ! great discov]ies ( ,newton to ! inve/igation ( ! movem5ts ( ! heav5ly bodies1 publi%+ ! results 9 8 immortal "w1 ,mcanique ,cle/e2 ,h]s*el has be5 ! greate/ & ! mo/ orig9al obs]v] ( ! heav5s s9ce ! telescope 0 inv5t$4 ,x is n a little rem>kable t ! great philosoph] f 8 pr(\nd m$itation1 ! great ma!matician f a life devot$ to calculations ab\t ! laws ( ,nature1 ! great obs]v] f s\nd+ ! dep?s ( ! firmam5t1 %\ld ea* 9 ! pursuit ( 8 own l9e ( "w h be5 l$ to believe t ! gr& c\rse ( ,nature is ess5tially express$ by ! nebul> !ory4 ,!re h be5 diff]5ces ( detail 9 ! ?ree !ories2 inde$1 !re h be5 diff]5ces 9 po9ts :i* are by no means unimportant4 ,?is 0 unavoidable 9 ! case ( work]s along l9es s di/9ct1 & ( a subject :]e _m ( ! elem5ts 7 /ill unkn[n1 z inde$ _m are /ill4 ,ev5 at ! pres5t day no man c give a complete acc\nt ( :at has happ5$ 9 ! great evolution4 ,b ! monum5tal fact rema9s t ^! ?ree mo/ sagaci\s m5 ( sci5ce1 ^: lives 7 devot$ to ! pursuit ( k1 ea* approa*+ ! subject f 8 own direction1 ea* pursu+ 8 c\rse 9 ignorance ( :at ! o!rs 7 do+1 7 sub/antially l$ to ! same result4 ,! progress ( k s9ce ! "t :5 ^! great m5 liv$ has confirm$1 9 ways :i* we %all endeav\r to set =?1 ! sublime doctr9e to :i* _! g5ius _h conduct$ !m4 ,immanuel ,kant1 ^: gr&fa!r 0 a ,scotsman1 0 born 9 #agbd at ,knigsb]g1 :]e 8 life 0 sp5t z a pr(essor 9 ! ,univ]sity1 & :]e he di$ 9 #ahjd4 ,9 ! ann\ncem5t ( ! application ( ! pr9ciple ( evolution to ! sol> sy/em1 ,laplace 0 prec$$ by ?is great ,g]man philosoph]4 ,! pr(\nd ?9k] :o exp\nd$ ! fam\s doctr9e ( "t & space did n disda9 to all[ 8 att5tion to be also occupi$ ) ?+s m mat]ial ?an ! subtleties ( metaphysical inve/igation4 ,z a natural philosoph] ,kant 0 mu* 9 advance ( 8 "t4 ,8 speculations on que/ions relat+ to ! op]ations 9 progress 9 ! mat]ial univ]se are 9 rem>kable con=mity ) :at is n[ accept$ z ! result ( mod]n inve/igation4 ,kant outl9$ ) a firmness inspir$ by g5ius t nebul> !ory to :i* ,laplace subsequ5tly & indep5d5tly gave a m def9ite =m1 & :i* n[ be>s 8 "n4 ,kant's fam\s "w ) :i* we are n[ conc]n$ appe>$ 9 #agee4a ,9 x he laid d[n ! immortal pr9ciple ( ! nebul> !ory4 ,! greatness ( ?is book is ackn[l$g$ by all :o h read x1 & not)/&+ t ! progress ( k has made x obvi\s t _m ( ! /atem5ts x conta9s mu/ n[ receive modification1 ,kant's "w conta9s ! ess5tial pr9ciple affirm+ t ! e>?1 ! sun1 ! planets1 & all ! bodies n[ =m+ ! sol> sy/em did really orig9ate f a va/ contract+ nebula4 ,9 lat] ye>s ,kant's att5tion 0 div]t$ f ^! physical que/ions to t pr(\nd sy/em ( philosophy ) :i* 8 "n is *iefly associat$4 ,! nebul> !ory is !re=e to be reg>d$ z incid5tal to ,kant's great lifework r ?an z =m+ a v l>ge & important "p ( x4 ,footnote #a3 ,we are n[ =tunately able to ref] ! ,engli% read] to ! "w ( ,pr(essor ,w4 ,ha/ie1 ,d4,d41 entitl$ 8,kant's ,cosmogony10 ,glasg[1 #aijj4 ,kant's mo/ int]e/+ c>e] is *>m+ly describ$ 9 ,de ,qu9cey's 8,la/ ,days ( ,immanuel ,kant40 ,illu/ration3 ,,immanuel ,,kant4 7,f an old ,pr9t47 ,at ! close ( ! la/ c5tury1 :ile ,france 0 9 ! ?roes ( ! ,revolution1 a s*ool ( ,fr5* ma!maticians 0 engag$ 9 ! accompli%m5t ( a task :i* m>k$ an epo* 9 ! hi/ory ( human ?\ght4 ,=emo/ among ! ma!maticians :o devot$ _! en]gies to ! discussion ( ! great problems ( ! univ]se 0 ! illu/ri\s ,laplace4 ,z a p]sonal fri5d ( ,napoleon1 ,laplace receiv$ m>k$ di/9ction f ! ,emp]or1 :o 0 himself en\gh ( a ma!matician to be able to e/imate at _! true value ! magnific5t results to :i* ,laplace 0 conduct$4 ,x 0 at ! comm5cem5t ( ,kant's c>e]1 & be=e 8 great lifework 9 metaphysics 0 und]tak51 t he 0 l$ to 8 nebul> !ory ( ! sol> sy/em4 ,9 ! case ( ,laplace1 on ! o!r h&1 ! nebul> !ory 0 n advanc$ until ! close ( ! great "w ( 8 life4 ,! ,mcanique ,cle/e _h be5 writt51 & ! fame ( its au?or _h be5 e/abli%$ = all "t2 & !n 9 a few pages ( a subsequ5t volume1 call$ ! ,sy/me du ,monde1 he laid d[n 8 fam\s nebul> !ory4 ,9 t small space he gave a wond]ful outl9e ( ! hi/ory ( ! sol> sy/em4 ,he _h n read t hi/ory 9 any books or manuscripts2 he _h n le>n$ x f any anci5t inscriptions2 he _h tak5 x direct f ! great book ( ,nature4 ,influ5c$ by ! caution s *>act]i/ic ( "o ^: life _h be5 devot$ entirely to ! pursuit ( ! mo/ accurate ( all ! sci5ces1 ,laplace accompani$ 8 ann\ncem5t ( ! nebul> !ory ) becom+ words ( w>n+4 ,! great philosoph] po9t$ out t !re are two me?ods ( discov]+ ! tru?s ( a/ronomy4 ,"s tru?s may be discov]$ by obs]v+ ! heav5ly bodies ) telescopes1 by measur+ ) e c>e _! dim5sions & _! positions1 & by foll[+ _! movem5ts ) assidu\s wat*fulness4 ,b !re is ano!r totally diff]5t me?od :i* has enabl$ _m rem>kable discov]ies to be made 9 a/ronomy2 = discov]ies may be made by ma!matical calculations :i* h z _! basis ! num]ical facts obta9$ by actual obs]vation4 ,?is ma!matical me?od (t5 yields results f> m pr(\nd ?an any :i* c be obta9$ by ! a/ronom]'s telescope4 ,! p5 ( ! ma!matician is inde$ an in/rum5t :i* sometimes anticipates revelations t are subsequ5tly confirm$ by actual obs]vation4 ,x is an in/rum5t :i* frequ5tly p]=ms ! highly useful task ( *eck+ ! d$uctions t might too ha/ily be drawn f telescopic obs]vations4 ,x is an in/rum5t ! scope ( ^: discov]ies embraces regions immeasurably beyond ! rea* ( ! greate/ telescope4 ,! p5 ( ! ma!matician c give u in=mation z to ev5ts :i* took place long be=e telescopes came into exi/5ce--nay1 ev5 unnumb]$ ages prior to ! adv5t ( man on ?is e>?4 ,laplace 0 c>eful to say t ! nebul> !ory :i* he sket*$ mu/ necess>ily be judg$ by a /&>d diff]5t f t :i* we apply to a/ronomical tru?s reveal$ by telescopic obs]vation or asc]ta9$ by actual calculation4 ,! nebul> !ory1 said ! great ,fr5* ma!matician1 has to be receiv$ ) caution1 inasmu* z f ! nature ( ! case x _c be v]ifi$ by obs]vation1 nor does x admit ( pro( possess+ ma!matical c]ta9ty4 ,a l>ge "p ( ^! lectures w be devot$ to ! evid5ce be>+ ^u ?is fam\s doctr9e4 ,let x suffice "h to rem>k t ! quantity ( evid5ce n[ available is va/ly great] ?an x 0 a hundr$ ye>s ago1 & fur!rmore1 t !re are l9es ( evid5ce :i* c n[ be foll[$ :i* 7 :olly undreamt ( 9 ! days ( ,kant & ,laplace4 ,! p>ticul> canons laid d[n by ,laplace1 to :i* we h j ref]r$1 are p]haps n reg>d$ z s absolutely b9d+ 9 mod]n days4 ,if we 7 to reject belief 9 ev]y?+ :i* _c be prov$ ei!r by ! te/imony ( actual eye-witnesses or by /rict ma!matical d$uctions1 x w\ld1 ,i fe>1 f>e badly ) n a few great dep>tm5ts ( mod]n sci5ce4 ,x w n be necess>y to d m at pres5t ?an j to m5tion1 9 illu/ration ( ?is1 ! great doctr9e ( ! evolution ( life1 :i* acc\nts = ! exi/+ races ( plants & animals1 includ+ ev5 man himself4 ,i ne$ h>dly say t ! ,d>w9ian !ory1 :i* claims t man has come by l9eal desc5t f animals ( a l[] type1 admits ( no pro( by ma!matics2 x receives assur$ly no direct te/imony f eye witnesses2 & yet ! fact t man has s desc5d$ is1 ,i suppose1 n[ almo/ univ]sally admitt$4 ,9 ! case ( ! great ,g]man philosoph]1 z well z 9 ! case ( ! great ,fr5* ma!matician1 ! enunciation & ! promulgation ( _! nebul> !ories 7 m]ely incid5tal to ! important sci5tific und]tak+s ) :i* _! respective lives 7 ma9ly occupi$4 ,! relation ( ! nebul> !ory to ! ma9 lifework ( ! ?ird philosoph] ,i h nam$1 has be5 some:at diff]5t4 ,:5 ,william ,h]s*el con/ruct$ ! telescopes ) :i*1 9 conjunction ) 8 illu/ri\s si/]1 he conduct$ 8 long night-wat*es1 he discov]$ ?\s&s ( new nebul2 he may1 9 fact1 be said to h creat$ nebul> a/ronomy z we n[ "k x4 ,ev] m$itat+ on ! objects :i* 8 telescopes br\ght to light1 ev] /riv+ to s\nd ! my/]ies ( ! univ]se1 ,h]s*el p]ceiv$ t betwe5 a nebula :i* 0 m]ely a diffus$ /a9 ( light on ! sky1 & an object :i* 0 h>dly di/+ui%able f a /> ) a slight haze ar\nd x1 e int]m$iate grade c\ld be f\nd4 ,9 ?is way he 0 l$ to ! spl5did discov]y :i* ann\nc$ ! gradual trans=mation ( nebul into />s4 ,we h already not$ h[ ! pr(\nd ma!matician 0 conduct$ to a view ( ! orig9 ( ! sol> sy/em :i* 0 sub/antially id5tical ) t :i* _h be5 arriv$ at by ! consummate metaphysician4 ,! int]e/ is greatly increas$ :5 we f9d t simil> conclusions 7 drawn indep5d5tly f ! telescopic "w ( ! mo/ dilig5t & mo/ fam\s a/ronomical obs]v] :o has ev] liv$4 ,n f ab/ract speculation l ,kant1 n f ma!matical sugge/ion l ,laplace1 b f accurate & labori\s /udy ( ! heav5s 0 ! great ,william ,h]s*el l$ to ! conception ( ! nebul> !ory ( evolution4 ,t ?ree diff]5t m5 ( sci5ce1 approa*+ ! /udy ( p]haps ! greate/ problem :i* ,nature (f]s u f po9ts ( view s fundam5tally diff]5t1 %\ld h be5 l$ sub/antially to ! same result1 is a rem>kable incid5t 9 ! hi/ory ( k4 ,surely ! !ory introduc$ "u su* auspices & su/a9$ by su* a weight ( te/imony has ! v /ronge/ claim on our att5tion & respect4 ,9 ! discussion on :i* we are ab\t to ent] 9 ^! lectures we mu/ (t5 be prep>$ to make a special ef=t ( ! imag9ation to help u to realise h[ greatly ! scale ( ! op]ations on :i* ! att5tion is fix$ transc5ds t ( ! ph5om5a ) :i* our ord9>y affairs are conc]n$4 ,our eyes c explore a region ( space :i*1 h[ev] va/1 mu/ /ill be only inf9itesimal 9 comp>ison ) ! ext5t ( space itself4 ,not)/&+ all t telescopes c d = u1 our k ( ! univ]se mu/ be necess>ily re/rict$ to a m]e speck 9 space1 a speck :i* be>s to ! :ole ( space a ratio less--we might p]haps say inf9itely less--?an t :i* ! area ( a s+le daisy be>s to ! area ( ! cont95t :]e t daisy blooms4 ,b we ne$ n rep9e at ?is limitation2 a :ole life devot$ to ! /udy ( a daisy w\ld n be long en\gh to explore all ! my/]ies ( its life4 ,9 l mann] ! duration ( ! human race w\ld n be long en\gh to explore adequately ev5 t small "p ( space :i* is submitt$ = our exam9ation4 ,b x is n m]ely ! necess>y limits ( our s5ses :i* re/rict our opportunities = ! /udy ( ! great ph5om5a ( ! univ]se4 ,man's life is too %ort = ! purpose4 ,t our days are b a span is ! commonplace ( ! prea*]4 ,b x is a commonplace specially br\ght home to u 9 ! /udy ( ! nebul> !ory4 ,a man ( f\rscore w allude to 8 life z a long "o1 & no d\bt x may be consid]$ long 9 relation to ! ord9>y affairs ( our abode on e>?2 b :at is a p]iod ( eighty ye>s 9 ! hi/ory ( ! =mation ( a sol> sy/em 9 ! great laboratory ( ! univ]se8 ,su* a p]iod !n seems to be b a trifle--x is no?+4 ,eighty ye>s may be long en\gh to witness ! gr[? ( *ildr5 & gr&*ildr52 b x is too %ort = a s+le he>tbeat 9 ! great life ( ,nature4 ,ev5 ! longe/ lifetime is f> too brief to witness a p]ceptible advance 9 ! gr& trans=mation4 ,! p]iods ( "t dem&$ 9 ! great evolution %ad[$ =? by ! nebul> !ory utt]ly transc5d our ord9>y notions ( *ronology4 ,! dates at :i* supreme ev5ts occurr$ 9 ! cele/ial evolution are immeasurably m remote ?an any o!r dates :i* we are ev] call$ ^u to consid] 9 o!r dep>tm5ts ( sci5ce4 ,! "t ( ! /ory on :i* we are to be engag$ is e>li]1 f> e>li]1 ?an any date we h ev] le>n$ at s*ool1 or h ev] =gott5 s9ce4 ,! incid5ts ( t p]iod took place long be=e any date 0 writt5 9 figures--e>li] ?an any ( ^? v anci5t dates :i* ! geologi/s indicate n by figures inde$1 b by creatures ^: rema9s imb$d$ 9 ! rocks suffice to give a "* to ! p]iod ref]r$ to4 ,! geologi/ w specify "o epo* z t 9 :i* ! fossiliz$ bone ( "s huge ext9ct reptile 0 "p ( a liv+ animal2 he may specify ano!r by ! /atem5t t ! %ell ( "s beautiful ammonite 0 !n inhabit$ by a liv+ =m :i* swam 9 ! w>m primval seas4 ,! date ( our /ory has at lea/ ?is mu* c]ta9ty3 t x is prior--immeasurably prior--to ! "t :5 t m>vell\s ?+ :i* we call life fir/ came into be+4 ,voltaire has an in/ructive fable :i* ,i _c resi/ repeat+4 ,x w s]ve1 at all ev5ts1 to br+ be=e u ! way 9 :i* ! lapse ( "t ought to be reg>d$ by "o :o desires to view ! great op]ations ( ,nature 9 _! prop] proportions4 ,he tells h[ an inhabitant ( ! /> ,sirius w5t =? on a voyage ( exploration ?r\gh ! remote dep?s ( space4 ,9 ! c\rse ( 8 travels he visit$ _m o!r worlds1 & at l5g? rea*$ ,saturn1 t maje/ic orb1 :i* revolv$ ^u ! fronti] ( ! sol> sy/em1 z !n kn[n4 ,alight+ on ! r+$ globe = re/ & inve/igation1 ! ,sirian w&]]1 9 que/ ( k1 0 successful 9 obta9+ an int]view ) a /ately inhabitant ( ,saturn :o enjoy$ ! reputation ( exceptional le>n+ & wisdom4 ,! ,sirian hop$ to h "s improv+ conv]sation ) ?is sage :o dwelt on a globe s utt]ly unlike 8 own1 & :o _h su* opportunities ( /udy+ ! maje/ic processes ( ,nature 9 remote p>ts ( ! univ]se4 ,he ?\ght p]haps !y might be able to comp>e in/ructive notes ab\t ! con/itution ( ! suns & sy/ems 9 _! respective neighb\rhoods4 ,! visitor accord+ly prattl$ away gaily4 ,he op5$ all 8 little /ore ( k ab\t ! ,milky ,way1 ab\t ! ,great ,be>1 & ab\t ! great ,nebula 9 ,orion2 & !n paus+1 he ask$ :at ! ,saturnian _h to communicate 9 reply4 ,b ! philosoph] rema9$ sil5t4 ,eag]ly press$ to make "s response1 ! grave /ud5t :o dwelt on ! fronti] globe at la/ said 9 effect3 8,sirian1 ,i c tell y b little ( ,nature4 ,i c tell y inde$ no?+ t is really wor?y ( ! great !me :i* ,nature proposes2 = ! gr& op]ations ( ,nature are v sl[2 !y are s sl[ t ! great trans=mations 9 progress ar\nd u w\ld h to be wat*$ = a v long "t be=e !y c\ld be prop]ly und]/ood4 ,to obs]ve ,nature s z to p]ceive :at is really happ5+1 x w\ld be necess>y to h a long life2 b ! lives ( ! inhabitants ( ,saturn are n long2 none ( u ev] lives m ?an fifte5 ?\s& ye>s40 ,*ange is ! ord] ( ,nature4 ,_m *anges no d\bt take place rapidly1 b ! great *anges by :i* ! sy/em has be5 wr\ght into its pres5t =m1 ^? pr(\nd *anges :i* h produc$ results ( ! greate/ magnific5ce 9 cele/ial ar*itecture are extremely sl[4 ,we %\ld make a huge mi/ake if we imag9$ t *anges--ev5 imm5se *anges--are n 9 progress1 m]ely because our brief day is too %ort a p]iod :]e9 to p]ceive !m4 ,on ! village gre5 /&s an oak-tree1 a vet]an :i* "s say dates f ! "t ( ,william ! ,conqu]or1 b :i* all agree mu/ c]ta9ly h be5 a magnific5t piece ( timb] 9 ! days ( ,que5 ,elizabe?4 ,! *ildr5 play "u t tree j z _! p>5ts & _! gr&p>5ts did be=e !m4 ,a ye>1 a few ye>s1 ev5 a lifetime1 may %[ no appreciable *anges 9 a tree ( su* age & /ature4 ,its gir? does n p]ceptibly increase 9 su* a p]iod4 ,b suppose t a butt]fly ^: life la/s b a day or two 7 to pass 8 little span 9 & ab\t ?is v5]able oak4 ,he w\ld n be able to p]ceive any *anges 9 ! tree dur+ ! insignificant p]iod ov] :i* 8 little life ext5d$4 ,n alone ! mighty trunk & ! bran*es1 b ev5 ! v foliage itself w\ld seem ess5tially ! same 9 ! m9utes ( ! butt]fly's extreme old age z !y did 9 ! "t ( 8 life's m]idian or at ! e>lie/ mom5t ( 8 y\?4 ,to ! obs]vations ( a spectator :o view$ x "u su* ephem]al conditions ! oak-tree w\ld appe> /eadfa/1 & might incauti\sly be deem$ et]nal4 ,if ! butt]fly c\ld reflect on ! subject1 he might p]haps argue t !re c\ld n be any *ange 9 progress 9 ! oak-tree1 because al?\gh he _h obs]v$ x c>efully all 8 life he c\ld n detect any c]ta9 alt]ation4 ,he might !re=e n improbably draw ! prepo/]\s conclusion t ! oak-tree mu/ always h be5 j z l>ge & j z gre5 z he _h inv>iably kn[n x2 & he might also inf] t j z ! oak-tree is n[1 s w x rema9 = all "t4 ,illu/ration3 ,fig4 #b4--;,a ,,fa9t ,,diffus$ ,,nebulosity 7n4g4c4 #adii2 9 ,p]seus74 7,photograph$ by ,dr4 ,isaac ,rob]ts1 ,f4,r4,s47 ,9 our /udy ( ! heav5s we mu/ /rive to avoid inf]5ces s utt]ly fallaci\s z ^! :i* ,i h "h tri$ to illu/rate4 ,let x be grant$ t to our sup]ficial view ! sun & ! moon1 ! />s & ! con/ellations pres5t features :i* appe> to u z et]nal z ! bole ( ! oak seem$ to ! butt]fly4 ,b ?\gh ! sun may seem to u always ( ! same size & always ( ! same lu/re1 x w\ld be q wrong to inf] t ! lu/re & size ( ! sun are 9 tru? un*ang+4 ,! sun is no m un*ang+ ?an ! oak-tree is et]nal4 ,! sun & ! e>?1 no less ?an ! o!r bodies ( ! univ]se1 are 9 process ( a trans=mation no less a/oni%+ ?an t wond]ful trans=mation :i* 9 ! c\rse ( c5turies develops an acorn into ! giant ( ! =e/4 ,we c\ld n inde$ ) propriety apply to ! great trans=mation ( ! sun ! p>ticul> ^w gr[?2 ! "* ( ! sol> trans=mation _c be s describ$4 ,! oak-tree1 ( c\rse1 enl>ges ) its ye>s1 :ile ! sun1 on ! o!r h&1 is becom+ small]4 ,! resemblance betwe5 ! sun & ! oak-tree ext5ds no fur!r ?an t a trans=mation is tak+ place 9 ea*4 ,! rate at :i* ea* trans=mation is effect$ is b sl[2 ! gr[? ( ! oak is too sl[ to be p]ceiv$ 9 a day or two2 ! contraction ( ! sun is too sl[ to be appreciable )9 ! c5turies ( human hi/ory4 ,:atev] ! butt]fly's obs]vation might h sugge/$ ) reg>d to ! et]nity ( ! oak1 we "k !re 0 a "t :5 t oak-tree 0 n1 & we "k t a "t w come :5 t oak-tree w no long] be4 ,9 l mann] we "k !re 0 a "t :5 ! sol> sy/em 0 utt]ly diff]5t f ! sol> sy/em z we see x n[2 & we "k t a "t w come :5 ! sol> sy/em w be utt]ly diff]5t f t :i* we see at pres5t4 ,! mightie/ *anges are mo/ c]ta9ly 9 progress ar\nd u4 ,we mu/ n deem !m non-exi/5t1 m]ely because !y elude our scrut9y1 = our s5ses may n be quick en\gh to p]ceive ! small ext5t ( "s ( ^! *anges )9 our limit$ p]iod ( obs]vation4 ,! intellect 9 su* a case conf]s on man a p[] ( survey+ ,nature ) a p5etration immeasurably beyond t af=d$ by 8 organs ( s5se4 ,illu/ration3 ,fig4 #c4--,,! ,,crab ,,nebula 7n4g4c4 #aieb2 9 ,taurus74 7,photograph$ by ,dr4 ,isaac ,rob]ts1 ,f4,r4,s7 ,t ! great oak-tree :i* has liv$ = c5turies sprang f an acorn no "o c d\bt2 b :at is ! evid5ce on :i* we believe ?is to h be5 ! orig9 ( a vet]an ( ! =e/ :5 hi/ory & tradition are bo? sil5t8 ,9 ! abs5ce ( au!ntic docum5ts to trace ! gr[? ( t oak-tree f ! beg9n+1 h[ d we "k t x spr\t$ f an acorn8 ,! only reason we h = believ+ t ! oak-tree has gone ?r\gh ?is rem>kable developm5t is d$uc$ f ! obs]vation ( o!r oak-trees4 ,we "k ! acorn t has j spr\t$2 we "k ! "y sapl+ z ?ick z a walk+ /ick2 we "k ! vigor\s "y tree z /\t z a man's arm or z 8 body2 we "k ! tree :5 x fir/ approa*es ! dignity ( be+ call$ timb]2 we c !re=e obs]ve diff]5t trees grade by grade 9 a cont9u\s succession f ! acorn to ! mon>* ( five c5turies4 ,no "o d\bts = a mom5t t ! gr[? z witness$ 9 ! /ages exhibit$ by sev]al diff]5t trees1 gives a sub/antially accurate picture ( ! developm5t ( any individual tree4 ,su* is ! nature ( "o ( ! argum5ts :i* we apply to ! great problem be=e u4 ,we are to /udy :at ! sol> sy/em has be5 9 ! c\rse ( its hi/ory by ! /ages :i* we witness at ! pres5t mom5t 9 ! evolution ( o!r sy/ems ?r\gh\t ! univ]se4 ,we _c inde$ read ! hi/ory 9 "t1 b we c read x 9 space4 ,! mighty trans=mation ?r\gh :i* ! sol> sy/em has pass$1 & is ev5 n[ at ?is mom5t pass+1 _c be actually beheld by u poor creatures ( a day4 ,x might p]haps be survey$ by be+s ^: pulses c\nt$ c5turies1 z our pulses c\nt seconds1 by be+s ^: m9utes la/$ long] ?an ! dyna/ies ( human hi/ory1 by be+s to :om a ye> 0 comp>able ) ! p]iod s9ce ! e>? 0 "y1 & s9ce life began to move 9 ! wat]s4 ,may ,i1 ) all rev]5ce1 try to attune our ?\ghts to ! "t conceptions requir$ 9 ?is mighty !me by quot+ ^? noble l9es ( ! hymn-- 8,a ?\s& ages 9 ,?y sight ,are l an ev5+ gone1 ,%ort z ! wat* t ends ! night1 ,be=e ! ris+ sun40 ---------------------------------------- -------------------------------- ,,*apt] ,,ii4 ,,! ,,problem ,,/at$4 ,! ,great ,diurnal ,motion--,! ,di/9ction betwe5 ,/>s & ,planets--,! ,e>? no m ?an a ,planet--,relation ( ! ,/>s to ! ,sol> ,sy/em--,contra/ betwe5 ,aldeb>an & ,m>s--,illu/ration ( ,/>-di/ances--,! ,cele/ial ,p]spective--,illu/ration ( an ,attractive ,=ce--,in/ructive ,exp]im5ts--,! ,globe & ! ,t5nis ,ball--,! ,law ( ,gravitation--,! ,focal ,ellipse--,! ,sol> ,sy/em z x is n[ ,kn[n--,/atem5t ( ! ,great ,problem be=e u4 ,,:5 we raise our eyes to ! heav5s on a cle> night1 ?\s&s ( bright objects claim our att5tion4 ,we obs]ve t all ^! objects move z if !y 7 fa/5$ to ! inside ( an invisible sph]e4 ,!y are se5 gradually asc5d+ f ! ea/1 pass+ across ! s\?1 & 9 due c\rse s9k+ t[>ds ! we/4 ,! sun & ! moon1 z well z all ! o!r bodies1 alike p>ticipate 9 ?is great diurnal movem5t4 ,! :ole s*eme ( cele/ial objects seems to turn ar\nd ! two po9ts 9 ! heav5s t we call ! ,poles1 & s f> z ! pole 9 ! nor!rn hemisph]e is conc]n$1 its position is mo/ conv5i5tly indicat$ by ! proximity ( ! well-kn[n ,pole ,/>4 ,except ?is great diurnal motion1 ! va/ majority ( ! bodies on ! cele/ial sph]e h no o!r movem5t easily recognisable1 & c]ta9ly none :i* x is necess>y = u to consid] at pres5t4 ,! gr\ps 9 :i* ! />s h be5 arrang$ by ! poetical imag9ation ( ! anci5ts exi/ to-day1 z !y h exi/$ dur+ all ! ages s9ce !y 7 fir/ recognis$1 )\t any noticeable alt]ation 9 _! l9eam5ts4 ,! /ately belt ( ,orion is se5 to-night z ,job beheld x ?\s&s ( ye>s ago2 ! />s 9 ! ,pleiades h n alt]$ _! positions1 relatively to ! adjac5t />s nor _! arrangem5t among !mselves1 s9ce ! "t :5 a/ronom]s 9 e>ly ,greece obs]v$ !m4 ,all ! bodies :i* =m ^! gr\ps are !re=e kn[n z fix$ />s4 ,b besides ! fix$ />s1 :i* exi/ 9 _m ?\s&s1 &1 ( c\rse1 ! sun & ! moon1 !re are o!r cele/ial objects1 s few 9 numb] z to be c\nt$ on ! f+]s ( "o h&1 :i* are 9 no s5se fix$ />s4 ,x is q true t ^! w&]+ bodies1 or planets1 z !y are g5]ally designat$1 be> a c]ta9 resemblance to ! fix$ />s4 ,9 ea* case ! /> or ! planet appe>s z a bright po9t1 l _m o!r bright po9ts 9 ! heav5s1 & /> & planet bo? p>ticipate 9 ! g5]al diurnal motion4 ,b a little att5tion w %[ t :ile ! />s1 prop]ly s call$1 reta9 _! relative places = mon?s & ye>s & c5turies1 ! planets *ange _! places s rapidly t 9 ! c\rse ( a few nights x is q easy to see1 ev5 )\t ! aid ( any in/rum5t1 t !y h indep5d5t motion4 ,we may comp>e ! movem5ts ( ^! bodies to ! movem5t ( ! moon1 :i* nightly %ifts h] place ov] a long track 9 ! sky2 & al?\gh we are n able to see ! />s 9 ! vic9ity ( ! sun1 inasmu* z ! brilliant light ( ! orb qu5*es ! feeble radiance f su* />s1 !re is no d\bt t1 did we see !m1 ! sun itself w\ld seem to move relatively to ! />s1 j z does ! moon & j z d ! planets4 ,! fundam5tal di/9ction betwe5 />s & planets 0 notic$ by acute obs]v]s ( ,nature 9 ! v e>lie/ times4 ,! names ( ! planets come to u z survivals f ! "t :5 ! sun1 ! moon1 & ! />s 7 objects ( wor%ip1 & !y come to u be>+ ! names ( ! deities ( :i* ^! mov+ globes 7 reg>d$ z ! symbols4 ,b x 0 n ! movem5ts ( ! planets alone :i* call$ = ! notice ( ! e>ly obs]v]s ( ! skies4 ,! brightness & c]ta9 o!r features peculi> to !m also attract$ ! att5tion ( ! primitive a/ronom]s4 ,!y c\ld n fail to obs]ve t :5 ! beautiful planet ,v5us 0 plac$ s z to be se5 to ! greate/ advantage1 h] orb 0 f> bright] ?an any o!r object 9 ! ho/ ( heav51 ! sun & ! moon bo? ( c\rse except$4 ,x 0 also obvi\s t ,jupit] at its be/ exce$$ ! />s 9 lu/re1 & sometimes approa*$ ev5 to t ( ,v5us itself4 ,?\gh ,m]cury 0 g5]ally s close to ! sun z to be invisible among its beams1 yet on ! r>e occasions :5 t planet 0 se51 j aft] sunset or j be=e sunrise1 its lu/re 0 su* z to m>k x out z "o ( ! rem>kable bodies 9 ! heav5s4 ,?us ! a/ronom]s ( ! e>lie/ ages po9t$ to ! five planets & ! sun & ! moon z ! sev5 w&]+ />s4 ,! dilig5t att5tion ( ! le>n$ ( e subsequ5t p]iod 0 giv5 to ! discov]y ( ! "* ( _! movem5ts4 ,! problems t ^! motions pres5t$ 71 h[ev]1 s difficult t n until aft] ! lapse ( ?\s&s ( ye>s did _! nature become und]/ood4 ,! supreme importance ( ! e>? appe>$ s obvi\s to ! e>ly a/ronom]s t x did n at fir/ occur to !m to assign to our e>? a position :i* w\ld r$uce x to ! same class z any ( ! cele/ial bodies4 ,! obvi\sly great size ( our globe1 ! fact t to ! un9/ruct$ s5ses ! e>? seem$ to be at re/1 :ile ! o!r bodies seem$ to be 9 motion1 & _m o!r analog\s circum/ances1 appe>$ to %[ t ! e>? mu/ be a body totally diff]5t f ! o!r objects di/ribut$ ar\nd u 9 space4 ,x 0 only by sl[ degrees1 & aft] mu* obs]vation & reflection1 & n a little controv]sy1 t at la/ ! true nature ( our sy/em 0 detect$4 ,^? :o h be5 br\ght up f *ildhood 9 full k ( ! rotation ( ! e>? & ( ! o!r fundam5tal facts relat+ to ! cele/ial sph]e1 w (t5 f9d x difficult to realise ! way su* problems mu/ h pres5t$ !mselves to ! obs]v]s ( old1 :o believ$1 z = c5turies m5 did believe1 t ! e>? 0 a plane ( indef9ite ext5t fix$ 9 space1 & t ! sun & ! planets1 ! moon & ! />s1 7 relatively small bodies ^: movem5ts mu/ be acc\nt$ = z be/ !y c\ld be1 consi/5tly ) ! fixity & flatness ( ! e>?4 ,illu/ration3 ,fig4 #d4--;,,jupit] 7,may #cj?1 #ahii1 #aj;h4 #i4em42 g4m4t474 7,e4 ,m4 ,antoniadi47 ,b at la/ x began to be se5 t ! e>? mu/ be relegat$ to a position inf9itely less important ?an t :i* ! untutor$ imag9ation assign$ to x4 ,x 0 f\nd t ! e>? 0 n an indef9ite plane2 x 0 r a globe pois$ 9 space1 )\t direct mat]ial support f any o!r body4 ,x 0 f\nd t ! e>? 0 turn+ r\nd on its axis3 :ile in/ead ( ! sun revolv+ ar\nd ! e>?1 x 0 mu* m correct to say t ! e>? revolv$ ar\nd ! sun4 ,! a/oni%+ tru? 0 !n disclos$ t ! five planets1 ,jupit] & ,saturn1 ,m]cury1 ,v5us & ,m>s1 /ood 9 a rem>kable relation to ! e>?4 ,= z ea* ( ^! planets 0 f\nd to revolve r\nd ! sun1 & z ! e>? also revolv$ r\nd ! sun1 ! assum$ diff]5ce 9 "* betwe5 ! e>? & ! planets t5d$ to vani% altoge!r4 ,!re 0 9 fact no ess5tial diff]5ce4 ,if inde$ ! e>? 0 small] ?an ,jupit] & ,saturn1 yet x 0 consid]ably great] & heavi] ?an ,m>s or ,m]cury1 & x 0 almo/ exactly ! same size & weight z ,v5us4 ,!re 0 cle>ly no?+ 9 ! "q ( bulk to indicate any m>k$ diff]5ce betwe5 our e>? & ! planets4 ,x 0 also obs]v$ t !re 0 no di/9ction to be drawn betwe5 ! way 9 :i* ! e>? revolv$ r\nd ! sun & ! movem5ts ( ! planets4 ,no d\bt ! e>? is n s ne> ! sun z ,m]cury2 x is n s ne> ! sun z ev5 ,v5us2 on ! o!r h& ! sun is ne>] ! e>? ?an ,m>s1 :ile ,jupit] is a long way fur!r (f ?an ,m>s1 & ,saturn is ev5 beyond ,jupit] aga94 ,x is ^! consid]ations :i* ju/ify u 9 reg>d+ our e>? z "o ( ! planets4 ,we h also to note ! ov]:elm+ magnitude ( ! sun 9 comp>ison ) any "o ( ! planets4 ,x w suffice to give a s+le illu/ration4 ,! sun is m ?an a ?\s& times z massive z ,jupit]1 & ,jupit] is ! greate/ ( ! planets4 ,?is latt] noble globe is 9 fact great] ?an all ! re/ ( ! planets put toge!r4 ,b be=e we c fully realise ! circum/ances ( ! sol> sy/em1 x w be necess>y to see h[ ! />s1 prop]ly s call$1 ent] into ! s*eme ( ?+s cele/ial4 ,! />s look s l ! planets t x has n infrequ5tly happ5$ t ev5 an exp]i5c$ a/ronom] has mi/ak5 "o = ! o!r4 ,! planet ,m>s is (t5 v l ! /> ,aldeb>an1 & !re are n a few fir/-magnitude />s :i* on a sup]ficial view closely resemble ,saturn4 ,b h[ great is ! intr9sic diff]5ce betwe5 a /> & a planet6 ,9 ! fir/ place we h to note t e planet is a d>k object l ?is e>? ( ours1 possess+ no light ( its own1 & dep5d5t entirely on ! sun = ! supply ( light by :i* x is illum9$4 ,b a /> is totally diff]5t4 ,! /> is n a d>k object1 b is really an object :i* is 9 itself int5sely lum9\s & brilliant2 ! /> is 9 fact a sun-l body4 ,h[ !n1 x may well be ask$1 does a /> l ,aldeb>an1 :i* is inde$ a sun-l body1 & 9 all probability is q z l>ge & q z brilliant z ! sun itself1 be> ev5 a sup]ficial resemblance to an object l ,m>s1 :i* w\ld n be visible at all 7 x n = ! illum9ation ) :i* ! beams f ! sun end[ x8 ,! explanation ( ?is /rik+ resemblance is to be s\ght 9 ! relative di/ances ( ! two objects4 ,a light :i* is ne> to ! eye may produce an effect q z great z a v mu* /rong] light :i* is fur!r away4 ,! int5sity ( a light v>ies inv]sely z ! squ>e ( ! di/ance4 ,if ! di/ance ( a light f ! eye be d\bl$1 !n ! int5sity ( t light is r$uc$ to "o-f\r?4 ,n[ ,aldeb>an z a sun-l body emits light :i* is lit]ally millions ( times z great z ! gleam ( sun%9e :i* />ts back to u aft] reflection f ,m>s2 b ,aldeb>an is1 let u say1 a million times z f> away f u z ,m>s1 & ?is be+ s1 ! light f ,aldeb>an w\ld come to u ) only a million-million? "p ( ! int5sity t x w\ld h if ! /> 7 at ! same di/ance z ! planet4 ,!re c be no d\bt t if ,aldeb>an 7 m]ely at ! same di/ance f ! e>? z ,m>s1 !n ,aldeb>an w\ld disp5se lu/re l a spl5did sun4 ,by mov+ ,aldeb>an fur!r (f its light1 or r ! light t arrives at ! e>?1 w gradually decrease until by ! "t t ! /> is a million times z f> z ,m>s1 ! light t x s5ds u is ab\t equal to t ( ,m>s4 ,if x 7 remov$ fur!r /ill1 ! light t x w\ld s5d u w\ld become less ?an t :i* we receive f ,m>s1 & if /ill m remote1 ,aldeb>an might cease to be visible altoge!r4 ,?is illu/ration w suffice to expla9 ! fundam5tal diff]5ce betwe5 planets & />s1 not)/&+ ! fact t ! two classes ( bodies be> to ea* o!r a resemblance :i* is extremely rem>kable1 ev5 if x mu/ be describ$ z be+ 9 a s5se accid5tal4 ,b we n[ "k t all ( ! ?\s&s ( />s are to be reg>d$ z brilliant suns1 "s ( :i* may n be s f> (f z ,aldeb>an1 ?\gh d\btless "s are v mu* fur!r4 ,! actual di/ances are immat]ial1 = ! ess5tial po9t to notice is t ! five planets are di/+ui%$ f ! />s1 n m]ely by ! fact t !y are mov+1 :ile ! />s are at re/1 b by ! circum/ance t ! planets are comp>atively close to ea* o!r & close to ! sun1 :ile ! />s are at di/ances millions ( times z great z ! di/ances :i* ! planets are f ea* o!r & f ! sun4 ,we are n[ enabl$ to place ! s*eme ( ?+s cele/ial 9 its prop] p]spective4 ,i %all suppose t at a po9t 9 a field 9 ! c5tre ( ,engl&1 some:]e ne> ,leam+ton1 let u say1 we drive 9 a peg to repres5t ! sun4 ,let u draw a circle ) t peg z c5tre1 a y>d be+ ! radius1 & let t circle repres5t ! track 9 :i* ! e>? goes r\nd ! sun4 ,i d n inde$ say t ! orbit ( ! e>? is exactly a circle1 & ! actual %ape ( t orbit we may h to ref] to lat]4 ,z1 h[ev]1 ! app>5t size ( ! sun does n greatly alt] ) ! seasons1 x is evid5t t ! track :i* our e>? pursues _c be v diff]5t f a circul> pa?4 ,inside ?is circle :i* we h drawn ) a y>d radius1 we %all put two small] circles :i* are to repres5t ! pa? 9 :i* ,v5us moves1 & ! pa? 9 :i* ,m]cury moves4 ,outside ! pa? ( ! e>? we %all draw ano!r circle ) a radius ( five y>ds2 ?is w be ! highway along :i* ! maje/ic ,jupit] w5ds 8 way4 ,inside ! pa? ( ,jupit] we %all put a circle :i* w repres5t ! track ( ,m>s1 & outside ! pa? ( ,jupit] a circle ) t5 y>ds z radius w repres5t ! track ( ,saturn4 ,9 ea* ( ^! circles we %all suppose ! correspond+ planet to revolve1 & ! "t ( revolution w ( c\rse be great] ! fur!r ! planet is f ! sun4 ,to complete "o ( its circuits ! e>? w require a ye>1 ,jupit] twelve ye>s1 :ile ,saturn1 :i* 9 ! anci5t a/ronomy mov$ on ! fronti] ( ! sol> sy/em1 w ne$ ?irty ye>s to accompli% its mighty j\rney4 ,we h ?us obta9$ a plan ( ! sol> sy/em2 b n[ we %\ld l to indicate ! positions :i* "s ( ! />s are to occupy on ! same scale4 ,let u1 to beg9 )1 see :]e ! v ne>e/ fix$ /> is to be plac$4 ,we may suppose t ! field at ! c5tre ( ,engl&1 9 :i* our little diagram has be5 con/ruct$1 is a l>ge "o1 s t we c repres5t ! places ( objects :i* are t5 or tw5ty times z f> f ! sun z ,saturn4 ,x is1 h[ev]1 c]ta9 t no actual field w\ld be l>ge en\gh to conta9 )9 its b\nds ! po9ts :i* w\ld fai?fully repres5t ! positions ( ev5 ! ne>e/ fix$ />s4 ,! :ole c\nty ( ,w>wick w\ld n be ne>ly big en\gh = ?is purpose2 inde$ we may say t ! :ole ( ,engl&1 or inde$ ( ! ,unit$ ,k+dom1 w\ld n be suffici5tly ext5sive4 ,if we repres5t$ ! /> at its true relative di/ance1 x c\ld n be put d[n any:]e )9 ! b\nds ( ! ,unit$ ,k+dom2 ! ne>e/ object ( ?is k9d w\ld h to be f> away out on ! cont95t ( ,europe1 or f> away out on ! ,atlantic ,ocean1 f> away d[n ne> ! equator1 or f> away up ne> ! pole4 ,?is illu/ration w at all ev5ts give "s notion ( ! isolat$ position ( ! sun1 ) ! planets revolv+ ar\nd x1 9 relation to ! re/ ( ! ho/ ( heav54 ,we ?us le>n t ! real s*eme ( ! univ]se is widely diff]5t f t :i* a sup]ficial glance at ! heav5s w\ld lead u to expect4 ,we are n[ able to put our sy/em into its prop] p]spective4 ,we are to ?9k ( ! univ]se z consi/+ ( a myriad suns1 ea* sun1 h[ev]1 be+ s f> f ! o!r suns t view$ f any "o ( its neighb\rs x appe>s only ( />-l insignificance4 ,let u fix our att5tion on "o ( ^! suns 9 space1 & imag9e t ar\nd x1 & comp>atively close to x1 !re are a numb] ( small p>ticles 9 revolution1 ! p>ticles be+ illum9$ by ! light & w>m$ by ! heat ( ! c5tral body to :i* !y are atta*$4 ,view$ f "o ( ^? p>ticles1 ! sun to :i* !y belong w\ld d\btless appe> z a great & glori\s orb1 :ile a glance f "o ( ^! p>ticles to any ( ! o!r myriad suns 9 space w %[ ^! orbs r$uc$ to m]e po9ts ( /ell> light by reason ( _! enorm\s di/ance4 ,?is sun & ! p>ticles ar\nd x1 by :i* ( c\rse we %all und]/& ! planets1 con/itute :at we "k z ! sol> sy/em4 ,?is illu/ration may suffice to %[ ! isolation ( our sy/em 9 space1 & t isolation is due to ! va/ di/ances by :i* ! sun & its att5dant worlds are sep>at$ f ! myriads ( o!r bodies :i* =m ! sid]eal heav5s4 ,we mu/ next1 s f> z our pres5t subject requires x1 consid] ! laws accord+ to :i* ! planets belong+ to t sy/em revolve ar\nd ! sun4 ,let u ?9k fir/ ( a s+le "o ( ^! bodies :i*1 z is mo/ natural1 we %all take to be ! e>? itself1 & n[ let u consid] by :at ag5cy ! movem5t ( ! e>? ar\nd ! sun is guid$ along ! pa? :i* s closely resembles a circle4 ,x mu/1 ( c\rse1 be borne 9 m9d t !re c be no direct mat]ial connection betwe5 ! two bodies2 !re is no physical bond unit+ ! e>? to ! sun4 ,x is1 h[ev]1 c]ta9 t "s influ5ce proce$+ f ! sun does really control ! motion4 ,we may p]haps illu/rate :at takes place 9 ! foll[+ mann]4 ,"h is a globe1 & "h 9 my h& ,i hold a t5nis ball1 :i* is atta*$ to a silk5 ?read1 ! o!r end ( ! ?read be+ atta*$ to ! ceil+4 ,! t5nis ball is to hang s t bo? globe & ball are ab\t ! same height f ! floor4 ,we put ! globe directly und]nea? ! po9t on ! ceil+ f :i* ! silk5 ?read hangs4 ,if ,i draw ! t5nis ball aside & simply release x1 !n ( c\rse ev]ybody kn[s :at happ5s--x is h>dly necess>y to try ! exp]im5t--! t5nis ball falls at once t[>ds ! globe & /rikes x4 ,we may1 if we please1 reg>d t t5d5cy ( ! t5nis ball t[>ds ! globe z a sort ( attraction :i* ! globe ex]cises ^u ! ball4 ,i mu/1 h[ev]1 say t ?is is n a /rictly accurate v]sion ( :at actually takes place4 ,! attraction ( ! e>? = ! t5nis ball is ( c\rse l>gely neutralis$ by ! support giv5 by ! silk ?read4 ,!re is ?us only a slight out/&+ compon5t ( gravitation act+ on ! ball1 & ?is compon5t1 :i* is virtually ! effective =ce on ! ball1 t5ds to draw ! ball directly t[>ds ! globe4 ,= ! purpose ( our illu/ration we may neglect ! direct attraction ( ! e>? altoge!r2 we may omit all ?\ght ( ! t5sion ( ! silk5 ?read4 ,if !re 7 inde$ no attraction f ! e>?1 ! t5nis ball might rema9 pois$ 9 space )\t fall+2 & if x 7 !n attract$ by ! globe x w\ld fly t[>ds ! globe j z we actually see x d4 ,we are !re=e ju/ifi$ 9 reg>d+ ! movem5t ( ! t5nis ball z equival5t to t :i* w\ld be produc$ if an attractive virtue resid$ 9 ! globe by :i* x pull$ ! t5nis ball4 ,we may also imag9e t ! globe attracts ! t5nis ball 9 all its positions2 = :atev] be ! po9t at :i* ! ball is releas$ x />ts (f /raight t[>ds ! globe4 ,?is is our fir/ exp]im5t 9 :i*1 hav+ )drawn ! ball1 x is m]ely releas$ )\t receiv+ an initial impulse to "o side4 ,illu/ration3 ,fig4 #e4--,,nebul\s ,,region ,,& ,,/>-,,clu/] 7n4g4c4 #bbcg-i 9 ,monoc]os74 7,photograph$ by ,dr4 ,isaac ,rob]ts1 ,f4,r4,s47 ,let u n[ try a diff]5t exp]im5t4 ,we )draw ! ball1 &1 in/ead ( m]ely releas+ x quietly & all[+ x to drop directly to ! globe1 we give x a little ?r[ sideways1 p]p5dicul> to ! l9e jo9+ x to ! c5tre ( ! globe4 ,if we />t x ) ! prop] spe$1 :i* a few trials w indicate1 ! ball c be made actually to move 9 a circle r\nd ! globe4 ,if ! initial spe$ be some:at diff]5t1 ! pa? 9 :i* ! t5nis ball moves w n be a circle2 x w r be an ellipse ( "s =m4 ,ev5 if ! spe$ be correct ! orbit w always be an ellipse if ! direction ( ! initial ?r[ be n p]p5dicul> to ! l9e jo9+ ! ball to ! c5tre ( ! globe4 ,we c make ! ball describe a v long ellipse or an ellipse :i* diff]s b little f a circle4 ,b ,i w\ld ask y to note p>ticul>ly t1 no matt] h[ we may />t ! t5nis ball into motion1 x w1 s long z x passes cle> ( ! globe1 move 9 an ellipse ( "s k9d2 b 9 mak+ ?is /atem5t we assume t a circle is a p>ticul> =m ( ! ellipse4 ,& n[ = ! lesson :i* we are to le>n f ?is exp]im5t1 :i*1 z x is s easily p]=m$1 ,i w\ld wi% ev]yone to try = himself4 ,we h 9 ?is simple device an illu/ration ( ! movem5t ( a planet ar\nd ! sun4 ,we see t ?is t5nis ball c be made to move 9 a circle r\nd ! globe1 & t z x p]=ms ?is circul> movem5t ! globe is all ! "t attract+ ! ball t[>ds x4 ,?us we illu/rate ! important law t :5 "o body moves r\nd ano!r 9 a circul> pa? ?is movem5t takes place 9 consequ5ce ( a =ce ( attraction con/antly ex]t$ betwe5 ! l>ge body 9 ! c5tre & ! body revolv+ r\nd x4 ,! pr9ciple "h involv$ w provide ! explanation ( ! movem5ts ( ! planets r\nd ! sun4 ,ea* ( ! planets revolves r\nd ! sun 9 an orbit :i* is approximately circul>1 & ea* ( ! planets p]=ms t movem5t because x is cont9ually attract$ by ! sun4 ,x is1 h[ev]1 necess>y to add t !re is a fundam5tal diff]5ce betwe5 ! attraction ( ! sun = ! planets & ! attraction :i* ! globe appe>$ to ex]t on ! t5nis ball 9 our exp]im5t4 ,! diff]5ce relates to ! "* ( ! =ces 9 ! two cases4 ,if ! t5nis ball be drawn b a v small di/ance f ! globe1 ! attraction betwe5 ! two bodies is v slight4 ,if ! t5nis ball be drawn to a great] di/ance f ! globe1 ! attraction is increas$ correspond+ly2 &1 inde$1 9 ?is exp]im5t ! attraction betwe5 ! two bodies increases ) ! di/ance1 & is said to be proportional to ! di/ance4 ,b ! case is v diff]5t 9 t p>ticul> k9d ( attraction by :i* ! sun controls ! movem5ts ( ! planets4 ,?is attraction ( gravitation1 z x is call$1 also dep5ds on ! di/ance betwe5 ! two bodies4 ,b ! attraction does n increase :5 ! di/ance ( ! two bodies increases1 = ! *ange lies ! o!r way4 ,! attraction1 9 fact1 dim9i%es m rapidly ?an ! di/ance increases4 ,if ! di/ance betwe5 ! sun & a planet be d\bl$1 !n ! attraction betwe5 ! two bodies is only a f\r? ( :at ! attraction 0 betwe5 ! two bodies 9 ! =m] case4 ,?is diff]5ce betwe5 ! law ( attraction z x exi/s 9 ! sol> sy/em & ! law ( attraction :i* is exemplifi$ 9 our little exp]im5t produces a rem>kable contra/ 9 ! result+ movem5ts4 ,! orbit 9 ea* case is1 no d\bt1 an ellipse1 b 9 ! case ( ! t5nis ball revolv+ r\nd ! globe ! ellipse is s circum/anc$ t ! fix$ attract+ body /ood at its c5tre1 :ile 9 ! case ( a planet revolv+ r\nd ! sun ! conditions are n s simple4 ,! sun does n /& 9 ! c5tre ( ! ellipse4 ,! sun is plac$ at t rem>kable po9t ( ! ellipse s de> to ! he>t ( ! geomet]1 :i* he calls ! focus4 ,! sol> sy/em consi/s1 fir/1 ( ! great regulat+ orb1 ! sun2 !n ( ! planets1 ea* ( :i* revolves 9 its own track r\nd ! sun2 ea* ( ^! tracks is an ellipse1 & all ^! ellipses h ?is 9 common1 t a focus 9 ea* is id5tical ) ! c5tre ( ! sun4 ,9 o!r respects ! ellipses may be q diff]5t4 ,to beg9 )1 !y are n 9 ! same plane1 ?\gh x is mo/ important to notice1 z we %all h to discuss m fully h]eaft]1 t ^! planes are n v mu* sep>at$4 ,! dim5sions ( ! ellipses v>y1 ( c\rse1 = ! diff]5t planets1 & ! p]iods t ! planets require = _! sev]al revolutions are also widely diff]5t 9 ! cases ( ! diff]5t bodies2 = ! great] ! diamet] ( a planet's orbit1 ! long] is ! "t requir$ = t planet to complete a s+le j\rney r\nd ! sun4 ,! sun presid+ at ! common focus ( ! orbits :ile gov]n+ ! planets by its attraction1 at ! same "t t x illum9es !m ) its light & w>ms !m by its rays1 gives ! conception ( ! sol> sy/em4 ,b ! planet>y sy/em ,i h "h indicat$ is m]ely t sy/em z kn[n to ! anci5ts4 ,x is v imp]fect f ! /&po9t ( our pres5t k4 ,! sol> sy/em z we n[ "k x1 :5 telescopes h be5 appli$ ) su* m>vell\s dilig5ce & success to ! discov]y ( new bodies1 is a sy/em ( mu* great] complexity4 ,to ! five old planets h be5 add$ two new & maje/ic planets--,uranus & ,neptune--:i* revolve outside ! track ( ,saturn4 ,hundr$s ( small] planets1 invisible to ! unaid$ eye1 ! a/]oids z !y are call$1 also describe _! ellipses r\nd ! presid+ lum9>y4 ,& !n j z ! sun controls ! planets revolv+ r\nd x1 s d _m ( ! planets !mselves preside ov] subord9ate sy/ems ( revolv+ globes4 ,our e>? has a s+le att5dant1 ! moon1 :i*1 "u ! guidance ( ! e>?'s attraction1 p]=ms its mon?ly j\rney2 ,jupit] has its five moons1 :ile ,m>s has two1 & ,saturn eight or n9e1 besides 8 incomp>able sy/em ( r+s1 & we mu/ also add t ,uranus has f\r satellites & ,neptune "o4 ,to complete ! tale ( bodies 9 ! sol> sy/em1 we %\ld add _m ?\s&s ( comets1 n to m5tion _! m humble associates ! meteors1 :i* sw>m 9 c\ntless myriads4 ,f9ally1 we are to rememb] t ?is elaborate sy/em associat$ ) ! sun is an isolat$ object 9 ! univ]se2 x is b z a gra9 ( s& 9 ! ext5t ( inf9ite space4 ,z we contemplate a sy/em s wond]ful1 ! "q naturally arises1 ,h[ came t sy/em into be+8 ,we h to consid] :e!r ! laws ( nature z we "k !m af=d any rational explanation ( ! mann] 9 :i* ?is sy/em came into exi/5ce1 any rational explanation ( h[ ! sun came to %9e1 h[ ! e>? _h its beg9n+1 h[ ! planets came to revolve r\nd ! sun1 & to rotate on _! own axes4 ,we h to seek = a rational explanation ( ! r+s ( ,saturn1 & ( ! satellites by :i* s _m planets are att5d$4 ,we h to %[ t a satisfactory explanation ( ^! rem>kable ph5om5a is =?com+1 & t x is provid$ by ! fam\s doctr9e ( evolution1 :i* x is ! object ( ^! lectures to discuss4 ---------------------------------------- -------------------------------- ,,*apt] ,,iii4 ,,! ,,fire-,,mi/4 ,evolution ( o!r ,bodies 9 ! ,univ]se--,! ,nebul--,e/imate ( ! ,size ( ! ,great ,nebula 9 ,orion--,photograph ( t ,nebula tak5 at ,lick ,obs]vatory--,! ,dumb-bell ,nebula--,! ,crossley ,reflector--,! late ,pr(essor ,keel]--,a/oni%+ ,discov]y ( ,new ,nebul--#abj1jjj ,nebul--,! ,cont9u\s ,*a9 f a ,fluid ,haze ( ,light to a ,/>--,! ,cele/ial ,evolution4 ,,we comm5ce ?is *apt] ) a scrut9y ( ! heav5s1 to see :e!r1 among ! bodies :i* x conta9s1 we c discov] any :i* appe> at ?is mom5t to be 9 ! condition ?r\gh :i* our sy/em has pass$ 9 "s ( its e>li] /ages4 ,s f> z our unaid$ vision is conc]n$1 we c see little or no?+ 9 ! skies :i* w r5d] u assi/ance 9 our pres5t endeav\r4 ,! objects t we d see 9 ?\s&s are1 ( c\rse1 ! />s1 &1 z we h already po9t$ out1 ! />s are sun-l objects1 & z su* h advanc$ _m /ages beyond ! elem5t>y condition4 ,! />s are !re=e n imm$iately available = ! illu/ration we require4 ,b :5 we come to look at ! heav5s ?r\gh our telescopes we pres5tly f9d t !re are objects :i* 7 n visible to ! eye1 & :i* are nei!r />s nor planets4 ,clos] exam9ation ( ^! objects ) ! p[]ful in/rum5ts ( mod]n obs]vatories1 & especially ) ! help ( ^? m>vell\s appliances :i* h enabl$ u to le>n ! actual *emi/ry ( ! heav5ly bodies1 supplies ! sugge/ions t are requir$4 ,= n only does ! telescope reveal myriads ( />s :i* ! nak$ eye _c detect2 n only does x reveal wond]ful clu/]s 9 :i* ?\s&s ( />s are gr\p$ closely toge!r s z to =m spectacles ( indescribable magnific5ce1 :5 we take into acc\nt ! intr9sic spl5d\r ( ea* />-l po9t1 b x also reveals totally diff]5t objects1 kn[n z nebul4 ,^! objects are n />s & are n compos$ ( />s1 b are va/ ext5sions ( matt] exi/+ 9 a f> m elem5t>y condition4 ,x is to ^! curi\s bodies t we invite special att5tion at pres5t4 ,x is believ$ t !y (f] a rem>kable illu/ration ( ! orig9 ( ! sol> sy/em4 ,we %all fir/ consid] ! be/ kn[n object ( ?is class4 ,x is ! ,great ,nebula 9 ,orion4 ,illu/ration3 ,fig4 #f4--,,! ,,great ,,nebula ,,9 ,,orion 7,lick ,obs]vatory1 ,cali=nia74 7,f ! ,royal ,a/ronomical ,society ,s]ies47 ,& "h x may be well to give an e/imate :i* w enable u to =m "s notion ( ! size ( ?is object4 ,we are accu/om$ to recognise ! />s z pres5t+ ! appe>ance ( m]e po9ts ( light2 b an object l ! ,great ,nebula /ret*es ov] a wide area ( ! sky4 ,z to ! actual ext5t ( ! space :i* x occupies we _c speak ) confid5ce4 ,! fact is t ) e increase 9 ! p[] ( ! telescope ! nebula appe>s to encroa* m & m on ! d>kness ( space ar\nd4 ,we give 9 ,fig4 #f a repres5tation ( ! ,great ,nebula z x appe>s on a photographic plate obta9$ at ! ,lick ,obs]vatory 9 ,cali=nia4 ,b no picture c adequately repres5t ! extraord9>y delicacy ( ! object & ! s(tness & t5d]ness ) :i* ! blue nebul\s light fades into ! black sky ar\nd4 ,& x mu/ n be imag9$ t ! nebula1 z se5 on ?is picture1 repres5ts ! utmo/ limits ( ! object itself4 ,e prolongation ( ! exposure1 e increase 9 ! s5sitiv5ess ( ! plate1 %[ m & m ! ext5t ( ! nebula4 ,we %all1 ,i d\bt n1 /ill be )9 ! b\nds ( tru? if we say t ! nebula ext5ds ov] an area t5 times z great z t repres5t$ 9 ?is photograph4 ,b we w take only ! area ( ! object z %[n 9 ! photograph = ! purpose ( our calculation4 ,let u say t ! nebula1 z x is "h repres5t$1 cov]s ab\t two degrees squ>e4 ,i %all n attempt to express 9 miles ! dim5sions ( an object s va/4 ,i w try to give a conception ( ! size ( ! ,great ,nebula 9 a diff]5t mann]4 ,let u employ ! dim5sions ( our sol> sy/em = ! purpose ( comp>ison4 ,let u suppose t we draw1 ^u ! scale ( ?is cele/ial photograph1 a map :i* %all repres5t ! sun 9 ! c5tre1 ! e>? at h] prop] di/ance f ! sun1 & ,jupit] 9 8 orbit1 :i* is five times ! diamet] ( ! e>?'s orbit2 & !n let u m>k ! o!r planets at _! respective di/ances1 ev5 to ,neptune1 revolv+ 9 8 great ellipse1 ) a diamet] ?irty times t ( ! e>?'s orbit4 ,let u !n take ! area ( ! orbit describ$ by ,neptune z a unit ) :i* to measure ! size ( ! ,great ,nebula 9 ,orion4 ,we %all c]ta9ly be well )9 ! actual tru? if we say t a million circles z big z t describ$ by ,neptune w\ld n suffice to cov] ! area t is repres5t$ on ?is photograph4 ,?is w give "s idea ( ! impos+ dim5sions ( ! ,great ,nebula 9 ,orion4 ,b ,i w\ld n h x to be suppos$ t ! ,great ,nebula 9 ,orion is unique1 unless 9 respect to its conv5i5t position4 ,! circum/ances ( its situation 9 space happ5 to make x a comp>atively easy object = obs]vation by dwell]s on ! e>?4 ,!re are1 h[ev]1 v _m o!r nebul1 al?\gh1 ) "o exception--namely1 ! ,great ,nebula 9 ,&rom$a1 to :i* we %all h to ref] 9 a lat] *apt]--!y d n f our po9t ( obs]vation appe> to be s brilliant z ! nebula 9 ,orion4 ,! fact is t by l>ge & p[]ful telescopes multitudes ( ^! nebul are reveal$1 & ! numb] ev] t5ds to increase z great] dep?s 9 space are s\nd$4 ,_m ( ! nebul are objects :i* possess suffici5t detail to m]it ! p>ticul> att5tion :i* !y receive f a/ronom]s4 ,x mu/1 h[ev]1 be confess$ t by f> ! great] numb] ( ^! objects are s dimly disc]n$ t x is impossible to /udy _! individual *>act]i/ics4 ,among ! nebul :i* possess suffici5t individuality to m]it /udy = our pres5t purpose1 ,i mu/ m5tion ! s-call$ ,dumb-bell4 ,?is mo/ int]e/+ object c be se5 9 any good telescope4 ,x requires1 h[ev]1 z inde$ d all su* objects1 an in/rum5t ( ! highe/ p[] to d x ju/ice2 9 ^! mod]n days1 h[ev]1 ! eye obs]vation ( nebul ?r\gh great telescopes has be5 sup]s$$ by ! employm5t ( ! photographic plate4 ,i may take ?is opportunity ( m5tion+ t a photograph really %[s m details 9 ! nebula ?an c be p]ceiv$ ev5 by ! mo/ exp]i5c$ eye :5 appli$ to ! mo/ p[]ful telescope plac$ 9 ! mo/ fav\r$ situation z to climate4 ,^? lov]s ( nature :o desire to obs]ve cele/ial objects ?r\gh a great telescope1 & h n ! opportunity ( gratify+ _! wi%es1 may p]haps d]ive consolation f ! fact t a good photograph actually repres5ts ! object mu* bett] ?an any eye c see x4 ,m ( ! nebula is to be se5 by look+ at ! photograph ?an has actually be5 directly obs]v$ by any a/ronom]4 ,we h *os5 ! ,dumb-bell 7,fig4 #g7 & ! ,great ,nebula 9 ,orion z *>act]i/ic examples ( ?is rem>kable class ( cele/ial objects2 b !re are _m o!rs to :i* ,i might ref]1 "s ( :i* we repres5t 9 ^! pages4 ,! ,crab ,nebula 7,fig4 #c7 & o!rs h be5 di/+ui%$ by special names2 b ,i mu/ =be> to dwell fur!r on !m1 & r ha/5 to give ! results ( rec5t obs]vations :i* h enorm\sly ext5d$ our k ( ! nebul\s bodies 9 ! univ]se4 ,let me fir/ expla9 ! s\rce :5ce ?is extraord9>y accession to our k has aris54 ,we owe x to ! a/ronom]s at ! ,lick ,obs]vatory1 t rem>kable in/itution plac$ on ! summit ( ,m\nt ,hamilton 9 ,cali=nia4 ,_m important discov]ies _h already be5 made ) ! noble in/rum5ts ) :i* ! fam\s ,lick ,obs]vatory _h orig9ally be5 end[$ by its f\nd]2 x is1 h[ev]1 by a rec5t addition to its magnific5t app>atus t ! discov]ies h be5 made :i* are specially significant = our pres5t purpose4 ,_m ye>s ago ,dr4 ,a4 ,a4 ,common1 ! di/+ui%$ ,engli% a/ronom]1 con/ruct$ an exquisite reflect+ telescope ( ?ree feet ap]ture 7,fig4 #h74 ,) ?is telescope ,dr4 ,common himself obta9$ notable results 9 photograph+ ! heav5s1 & 8 success e>n$ ! aw>d ( ! ,gold ,m$al ( ! ,royal ,a/ronomical ,society4 ,?is telescope pass$ into ! possession ( ,mr4 ,e4 ,crossley1 ( ,halifax1 & "s "t lat] ,mr4 ,crossley pres5t$ x to ! ,lick ,obs]vatory4 ,! great mirror1 aft] its voyage across ! ,atlantic1 0 duly erect$ on ! top ( ,m\nt ,hamilton1 & =tunately = sci5ce ,pr(essor ,keel]1 ^: e>ly dea? a/ronom]s ( bo? cont95ts greatly deplore1 devot$ himself to ! /udy ( ! heav5s ) its aid4 ,he enc\nt]$ _m difficulties1 z might p]haps be expect$ 9 su* a task z he propos$4 ,8 pati5ce & skill1 h[ev]1 ov]came !m1 & ?\gh dea? t]m9at$ 8 lab\rs :5 8 great programme _h b little m ?an comm5c$1 ! "w he _h already accompli%$ has l$ to results ( ! mo/ /rik+ "*4 ,( ! skill t he obta9$ 9 photograph+ cele/ial nebul we h giv5 illu/rations 9 ,figs4 #f & #g4 ,illu/ration3 ,fig4 #g4--,,! ,,dumb-,,bell ,,nebula 7,lick ,obs]vatory1 ,cali=nia74 7,f ! ,royal ,a/ronomical ,society ,s]ies47 ,x is n to ! individual portraits ( notable nebul t we are n[ ab\t to ref]4 ,! mo/ /rik+ *>act]i/ic ( ! sid]eal heav5s is n to be f\nd 9 ! fact t 9 "o "p ( ! sky we h a brilliant ,sirius1 9 ano!r a ,capella1 & 9 a ?ird a ,canopus1 b 9 ! fact t ! heav5s :]ev] we may te/ !m are /rewn ) incalculable myriads ( />s1 _m ( :i* appe> fa9t only on acc\nt ( _! di/ance & n because !y are intr9sically small4 ,9 l mann] ! rem>kable fact ) reg>d to ! nebul :i* has be5 disclos$ by ,keel]'s memorable rese>*es ) ! ,crossley ,reflector is ! exi/5ce n alone ( ! great nebul1 b ( unexpect$ scores ( ?\s&s ( small nebul1 or r1 ,i %\ld say1 ( nebul :i* appe> small1 ?\gh d\btless 9 _m cases ^! objects are intr9sically q z spl5did z ! ,dumb-bell ,nebula or ! ,nebula 9 ,orion4 ,!y only seem small 9 consequ5ce ( be+ _m times fur!r f u ?an are ! m fam\s objects4 ,pr(essor ,keel]'s exp]i5ce 0 a rem>kable "o4 ,he 0 photograph+ a well-kn[n nebula ) ! ,crossley ,reflector1 & he 0 a little surpris$ to f9d t on ! same plate :i* gave him ! nebula at :i* he 0 aim+ !re 7 no few] ?an sev5 o!r small nebul\s objects previ\sly unkn[n to a/ronom]s4 ,x at fir/ appe>$ to him t ?is mu/ be an unusual numb] ( nebul to f9d cr[d$ toge!r on "o plate :i* cov]$ no m ?an "o squ>e degree ( ! heav5s1 an area ab\t five or six times z l>ge z ! area ( ! full moon4 ,subsequ5t exp]i5ce1 h[ev]1 %[$ him t ?is fact1 h[ev] a/oni%+1 0 n at all unusual4 ,9 fact1 he f\nd to 8 amazem5t t1 expose ! plate :]e he pleas$1 he g5]ally obta9$ new nebul ^u x1 & sometimes ev5 a mu* l>g] numb] ?an ! sev5 :i* s greatly surpris$ him at fir/4 ,i may m5tion j "o or two in/ances4 ,!re is a well-kn[n & int]e/+ nebula 9 ,pegasus :i* ,pr(essor ,keel] photograph$4 ,:5 he develop$ ! plate1 :i*1 ( c\rse1 includ$ a consid]able region ( ! heav5s 9 ! vic9ity ( ! p>ticul> nebula1 he f\nd to 8 a/oni%m5t t1 besides ! nebula he want$1 !re 7 n less ?an tw5ty o!r nebul on ! plate4 ,b !re is a m /rik+ in/ance ev5 ?an ?is4 ,a plate direct$ to a "p ( ! con/ellation ( ,&rom$a1 ) ! object ( tak+ a portrait ( a p>ticul> nebula ( consid]able int]e/1 0 f\nd to conta9 n only ! desir$ nebula1 b no few] ?an ?irty-"o o!r new nebul & nebul\s />s4 ,nor h we 9 ^! /atem5ts exhau/$ ! nebul\s cont5ts ( ^! wond]ful plates1 if inde$ we h rightly int]pret$ _! nature4 ,pr(essor ,keel] tells u t he f9ds ^u !m a consid]able numb] ( objects :i* 9 all probability are also nebul1 ?\gh !y are s small t ! telescope is unable to reveal !m 9 _! true "*4 ,exam9ation does little m ?an %[ ^! objects z po9ts ( light :i*1 h[ev]1 are app>5tly n />s4 ,9 ! rem>kable pap] f :i* ,i h tak5 ^! facts ,pr(essor ,keel] makes an e/imate :i* is f\nd$ on ! exam9ation ( 8 plates4 ,if ! heav5s 7 to be divid$ into panels1 ea* "o squ>e degree 9 area1 !re w\ld be ab\t =ty ?\s& panels4 ,x foll[s t if we desir$ to photograph ! :ole heav5s1 & if ea* ( ! plates 0 to cov] "o squ>e degree1 =ty ?\s& pictures w\ld be ne$$ = ! repres5tation ( ! :ole cele/ial sph]e4 ,keel]'s "w conv9c$ him t su* plates tak5 by ! ,crossley ,reflector w\ld1 on an av]age1 ea* %[ at lea/ ?ree new nebul4 ,he admitt$ x is q possible t !re may be regions ( ! sky 9 :i* no new nebul are to be f\nd4 ,b 9 ! regions :i* he _h s f> te/$ he inv>iably f\nd m ?an ?ree nebul on ea* squ>e degree2 inde$1 z we h se51 on "s ( 8 plates he f\nd a mu* l>g] numb] ( ^! rem>kable objects4 ,he !re=e said t he makes b a v mod]ate e/imate :5 he gives a hundr$ & tw5ty ?\s& z ! probable numb] ( ! new nebul )9 ! rea* ( ! photographic plates ( ! ,crossley ,reflector4 ,! enorm\s ext5sion :i* ^! inve/igations h giv5 to our k dem&s ! s]i\s att5tion ( all int]e/$ 9 ! heav5s4 ,! discov]ies ( ! e>li] a/ronom]s _h l$ to ! k ( ab\t six ?\s& nebul2 ! ,crossley ,reflector at ! ,lick ,obs]vatory has n[ r5d]$ x practically c]ta9 t ! numb] ( nebul 9 ! heav5s mu/ be at lea/ tw5ty-fold z great z _h be5 hi!rto suppos$4 ,illu/ration3 ,fig4 #h4--,,! ,,crossley ,,reflector 7,,con/ruct$ ,,by ,,dr4 ,a4 ,a4 ,,common ,f4,r4,s4 ,,& ,,n[ ,,at ,,! ,,lick ,,obs]vatory74 ,9 subsequ5t *apt]s we are to pres5t ! evid5ce = ! belief t ?is e>? ( ours1 z well z ! sun & all ! o!r bodies :i* =m ! sol> sy/em1 did once orig9ate 9 a nebula4 ,accord+ to ?is view ! mat]ials :i* at pres5t are f\nd 9 ! globes ( ! sol> sy/em 7 once di/ribut$ ov] a va/ ext5t ( space z a fire-mi/1 or nebula4 ,x is surely v p]t95t to be able to %[ t a nebula1 su* z we suppose to h be5 ! orig9 ( our sy/em1 is n a m]e figm5t ( ! imag9ation4 ,no d\bt x is impossible = u n[ to %[ ! orig9al nebula f :i* ! sol> sy/em has be5 evolv$4 ,x is nev]!less possible1 z we h se51 to %[ t a hundr$ & tw5ty ?\s& nebul are n[ actually exi/+ ( e grade ( magnitude4 ,!y range f su* magnific5t objects z ! ,great ,nebula 9 ,orion & ! ,dumb-bell ,nebula1 d[n to objects :olly invisible1 n m]ely to ! unaid$ eye1 b ev5 9 ! mo/ p[]ful telescope1 & only to be disc]n$ z hazy spots ( light on ! photographic plates ( an in/rum5t su* z ! ,crossley ,reflector4 ,?\gh no eye has se5 ! actual /ages 9 ! gr& evolution ( our sol> sy/em1 we may at lea/ witness p>allel /ages 9 ! evolution ?r\gh :i* "s ( ! myriads ( o!r nebul are n[ pass+4 ,we f9d "s ( ^! nebul 9 t excessively diffus$ condition 9 :i* !y are devoid ( visible /ructure4 ,mat]ial 9 ?is =m may be reg>d$ z ! primval nebula4 ,!re is at lea/ "o ( ^! extraord9>y objects :i* is l>g] a great deal ?an ev5 ! ,great ,nebula 9 ,orion1 b altoge!r too fa9t to be se5 except by ! photographic plate4 ,"h we f9d1 z x 71 ! "m-sub/ance 9 its mo/ elem5t>y /age ( wide/ possible diffusion1 f :i* worlds & sy/ems1 x may be1 are yet to be evolv$4 ,f diffus$ objects su* z %[n 9 ,fig4 #e we c pass to o!r nebul 9 :i* we see a c]ta9 advance be+ made 9 ! process by :i* ! nebula is trans=m$ f ! primitive condition4 ,we c po9t to yet o!r nebul 9 :i* ! advance to a fur!r /age ( developm5t is m & m pron\nc$4 ,?us ! v>i\s /ages 9 ! evolution ( a sy/em are to be witness$1 n inde$ 9 ! trans=mation ( a s+le nebula1 b by obs]v+ a prop]ly arrang$ s]ies ( nebul 9 all gradations1 f ! diffus$ lum9\s haze to a /> ) a fa9t nebul\s surr\nd+4 ,su* 0 ,h]s*el's orig9al argum5t1 & its cog5cy has /eadily increas$ f ! "t he fir/ /at$ x d[n to ! pres5t h\r4 ---------------------------------------- -------------------------------- ,,*apt] ,,iv4 ,,nebul--,,app>5t ,,& ,,real4 ,! ,globul> ,/>-clu/]s--,/ructure ( ^! ,objects--,v>iability ( ,/>s 9 ! ,clu/]--,telescopic ,resemblance ( a ,clu/] to a ,nebula--,resolution ( a ,nebula--,supposition t all ,nebul may be ,clu/]s--,a ,crit]ion = di/+ui%+ a ,nebula & a ,clu/]--,d>k ,l9es on a bright ,backgr\nd *>act]ise ! ,/ructure ( a ,/>--,bright ,l9es on a d>k ,backgr\nd *>act]ise ! ,/ructure ( a ,nebula--,*>act]i/ics ( ! ,spectrum ( a true ,nebula & ( a ,resolvable ,nebula--,spectra ( ! ,sun & ,capella--,spectra ( ! ,nebula 9 ,orion & ( a ,:ite ,/> comp>$--,numb] ( ,l9es 9 a ,nebul> ,spectrum--,crit]ion ( a ,nebul> ,spectrum--,spiral ,nebula n ,gase\s--,sol> ,spectra dur+ an ,eclipse--,be>+ on ! ,nebul> ,!ory--,h]s*el's ,"w--,! ,objection to ! ,!ory--,! ,objection ,remov$ 9 #ahfd4 ,,!re is p]haps h>dly any telescopic object m pleas+ or m in/ructive ?an a globul> clu/] ( />s :5 view$ ?r\gh an in/rum5t suffici5tly p[]ful to d ju/ice to ! spectacle4 ,!re are sev]al />-clu/]s ( ! class designat$ z 8globul>40 ,! mo/ fam\s ( ^!1 or1 at all ev5ts1 ! "o be/ kn[n to nor!rn a/ronom]s1 is f\nd 9 ! con/ellation ( ,h]cules1 & is = mo/ purposes suffici5tly describ$ by ! expression1 8,! ,clu/] 9 ,h]cules40 ,! g5u9e lov] ( ,nature f9ds x h>d to )hold an exclamation ( wond] & admiration :5 = ! fir/ "t1 or ev5 = ! hundr$? "t1 ! ,clu/] 9 ,h]cules is adequately display$ 9 ! field ( a fir/-class telescope4 ,illu/ration3 ,fig4 #i4--,,! ,,clu/] ,,9 ,,h]cules4 7,photograph$ by ,dr4 ,w4 ,e4 ,wilson1 ,f4,r4,s47 ,9 ,fig4 #i is a photograph ( ?is celebrat$ object1 :i* 0 tak5 by ,dr4 ,w4 ,e4 ,wilson1 ,f4,r4,s41 at 8 obs]vatory at ,d>amona1 9 ,irel&4 ,! picture has be5 obta9$ f an enl>gem5t ( ! orig9al photograph tak5 ) ! telescope 9 ,mr4 ,wilson's obs]vatory4 ,x is1 h[ev]1 precisely z ,nature has giv5 x1 except = ?is enl>gem5t4 ,y w note t t[>ds ! m>g9 ( ! clu/] ! sev]al />s are se5 sep>ately1 & 9 _m cases ) admirable di/9ctness4 ,we d1 h[ev]1 occasionally f9d two or m />s s close toge!r t _! images ov]lap2 &1 inde$1 9 ! c5tre ( ! clu/] ! />s are s close toge!r t x is impossible to diff]5tiate !m1 s z to see !m z individual po9ts ( light4 ,we ne$ h no d\bt1 h[ev]1 t ! clu/] is ma9ly compos$ ( sep>ate />s1 al?\gh ! difficulties int]pos$ by our atmosph]e1 add$ to ! necess>y imp]fections ( our appliances1 make x impossible = u to discrim9ate ! individual />s4 ,9 look+ at a /> gr\p ( ?is p>ticul> k9d ! obs]v] may p]haps be rem9d$ ( a sw>m ( bees 9 flight f ! hive1 = ! />s 9 ! clu/] are1 on a va/ scale1 app>5tly associat$ 9 ! same way z ! bees1 on a small scale1 are associat$ 9 ! sw>m4 ,we may also comp>e ! />s 9 ! clu/] to ! bees 9 ! sw>m 9 ano!r respect4 ,ea* bee 9 ! sw>m is 9 incessant movem5t4 ,!re c be no d\bt t ea* /> 9 a globul> clu/] is unceas+ly *ang+ its position ) ref]5ce to ! o!rs4 ,! di/ance by :i* ! clu/] is sep>at$ f ! e>? r5d]s x impossible = u to see ^? movem5ts1 at all ev5ts )9 ^? n>r[ limits ( "t ov] :i* our obs]vations h z yet ext5d$2 b ! laws ( me*anics assure u t ! mutual attraction ( ! />s 9 ?is clu/] mu/ give rise to incessant movem5ts1 & t ?is mu/ be ! case not)/&+ ! fact t ! relative places ( ! />s 9 ! clu/] %[ no alt]ation t c be recognis$ f "o ye>'s end to ano!r4 ,i may1 h[ev]1 m5tion t ?\gh !re may be no movem5ts 9 ^! />s great en\gh to be obs]v$1 yet ! brightness ( "s ( !m %[s mo/ rem>kable fluctuations4 ,! inve/igations ( ,pr(essor ,bailey & o!r a/ronom]s h1 inde$1 disclos$ su* curi\s v>iability 9 ! brightness ( "s ( ^! />s t if x 7 n = ! exce$+ly high au?ority by :i* ?is ph5om5on has be5 gu>ante$ we %\ld1 p]haps1 almo/ hesitate to believe s />tl+ a fact4 ,x has1 h[ev]1 be5 mo/ c]ta9ly prov$ t _m ( ! />s 9 c]ta9 globul> clu/]s pass ?r\gh a s]ies ( p]iodical *anges ( lu/re4 ,! p]iod is a v %ort "o z comp>$ ) ! p]iods ( bett] kn[n v>iable />s1 = 9 ?is case tw5ty-f\r h\rs are m ?an suffici5t = a complete cycle ( *anges1 & x n infrequ5tly happ5s t 9 ! c\rse ( a s+le qu>t] ( an h\r a /> w lose or ga9 brightness to ! ext5t ( a :ole magnitude4 ,! ph5om5on ref]r$ to is at ! pres5t mom5t engag+ ! c>eful att5tion ( a/ronom]s2 b x (f]s a problem ( :i*1 inde$1 x is n at pres5t easy to see ! solution4 ,our imm$iate conc]n1 h[ev]1 ) ! globul> />-clu/]s relates to a po9t h>dly ( su* ref9em5t z t to :i* ,i h j ref]r$2 x is "o ( a mu* m elem5t>y nature4 ,! photograph 9 ! figure may be consid]$ to repres5t ! ,clu/] 9 ,h]cules z x w\ld be se5 ) a telescope ( v consid]able visual p[]1 = ! object w\ld assume a diff]5t appe>ance 9 a telescope :i* 0 n fir/ class4 ,! p]fection ( a really p[]ful in/rum5t is te/$ by its capability ( exhibit+ z two sep>ate po9ts a pair ( />s :i* are excessively close toge!r1 & :i* 9 an in/rum5t ( inf]ior p[] _c be di/+ui%$1 b seem fus$ into a s+le object4 ,! def9+ p[] ( a telescope--t is to say1 its capability = sep>at+ close d\ble />s--is increas$ ) ! size ( ! in/rum5t1 always grant+1 ( c\rse1 t !re is equal optical p]fection 9 bo? cases4 ,x foll[s t ! m p[]ful ! telescope ! m num]\s are ! />s :i* c be se5 sep>ately 9 a globul> clu/]4 ,if1 h[ev]1 a small telescope be us$1 or a telescope :i*1 ?\gh ( consid]able size1 has n ! high optical p]fection t is dem&$ 9 ! be/ mod]n in/rum5ts1 !n adjac5t />s are n always to be se5 sep>ately4 ,x may be t ! telescope1 on acc\nt ( its small size1 _c sep>ate ! objects suffici5tly1 or x may be t ! imp]fections ( ! telescope d n pres5t ! /> z a po9t ( light1 b r z a m or less diffus$1 lum9\s disc4 ,9 ei!r case x may happ5 t a /> ov]laps o!r />s 9 its imm$iate neighb\rhood1 & consequ5tly an object :i* is really a clu/] ( sep>ate />s may fail altoge!r to pres5t ! appe>ance ( a clu/]4 ,i h be5 allud+ to some?+ :i*1 z e a/ronom] kn[s1 is ( practical importance 9 ! obs]vatory4 ,l e "o else :o has ev] us$ a telescope1 ,i h myself se5 ! ,clu/] ( ,h]cules ) j ! same mi/y appe>ance 9 a small telescope t an und\bt$ nebula possesses 9 ! v f9e/ in/rum5t4 ,x is1 accord+ly1 sometimes impossible1 m]ely by obs]vation ) a small in/rum5t1 to di/+ui% betwe5 :at is c]ta9ly a clu/] ( />s & :at is c]ta9ly a nebula4 ,x has inde$ n infrequ5tly happ5$ t an obs]v] ) a small telescope has discov]$ :at appe>$ to him to be a nebula1 & he has record$ x z su*2 & yet :5 ! same object 0 subsequ5tly exam9$ ) an in/rum5t ( great] def9+ p[] ! nebul\s "* has be5 se5 to h be5 wrongly attribut$4 ,! object 9 su* a case is prov$ to be no?+ m ?an a clu/] ( />s1 ( :i* ! individual memb]s are ei!r intr9sically fa9t or exce$+ly remote2 x c]ta9ly is n a mass ( t fire-mi/ or gase\s mat]ial :i* alone is entitl$ to be call$ a nebula4 ,x is !re=e a "q ( importance 9 practical a/ronomy to decide :e!r objects :i* appe> to be nebul are really entitl$ to ! "n1 or :e!r ! nebul\s appe>ance may n be an optical illusion4 ,! op]ation by :i* an object previ\sly deem$ to be a nebula is %[n by ! application ( increas$ telescopic p[] to be a clu/] ( />s is commonly kn[n z ! resolution ( a nebula4 ,ab\t fifty ye>s ago ! mighty six-foot reflect+ telescope ( ,"l ,rosse1 & o!r great in/rum5ts1 7 l>gely employ$ on ?is "w4 ,x 01 inde$1 at t "t held to be "o ( ! special tasks :i* came mo/ legitimately )9 ! prov9ce ( ! big telescopes1 to %[ t ! s-call$ nebul ( e>li] obs]v]s 7 resolvable into />-clu/]s "u ! sup]ior p[]s n[ br\ght to be> ^u !m4 ,! success ) :i* ?is process 0 appli$ to _m reput$ nebul1 :i* 7 !reby %[n to be n entitl$ to ! "n1 l$ n unnaturally to a c]ta9 conjecture4 ,x 0 admitt$ t c]ta9 objects :i* _h successfully resi/$ ! resolv+ p[]s ( inf]ior in/rum5ts 7 =c$ to confess !mselves z m]e />-clu/]s :5 greatly increas$ telescopic p[] 0 br\ght to be> on !m2 & x 0 conjectur$ t simil> success w\ld att5d ! attempts to resolve /ill o!r nebul4 ,x 0 ev5 suppos$ t e object describ$ z a nebula c\ld only be entitl$ to be> t designation provisionally1 only inde$ until "s telescope ( suffici5t p[] %\ld h be5 br\ght to be> on x4 ,x seem$ n unreasonable to surmise t e "o ( ! s-call$ nebul is a clu/] ( />s1 ev5 ?\gh a telescope suffici5tly p[]ful to effect its resolution might nev] be actually =?com+4 ,i d n1 inde$1 believe t ?is op9ion z to ! ultimate resolvability ( all nebul c\ld h be5 %>$ by ^? :o _h mu* practical exp]i5ce 9 ! actual obs]vation ( ^! objects ) ! great telescopes1 = ! p>ticul> classes ( nebul :i* 9 telescopes ( sup]ior p[]s resolv$ !mselves into gr\ps ( />s _h a *>act]i/ic appe>ance4 ,aft] a little exp]i5ce ! obs]v] soon le>n$ to recognise ^? nebul :i* promis$ to be resolvable4 ,! object might n inde$ be resolvable ) ! p[]s at 8 disposal1 b yet f its appe>ance he (t5 felt t ! nebula w\ld be probably resolv$ if ev] ! "t %\ld come t great] p[]s 7 appli$ to ! task4 ,x is easy to illu/rate ! "q at issue by ! help ( ! photograph ( ! ,clu/] 9 ,h]cules 9 ,fig4 #i4 ,ea* ( ! />s is !re di/9ct1 except :]e !y are mu* cr[d$ 9 ! c5tre4 ,if1 h[ev]1 ! photograph be exam9$ ?r\gh "o ( ^? l>ge l5ses :i* are (t5 us$ = ! purpose1 & if ! l5s be held v mu* out ( focus1 ! />s w n be di/+ui%able sep>ately1 & ! :ole object w be m]ely a haze ( light4 ,?is illu/ration may help to expla9 h[ ! diff]5t optical conditions "u :i* an object is look$ at may exhibit1 at "o "t z a diffus$ nebula1 an object :i* 9 bett] circum/ances is se5 to be a />-clu/]4 ,! a/ronom] :o 0 =tunate en\gh to h ! use ( a really great telescope w\ld n fail to notice t1 9 addition to ! s-call$ nebul already ref]r$ to1 :i* 7 presumably resolvable1 !re 7 c]ta9 o!r objects1 g5]ally *>act]is$ by a blui% hue1 :i* 9 no circum/ances :atev] pres5t$ ! appe>ance ( be+ compos$ ( sep>ate />s4 ,we n[ "k = c]ta9 t ^! blui% objects are n clu/]s ( />s1 b t !y are 9 ! /ricte/ s5se entitl$ to ! "n ( nebul1 & t !y are gase\s masses or mi/s ( fire-cl\d4 ,! full demon/ration ( ?is important po9t 0 n effect$ until #ahfd4 ,! fact t s v _m ( ! nebul 7 resolv$ l$ n unreasonably to ! presumption t all ! nebul w\ld 9 due "t also yield4 ,b !re 7 _m :o c\ld n accept ?is view1 & !re 0 a long discussion on ! subject4 ,at la/1 h[ev]1 ! improvem5ts 9 a/ronomical me?ods h cle>$ up ! "q4 ,sir ,w4 ,hugg9s has %[n t !re are two totally di/9ct classes ( nebul1 or r ( s-call$ nebul4 ,!re are c]ta9 nebul :i* c be resolv$1 & !re are c]ta9 nebul :i* _c4 ,a nebula :i* c be resolv$ w\ld be a v]itable clu/] ( />s1 & is n really entitl$ to ! "n ( nebula2 a nebula :i* _c be resolv$ w\ld be entitl$ to ! "n1 = x is a volume ( gas or ( gase\s mat]ial :i* is itself inc&esc5t4 ,we h be5 provid$ ) a beautiful crit]ion by :i* we c decide to :i* ( ^! classes any nebul\s-look+ object belongs4 ,! spectroscope is ! in/rum5t :i* discrim9ates ! two diff]5t classes ( objects4 ,?is rem>kable app>atus1 to :i* we owe s mu* 9 e dep>tm5t ( a/ronomy1 receives ! beam ( light f ! cele/ial body4 ,! in/rum5t !n analyses ! light into its compon5t rays1 & conducts ea* "o ( ^? rays sep>ately to a di/9ct place on ! photographic plate4 ,:5 ! photograph is develop$ we f9d on ! v>i\s p>ts ( ! plate ! evid5ce z to ! class ( rays :i* h ent]$ into ! composition ( ! light t has be5 submitt$ to ?is v se>*+ =m ( exam9ation4 ,! light :i* comes f a /> or any />-l body1 includ+ ! sun itself1 may fir/ be describ$4 ,t light1 aft] pass+ ?r\gh ! spectroscope & hav+ be5 conduct$ to ! photographic plate1 w produce a picture ( d>k l9es on a bright backgr\nd2 ?is is1 at lea/1 ! spectrum :i* a /> g5]ally pres5ts4 ,!re are1 inde$1 _m types ( /ell> spectra1 = !re are _m diff]5t k9ds ( />s1 & ea* k9d ( /> is conv5i5tly *>act]is$ by ! p>ticul> spectrum t x yields4 ,if ! /> be "o ( small magnitude1 !n ! l9es 9 its spectrum may be detect$1 b only ) great difficulty4 ,x n infrequ5tly happ5s t ! photograph ( ! spectrum ( su* a /> w %[ no m ?an a cont9u\s b& ( light )\t recognisable l9es2 & ?is is :at occurs 9 ! case ( a resolvable nebula1 :]e ! />s are s closely associat$ t ! spectrum ( ea* sep>ate /> _c be di/+ui%$4 ,! spectrum ( a resolvable nebula is m]ely a /reak ( light1 :i* is ! jo9t effect ( all ! spectra4 ,! spectrum is !n too fa9t to %[ ! ra9b[ hues :i* pres5t su* beautiful features 9 ! spectrum ( a bright />1 z !y d 9 ! spectrum ( ! sun itself4 ,i give1 9 ! adjo9+ figure 7,fig4 #aj71 portions ( ! photographs ( two spectra ( cele/ial objects4 ,!y h be5 tak5 f ! ,atlas ( repres5tative /ell> spectra 9 :i* ,sir ,william & ,lady ,hugg9s h record$ ! results ( _! great lab\rs4 ,two spectra are repres5t$ 9 ?is picture1 ! upp]mo/ be+ ! spectrum ( ! sun1 :ile ! l[] & broad] "o is ! spectrum ( ! bright /> ,capella4 ,x has n be5 possible )9 ! limits ( ?is picture to include ! :ole l5g? ( ^! two spectra1 & x mu/ !re=e be und]/ood t ! photographs giv5 9 ! ,atlas are ea* ab\t five times z long z ! p>ts :i* are "h reproduc$4 ,illu/ration3 ,fig4 #aj4--,,sun ,,& ,,capella4 ,sun above4 ,capella bel[4 7,sir ,william & ,lady ,hugg9s47 ,b ! *>act]i/ic portions ( ! spectra select$ are suffici5t = our pres5t argum5t4 ,x w be not$1 fir/ ( all1 t !re is a s+ul> resemblance betwe5 ! details ( ! spectrum ( ! sun & ^? ( ! spectrum ( ! />4 ,no d\bt ! bread? ( ! /ell> picture 9 ! l[] l9e is great] ?an t ( ! sol> picture 9 ! upp] l9e2 b ?is po9t is n significant4 ,! bread? ( ! spectrum ( ! sun c\ld easily h be5 made z wide or wid] if necess>y4 ,! bread? is immat]ial1 = ! "* ( a spectrum is det]m9$ n by its bread?1 b by ^? l9es :i* cross x transv]sely4 ,x w be se5 t !re are "h a multitude ( l9es1 "s be+ v d>k1 & "s s fa9t z to be h>dly visible4 ,bo? spectra exhibit e v>iety ( l9e1 betwe5 ! delicate m>ks :i* c b>ely be se5 & ! two bold columns on ! "r-h& side ( ! picture4 ,! *>act]i/ic ( ! spectrum is giv5 by ! numb]1 ! arrangem5t1 ! bread?1 ! d>kness1 & ! def9it5ess ( ! l9es by :i* x is cross$1 & ! fir/ po9t t we note is ! rem>kable resemblance 9 ^! diff]5t respects betwe5 ! two spectra4 ,! l9es are practically id5tical1 at lea/ s f> z ^? p>ts ( ! spectrum repres5t$ 9 ?is picture are conc]n$4 ,we h ?us a /rik+ illu/ration ( ! important fact1 to :i* we h s (t5 to make allusion1 ( ! g5]al resemblance ( ! sun to ! />s4 ,n only d we "k t if ! sun 7 remov$ ab\t a million times z f> z x is at pres5t its light w\ld be r$uc$ to t ( a />1 b t ! /> ,capella transmits to u light consi/+ ess5tially ( ! same waves z ^? :i* ent] into a beam ( sunlight4 ,no m /rik+ illu/ration ( ! analogy betwe5 ! sun & a /> c be f\nd ?an t :i* is giv5 9 ?is photograph f ! fam\s ,obs]vatory at ,tulse ,hill4 ,b x mu/ n be inf]r$ t because ! spectra ( sun & /> are l ea* o!r1 !y are !re=e absolutely id5tical4 ,!re are _m l9es & details to be se5 on ! actual photographic plate :i* are too delicate to be reproduc$ 9 su* copies z x is possible to make4 ,:5 a close comp>ison is made on ! actual plate itself ( ! l9es 9 ! sol> spectrum & ! l9es 9 ! spectrum ( ,capella1 x is obs]v$ t1 ?\gh !y are ! same s f> z ! m important l9es are conc]n$1 yet t !re are _m l9es f\nd 9 ! spectrum ( ,capella :i* are n f\nd 9 ! spectrum ( ! sun4 ,illu/ration3 ,fig4 #aa4--,,spectrum ,,( ,,nebula ,,9 ,,orion ,,& ,,spectrum ,,( ,a ,,:ite ,,/>4 7,sir ,william ,hugg9s1 ,k4,c4,b47 ,! contra/ betwe5 ! spectrum ( a nebula prop]ly s call$ & ! spectrum ( a /> is well illu/rat$ by ! accompany+ picture 7,fig4 #aa71 9 :i* ,sir ,w4 ,hugg9s exhibits ! photograph ( ! spectrum ( ! ,nebula 9 ,orion 9 comp>ison ) ! spectrum ( a />4 ,! upp]mo/ ( ! two is ! spectrum ( ! />4 ,x w be not$ t ?is spectrum is v diff]5t f t :i* we h already se5 9 ,capella4 ,in/ead ( a va/ multitude ( l9es resembl+ ! l9es ( ! sol> spectrum1 ! spectrum ( a /> ( ! type "h repres5t$1 ( :i* we may take ,sirius z ! mo/ /rik+ example1 exhibits b a few l9es4 ,we reg>d !m z "o sy/em ( l9es1 = we "k !y are physically connect$4 ,!y are all alike due to ! pres5ce ( a s+le elem5t 9 ! />1 t elem5t be+ 9 fact hydrog54 ,b ?\gh ! spectra ( ,capella & ,sirius are s totally diff]5t1 ! diff]5ces relate only to ! di/ribution ( ! l9es1 & to _! numb]1 d>kness1 & wid?4 ,9 bo? cases we obs]ve ! *>act]i/ic ( ! light f an ord9>y bright />1 namely1 t ! spectrum is compos$ ( a bright b& ) d>k l9es across x4 ,x ought1 p]haps1 to be m5tion$ "h t !re are c]ta9 v special />s :i* d exhibit "s bright l9es 9 addition to a m ord9>y spectrum2 ?is is especially ! case 9 ! new />s :i* occasionally appe>4 ,?us 9 ! case ( ! new /> :i* appe>$ 9 ,p]seus1 9 #aija1 !re 7 sev]al rem>kable bright l9es4 ,?is mo/ int]e/+ object w be ref]r$ to aga9 9 a lat] *apt]4 ,widely diff]5t f ! spectrum ( any /> :atev] is ! l[] ( ! two spectra :i* are %[n 9 ! figure4 ,?is l[] spectrum is t ( ! ,great ,nebula 9 ,orion4 ,at once we see ! fundam5tal *>act]i/ic ( a nebula2 its spectrum exhibits five bright l9es on a d>k field4 ,i d n say t ! ,great ,nebula 9 ,orion has n m ?an five l9es2 !re are inde$ _m o!rs1 = ,sir ,william ,hugg9s has himself po9t$ out a consid]able numb]1 & ! lab\rs ( o!r obs]v]s h add$ /ill m2 b ! five l9es "h set d[n are ! pr9cipal l9es4 ,!y are ^? mo/ easily se52 ! o!rs are g5]ally extremely delicate objects arrang$ 9 gr\ps ( five or six4 ,b ! l9es :i* ?is picture %[s are q suffici5t to exhibit t fundam5tal *>act]i/ic ( ! nebul> spectrum1 namely1 a sy/em ( bright l9es on a d>k field4 ,i may fur!r m5tion t c]ta9 l9es 9 ! spectrum indicate ! pres5ce ( ! elem5t hydrog5 9 ! ,great ,nebula 9 ,orion1 & we owe to ,dr4 ,copel& ! int]e/+ discov]y t ! rem>kable elem5t helium is also prov$ to exi/ 9 ! nebula4 ,! pictures1 at :i* we h be5 look+1 w suffice to make cle> ! crit]ion1 :i* a/ronom]s n[ possess1 = decid+ :e!r an object :i* looks nebul\s is really a gase\s nebula1 or ought r to be reg>d$ z a />-clu/]4 ,if ! object be a />-clu/]1 !n ! spectrum t x gives w be ! resultant ( ! spectra ( ! />s1 & ?is w be a cont9u\s b& ( light4 ,if ! />s are bright en\gh1 x may be t d>k l9es c be detect$ cross+ ! spectra1 b 9 ! case ( ! clu/]s x w be m usual to f9d ! cont9u\s b& ( light s fa9t t ! d>k l9es1 ev5 if !y are !re1 are n di/+ui%able4 ,if1 on ! o!r h&1 ! object at :i* we are look+1 n be+ a clu/] ( />s1 is inde$ a mass ( gl[+ gas1 or true nebula1 !n ! spectrum t x s5ds u is n ! cont9u\s spectrum su* z we expect f ! />s4 ,! spectrum :i* ! nebula prop] transmits to ! plate is said to be discont9u\s4 ,9 "s cases x is *>act]is$ by only a s+le bright l9e1 & 9 o!rs !re may be two1 or ?ree1 or f\r bright l9es1 or1 z 9 ! case %[n 9 ,fig4 #aa1 ! numb] ( bright l9es may be z _m z five4 ,x may inde$ happ51 9 ! case ( "s exquisite photographs1 t ! numb] ( l9es 9 ! spectrum ( ! nebula w be increas$ to a score or possibly m4 ,!re may also be fa9t traces ( a cont9u\s spectrum pres5t1 ?is be+ due to ! />s scatt]$ ?r\gh ! object1 f :i* p]haps ev5 ! mo/ gase\s nebula is n entirely free4 ,b ! *>act]i/ic type ( nebul> spectrum is t 9 :i* ! bright l9es1 be !y "o1 or few1 or _m1 are sep>at$ by int]vals ( p]fect d>kness4 ,:5 x is f\nd t ! spectrum ( a nebula c be ?us describ$1 x is correct to say t ! nebula is truly a gase\s object4 ,9 ! li/s giv5 by ,s*e9] 9 8 int]e/+ book1 8,a/ronomical ,photography10 ! numb] ( gase\s nebul is set d[n z sev5ty-?ree4 ,( c\rse no "o pret5ds t ?is enum]ation is exhau/ive4 ,x claims to be no m ?an a /atem5t ( ! numb] ( nebul :i* h be5 prov$1 by obs]vations made up to ! pres5t1 to be ( a gase\s description4 ,see+ t !re are1 z we h already /at$1 _m scores ( ?\s&s ( nebul\s-look+ objects1 x is probable t ! numb] above giv5 is n m ?an a small fraction ( ! numb] ( gase\s nebul actually )9 rea* ( our in/rum5ts4 ,x may1 h[ev]1 be assum$ t m ?an half ! objects :i* are call$ nebul are n ( ! gase\s type4 ,?is is a po9t ( "s importance1 :i* appe>s to foll[ f ! facts /at$ by ,pr(essor ,keel] 9 connection ) 8 memorable rese>*es ) ! ,crossley ,reflector4 ,9 a lat] *apt] we discuss important que/ions connect$ ) :at are call$ spiral nebul4 ,we may1 h[ev]1 "h record t no spiral nebul h z yet be5 pron\nc$ gase\s4 ,pr(essor ,keel] assures u t1 ( ! "o hundr$ & tw5ty ?\s& nebul :i* he e/imates to be )9 rea* ( ! ,crossley ,reflector1 f> m ?an half are ( ! spiral "*4 ,if1 !n1 we assume t ! spectra ( spiral nebul are always cont9u\s1 x seems to foll[ t less ?an half ! nebul\s cont5ts ( ! heav5s possesses ! discont9u\s spectrum :i* is *>act]i/ic ( a gase\s object4 ,we are n entitl$ to assume t a nebula1 or reput$ nebula1 :i* %[s a cont9u\s spectrum1 mu/ necess>ily be a clu/]1 n m]ely ( />-l bodies1 b ( bodies ) masses comp>able ) ^? ( ! ord9>y />s4 ,our argum5t does mo/ c]ta9ly sugge/ t ! body :i* yields a cont9u\s spectrum is n a gase\s body2 b x may be go+ too f> to ass]t t !re=e x is a clu/] ( />s 9 ! ord9>y s5se4 ,we d (t5 f9d true nebul & />-clu/]s 9 close association4 ,! ,nebula 9 ! ,pleiades 7,fig4 #ac7 is an example4 ,x may be desirable to add a few words "h z to ! physical diff]5ce betwe5 a cont9u\s spectrum & a discont9u\s spectrum4 ,! light f a body1 kn[n to be gase\s1 %[s ?r\gh ! prism ! discont9u\s spectrum ( bright l9es ^u a d>k backgr\nd4 ,if1 on ! o!r h&1 a solid be rais$ to inc&esc5ce1 su*1 = in/ance1 z a plat9um wire heat$ :ite-hot by an electric curr5t1 or a cyl9d] ( lime submitt$ to an oxyhydrog5 bl[pipe1 !n ! spectrum t x yields is cont9u\s4 ,all ! col\rs ( ! ra9b[1 r$1 orange1 yell[1 gre51 blue1 indigo1 violet1 are %[n 9 su* a spectrum z a cont9u\s b& ( light1 ?\gh ! b& is n cross$ by d>k l9es4 ,x w\ld !re=e appe> t ! cont9u\s spectrum is *>act]i/ic ( an inc&esc5t solid1 & ! discont9u\s spectrum ( a gl[+ gas4 ,b "h x may be urg$ t ! sun pres5ts a difficulty4 ,we s (t5 ref] to ! spectrum ( ! sun z cont9u\s1 t x might at fir/ appe> z if ! spectrum ( ! sun resembl$ t produc$ by radiation f a solid body4 ,b1 z is well kn[n1 ! sun is n a solid body4 ,ev5 if ! sun be solid at ! c5tre1 x is c]ta9ly f> f be+ solid 9 ^? sup]ficial regions call$ ! photosph]e1 f :i* alone its copi\s radiation is emitt$4 ,if ! sun is n a solid body1 h[ comes x to emit a radiation *>act]is$ 9 ! same way z ! radiation f a :ite-hot solid8 ,:y does ! sol> spectrum n exhibit features *>act]i/ic ( radiation f an inc&esc5t gas8 ,! po9t is well wor?y ( att5tion2 x f9ds an explanation 9 ! nature ( ! photosph]e f :i* ! sun's radiation proce$s4 ,! photosph]e1 ?\gh n1 ( c\rse1 to be describ$ z a solid body1 does n mo/ c]ta9ly1 s f> z its radiation is conc]n$1 behave l a gase\s body4 ,9 ! gl[+ cl\ds ( ! photosph]e ! c>bon1 ( :i* !y are compos$1 is n 9 ! gase\s =m2 x has pass$ into solid p>ticles1 & x is ^! p>ticles1 9 ! highe/ condition ( inc&esc5ce1 :i* emit ! sol> radiation4 ,al?\gh ^! p>ticles are su/a9$ by ! gases ( ! sun1 & are associat$ 9 aggregations :i* =m ! dazzl+ cl\ds ( ! photosph]e1 yet ea* "o ( !m1 9 s f> z its individual radiation is conc]n$1 ought to be reg>d$ z a solid body4 ,! radiation f ! sun is1 !re=e1 ess5tially n ! radiation f an inc&esc5t gas2 x is ! radiation f a gl[+ solid4 ,?is is ! reason :y ! sol> spectrum is ( ! cont9u\s type4 ,illu/ration3 ,fig4 #ab4--,,sol> ,,spectra ,,) ,,bright ,,l9es ,,& ,,d>k ,,l9es ,,dur+ ,,eclipse4 7,photograph$ by ,capta9 ,hills1 ,r4,e47 ,by ! k9dness ( ,capta9 ,hills1 ,r4,e41 ,i am able to %[ a photograph 7,fig4 #ab7 conta9+ two spectra tak5 dur+ a rec5t eclipse1 :i* w s]ve z an excell5t illu/ration ( ! diff]5t po9ts :i* we h be5 discuss+4 ,x is1 inde$1 true t nei!r ( ! spectra1 "h ref]r$ to1 belongs to nebul1 :e!r g5u9e gase\s objects or n4 ,bo? ( ! spectra 9 ,capta9 ,hills' picture are actually tak5 f ! sun4 ,! conditions "u :i* ^! spectra 7 obta9$ make !m1 h[ev]1 s]ve z excell5t illu/rations ( ! diff]5t types ( spectra4 ,we are to notice t ! upp] b&1 :i* conta9s :at is call$ ! 8fla%0 spectrum1 exhibits bright l9es on a d>k backgr\nd4 ,see1 = in/ance1 ! two l9es s v di/9ctly m>k$1 :i* are indicat$ by ! lett]s ,h & ,k4 ,^! l9es are v *>act]i/ic ( ! sol> spectrum1 & x may be m5tion$ t !y are indications ( ! pres5ce ( a well-kn[n elem5t4 ,^! l9es prove t ! sun conta9s calcium1 ! metal ( :i* common lime is ! oxide4 ,x is1 inde$1 ! pres5ce ( ?is sub/ance 9 ! sun :i* gives rise to ^! l9es4 ,we %all ref] aga9 to ?is subject 9 a lat] *apt]4 ,z ! upp] ( ! two spectra exhibit ,h & ,k z :ite l9es on a d>k backgr\nd1 s ! l[] repres5ts ! same l9es z d>k objects on a :ite backgr\nd4 ,^! photographs give illu/rations ( spectra ( ! two diff]5t classes :i* provide means ( discrim9at+ betwe5 a g5u9e nebula & an object :i*1 ?\gh x looks l a nebula1 is n itself gase\s4 ,illu/ration3 ,fig4 #ac4--,,! ,,nebula ,,9 ,,! ,,pleiades 7,exposure #aj h\rs74 7,photograph$ by ,dr4 ,isaac ,rob]ts1 ,f4,r4,s47 ,b1 x w be ask$1 h[ c ! spectra ( ! two di/9ct types bo? be obta9$ f ! sun8 ,! explanation ( ?is po9t is an int]e/+ "o4 ,! l[] ( ! two is ! ord9>y sol> spectrum2 x is a cont9u\s spectrum %[+ d>k l9es on a bright field4 ,! upp] spectrum1 :i* %[s bright l9es on a d>k field1 is produc$ by a small "p ( ! sun j at ! mom5t :5 ! eclipse is total4 ,! circum/ances 9 :i* t picture 0 secur$ w expla9 its "*4 ,! moon _h completely cov]$ t dazzl+ "p ( ! sun :i* we ord9>ily see1 b a region ( int5sely gl[+ gase\s mat]ial 9 ! sun's atmosph]e 0 too high above ! surface to be completely hidd5 by ! moon4 ,! spectrum ( ?is region1 consi/+ ( ! *>act]i/ic bright gase\s l9es1 is "h repres5t$4 ,! ord9>y light ( ! sun be+ cut (f1 opportunity 0 ?us af=d$ = ! production ( ! spectrum ( ! light f ! gl[+ gas1 & we see ?is spectrum to be ( ! nebul> type4 ,& n[ we may br+ ?is *apt] to a close by call+ att5tion to ! v important be>+ :i* its facts h on ! ,nebul> ,!ory4 ,x is ess5tial = u to see h[ f> mod]n inve/igation & discov]y h t5d$ ei!r to sub/antiate or refute t fam\s doctr9e :i* traces ! developm5t ( ! sol> sy/em f a nebula4 ,to d ?is x is necess>y to contra/ ! k ( nebul1 z x exi/s at pres5t1 ) ! k ( nebul z x exi/$ 9 ! days ( ,kant & ,laplace & ,h]s*el4 ,we assur$ly d no inju/ice to ,kant or to ,laplace if we say t _! actual k ( ! nebul\s cont5ts ( ! heav5s 0 va/ly inf]ior to t possess$ by ,h]s*el4 ,!re is n a s+le a/ronomical obs]vation ( nebul record$ by ei!r ,kant or ,laplace2 x may be d\bt$ :e!r ei!r ( !m ev] ev5 saw a nebula4 ,_! spl5did contributions to sci5ce 7 made 9 directions f> remov$ f ^? ( ! practical obs]v]1 :o passes long h\rs ( d>kness 9 ! scrut9y ( ! cele/ial bodies4 ,h]s*el1 on ! o!r h&1 0 pre-em95tly an obs]v]4 ,8 nights 7 sp5t 9 ! mo/ dilig5t practical obs]vation ( ! heav5s1 & at all times ! nebul 7 ! objects :i* receiv$ ! l>ge/ measure ( 8 att5tion1 ) ! result t ! k ( nebul receiv$ ! mo/ extraord9>y developm5t f 8 lab\rs4 ,e>li] a/ronom]s _h no d\bt obs]v$ nebul occasionally1 b ) _! imp]fect appliances only ! bright] ( ^! objects 7 disc]nible by !m4 ,! a/oni%+ advance made by ! obs]vations ( ,h]s*el is only p>allel$ by ! advance made a hundr$ ye>s lat] by ! photographs ( ,keel]4 ,b x mu/ be rememb]$ t ?\gh ,h]s*el obs]v$ nebul1 & discov]$ nebul1 & disc\rs$ on nebul 9 pap]s :i* to ?is day are classics 9 ?is important subject1 yet n to ! la/ day ( 8 life c\ld he h felt sure t he _h ev] se5 a g5u9e nebula4 ,he might h surmis$1 & he did surmise1 t _m ( ! objects he set d[n z nebul 7 actually gase\s objects1 b he knew t _m app>5t nebul 7 9 tru? clu/]s ( />s1 & he _h no means ( kn[+ :e!r all s-call$ nebul might n belong to ! same category4 ,x 0 n till ne>ly half a c5tury aft] ,sir ,william ,h]s*el's unrivall$ c>e] _h clos$ t ! spectroscope 0 invok$ to decide f9ally on ! nature ( ^! my/]i\s objects4 ,t decision1 :i* has be5 ( su* transc5d5t importance 9 ! /udy ( ! heav5s1 0 n pron\nc$ till #ahfd4 ,9 t ye> ,sir ,william ,hugg9s e/abli%$ ! fundam5tal tru? t ! s-call$ nebul are n all />-clu/]s1 b t ! univ]se does conta9 objects :i* are mo/ c]ta9ly gigantic volumes ( inc&esc5t gases4 ,?is great a*ievem5t provid$ a complete answ] to ^? :o urg$ an objection1 :i* seem$ once v weighty1 aga9/ ! ,nebul> ,!ory4 ,x mu/ be admitt$ t be=e #ahfd no "o c\ld h affirm$ ) confid5ce t any g5u9e nebula really exi/$4 ,x 01 !re=e1 impossible = ! au?ors ( ! ,nebul> ,!ory to po9t to any object 9 ! heav5s :i* might h illu/rat$ ! great pr9ciples involv$ 9 ! !ory4 ,! ,nebul> ,!ory requir$ t 9 ! beg9n+ !re %\ld h be5 a gase\s nebula f :i* ! sol> sy/em has be5 evolv$4 ,b ! objector1 :o 0 pleas$ to cont5d t ! gase\s nebula 0 a figm5t ( ! imag9ation1 c\ld nev] h be5 effectively sil5c$ by ,kant or ,laplace or ,h]s*el4 ,x w\ld h be5 useless = !m to po9t to ! ,nebula 9 ,orion1 = ! objector might say t x 0 only a clu/] ( />s1 & at t "t !re w\ld h be5 no way ( confut+ him4 ,! au?ors ( ! ,nebul> ,!ory _h1 9 respect to ?is class ( objector1 a mu* m difficult task ?an falls to its mod]n advocate4 ,! latt] is able to d5y 9 ! mo/ emphatic mann] t a gase\s nebula is no m ?an an imag9>y conception4 ,! fam\s discov]y ( ,sir ,w4 ,hugg9s has remov$ ! fir/ great objection to ! ,nebul> ,!ory4 ---------------------------------------- -------------------------------- ,,*apt] ,v4 ,,! ,,heat ,,( ,,! ,,sun4 ,! ,sun to be fir/ consid]$3 its ,evolution is 9 vigor\s ,progress--,consid]ations on ,sol> ,heat--,size ( ! ,sun--,wa/e ( ,sun-heat--,langley's ,illu/ration--,sun 9 ,anci5t ,days--,problem ,/at$--,! ,sol> ,con/ant expla9$--,its ,value det]m9$--,e/imate ( ,radiation f a ,squ>e ,foot ( ! ,sun--,illu/rations ( ,sol> ,en]gy--,decl9e ( ,sol> ,en]gy--,! ,w>eh\se ( ,gra9--,:ite-hot ,globe ( ,iron w\ld ,cool 9 ,=ty-eight ,ye>s--,sun's ,heat is n su/a9$ by ,combu/ion--,inadequacy ( ,combu/ion ,demon/rat$--,j\le's ,unit--,en]gy ( a ,mov+ ,body--,en]gy ( a ,body mov+ ,five ,miles a ,second--,en]gy ( ! ,e>? due to its ,motion4 ,,x w be conv5i5t to consid] diff]5t bodies 9 ! sol> sy/em1 & to /udy !m ) ! special object ( asc]ta9+ :at in=mation !y af=d z to ! great cele/ial evolution4 ,we _c hesitate z to :i* ( ! bodies %\ld fir/ claim our att5tion4 ,n on acc\nt ( ! pr$om9ant importance ( our sun to ! inhabitants ( ! e>?1 b r because ! sun is ne>ly a ?\s& times great] ?an ! greate/ ( ! planets1 d we assign to ! great lum9>y ! fir/ position 9 ?is discussion4 ,! sun is1 inde$1 especially in/ructive on ! subject ) :i* we are occupi$4 ,by reason ( its great mass1 ! process ( evolution takes place m sl[ly 9 ! sun ?an 9 ! e>? or 9 any o!r planet4 ,evolution has1 no d\bt1 l>gely trans=m$ ! sun f its primval condition1 b x has n yet produc$ a trans=mation s radical z t :i* ! e>? & ! o!r planets h und]gone4 ,on ?is acc\nt ! sun c give u in=mation ab\t ! process ( evolution :i* is n to be s easily obta9$ f any ( ! o!r heav5ly bodies4 ,! sun c /ill exhibit to u "s ve/iges1 if we may s speak1 ( t great primval nebula f :i* ! :ole sy/em has sprung4 ,! heat ( ! sun is inde$ "o ( ! mo/ a/oni%+ conceptions :i* ! /udy ( ,nature (f]s to u4 ,let me try to illu/rate x4 ,?9k fir/ ( a p]fect mod]n furnace 9 :i* ev5 /eel itself1 hav+ fir/ atta9$ a dazzl+ brilliance1 c be fur!r melt$ into a liquid t w run l wat]4 ,let u imag9e ! temp]ature ( t liquid to be multipli$ sev5-fold1 & !n we %all obta9 "s conception ( ! fe>ful int5sity ( ! heat :i* w\ld be f\nd 9 t wond]ful cele/ial furnace ! great sun 9 ! heav5s4 ,pond] also ^u ! /up5d\s size ( t orb1 :i* gl[s at e po9t ( its surface ) ! a/oni%+ f]v\r t ?is illu/ration sugge/s4 ,! e>? on :i* we /& is a mighty globe2 yet :at are ! dim5sions ( our e>? 9 comp>ison ) ^? ( ! sun8 ,if we repres5t ! e>? by a gra9 ( mu/>d se$1 !n on ! same scale ! sun %\ld be repres5t$ by a cocoanut4 ,we may p]haps obta9 a m impressive conception ( ! proportions ( ! orb ( day 9 ! foll[+ mann]4 ,look up at ! moon :i* revolves r\nd ! heav51 describ+ z x does s maje/ic a track t x is g5]ally at a di/ance ( two hundr$ & =ty ?\s& miles f ! e>?4 ,yet ! sun is s l>ge t if !re 7 a holl[ globe equally great1 & ! e>? 7 plac$ at its c5tre1 ! entire orbit ( ! moon w\ld lie completely )9 x4 ,e portion ( t /up5d\s des]t ( flame is p\r+ =? torr5ts ( heat4 ,x has1 inde$1 be5 e/imat$ t ! heat :i* issues f an area ( two squ>e feet on ! sun w\ld m ?an suffice1 if x c\ld be all utilis$1 to drive ! eng9es ( ! l>ge/ ,atlantic l9] betwe5 ,liv]pool & ,new ,york4 ,?is sol> heat is scatt]$ ?r\gh space ) b\ndless prodigality4 ,no d\bt ! dwell]s on ! e>? d receive a fair supply ( sunbeams2 b :at is available = ! use ( mank9d c be h>dly m ?an an inf9itesimal fraction ( :at ! sun emits4 ,we %all sc>cely be s presumptu\s z to suppose t ! sun has be5 design$ solely = ! b5efit ( ! poor humanity :i* ne$s light & w>m?4 ,! heat & light daily lavi%$ by ! sun w\ld suffice to w>m & to illum9ate two ?\s& million globes1 ea* z great z ! e>?4 ,if1 inde$1 x 7 true t ! only object ( ! sun's exi/5ce 0 to *]i% ?is imm$iate _w ( ours1 !n all we c say is t ! sun c>ries on its bus9ess 9 a mo/ outrage\sly wa/eful mann]4 ,:at w\ld be ?\ght ( ! prud5ce ( "o :o1 hav+ be5 end[$ ) a =tune ( t5 million p\nds1 sp5t "o s+le p5ny ( t va/ sum 9 a pr(itable mann] & dissipat$ e o!r p5ny & e o!r p\nd ( 8 =tune 9 aimless extravagance8 ,b ?is is app>5tly ! way 9 :i* ! sun manages its affairs1 s f> z our e>? is conc]n$4 ,out ( e t5 million p\nds wor? ( heat issu+ f ! glori\s orb ( day1 we on ?is e>? secure "o p5nywor?1 & all b t solit>y p5nywor? seems to be utt]ly squ&]$4 ,we may say x c]ta9ly is squ&]$ s f> z humanity is conc]n$4 ,:at1 inde$1 its actual de/9ation may be sci5ce is unable to tell4 ,& n[ = ! great "q z to h[ ! sun's heat is su/a9$4 ,h[ is x t ?is c>e] ( trem5d\s prodigality has n ages ago be5 *eck$ by absolute exhau/ion8 ,e *ild kn[s t ! fire on ! he>? w g out unless coal be provid$4 ,! workman kn[s t 8 dev\r+ furnace 9 ! ironworks requires to be incessantly /ok$ ) fre% supplies ( fuel4 ,h[1 !n1 comes x t ! wond]ful furnace on high c /ill cont9ue1 z x has cont9u$ = ages1 to p\r =? its amaz+ /ores ( heat )\t be+ exhau/$8 ,pr(essor ,langley has suppli$ u ) an admirable illu/ration %[+ ! am\nt ( fuel :i* w\ld be necess>y1 if inde$ x 7 by successive additions ( fuel t ! sun's heat 0 su/a9$4 ,suppose t all ! coal-seams :i* und]lie ,engl& & ,scotl& 7 made to yield up _! /ores2 t ! va/ coalfields 9 ,am]ica1 ,au/ralia1 ,*9a1 & else:]e 7 compell$ to contribute e combu/ible p>ticle !y conta9$2 suppose1 9 fact1 t we extract$ f ?is e>? e ton ( coal :i* x possesses 9 e isle & e cont95t2 suppose t ?is mighty /ore ( fuel1 suffici5t to supply all ! wants ( ! e>? = c5turies1 7 to be accumulat$1 & t by "s mighty ef=t t mass 7 to be hurl$ into ! sun & 7 =?) to be burnt to a%es2 !re c be no d\bt t a /up5d\s quantity ( heat w\ld be produc$4 ,b :at is t heat 9 comp>ison1 we d n say ) ! heat ( ! sun1 b ) ! daily exp5diture ( ! sun's heat8 ,h[ long1 ?9k y1 w\ld ! combu/ion ( s va/ a mass ( fuel provide = ! sun's exp5diture8 ,we are giv+ delib]ate expression to a sci5tific fact :5 we say t a conflagration :i* de/roy$ e p>ticle ( coal conta9$ 9 ?is e>? w\ld n g5]ate z mu* heat z ! sun lavi%es 9 ! t5? "p ( e s+le second4 ,dur+ ! few m9utes t y h be5 read+ ^! words a quantity ( heat has gone = ev] f ! sun :i* is five ?\s& times z great z all ! heat t ev] has be5 or ev] w be produc$ by ! combu/ion ( ! coal t ?is e>? has furni%$4 ,b we h /ill ano!r conception to introduce be=e we c appreciate ! full significance ( ! sun's extraord9>y exp5diture ( heat & light4 ,we h be5 ?9k+ ( ! sun z x %9es n[2 b z ! sun %9es to-day1 s x has %one ye/]day1 & s x %one a hundr$ ye>s ago1 a ?\s& ye>s ago2 s x %one 9 ! e>lie/ dawn ( hi/ory1 s x %one dur+ ^? /ill remot] p]iods :5 great animals fl\ri%$ :i* h n[ vani%$ = ev]2 s ! sun %one dur+ ^? remote ages :5 life began to dawn on an e>? :i* /ill 0 "y4 ,we d n1 inde$1 say t ! int5sity ( ! sunbeams has rema9$ actually uni=m ?r\gh\t a p]iod s va/2 b !re is e reason to believe t ?r\gh\t ^! illimitable p]iods ! sun has exp5d$ its radiance ) ! mo/ lavi% g5]osity4 ,a mo/ important "q is sugge/$ by ^! consid]ations4 ,! consequ5ces ( frightful extravagance are kn[n to u all2 we "k t su* conduct t5ds to bankruptcy & ru92 & c]ta9ly ! exp5diture ( heat by ! sun is ! mo/ magnific5t extravagance ( :i* our k gives u any conception4 ,accord+ly1 ! important "q arises3 ,z to h[ ! consequ5ces ( su* awful prodigality h be5 hi!rto av]t$4 ,h[ is x t ! sun is /ill able to draw on its heat res]ve1 f ye> to ye>1 f c5tury to c5tury1 f on to on1 ev] squ&]+ two ?\s& million times z mu* heat z t :i* g5ially w>ms our temp]ate regions1 z t :i* draws =? ! exub]ant vegetation ( ! tropics or :i* rages 9 ! des]t ( ,sah>a8 ,t is ! great problem to :i* our att5tion has to be giv54 ,we mu/ fir/ asc]ta91 ) su* precision z ! circum/ances p]mit1 ! actual am\nt ( heat :i* ! sun p\rs =? 9 its daily radiation4 ,! det]m9ation ( ?is quantity has engag$ ! att5tion ( _m inve/igators1 & ! int]pretation ( _! results is by no means free f difficulty4 ,x is to be obs]v$ t :at we are n[ seek+ to asc]ta9 is n exactly a "q ( temp]ature1 b ( some?+ q diff]5t4 ,:at we h to measure is a quantity ( heat1 :i* is to be express$ 9 ! prop] units = quantities ( heat4 ,! unit ( heat :i* we %all employ is ! quantity ( heat necess>y to raise "o p\nd ( wat] ?r\gh "o degree ,fahr5heit4 ,! sol> con/ant is ! numb] ( units ( heat :i* fall1 9 "o m9ute1 on "o squ>e foot ( a surface plac$ at "r angles to ! sun's rays1 & situat$ at ! mean di/ance ( ! e>? f ! sun4 ,we %all suppose t losses due to atmosph]ic absorption h be5 all[$ =1 s t ! result w express ! numb] ( units ( heat t w\ld be receiv$ 9 "o m9ute on a squ>e foot turn$ directly to ! sun1 & at a di/ance ( #ic1jjj1jjj miles4 ,illu/ration3 ,fig4 #ad4--,,! ,,sun 7,july #h?1 #ahib74 7,royal ,obs]vatory1 ,gre5wi*47 7,f ! ,royal ,a/ronomical ,society ,s]ies47 ,?is is a matt] = det]m9ation by actual obs]vation & measurem5t4 ,!ory c d little m ?an sugge/ ! precautions to be obs]v$ & discuss ! actual figures :i* are obta9$4 ,!re h be5 _m diff]5t me?ods ( mak+ ! obs]vations1 & ! results are some:at v>i\s1 b ! discrepancies are n great] ?an might be expect$ 9 an inve/igation ( su* difficulty4 ,! mean value :i* has be5 arriv$ at is f\rte51 & ! fundam5tal fact ) reg>d to ! sol> radiation :i* we are ?us enabl$ to /ate is t an area ( a squ>e foot expos$ at "r angles to ! sol> rays1 at a di/ance ( #ic millions ( miles1 w 9 ea* m9ute receive f ! sun z mu* heat z w\ld raise "o p\nd ( wat] f\rte5 degrees ,fahr5heit4 ,x foll[s t ! total radiation f ! sun mu/ suffice to convey1 9 ea* m9ute1 to ! surface ( a sph]e ^: radius is #ic1jjj1jjj miles1 f\rte5 units ( heat p] squ>e foot ( t surface4 ,?is radiation comes f ! surface ( ! sun4 ,x is easily %[n t ! heat f ea* squ>e foot on ! sun w h to supply an area ( #df1jjj squ>e feet at ! di/ance ( ! e>?4 ,h5ce ! numb] ( units ( heat em]g+ ea* m9ute f a squ>e foot on ! sun's surface mu/ be ab\t #fdj1jjj4 ,we c be/ realise :at ?is /atem5t implies by f9d+ ! am\nt ( coal :i* w\ld produce ! same quantity ( heat4 ,x c be %[n t ! heat giv5 out by ea* squ>e foot ( ! sol> surface 9 "o m9ute w be equival5t to t produc$ 9 ! combu/ion ( =ty-six p\nds ( coal4 ,if ! sun's heat 7 su/a9$ by combu/ion1 e "p ( ! sun's surface z l>ge z ! grate ( an ord9>y furnace w\ld h to be do+ at lea/ "o hundr$ times z mu* heat+ z ! mo/ vigor\s /ok+ c\ld extract f any actual furnace4 ,! radiation ( heat f a s+le squ>e foot ( ! sol> surface 9 ! c\rse ( a ye> mu/1 !re=e1 be equival5t to ! heat g5]at$ 9 ! combu/ion ( #aa1jjj tons ( ! be/ coal4 ,if we e/imate ! annual coal production ( ,great ,brita9 at #bej1jjj1jjj tons1 we f9d t ! total heat :i* ?is coal c produce is n great] ?an ! annual emission f a squ>e ( ! sun's surface ( :i* ea* side is fifty y>ds4 ,all ! coal export$ f ,engl& 9 a ye> does n give z mu* heat z ! sun radiates 9 ! same "t f e pat* on its surface :i* is z big z a croquet gr\nd4 ,!re is p]haps no great] "q 9 ! /udy ( ,nature ?an t :i* enquires h[ ! sun's heat is su/a9$ s t ! radiation is /ill disp5s$ ) un/9t$ lib]ality4 ,if we are ask$ h[ ! sun c be f$ s z to su/a9 ?is exp5diture1 we h to expla9 t ! sun is n really f$4 ,if1 !n1 x receives no adequate supplies ( en]gy f )\t1 we h to admit t ! sun mu/ be gett+ exhau/$4 ,i ought1 inde$1 to anticipate objection by at once mak+ ! admission t ! sun does receive "s small supply ( en]gy f ! meteors :i* are p]5nially drawn into x4 ,! quantity ( en]gy !y yield is1 h[ev]1 insignificant 9 comp>ison ) ! sol> exp5diture ( heat4 ,we may return to ?is subject at a lat] p]iod1 & x ne$ n n[ receive fur!r att5tion4 ,we mu/ delib]ately face ! fact t ! en]gy ( ! sun is becom+ exhau/$4 ,b ! rate ( exhau/ion is s sl[ t x af=ds no prospect ( inconv5i5ce to humanity2 x does n excite al>m4 ,we grant t we are n able to obs]ve by in/rum5tal means any p]ceptible dim9ution ( sol> en]gy4 ,/ill1 z we "k t en]gy is be+ /eadily dissipat$ f ! sun1 & t en]gy _c be creat$ f no?+1 x is c]ta9 ! decl9e is 9 progress4 ,b ! res]ve ( en]gy :i* ! sun possesses1 & :i* c be ultimately r5d]$ available to su/a9 ! radiation1 is s enorm\s 9 comp>ison ) ! annual exp5diture ( en]gy1 t myriads ( c5turies w h to elapse be=e !re is any appreciable alt]ation 9 ! effectiv5ess ( ! sun4 ,let me illu/rate ! po9t by lik5+ ! sun to a gra9 w>eh\se1 9 :i* #b1ejj tons ( :eat c be accommodat$4 ,let u suppose t ! w>eh\se 0 q full at ! beg9n+1 & t ! :eat 0 to be gradually ab/ract$1 b only at ! rate ( "o gra9 ea* day4 ,let u fur!r suppose t no m :eat is to be add$ to t already 9 ! w>eh\se1 & let u assume t ! :eat ?us /or$ away exp]i5ces no det]ioration & no loss :atev] except by ! removal ( "o gra9 p] diem4 ,x is easy to see t v _m c5turies w\ld h to elapse be=e ! gra9 9 t w>eh\se _h decreas$ to any appreciable ext5t4 ,) a consumption at ! rate ( a s+le gra9 a day a ton ( corn w\ld la/ ab\t f\r ?\s& ye>s1 & #b1ejj tons ( corn w\ld accord+ly la/ ab\t t5 million ye>s4 ,x foll[s1 !re=e1 t if ! gra9 9 t /ore 7 consum$ at ! rate ( only "o gra9 p] day ! w>eh\se w\ld n be empti$ = t5 million ye>s4 ,illu/ration3 ,fig4 #ae4--;,i4 ,,spectrum ,,( ,,! ,,sun4 ,,ii4 ,,spectrum ,,( ,,arcturus4 7,pr(essor ,h4 ,c4 ,"l47 ,! quantity ( heat1 or r ! res]ve ( en]gy equival5t to heat1 :i* /ill rema9s /or$ up 9 ! sun be>s to ! quantity ( heat :i* ! sun radiates away 9 a s+le day a ratio some?+ l t :i* a s+le gra9 ( corn be>s to #b1ejj tons ( corn4 ,! sun's pot5tial /ore ( heat is no d\bt v great1 ?\gh n indef9itely great4 ,t heat is beyond all d\bt to be ultimately exhau/$2 b ! res]ve is s prodigi\s t = ! myriads ( ye>s dur+ :i* ! sun has be5 subject$ to human obs]vation !re has be5 no appreciable alt]ation 9 ! effici5cy ( radiation4 ,x might be suppos$ t ! sun 0 m]ely a :ite-hot globe cool+ d[n1 & t ! sol> radiation 0 to be expla9$ 9 ?is way4 ,b a little calculation w prove x to be utt]ly impossible t ! heat ( ! great lum9>y c\ld be s acc\nt$ =4 ,a k ( ! curr5t exp5diture ( sol> heat %[s t if ! sun _h be5 a globe ( iron at its fus+ po9t1 !n at ! pres5t rate ( radiation x w\ld h sunk to ! temp]ature ( freez+ wat] 9 =ty-eight ye>s4 ,p]haps ,i ought "h to expla9 a po9t :i* might o!rwise cause misappreh5sion4 ,= our ord9>y s\rces ( artificial heat we1 ( c\rse1 employ "s =m ( combu/ion4 ,:5ev] combu/ion takes place !re is *emical union betwe5 ! c>bon or o!r fuel1 :atev] x may be1 & ! oxyg5 ( ! atmosph]e4 ,a c]ta9 quantity ( c>bon ent]s into *emical union ) a def9ite quantity ( oxyg51 &1 z an incid5t 9 ! process1 a def9ite quantity ( heat is lib]at$4 ,s mu* coal1 = in/ance1 requires = complete combu/ion s mu* air1 &1 grant$ a suffici5cy ( air1 ! union ( ! c>bon & hydrog5 9 ! coal w give out a c]ta9 quantity ( heat :i* may be conv5i5tly express$ by ! numb] ( p\nds ( wat] :i* t heat w\ld suffice to trans=m into /eam4 ,x is necess>y to obs]ve t !re are def9ite num]ical relations among ^! quantities4 ,! quantity ( heat t c be produc$ by ! combu/ion ( a p\nd ( any p>ticul> sub/ance w dep5d ^u ! nature ( t sub/ance4 ,z *emical comb9ation is ! ma9 s\rce ( ! artificial heat :i* we employ = innum]able purposes on ! e>?1 x seems prop] to consid] :e!r x c be any =m ( *emical comb9ation :i* con/itutes ! s\rce ( ! heat :i* ! sun radiates 9 su* abundance4 ,x is easy to %[ t ! sol> radiation _c be ?us su/a9$4 ,! po9t to :i* ,i am n[ ref]r+ 0 v cle>ly illu/rat$ by ,helmholtz 9 a lecture he deliv]$ _m ye>s ago on ! orig9 ( ! planet>y sy/em4 ,to inve/igate :e!r ! sol> heat c be attribut$ to *emical comb9ation1 we %all assume = ! mom5t t ! sun is compos$ ( ^? p>ticul> mat]ials :i* w\ld produce ! utmo/ quantity ( heat = a giv5 weight2 9 o!r words1 t ! sun is =m$ ( hydrog5 & oxyg5 9 quantities hav+ ! same ratio z t 9 :i* !y %\ld be unit$ to =m wat]4 ,! quantity ( heat g5]at$ by ! union ( kn[n weights ( oxyg5 & hydrog5 has be5 asc]ta9$1 by exp]im5ts 9 ! laboratory1 to exce$ t :i* c be g5]at$ by correspond+ weights ( any o!r mat]ials4 ,we c calculate h[ mu* ( ! sun's mass1 if ?us con/itut$1 w\ld h to ent] into comb9ation e h\r 9 ord] to g5]ate z mu* heat z ! h\rly radiation ( ! sun4 ,we ne$ n "h p]=m ! actual calculation1 b m]ely /ate ! result1 :i* is a v rem>kable "o4 ,x %[s t ! heat aris+ f ! suppos$ *emical action w\ld n suffice to su/a9 ! radiation ( ! sun at its pres5t rate = m ?an #c1jjj ye>s4 ,?irty c5turies is a long "t1 no d\bt1 yet /ill we mu/ rememb] t x is no m ?an a "p ev5 ( ! p]iod kn[n to human hi/ory4 ,if1 inde$1 x _h be5 by combu/ion t ! sun's heat 0 produc$1 !n f ! beg9n+ ( ! sun's c>e] z a lum9\s object to its f9al ext9ction & dea? c\ld n be long] ?an #c1jjj ye>s1 if we assum$ t its radiation 0 to be uni=mly t :i* x n[ disp5ses4 ,b x may be said t we are deal+ only ) elem5ts kn[n to u & ) :i* t]re/rial *emi/s are famili>1 & x may be urg$ t ! sun possibly conta9s mat]ials ^: *emical union produces heat 9 mu* great] abundance ?an d ! elem5ts ) :i* alone we are acqua9t$4 ,b ?is argum5t _c be su/a9$4 ,"o ( ! mo/ important discov]ies ( ! la/ c5tury1 ! discov]y :i* p]haps m ?an any o!r has t5d$ to place ! nebul> !ory 9 an impregnable position1 is t :i* tells u t ! elem5ts ( :i* ! sun is compos$ are ! same z ! elem5ts ( :i* our e>? is made4 ,we %all h to ref] to ?is 9 detail 9 a lat] *apt]4 ,we n[ only make ?is pass+ ref]5ce to x 9 ord] to dismiss ! notion t !re c be unkn[n sub/ances 9 ! sun ^: heat ( combu/ion w\ld be suffici5tly great to (f] an explanation ( ! extraord9>y abundance ( sol> radiation4 ,!re is no?+ m *>act]i/ic ( ! physical sci5ce ( ! c5tury j clos$ ?an ! fam\s discov]y ( ! num]ical relation :i* exi/s betwe5 heat & en]gy4 ,we are indebt$ to ! life-long lab\rs ( ,j\le1 foll[$ by ^? ( _m o!r inve/igators1 = ! accurate det]m9ation ( ! fundam5tal con/ant :i* is kn[n z ! me*anical equival5t ( heat4 ,j\le %[$ t ! quantity ( heat :i* w\ld suffice to raise "o p\nd ( wat] ?r\gh a s+le degree ,fahr5heit 0 ! precise equival5t ( ! quantity ( en]gy :i* w\ld suffice to raise #ggb p\nds ?r\gh a height ( "o foot4 ,x w\ld be h>d to say :e!r ?is rem>kable pr9ciple has _h a m pr(\nd effect on practical eng9e]+ or on ! c\rse ( physical sci5ce4 ,9 practical eng9e]+1 ! k ( ! me*anical equival5t ( heat w %[ ! eng9e] ! utmo/ am\nt ( "w t c\ld by any conceivable app>atus be extract$ f ! heat pot5tially conta9$ 9 a ton ( coal4 ,9 ! /udy ( a/ronomy ! application ( ! same pr9ciple w suffice to expla9 h[ ! sun's heat has be5 su/a9$ = illimitable ages4 ,illu/ration3 ,fig4 #af4--;,,brooks' ,,comet ,,& ,,meteor ,,trail4 7,novemb] #ac?1 #ahic4 ,exposure #b h\rs47 7,photograph$ by ,pr(essor ,e4 ,e4 ,b>n>d47 ,x w be conv5i5t to comm5ce ) a little calculation1 :i* w provide u ) a result v in/ructive :5 consid]+ cele/ial ph5om5a 9 connection ) en]gy4 ,we h se5 t ! unit ( heat--= s we t]m ! quantity ( heat necess>y to raise a p\nd ( wat] "o degree--w suffice1 :5 trans=m$ into me*anical en]gy1 to raise #ggb p\nds ?r\gh a s+le foot4 ,?is w\ld1 ( c\rse1 be precisely ! same ?+ z to raise "o p\nd ?r\gh #ggb feet4 ,suppose a p\nd weight 7 c>ri$ up #ggb feet high & 7 !n all[$ to drop4 ,! p\nd weight w\ld gradually ga!r spe$ 9 its desc5t1 &1 at ! mom5t :5 x 0 j rea*+ ! e>?1 w\ld be mov+ ) a spe$ ( ab\t #bbd feet a second4 ,we may obs]ve t ! "w :i* 0 done 9 rais+ ! body to ?is height has be5 entirely exp5d$ 9 giv+ ! body ?is p>ticul> velocity4 ,a weight ( "o p\nd1 mov+ ) a spe$ ( #bbd feet a second1 w !re=e conta91 9 virtue ( t motion1 a quantity ( en]gy precisely equival5t to ! unit ( heat4 ,x is a well-kn[n pr9ciple 9 me*anics t if a body be dropp$ f any height1 ! velocity ) :i* x w\ld rea* ! gr\nd is j ! velocity ) :i* ! body %\ld be project$ upw>ds f ! gr\nd 9 ord] to re-asc5d to ! height f :i* x fell 7! resi/ance ( ! air is "h ov]look$ z n hav+ any be>+ ^u ! pres5t argum5t74 ,?us we see t a weight1 mov+ ) a velocity ( #bbd feet p] second1 conta9s )9 itself1 9 virtue ( its motion1 en]gy adequate to make x asc5d aga9/ gravity to ! height ( #ggb feet4 ,t is to say1 ?is velocity 9 a body ( a p\nd weight c d = ! body precisely :at ! unit ( heat c d = x2 h5ce we say t 9 virtue ( its movem5t ! body conta9s a quantity ( en]gy equal to ! en]gy 9 ! unit ( heat4 ,let u n[ c>ry our calculation a little fur!r4 ,if a p\nd ( good coal be burn$ ) a suffici5t supply ( oxyg51 & if e precaution be tak5 s t no portion ( ! heat be wa/$1 x c be %[n t ! combu/ion ( ! coal is suffici5t to produce #ad1jjj units ( heat4 ,9 o!r words1 ! burn+ ( "o p\nd ( coal ought to be able to raise #ad1jjj p\nds ( wat] "o degree1 or #adj p\nds ( wat] a hundr$ degrees1 or #gj p\nds ( wat] two hundr$ degrees4 ,i d n mean to say t effici5cy l ?is w be atta9$ 9 ! actual circum/ances ( ! combu/ion ( coal 9 ! fireplace4 ,a p\nd ( coal does1 no d\bt1 conta9 suffici5t heat to boil sev5 gallons ( wat]2 b x _c be made to effect ?is1 because ! fireplace wa/es 9 ! mo/ extravagant mann] ! heat :i* ! coal produces1 s t no m ?an a small fraction ( t heat is g5]ally r5d]$ available4 ,b 9 ! cosmical op]ations ) :i* we %all be conc]n$ we consid] ! full effici5cy ( ! heat2 & s we take = ! p\nd ( coal its full !oretical equival5t1 namely1 #ad1jjj !rmal units4 ,let u n[ f9d ! quantity ( en]gy express$ 9 foot-p\nds#b to :i* ?is w correspond4 ,x is obta9$ by multiply+ #ad1jjj units ( heat by #ggb1 & we get z ! result #aj1hjh1jjj4 ,t is to say1 a p\nd ( good coal1 9 virtue ( ! fact t x is combu/ible & w give out heat1 conta9s a quantity ( en]gy :i* is repres5t$ by t5 or elev5 million foot-p\nds4 ,footnote #b3 ,a foot-p\nd is ! am\nt ( en]gy requir$ to raise a p\nd weight ?r\gh a height ( "o foot4 ,we n[ approa* ! "q 9 ano!r way4 ,let u ?9k ( a piece ( coal 9 rapid motion2 if ! coal weigh$ a p\nd1 & if x 7 mov+ at #bbd feet a second1 !n ! en]gy x conta9s 9 consequ5ce ( t velocity w\ld1 z we h se51 correspond to "o !rmal unit4 ,we h1 h[ev]1 to suppose t ! piece ( coal is mov+ ) a spe$ mu* high] ?an t j /at$2 & "h we %\ld note t ! en]gy :i* a mov+ body possesses1 9 virtue ( its velocity1 increases v rapidly :5 ! spe$ ( t body increases4 ,if ! velocity ( a mov+ body be d\bl$1 ! en]gy t x possesses increases f\rfold4 ,if ! velocity ( ! body be increas$ t5fold1 !n ! en]gy t x possesses w be increas$ a hundr$fold4 ,m g5]ally1 we may say t ! en]gy ( a mov+ body is proportional to ! squ>e ( ! velocity ) :i* ! body is animat$4 ,let u1 !n1 suppose t ! piece ( coal1 weigh+ "o p\nd1 is mov+ ) a spe$ z swift z a %ot f ! f9e/ piece ( artill]y1 t is to say1 ) a spe$ ( #b1bdj feet a second2 & z ?is figure is t5 times #bbd1 x %[s u t ! mov+ body w !n possess1 9 virtue ( its velocity1 ! equival5t ( "o hundr$ units ( heat4 ,b we h to suppose a motion a good deal m rapid ?an t obta9$ by any artill]y2 we %all consid] a spe$ r m ?an t5 times z fa/4 ,x is easy to calculate t if ! piece ( coal :i* weighs a p\nd is mov+ at ! spe$ ( five miles a second1 ! en]gy t x w\ld possess 9 consequ5ce ( t motion w\ld approximate to #ad1jjj !rmal units4 ,9 o!r words1 we come to ! conclusion t any body mov+ ) a velocity ( five miles a second w possess1 9 virtue ( t velocity1 a quantity ( en]gy j equal to ! en]gy :i* an equally heavy piece ( good coal c\ld produce if burnt 9 oxyg51 & if e portion ( ! heat 7 utilis$4 ,x is q true t ! spe$ ( five miles a second "h suppos$ repres5ts a velocity mu* 9 excess ( any velocity ) :i* we are acqua9t$ 9 ! c\rse ( ord9>y exp]i5ce4 ,x is m ?an t5 times z fa/ z ! spe$ ( a rifle bullet4 ,b a velocity ( five miles a second is n at all l>ge :5 we consid] ! velocities ( cele/ial bodies4 ,we want ?is fact relat+ to ! en]gy 9 a piece ( coal to be rememb]$4 ,we %all f9d x v in/ructive z our subject develops1 & !re=e we give "s illu/rations ) ref]5ce to x4 ,! spe$ ( ! e>? z x moves r\nd ! sun is m ?an eighte5 miles a second--t is to say1 x is ?ree & a half times ! critical spe$ ( five miles4 ,9 virtue ( ?is spe$ ! e>? has a correspond+ quantity ( en]gy4 ,to f9d ! equival5t ( t en]gy x mu/1 z already expla9$1 be rememb]$ t ! en]gy ( a mov+ body is proportional to ! squ>e ( its velocity2 x foll[s t ! en]gy ( ! e>?1 due to its motion r\nd ! sun1 mu/ be almo/ twelve times z great z ! en]gy ( ! e>? w\ld be if x mov$ at ! rate ( only five miles a second4 ,b1 we h already se5 t a body ) ! velocity ( five miles a second w\ld1 9 virtue ( t motion1 be end[$ ) a quantity ( en]gy equal to t :i* w\ld be giv5 out by ! p]fect combu/ion ( an equal weight ( coal4 ,x foll[s1 !re=e1 t ?is e>? ( ours1 solely 9 consequ5ce ( ! fact t x is mov+ 9 its orbit r\nd ! sun1 is end[$ ) a quantity ( en]gy twelve times z great z all ! en]gy t w\ld be giv5 out 9 ! combu/ion ( a mass ( coal equal to ! e>? 9 weight4 ,?is may seem an a/oni%+ /atem5t2 b its tru? is und\bt$4 ,if x %\ld happ5 t ! e>? came into collision ) ano!r body by :i* its velocity 0 /opp$1 ! pr9ciple ( ! cons]vation ( en]gy tells u t ?is en]gy1 :i* ! e>? has 9 consequ5ce ( its motion1 mu/ =?) be trans=m$1 & ! =m :i* x w assume is t ( heat4 ,su* a collision w\ld g5]ate z mu* heat z c\ld be produc$ by ! combu/ion ( twelve globes ( solid coal1 ea* z heavy z ! e>?4 ,we may inde$ rem>k t ! coal-seams 9 our e>?'s cru/ conta91 9 virtue ( ! fact t !y p>take ( ! e>?'s orbital motion1 twelve times z mu* en]gy z w ev] be produc$ by _! combu/ion4 ,x c h>dly be d\bt$ t su* collisions z we h "h imag9$ d occasionally happ5 9 "s p>ts ( space4 ,^? rem>kable new />s :i* f "t to "t break out d]ive1 9 all probability1 _! tempor>y lu/re f collisions betwe5 bodies :i* 7 previ\sly non-lum9\s4 ,b we ne$ n g s f> z int]-/ell> space = a /rik+ illu/ration ( ! trans=mation ( en]gy into heat4 ,9 ! pleas+ ph5om5a ( %oot+ />s our own atmosph]e provides u ) beautiful illu/rations ( ! same pr9ciple4 ,! %oot+ /> s happily caught on ,pr(essor ,b>n>d's plate 7,fig4 #af7 may be cit$ z an example4 ---------------------------------------- -------------------------------- ,,*apt] ,,vi4 ,,h[ ,,! ,,sun',s ,,heat ,,is ,,ma9ta9$4 ,! ,contraction ( a ,body--,helmholtz ,expla9$ ,sun-heat--,*ange ( a ,mile e ,elev5 ,ye>s 9 ! ,sun's ,diamet]--,effect ( ,contraction on ,temp]ature--,! ,sol> ,con/ant--,limits to ! ,sol> ,%r9kage--,a/ronom]s c ,weigh ! ,sun--,d5sity ( ! ,sun--,heat ,develop$ by ! ,fall+ ,toge!r ( ! ,sol> ,mat]ials--,contraction ( ,nebula to ,=m ! ,e>?--,heat ,produc$ 9 ! ,e>?'s ,contraction--,simil> ,calculation ab\t ! ,sun--,e>? & ,sun ,contra/$--,heat ,produc$ 9 ! ,sol> ,contraction f an indef9itely ,great ,nebula--,! ,coal-,unit ,employ$--,calculation ( ! ,heat giv5 out by ! ,sun4 ,,! law :i* decl>es t a body :i* gives out heat mu/ 9 g5]al submit to a correspond+ dim9ution 9 volume appe>s1 s f> z we c judge1 to be "o ( ^? laws :i* h to be obey$ n alone by bodies on :i* we c exp]im5t1 b by bodies ?r\gh\t ! ext5t ( ! univ]se4 ,! law :i* bids ! m]cury asc5d ! /em ( ! !rmomet] :5 ! temp]ature rises1 & desc5d :5 ! temp]ature falls1 af=ds ! pr9ciple :i* expla9s "s ( ! gr&e/ ph5om5a ( ! heav5s4 ,appli$ to ! sol> sy/em x decl>es t z ! sun1 9 disp5s+ its b5efits to ! e>? day by day1 has to p\r =? heat1 s 9 l mann] mu/ x be dim9i%+ 9 bulk4 ,assum+ t ?is pr9ciple ext5ds suffici5tly widely ?r\gh "t & space1 we %all v5ture to apply its consequ5ces ov] ! mighty spaces & p]iods requir$ = cele/ial evolution4 ,we disda9 to notice ! paltry c5turies or m]e ?\s&s ( ye>s :i* include t inf9itesimal trifle kn[n z human hi/ory4 ,our "t conceptions mu/ und]go a va/ ext5sion4 ,x 0 ,helmholtz :o fir/ expla9$ by :at ag5cy ! sun is able to cont9ue its wond]ful radiation ( heat1 not)/&+ t x receives no appreciable aid f *emical comb9ation4 ,helmholtz po9t$ out t inasmu* z ! sun is p\r+ out heat x mu/1 l e o!r cool+ body1 contract4 ,we ought n1 inde$1 to say e cool+ body2 x w\ld be m correct to say1 e body :i* is giv+ out heat1 = ! two ?+s are n necess>ily ! same4 ,inde$1 /range z x may appe>1 x w\ld be q possible t a mass ( gas %\ld be ga9+ 9 temp]ature ev5 ?\gh x 7 los+ heat all ! "t4 ,at fir/ ?is seems a p>adox1 b ! p>adox w be expla9$ if we reflect ^u ! physical *anges :i* ! gas und]goes 9 consequ5ce ( its contraction4 ,let u dwell = a mom5t on ! rem>kable /atem5t t ! sun is becom+ gradually small]4 ,! r$uction requir$ to su/a9 ! radiation corresponds to a dim9ution ( ! diamet] by ab\t a mile e elev5 ye>s4 ,x may s]ve to impress ^u u ! fact ( ! sun's %r9kage if we w rememb] t on t auspici\s day :5 ,que5 ,victoria came to ! ?rone ! sun _h a diamet] m ?an five miles great] ?an x _h at ! "t :5 h] long & glori\s c>e] 0 end$4 ,! sun t %one on ,pale/9e at ! beg9n+ ( ! pres5t era mu/ h _h a diamet] ab\t "o hundr$ & sev5ty miles great] ?an ! sun :i* n[ %9es on ! ,sea ( ,galilee4 ,?is process ( r$uction has be5 go+ on = ages1 :i* f ! human po9t ( view we may practically describe z illimitable4 ,! alt]ation 9 ! sun's diamet] )9 ! p]iod cov]$ by ! records ( man's sway on ?is e>? may be intr9sically l>ge2 x am\nts no d\bt to sev]al hundr$s ( miles4 ,b 9 comp>ison ) ! va/ bulk ( ! sun ?is *ange 9 its magnitude is unimportant4 ,a span ( t5 ?\s& ye>s w c]ta9ly include all human hi/ory4 ,let u take a p]iod :i* is f\r times z long4 ,x is easy to calculate :at ! diamet] ( ! sun mu/ h be5 =ty ?\s& ye>s ago1 or :at ! diamet] ( ! sun is to become 9 ! next =ty ?\s& ye>s4 ,calculat$ at ! rate we h giv51 ! alt]ation 9 ! sun's diamet] 9 ?is p]iod am\nts to r less ?an f\r ?\s& miles4 ,?is seems no d\bt a huge alt]ation 9 ! dim5sions ( ! orb ( day4 ,we mu/1 h[ev]1 rememb] t at ! pres5t mom5t ! diamet] ( ! sun is ab\t #hfc1jjj miles1 & t a loss ( f\r ?\s& miles1 or !reab\ts1 w\ld /ill leave a sun ) a diamet] ( #hei1jjj miles4 ,!re w\ld n be mu* recognisable diff]5ce betwe5 two suns ( ^! diff]5t dim5sions4 ,i ?9k ,i may say t if we c\ld imag9e two suns 9 ! sky at ! same mom5t1 :i* diff]$ only 9 ! circum/ance t "o _h a diamet] ( #hfc1jjj miles & ! o!r a diamet] ( #hei1jjj miles1 x w\ld n be possible )\t c>eful telescopic measurem5t to tell :i* ( ! two 0 ! l>g]4 ,aft] a contraction has tak5 place by loss ( heat1 ! heat t /ill rema9s 9 ! body is conta9$ )9 a small] volume ?an x _h orig9ally4 ,! temp]ature dep5ds n only on ! actual quantity ( heat t ! mass ( gas conta9s1 b also on ! volume ?r\gh :i* t quantity ( heat is diffus$4 ,if !re be two equal weights ( gas1 & if !y ea* h ! same absolute quantity ( heat1 b if "o ( !m occupies a l>g] volume ?an ! o!r1 !n ! temp]ature ( ! gas 9 ! l>ge volume w n be s high z ! temp]ature ( ! gas 9 ! small] volume4 ,?is is inde$ s mu* ! case1 t ! r$uction ( volume by ! loss ( heat may sometimes h a great] effect 9 rais+ ! temp]ature ?an ! v loss ( heat :i* produc$ ! contraction has 9 depress+ x4 ,on ! :ole1 !re=e1 a ga9 ( temp]ature may be %[n4 ,?is is :at1 inde$1 happ5s n unfrequ5tly 9 cele/ial bodies4 ,! contraction hav+ tak5 place1 ! less] quantity ( heat /ill %[s to su* advantage 9 ! r$uc$ volume ( ! body1 t no decl9e ( temp]ature w be p]ceptible4 ,x may happ5 t simultane\sly ) ! decrease ( heat !re is ev5 an increase ( temp]ature4 ,! pr9ciple "u consid]ation %[s t1 ?\gh ! sun is n[ giv+ out heat copi\sly1 x does n necess>ily foll[ t x mu/ at ! same "t be s9k+ 9 temp]ature4 ,z a matt] ( fact1 physici/s d n "k :at c\rse ! temp]ature ( ! sun is actually tak+ at ?is mom5t4 ,! sun may n[ be precisely at ! same temp]ature at :i* x /ood a ?\s& ye>s ago1 or x may be cool]1 or x may be hott]4 ,9 any case x is c]ta9 t ! *ange ( temp]ature p] c5tury is small1 too small1 9 fact1 to be decid$ 9 ! pres5t /ate ( our k4 ,we _c obs]ve any *ange1 & to e/imate ! *ange f me*anical pr9ciples w\ld only be possible if we knew mu* m ab\t ! int]ior ( ! sun ?an we "k at pres5t4 ,we are =c$ to ! conclusion t ! en]gy ( ! sun1 by :i* we mean ei!r its actual heat or :at is equival5t to heat1 mu/ be cont9ually wa/+4 ,a ?\s& ye>s ago !re 0 m heat1 or its equival5t1 9 ! sun ?an !re is at pres5t4 ,b ! sun ( a ?\s& ye>s ago 0 l>g] ?an ! sun t we n[ h1 & ! heat1 or its equival5t1 a ?\s& ye>s ago may n h be5 s effective 9 su/a9+ ! temp]ature ( ! bigg] sun z ! less] quantity ( heat is 9 su/a9+ ! temp]ature ( ! sun at ! pres5t day4 ,x w be notic$ t ! argum5t dep5ds ess5tially on ! alt]ation ( ! size ( ! sun4 ,( c\rse if ! orb ( day _h be5 no great] a ?\s& ye>s ago ?an x is n[1 !n ! sun ( ^? e>ly days w\ld n only h conta9$ m heat ?an our pres5t sun1 b x mu/ h %[n t x did conta9 m heat4 ,9 o!r words1 its temp]ature w\ld !n c]ta9ly h be5 great] ?an x is at pres5t4 ,?us we see ! importance--s f> z radiation is conc]n$--( ! gradual %r9k+ ( ! sun4 ,! great orb ( day decreases1 & its decrease has be5 e/imat$ num]ically4 ,we _c1 inde$1 det]m9e ! rate ( decrease by actual telescopic measurem5t ( ! sun's disc ) ! micromet]2 obs]vations ext5d+ ov] a p]iod ( ?\s&s ( ye>s w\ld be requir$ = ?is purpose4 ,b f kn[+ ! daily exp5diture ( heat f ! sun x is possible to calculate ! am\nt by :i* x %r9ks4 ,we _c conv5i5tly expla9 ! matt] fully 9 ^! pages4 ,^? :o desire to see ! calculation w f9d x 9 ! ,app5dix4 ,suffice x to say "h t ! sun's diamet] dim9i%es ab\t sixte5 in*es 9 e tw5ty-f\r h\rs4 ,?is is an important conclusion1 = ! rate ( contraction ( ! sol> diamet] is "o ( ! mo/ significant magnitudes relat+ to ! sol> sy/em4 ,x 0 ,helmholtz :o %[$ t ! contraction ( ! sun's diamet] by sixte5 in*es a day is suffici5t to acc\nt = ! su/5tation ( ! sol> radiation4 ,= imm5se p]iods ( "t ! heat may be disp5s$ ) practically unalt]$ lib]ality4 ,! "q !n arises z to :at "t-limit may be assign$ to ! effici5cy ( our orb4 ,obvi\sly ! sun _c g on contract+ sixte5 in*es a day indef9itely4 ,if t 7 ! case1 a c]ta9 numb] ( millions ( ye>s w\ld see x vani% altoge!r4 ,! limit to ! capacity ( ! sun to act z a disp5s] ( light & heat c be easily indicat$4 ,at pres5t ! sun1 9 its out] p>ts at all ev5ts1 is /rictly a vapor\s body4 ,! telescope %[s u no?+ resembl+ a solid or a liquid globe4 ,! sun seems compos$ ( gas 9 :i* cl\ds & vap\rs are susp5d$4 ,9 ! sun's c5tre ! temp]ature is probably v mu* great] ?an any temp]ature :i* c be produc$ by artificial means2 x w\ld d\btless be suffici5t n only to melt1 b ev5 to drive into vap\r ! mo/ refractory mat]ials4 ,on ! o!r h&1 ! enorm\s cond5s+ pressure to :i* ^? mat]ials are submitt$ by ! /up5d\s mass ( ! sun w h ! effect ( keep+ !m toge!r & ( compress+ !m to su* an ext5t t ! d5sity ( ! gas1 if inde$ we may call x gas1 is probably z great z ! d5sity ( any kn[n matt]4 ,! fact is t ! t]ms liquids1 gases1 & solids cease to reta9 intelligible di/9ctions :5 appli$ to mat]ials "u su* pressure z w\ld be f\nd 9 ! int]ior ( ! sun4 ,a/ronom]s c weigh ! sun4 ,x may well be imag9$ t ?is is a delicate & difficult op]ation4 ,x c1 h[ev]1 be effect$ ) b little m>g9 ( unc]ta9ty1 & ! result is a /rik+ "o4 ,x s]ves no useful purpose to express ! sun's weight z s _m myriads ( tons4 ,x is m useful = our pres5t purpose to set d[n ! d5sity ( ! sun1 t is to say1 ! ratio ( ! weight ( ! orb1 to t ( a globe ( wat] ( ! same size4 ,?is is ! useful =m 9 :i* to consid] ! weight ( ! sun4 ,a/ronom]s are accu/om$ to ?9k ( ! weight ( our own e>? 9 ?is same fa%ion1 & ! result %[s t ! e>? is r m ?an five times z heavy z a globe ( wat] ( ! same size4 ,we c be/ appreciate ?is by /at+ t if ! e>? 7 made ( granite1 & _h ?r\gh\t ! d5sity :i* we f9d granite to possess at ! surface1 our globe w\ld be ab\t ?ree times z heavy z a globe ( wat] ( ! same size4 ,if1 h[ev]1 ! e>? _h be5 entirely made ( iron1 x w\ld be m ?an sev5 times z heavy z a globe ( wat] ( ! same size4 ,z ! e>? actually has a d5sity ( #e1 x foll[s t our globe tak5 z a :ole is heavi] ?an a globe ( granite ( ! same size1 ?\gh n s heavy z a globe ( iron4 ,9 ! matt] ( d5sity !re is a rem>kable contra/ betwe5 ! sun & ! e>?4 ,! sun's d5sity is mu* less ?an t ( ! e>?4 ,( c\rse x w be und]/ood t ! sun is actually v mu* heavi] ?an our globe2 x is inde$ m ?an ?ree hundr$ ?\s& times great] 9 weight4 ,b ! sun is ab\t a million ?ree hundr$ ?\s& times z big z ! e>?1 & x foll[s f ^! figures t its d5sity _c be m ?an ab\t a f\r? ( t ( ! e>?4 ,! result is t1 at pres5t1 ! sun is ne>ly half z heavy aga9 z a globe ( wat] ! same size4 ,we h us$ r\nd numb]s3 ! d5sity ( ! sun is actually #a4d4 ,illu/ration3 ,fig4 #ag4--;,,argo ,,& ,,! ,,surr\nd+ ,,/>s ,,& ,,nebulosity4 7,photograph$ by ,sir ,david ,gill1 ,k4,c4,b47 ,9 ! foll[+ mann] we expla9 h[ heat is evolv$ 9 ! contraction ( ! sun4 ,9 its e>ly days ! sun1 or r ! mat]ials :i* 9 _! aggregate =m n[ con/itute ! sun1 7 spread ov] an imm5se tract ( space1 millions ( times great] ?an ! pres5t bulk ( ! sun4 ,we see nebulosities ev5 n[ 9 ! heav5s :i* may sugge/ :at ! primval nebula may h be5 be=e ! evolution _h made mu* progress4 ,look = in/ance at ,sir ,david ,gill's photograph ( ! ,nebula 9 ,argo 9 ,fig4 #ag1 or at ! ,trifid ,nebula 9 ,fig4 #ah4 ,we may1 inde$1 consid] ! primval nebula to h be5 s va/ t p>ticles f ! outside fall+ into ! position ( ! pres5t sol> surface w\ld acquire t velocity ( ?ree hundr$ & n9ety miles a second :i* we "k ! attraction ( ! sun is capable ( produc+ on an object :i* has fall5 9 f an indef9itely great di/ance4 ,z ^! p>ts are gradually fall+ toge!r at ! c5tre1 !re w be an enorm\s quantity ( heat develop$ f _! concurr5ce4 ,suppos+1 = in/ance1 t ! mat]ials ( ! sun 7 arrang$ 9 conc5tric sph]ical %ells ar\nd ! c5tre1 & imag9+ ^! %ells to be sep>at$ by long int]vals1 s t ! :ole mat]ial ( ! sun w\ld be ?us diffus$ ov] a va/ ext5t1 !n e p\nd weight 9 ! out]mo/ %ell1 by ! v fact ( its s9k+ d[nw>ds to ! pres5t sol> sy/em1 w\ld acquire a spe$ ( #cij miles a second1 & ?is corresponds to z mu* en]gy z c\ld be produc$ by ! burn+ ( ?ree tons ( coal4 ,b be ! fall ev] s g5tle1 ! great law ( ! cons]vation ( en]gy tells u t = ! same desc5t1 h[ev] p]=m$1 ! same quantity ( heat mu/ be giv5 out4 ,ea* p\nd 9 ! out] %ell w\ld !re=e give out z mu* heat z ?ree tons ( coal4 ,e p\nd 9 ! o!r %ells1 by gradual desc5t into ! int]ior1 w\ld also r5d] its correspond+ contribution4 ,x !n becomes easily intelligible h[1 9 consequ5ce ( ! orig9al diffusion ( ! mat]ials ( ! sun ov] millions ( times its pres5t volume1 a va/ quantity ( en]gy 0 available4 ,z ! sun contract$ ?is en]gy 0 turn$ into radiant heat4 ,we may anticipate a future *apt] s f> z to assume t !re 0 a "t :5 ev5 ?is solid e>? ( ours 0 a nebul\s mass diffus$ ?r\gh space4 ,we are n conc]n$ z to :at ! temp]ature ( t nebul\s mass may h be54 ,we may suppose x to be any temp]ature we please4 ,! po9t t we h n[ to consid] is ! quantity ( heat :i* is g5]at$ by ! contraction ( ! nebula4 ,t heat is produc$ 9 ! contraction w be pla9 f :at has gone be=e4 ,b we may also demon/rate x 9 a slightly diff]5t way4 ,let u take any two po9ts 9 ! nebula1 ,p & ,q4 ,aft] ! nebula has contract$ ! po9ts :i* 7 orig9ally at ,p & ,q w be f\nd at two o!r po9ts1 ,a & ,b4 ,z ! :ole nebula 9 its orig9al =m 0 l>g] ?an ! nebula aft] x has und]gone its contraction1 ! di/ance ,p ,q is g5]ally great] ?an ! di/ance ,a ,b4 ,we may suppose ! contraction to proce$ uni=mly1 s t ! same w be true ( ! di/ance betwe5 any o!r two p>ticles4 ,! di/ance betwe5 e pair ( p>ticles 9 ! contract$ nebula w be less ?an ! di/ance betwe5 ! same p>ticles 9 ! orig9al nebula4 ,illu/ration3 ,fig4 #ah4--,,trifid ,,nebula ,,9 ,,sagitt>ius 7,lick ,obs]vatory1 ,cali=nia74 7,f ! ,royal ,a/ronomical ,society ,s]ies47 ,if two attract+ bodies1 ,a & ,b1 are to be mov$ fur!r ap>t ?an !y 7 orig9ally1 =ce mu/ be appli$ & "w mu/ be done4 ,we may measure ! am\nt ( t "w 9 foot-p\nds1 & !n1 rememb]+ t #ggb foot-p\nds ( "w are equival5t to ! unit ( heat1 we may express ! en]gy necess>y to =ce ! two p>ticles to a great] di/ance asund] 9 ! equival5t quantity ( heat4 ,if1 !re=e1 we _h to re/ore ! nebula f ! contract$ /ate to ! orig9al /ate1 ?is w\ld involve a =cible enl>gem5t ( ! di/ance ,a ,b betwe5 e two p>ticles to its orig9al value1 ,p ,q4 ,"w w\ld be requir$ to d ?is 9 e case1 & t "w might1 z we h expla9$1 be express$ 9 t]ms ( its equival5t heat value4 ,ev5 ?\gh ! temp]ature ( ! nebula is ! same 9 its contract$ /ate z 9 its orig9al /ate1 we see t a quantity ( heat might be absorb$ or r5d]$ lat5t 9 =c+ ! nebula f "o condition to ! o!r4 ,9 o!r words1 keep+ ! temp]ature ( ! nebula always con/ant1 we %\ld h to apply a l>ge quantity ( heat to *ange ! nebula f its contract$ =m to its exp&$ =m4 ,x is equally true t :5 ! nebula is contract+1 & :5 ! di/ance betwe5 e two p>ticles is less5+1 ! nebula mu/ be giv+ out en]gy1 because ! total en]gy 9 ! contract$ /ate is less ?an x 0 9 ! exp&$ /ate4 ,?is en]gy is equival5t to heat4 ,we ne$ n "h pause to consid] by :at actual process ! heat is manife/$2 x suffices to say t ! heat mu/1 by "o ( ! g5]al laws ( ,nature1 be produc$ 9 "s =m4 ,we are n[ able to make a num]ical e/imate4 ,we %all suppose t ! e>?1 or r ! mat]ials :i* make ! e>?1 exi/$ orig9ally z a l>ge nebula di/ribut$ ?r\gh illimitable space4 ,! calculations %[ t ! quantity ( heat1 g5]at$ by ! cond5sation ( ^? mat]ials f _! nebul\s =m into ! condition :i* ! e>? n[ has1 0 enorm\sly great4 ,we ne$ n express ?is quantity ( heat 9 ord9>y units4 ,! unit we %all take is "o m suit$ to ! o!r dim5sions involv$4 ,let u suppose a globe ( wat] z heavy z ! e>?4 ,?is globe w\ld h to be five or six times z l>ge z ! e>?4 ,next let u realise ! quantity ( heat t w\ld be requir$ to raise t globe ( wat] f freez+ po9t to boil+ po9t4 ,x c be prov$ t ! heat1 or its equival5t1 :i* w\ld be g5]at$ m]ely by ! contraction ( ! nebula to =m ! e>?1 w\ld be n9ety times z great z ! am\nt ( heat :i* w\ld suffice to raise a mass ( wat] equal 9 weight to ! e>? f freez+ po9t to boil+ po9t4 ,we apply simil> calculations to ! case ( ! sun4 ,let u suppose t ! great lum9>y 0 once diffus$ z a nebula ov] an exce$+ly great area ( space4 ,x might at fir/ be ?\ght t ! figures we h j giv5 w\ld answ] ! "q4 ,we might p]haps conjecture t ! quantity ( heat w\ld be su* z w\ld raise a mass ( wat] equal to ! sun's mass f freez+ to boil+ po9t n9ety times ov]4 ,b we %\ld be v wrong 9 su* a det]m9ation4 ,! heat t is giv5 out by ! sun's contraction is enorm\sly great] ?an ?is e/imate w\ld repres5t1 & we %all be prep>$ to admit ?is if we reflect on ! foll[+ circum/ances4 ,a /one fall+ f an indef9itely great di/ance to ! sun w\ld acquire a spe$ ( #cij miles a second by ! "t x rea*$ ! sun's surface4 ,a /one fall+ f an indef9itely great di/ance 9 space to ! e>?'s surface w\ld1 h[ev]1 acquire a spe$ ( n m ?an sev5 miles a second4 ,! spe$ acquir$ by a body fall+ into ! sun by ! gravitation ( ! sun is1 !re=e1 fifty-six times z great z ! spe$ acquir$ by a body fall+ f inf9ity to ! e>? by ! gravitation ( ! e>?4 ,z ! en]gy ( a mov+ body is proportional to ! squ>e ( its velocity1 we see t ! en]gy ) :i* ! fall+ body w\ld /rike ! sun1 & ! heat t x might consequ5tly give =?1 w\ld be ab\t ?ree ?\s& times z great z ! heat :i* w\ld be ! result ( ! fall ( t body to ! e>?4 ,we ne$ n !re=e be surpris$ t ! draw+ toge!r ( ! elem5ts to =m ! sun %\ld be accompani$ by ! evolution ( a quantity ( heat :i* is enorm\sly great] ?an ! m]e ratio ( ! masses ( ! e>? & sun w\ld h sugge/$4 ,!re is ano!r l9e ( reason+ by :i* we may also illu/rate ! same important pr9ciple4 ,ow+ to ! imm5se attraction possess$ by ! l>ge mass ( ! sun1 ! weights ( objects on t lum9>y w\ld be v mu* great] ?an ! weights ( correspond+ objects "h4 ,inde$1 a p\nd on ! sun w\ld be f\nd by a spr+-balance to weigh z mu* z tw5ty-sev5 p\nds "h4 ,if ! mat]ials ( ! sun _h to be di/ribut$ ?r\gh space1 ea* p\nd lift$ a foot w\ld require tw5ty-sev5 times ! am\nt ( "w :i* w\ld be necess>y to lift a p\nd ?r\gh a foot on ! e>?'s surface4 ,x w ?us be se5 t n only ! quantity ( mat]ial t w\ld h to be displac$ is enorm\sly great] 9 ! sun ?an 9 ! e>?1 b t ! actual en]gy t w\ld h to be appli$ p] unit ( mass f ! sun w\ld be _m times z great z ! quantity ( en]gy t w\ld h to be appli$ p] unit ( mass f ! e>? to effect a displacem5t ?r\gh ! same di/ance4 ,to di/ribute ! sun's mat]ials into a nebula we %\ld !re=e require ! exp5diture ( a quantity ( "w f> m ?an proportional to ! m]e mass ( ! sun4 ,x foll[s t :5 ! sun is contract+ ! quantity ( "w t x w give out1 or1 :at comes to ! same ?+1 ! am\nt ( heat t w\ld be p\r$ =? 9 consequ5ce ( ! contraction p] unit ( mass ( ! sun w l>gely exce$ ! quantity ( heat giv5 out 9 ! simil> contraction ( ! e>? p] unit ( mass ( ! e>?4 ,^! consid]ations w prep>e u to accept ! result giv5 by accurate calculation4 ,x has be5 %[n t ! heat :i* w\ld be g5]at$ by ! cond5sation ( ! sun f a nebula fill+ all space d[n to its pres5t bulk is two hundr$ & sev5ty ?\s& times ! am\nt ( heat :i* w\ld be requir$ to raise ! temp]ature ( a mass ( wat] equal to ! sun f freez+ po9t to boil+ po9t4 ,?is is a result ( a mo/ in/ructive "*4 ,! am\nt ( heat t w\ld be requir$ to raise a p\nd ( wat] f freez+ po9t to boil+ po9t w\ld1 speak+ g5]ally1 be q en\gh if appli$ to a p\nd ( /one or iron to raise ei!r ( ^! masses to a r$ heat4 ,if1 !re=e1 we ?9k ( ! sun z a mighty globe ( /one or iron1 ! am\nt ( heat t w\ld be produc$ by ! contraction ( ! sun f ! primval nebula w\ld suffice to raise t globe ( /one or iron f freez+ po9t up to a r$ heat #bgj1jjj times4 ,?is w give u "s idea ( ! /up5d\s am\nt ( heat :i* has be5 plac$ at ! disposal ( ! sol> sy/em by ! process ( contraction ( ! sun4 ,?is contraction is /ill go+ on1 & consequ5tly ! yield ( heat :i* is ! consequ5ce ( ?is contraction is /ill 9 progress1 & ! heat giv5 out provides ! annual supply necess>y = ! su/5ance ( our sol> sy/em4 ,!re is "o po9t :i* %\ld be specially m5tion$ 9 connection ) ?is argum5t4 ,we h "h suppos$ t ! curr5t supply ( radiant heat f ! sun is entirely 9 virtue ( ! sun's contraction4 ,t is to say1 we suppose ! sun's temp]ature to be rema9+ unalt]$4 ,?is is p]haps n /rictly ! case4 ,!re may be reason = believ+ t ! temp]ature ( ! sun is increas+1 ?\gh n to an appreciable ext5t4 ,x w be conv5i5t to introduce a unit t w be on a scale adapt$ to our measurem5ts4 ,let u ?9k ( a globe ( coal z heavy z ! sun4 ,n[ suppose adequate oxyg5 7 suppli$ to burn t coal1 a def9ite quantity ( heat w\ld be produc$4 ,!re is no pres5t necessity to evaluate ?is 9 ! less] units adapt$ = o!r purposes4 ,9 discuss+ ! heat ( ! sun1 we may use :at we call ! coal-unit1 by :i* is to be und]/ood ! total quantity ( heat t w\ld be produc$ if a mass ( coal equal to ! sun 9 weight 7 burn$ 9 oxyg54 ,x c be %[n by calculations1 :i* w be f\nd 9 ! ,app5dix1 t 9 ! %r9kage ( ! sun f an inf9itely great ext5sion ?r\gh space d[n to its pres5t bulk ! contraction w\ld develop ! /up5d\s quantity ( heat repres5t$ by #c1djj coal-units4 ,x is also %[n t "o coal unit w\ld be adequate to supply ! sun's radiation at its pres5t rate = #b1hjj ye>s4 ---------------------------------------- -------------------------------- ,,*apt] ,,vii4 ,,! ,,hi/ory ,,( ,,! ,,sun4 ,! ,incon/ant ,sun--,repres5tation ( ! ,sol> ,sy/em at diff]5t ,epo*s--,primval ,d5sity ( ! ,sun--,illu/ration ( ,gas 9 ,extreme ,t5uity--,physical ,/ate ( ! ,sun at t ,p]iod--,! ,sun 0 !n a ,nebula4 ,,we po9t$ out 9 ! la/ *apt] h[1 9 consequ5ce ( its p]5nial loss ( heat1 ! orb ( day mu/ be und]go+ a gradual dim9ution 9 size4 ,9 ! pres5t *apt] we are to set d[n ! rem>kable conclusions ) respect to ! e>ly hi/ory ( ! sun to :i* we h be5 conduct$ by pursu+ to its legitimate consequ5ces ! %r9kage :i* ! sun _h und]gone 9 times pa/4 ,! out] circle 9 ,fig4 #ai repres5ts ! track 9 :i* our e>? n[ revolves ar\nd ! sun1 & we are to und]/& t ! radius ( ?is circle is ab\t n9ety-?ree million miles4 ,we mu/ imag9e t ! inn]mo/ ( ! f\r circles repres5ts ! position ( ! sun4 ,along its track ! e>? revolves ye> aft] ye>2 s x has revolv$ = c5turies1 s x has revolv$ s9ce ! days ( ! fir/ mon>* t ev] held sway 9 ,brita91 s x has revolv$ dur+ all ! "t ov] :i* hi/ory ext5ds1 s x has d\btless revolv$ = illimitable p]iods ant]ior to hi/ory4 ,= an int]val ( "t t no "o presumes to def9e ) any accuracy ! e>? has revolv$ 9 ! same track r\nd t sun 9 heav5 :i*1 dur+ all ^? ages1 has disp5s$ its b5efits ( light & heat = ! su/5ance ( life on our globe4 ,illu/ration3 ,fig4 #ai4--,,to ,,illu/rate ,,! ,,hi/ory ,,( ,,! ,,sun4 ,pres5t orbit ( ,e>?4 ,sun 9 times v mu* e>li] /ill4 ,sun 9 v e>ly times4 ,pres5t ,sun4 ,! sun appe>s con/ant dur+ ^? few ye>s 9 :i* man is all[$ to /rut 8 little h\r4 ,! size ( ! sun & ! lu/re ( ! sun has n appreciably alt]$4 ,b ! sun does n always rema9 ! same4 ,x has n always %one ) ! brightness & vig\r ) :i* x %9es n[2 x w n cont9ue = ev] to disp5se its b5efits ) ! same lib]ality t x does at pres5t4 ,! sun is always 9 a /ate ( *ange4 ,x w\ld n inde$ be correct to ref] to ^! *anges z gr[?s1 9 ! same s5se 9 :i* we speak ( ! gr[? 9 a tree4 ,decade aft] decade ! tree waxes great]2 b ! sun1 z we h already expla9$1 does n increase ) ! "t1 = ! *ange inde$ lies ! o!r way4 ,x may well be t 9 ?is pres5t era ! sun is ne> its prime1 9 s f> z its capacity to radiate w>m? & brightness is conc]n$4 ,x is1 h[ev]1 c]ta9 t ! sun is n n[ s l>ge z x 0 9 anci5t days4 ,! dim9ution ( ! orb is /ill 9 progress4 ,9 ^! pres5t days ( its glori\s spl5d\r ! orb ( day is mu* l>g] ?an x w be 9 t gloomy old age :i* de/9y assigns to x4 ,we h already %[n h[ to give num]ical precision to our facts4 ,we h /at$ t ! sun's diamet] is dim9i%+ at ! rate ( "o mile e elev5 ye>s4 ,we h dwelt ^u ! rem>kable significance ( t %r9kage 9 acc\nt+ = ! su/5tation ( ! sun's heat4 ,we h n[ to call on ?is p]5nial dim9ution ( ! sun's diamet] to provide "s in=mation z to ! e>ly hi/ory ( our lum9>y4 ,! inn]mo/ circle 9 our sket* is to sugge/ ! sun z x is at pres5t4 ,millions ( ye>s ago ! orb ( day 0 z l>ge z ,i h indicat$ x by ! circle ) ! words 8sun 9 v e>ly times40 ,x w1 ( c\rse1 be und]/ood t we d n make any claim to precise repres5tation ( ! magnitude ( ! orb4 ,at a p]iod mu* e>li] /ill1 ! sun mu/ h be5 l>g] /ill1 & we v5ture s to depict x4 ,we "k ! rate at :i* ! sun is n[ contract+1 & d\btless ?is rate has cont9u$ s5sibly unalt]$ dur+ ?\s&s ( ye>s1 & inde$ we might say scores ( ?\s&s ( ye>s4 ,b x w\ld n be at all safe to assume t ! annual rate ( *ange 9 ! sun's radius has rema9$ ! same ?r\gh\t excessively remote p]iods 9 its evolution>y hi/ory4 ,:at we d affirm is1 t 9 ! c\rse ( its evolution ! sun mu/ h be5 contract+ cont9ually1 & we h be5 able to le>n ! p>ticul> rate ( contraction *>act]i/ic ( ! pres5t "t4 ,b ?\gh we are ignorant ( ! rate ( contraction at v e>ly epo*s1 yet ! sun ev] looms l>g] & l>g] 9 days e>li] & /ill e>li]4 ,b 9 ^? e>ly days ! sun 0 n heavi]1 0 n1 inde$1 q s heavy z x is at pres5t4 ,= we rememb] t ! sun is p]5nially add+ ?\s&s ( tons to its bulk by ! influx ( meteors4 ,p]haps we ought to add t ! ga9 ( mass f ! meteors may be to "s ext5t comp5sat$ by ! loss ( sub/ance :i* ! sun n infrequ5tly exp]i5ces if1 z is sometimes suppos$1 x expels 9 "s viol5t convulsion a mass ( mat]ial :i* takes ! =m ( a comet 7,fig4 #ba74 ,let u n[ consid] :at ! d5sity ( ! sun mu/ h be5 9 ^? primval days1 say1 = example1 :5 ! lum9>y _h t5 times ! volume t x has at pres5t4 ,ev5 n[1 z already /at$1 x does n weigh half z mu* aga9 z a globe ( wat] ( ! same size1 s t :5 x 0 t5 times z big its d5sity mu/ h be5 only a small fraction ( t ( wat]4 ,b we may take a /age /ill e>li]4 ,let u ?9k ( a "t--x 01 p]haps1 _m scores ( millions ( ye>s ago--:5 ! sun 0 a ?\s& times z big z x is at pres5t4 ,! same quantity ( matt] :i* n[ con/itutes ! sun 0 !n exp&$ ov] a volume a ?\s& times great]4 ,a rem>kable conclusion foll[s f ?is consid]ation4 ,! air t we brea! has a d5sity :i* is ab\t ! sev5-hundr$? "p ( t ( wat]4 ,h5ce we see t at ! "t :5 ! mat]ials ( ! sun 7 exp&$ into a volume a ?\s& times z great z x is at pres5t ! d5sity ( ! lum9>y mu/ h be5 ab\t equal to t ( ord9>y air4 ,we ref]1 ( c\rse1 9 su* /atem5ts to ! av]age d5sity ( ! sun4 ,x w be rememb]$ t ! d5sity ( ! sun _c be uni=m4 ,! mutual attractions & pressures ( ! p>ticles 9 ! int]ior mu/ make ! d5sity great] ! ne>] we approa* to ! c5tre4 ,we mu/ pu% our argum5t fur!r /ill4 ,we h asc]ta9$ t ! primval sun c\ld n h be5 a d5se solid body l a ball ( metal4 ,x mu/ h be5 m ne>ly repres5t$ by a ball ( gas4 ,!re 0 a "t :5 t collection ( matt] :i* n[ con/itutes ! sun 0 s big t a balloon ( equal size1 fill$ at ord9>y pressure ) ! lighte/ ( kn[n gases1 w\ld conta9 )9 x a heavi] weight ?an ! sun4 ,at ?is e>ly p]iod ! sun mu/ h be5 z light z an equal volume ( hydrog54 ,! reason+ :i* has conduct$ u to ?is po9t rema9s /ill unimpair$4 ,f t e>ly p]iod we may !re=e look back to p]iods e>li] /ill4 ,we see t ! sun mu/ h be5 ev] l>g] & l>g]1 = ! same quantity ( mat]ial mu/ h be5 ev] m & m diffus$4 ,!re 0 a "t :5 ! mean d5sity ( ! sun mu/ h be5 f> less ?an t ( ! gas 9 any balloon4 ,we mu/ n pause to consid] int]m$iate /ages4 ,we %all look back at once to an excessively e>ly p]iod :5 ! sun--or p]haps we ought r to say ! matt] :i* 9 a m cond5s$ =m n[ con/itutes ! sun--0 exp&$ ?r\gh\t ! volume ( a globe ^: radius 0 z great z ! pres5t di/ance f ! sun to ! e>?4 ,h we n "h truly an a/oni%+ result1 d$uc$ z a necess>y consequ5ce f ! fundam5tal laws ( heat8 ,illu/ration3 ,fig4 #bj4--,,! ,,sol> ,,corona 7,janu>y #a/1 #ahii74 7,photograph$ dur+ ,eclipse by ,pr(essor ,w4 ,h4 ,pick]+47 ,i ne$ h>dly say t ! sun at t e>ly date did n at all resemble ! glori\s orb to :i* we owe our v exi/5ce4 ,! primval sun mu/ h be5 a totally diff]5t object1 z we c easily imag9e if we try to ?9k t ! sun's mat]ials !n fill$ a volume twelve million times z great z !y occupy at pres5t4 ,in/ead ( comp>+ su* an object ) ! gases 9 our ord9>y atmosph]e1 x %\ld r be lik5$ to ! residue left 9 an exhau/$ receiv] aft] ! res\rces ( *emi/ry h be5 tax$ to make z ne> an approa* z possible to a p]fect vacuum4 ,we c give a famili> illu/ration ( gas 9 a /ate ( extreme t5uity4 ,look at ! beautiful inc&esc5t light ) :i* 9 ^! days our build+s are illum9at$4 ,h[ brilliantly ^? little globes %9e6 ,! globe has to be mo/ c>efully seal$ aga9/ ! outside air4 ,if !re 7 ! smalle/ opportunity = access1 ! air f outside w\ld ru% 9 & ! lamp w\ld be de/roy$4 ,9 ! prep>ation ( su* a lamp elaborate precautions h to be tak5 to secure t ! exhau/ion ( ! air f ! little globe %all be z ne>ly p]fect z possible4 ,( c\rse x is impossible to remove all ! air4 ,no kn[n processes c produce a p]fect vacuum4 ,"s traces ( gas w\ld rema9 aft] ! air-pump _h be5 appli$ ev5 = h\rs4 ,we mu/ n[ imag9e a globe1 n m]ely two in*es 9 diamet] l "o ( ^! little lamps1 b a globe #ahf1jjj1jjj miles 9 diamet]1 a globe s l>ge t ! e>?'s orbit w\ld j =m a girdle r\nd x4 ,ev5 if ?is globe _h be5 exhau/$1 s t its d5sity 0 only ! twelve-?\s&? "p ( ! ord9>y atmosph]ic d5sity1 x w\ld /ill conta9 m mat]ial ?an is f\nd 9 ! sun 9 heav54 ,?us our reason+ has conduct$ u to ! notion ( an epo* :5 ! sun--or r ,i %\ld say ! matt] compos+ ! sun--=m$ some?+ totally diff]5t f ! orb :i* we "k s well4 ,! matt] 9 t v diffuse /ate w\ld n disp5se light & heat z a sun 9 ! s5se 9 :i* we und]/& ! ^w4 ,h[ev] va/ might be ! /ore ( en]gy :i* x conta9$--a /ore inde$ ?\s&s ( times great] ?an our pres5t sun possesses--yet x w\ld h>dly be possess$ ( ! p[] ( effective radiation4 ,x w\ld assur$ly n be able to w>m & light a _w associat$ ) x1 9 ! same way z ! sun n[ provides s glori\sly = our wants & com=t4 ,illu/ration3 ,fig4 #ba4--,,! ,,great ,,comet ,,( #ahhb4 7,photograph$ on ,novemb] #g?1 #ahhb1 by ,sir ,david ,gill1 ,k4,c4,b47 ,b x is c]ta9 t 9 ^? e>ly days !re 0 no e>? to be w>m$ & light$4 ,our globe1 ev5 if x c be said to h exi/$ at all1 0 truly 8)\t =m & void40 ,at ! "t :5 ! sun 0 swoll5 into a great globe ( gas or r>efi$ matt]1 ! elem5t>y sub/ances :i* 7 to =m ! future e>? 7 9 a condition utt]ly diff]5t f t ( our pres5t globe4 ,! hi/ory ( ?is e>? itself involves ano!r *apt] ( ! argum5t4 ,let x suffice to notice1 = ! pres5t1 t our reason+ has l$ u to a "t :5 ! sun consi/$ only ( a r>efi$ gase\s mat]ial1 & let u give to ! matt] 9 ?is condition ! "n :i* a/ronom]s apply to any object ( a simil> "* :]ev] !y may meet ) x 9 ! univ]se4 ,suppose t we c\ld obs]ve ?r\gh our telescopes at ! pres5t mom5t an object 9 remote space :i* 0 l :at ! sun mu/ h be5 at t e>ly /age ( its exi/5ce :i* we h be5 consid]+1 ,i d n ?9k t ! object w\ld be unfamili> to a/ronom]s4 ,!re is1 inde$1 no d\bt t !re are _m objects visible at ?is mom5t1 & nightly /udi$ 9 our obs]vatories1 :i* are =m$ ( matt] j 9 ! same /ate z ! sun 0 9 ^? e>ly times4 ,exam9$ ) a good telescope1 ! object w\ld seem l a small /a9 ( light on ! black backgr\nd ( ! sky4 ,! obs]v] w\ld at once call x a nebula4 ,9 ^! mod]n days he w\ld probably apply ! spectroscope to x1 & ?is in/rum5t w\ld assure him t ! object he 0 look+ at 0 a mass ( inc&esc5t gas4 ,su* an object w\ld 9 all probability n greatly diff] f _m nebul n[ kn[n to u4 ,?is be+ s1 :y %\ld we )hold f ! sun ( primitive days ! designation to :i* x seems to be s fully entitl$8 ,:y %\ld we n speak ( x z a nebula8 ,! application ( ! laws ( heat has %[n t ! great orb ( day 0 once "o ( ^? num]\s objects :i* a/ronom]s "k z nebul1 & p]haps x may n be too fanciful to suppose t a trace ( ! primval nebula /ill survives 9 :at we call ! ,sol> ,corona 7,fig4 #bj74 ---------------------------------------- -------------------------------- ,,*apt] ,,viii4 ,,! ,,e>?',s ,,beg9n+4 ,! ,e>? to be ,/udi$--,a great ,exp]im5t--,! ,diamond ,drill--,a ,bor+ upw>ds ( a ,mile ,deep--,a ,me*anical ,feat--,! ,sci5tific ,importance ( ! ,"w--,increase ( ,temp]ature ) ! ,dep?--,a special ,=m ( ,!rmomet]--,tak+ ! ,temp]ature 9 ! ,bor+--,! ,level ( ,con/ant ,temp]ature--,! ,rate ( ,increase ( ,temp]ature ) ! ,dep?--,"o degree ,fahr5heit = e ,sixty-six ,feet 9 ,dep?--,temp]atures at ,dep?s above a ,mile--,conclusions z to ! ,heat at v great ,dep?s--,! ,heat develop$ by ,tidal ,action--,?is w n acc\nt = ! ,e>?'s ,int]nal ,heat--,! ,e>? mu/ be cont9ually ,cool+--,inf]5ces f ! incessant loss ( ,heat f ! ,e>?--,! ,e>?'s ,surface once ,r$-,hot1 or ,molt5--,! ,e>? mu/ h orig9at$ f a ,nebula--,! ,e>?'s ,beg9n+4 ,,9 ! la/ *apt] we endeav\r$ to asc]ta9 :at c be le>n$ f ! radiation ( ! sun ) reg>d to ! hi/ory ( ! sol> sy/em4 ,9 ?is *apt] we %all n consid] any body 9 ! heav5s1 b ! condition ( ! e>? itself4 ,we h le>n$ some?+ ( ! hi/ory ( ! sol> sy/em f ! cele/ial bodies2 we %all n[ le>n some?+ ab\t x 9 ano!r way--f ! condition ( our globe at dep?s f> b5ea? our feet4 ,x w be conv5i5t to comm5ce by m5tion+ a rem>kable exp]im5t :i* 0 made a few ye>s ago4 ,?\gh t exp]im5t is ( great sci5tific int]e/1 yet x 0 n design$ ) any sci5tific object 9 view4 ,n less ?an #aj1jjj 0 exp5d$ on ! ent]prise1 & probably s l>ge a sum has nev] be5 exp5d$ on a s+le exp]im5t ( :i* ! sole object 0 to add to sci5tific k4 ,9 ! pres5t case ! imm$iate object 9 view 01 ( c\rse1 a comm]cial "o4 ,!re 01 x may be presum$1 reasonable expectation t ! great initial co/1 & a h&some pr(it z well1 w\ld be return$ z ! fruits ( ! ent]prise4 ,:e!r ! great exp]im5t 0 successful f ! money-mak+ po9t ( view does n n[ conc]n u1 b x does conc]n u to "k t ! exp]im5t 0 v successful 9 ! s5se t x incid5tally af=d$ sci5tific in=mation ( ! v highe/ value4 ,! exp]im5t 9 "q 0 made 9 ,g]many1 at ,s*ladeba*1 ab\t fifte5 miles f ,leipzig4 ,x 0 und]tak5 9 mak+ a se>* = coal4 ,"s ent]pris+ capitali/s consult$ ! geologi/s z to :e!r coal-seams 7 likely to be f\nd 9 ?is locality4 ,!y 7 assur$ t coal 0 !re1 ?\gh x mu/ c]ta9ly be a v long way d[n1 & consequ5tly ! pit by :i* alone ! seams c\ld be work$ w\ld h to be unusually deep4 ,! capitali/s 7 n daunt$ by ?is consid]ation4 ,b1 be=e incurr+ ! great exp5se ( s9k+ ! %aft1 !y det]m9$ to make a prelim9>y se>* & v]ily ! actual pres5ce ( workable seams ( useful fuel4 ,!y det]m9$ to bore a hole d[n ?r\gh ! rocks deep en\gh to rea* ! coal1 if x c\ld be rea*$4 ,a bor+ = coal 01 ( c\rse1 by no means a novelty2 b !re 0 an unprec$5t$ degree ( me*anical skill & sci5tific acum5 %[n 9 ?is memorable bor+ ne> ,leipzig4 ,! result ( ?is ent]prise 0 to make ! deepe/ hole :i*1 ) p]haps a s+le m rec5t exception n ( s mu* sci5tific int]e/1 has ev] be5 pi]c$ ?r\gh ! cru/ ( ! e>?4 ,?is bor+ 0 m]ely a prelim9>y to ! op]ations :i* w\ld foll[ if ! exp]im5t 7 successful 9 discov]+ coal4 ,x 0 accord+ly only necess>y to make a hole l>ge en\gh to all[ specim5s ( ! /rata to be br\ght to ! surface4 ,! in/rum5t employ$ 9 s9k+ a hole ( su* a ph5om5al dep? ?r\gh solid rock is *>act]i/ic ( mod]n ent]prise4 ,! bor+ tool _h a cutt+ edge ( diamonds3 = no o!r cutt+ implem5t is at once h>d en\gh & durable en\gh to advance /eadily1 y>d by y>d1 ?r\gh ! v>i\s rocks & m9]als t are met ) 9 ! desc5t ?r\gh ! e>?'s cru/4 ,we might1 p]haps1 illu/rate ! actual =m ( ! tool z foll[s3 imag9e a piece ( iron pipe1 ab\t six in*es 9 diamet]1 cut squ>ely across1 ) diamonds ins]t$ r\nd its circul> end1 & we h a notion ( ! diamond drill4 ,if ! drill be made to revolve :5 held v]tically1 ) ! diamonds 9 contact ) ! rocks1 ! cutt+ w comm5ce4 ,z ! rotation is cont9u$1 ! drill advances ?r\gh ! rocks1 & a solid core ( ! mat]ial w occupy ! holl[ ( ! pipe4 ,we d n n[ ent] into any description ( ! _m me*anical details2 !re are +5i\s contrivances = remov+ ! dbris produc$ by ! attrition ( ! rocks z ! diamonds cut _! way1 & provision is also made = c>efully rais+ ! valuable core :i*1 z x provides specim5s ( ! diff]5t /rata pi]c$1 w %[ ! coal1 if coal is ev] rea*$4 ,!re is1 ( c\rse1 an arrangem5t by :i*1 z ! fir/ l5g? ( drill becomes buri$1 successive l5g?s c be add$1 s z to transmit ! motion to ! cutt+ edge & enable ! tool to be rais$ :5 necess>y2 9 ?is mann] "o l5g? ( solid rock aft] ano!r is br\ght up = exam9ation4 ,^! cores1 :5 rang$ 9 s]ies1 give to ! m9] ! in=mation he requires z to ! diff]5t b$s ( rock ?r\gh :i* ! in/rum5t has pi]c$ 9 its desc5t & z to ! dep?s ( ! b$s4 ,a s]ies ( cores w sometimes %[ a/oni%+ v>iety 9 ! mat]ial ?r\gh :i* ! drill has pass$4 ,"h ! tool w be se5 pass+ ?r\gh a b$ ( h>d lime/one1 & !n ent]+ a b$ ( s(t %ale2 n[ ! tool bores ?r\gh d5se & h>d masses ( gre5/one1 anon x pi]ces1 x may be1 a /ratum ( :ite m>ble2 & f9ally ! explor] may hope to f9d 8 expectations realis$ by ! arrival at ! surface ( a cyl9d] ( solid coal4 ,! fam\s bor+ to :i* we are n[ ref]r+1 ?\gh v deep1 0 n l>ge 9 diamet]4 ,z x desc5d$ ! comp>atively l>ge tool fir/ employ$ 0 replac$ by a succession ( small] tools1 s t ! hole gradually tap]$ f ! surface to ! l[e/ po9t4 ,at its greate/ dep? ! hole 0 inde$ h>dly l>g] ?an a man's little f+]4 ,x increas$ gradually all ! way to ! surface1 :]e x 0 l>ge en\gh = a man's arm to ent] x easily4 ,h[ (t5 d we f9d t ! success :i* rew>ds me*anical ent]prise greatly transc5ds ev5 ! mo/ sangu9e e/imate previ\sly =m$6 ,)\t ! actual exp]i5ce :i* has be5 acquir$1 ,i d n ?9k anyone c\ld h anticipat$ ! extraord9>y facilities :i* ! diamond drill has giv5 9 ! op]ations ( a deep bor+4 ,?is hole at ,s*ladeba* 01 inde$1 a wond]ful success4 ,x pi]c$ deep] ?an any previ\s excavation1 deep] ?an any well1 deep] ?an any coal pit4 ,f ! surface ( ! gr\nd1 :]e ! hole 0 "s six in*es 9 diamet]1 d[n to ! l[e/ po9t1 :]e x 0 only z l>ge z a little f+]1 ! v]tical dep? 0 n less ?an "o mile & a hundr$ & sev5te5 y>ds4 ,x is wor? pond]+ = a mom5t on ! extraord9>y me*anical feat :i* ?is repres5ts4 ,:5 ! greate/ dep? 0 rea*$1 ! total l5g? ( ! s]ies ( bor+ rods f ! surface :]e ! ma*9]y 0 engag$ 9 rotat+ ! tool d[n to ! cutt+ diamonds at ! l[] end :]e ! p5etration 0 be+ effect$1 0 z long z f ,piccadilly ,circus to ! top ( ,portl& ,place4 ,if a hole ( equal l5g? _h be5 bor$ d[nw>ds f ! top ( ,b5 ,nevis1 x w\ld h rea*$ ! sea level & gone d[n #a1bjj feet l[] /ill4 ,:5 ! =eman 9 *>ge wi%$ to look at ! tool to see :e!r x 0 work+ satisfactorily1 or :e!r any ( ! diamonds _h got injur$ or displac$1 x 0 necess>y to raise t trem5d\s s]ies ( rods4 ,ea* "o ( !m _h to be lift$1 _h to be unc\pl$1 & _h to be laid aside4 ,i ne$ h>dly say t su* an op]ation 0 a v t$i\s "o4 ,! collective weight ( ! work+ sy/em ( rods 0 ab\t tw5ty tons1 & n less ?an t5 h\rs' h>d "w 0 requir$ be=e ! tool 0 rais$ f ! bottom to ! surface4 ,we may1 ,i believe1 conclude t s mu* +5uity & s mu* tr\ble 0 nev] be=e exp5d$ on ! act ( bor+ a hole2 b ! results are full ( in=mation on important problems ( sci5ce4 ,i am n go+ to speak ( ! geological results ( ?is exploration4 ,!re is n ! lea/ d\bt t ! rem>kable section ( ! e>?'s cru/ ?us obta9$ is ( mu* int]e/ to geologi/s4 ,our object 9 n[ allud+ to ?is wond]ful bor+ is1 h[ev]1 v diff]5t4 ,its significance w be realis$ :5 we say t x gives u m full & def9ite in=mation ab\t ! int]nal heat ( ! e>? ?an _h ev] be5 obta9$ by any o!r exp]im5t on ! e>?'s cru/4 ,no d\bt _m previ\s obs]vations ( ! int]nal heat ( ! globe 7 well kn[n to ! inve/igators :o feel an int]e/ 9 ^! important que/ions2 b ! exceptional dep? ( ?is bor+1 z well z ! exceptionally fav\rable conditions "u :i* x 0 made1 h r5d]$ ! in=mation d]iv$ f x ( ! utmo/ value to sci5ce4 ,we ought fir/ to record our special obligation to ! ,g]man eng9e]1 ,capta9 ,huyss51 :o bor$ ?is wond]ful hole4 ,he 0 n only a highly skilful m9+ eng9e]1 dilig5t 9 ! pursuit ( 8 pr(ession1 b1 by ! valuable sci5tific "w he has done1 he has %[n himself to be "o ( ^? cultivat$ & ?\ghtful /ud5ts :o love to avail !mselves ( e opportunity ( se>*+ into ,nature's secrets4 ,our ?anks are due to him = ! rem>kable zeal ) :i* he utilis$ ! exceptional opportunities = valuable sci5tific "w t arose1 incid5tally z x 71 9 connection ) ! "w committ$ to him4 ,( c\rse1 ev]ybody kn[s t ! temp]ature ( ! e>? is f\nd to increase gradually z great] dep?s are rea*$4 ,! rate at :i* ! increase takes place has be5 det]m9$ on _m occasions4 ,b :5 opportunities h aris5 = tak+ ! temp]ature at consid]able dep?s bel[ ! e>?'s surface1 x has happ5$ sometimes t ! obs]vations h be5 complicat$ by circum/ances :i* depriv$ !m ( a good deal ( _! accuracy4 ,if our object be to le>n ! law connect+ ! e>?'s temp]ature ) ! dep? bel[ ! surface1 x is n suffici5t to /udy ! !rmometric read+s 9 diff]5t coal pits4 ,?r\gh\t ! work+s 9 e pit !re mu/ be arrangem5ts = v5tilation4 ,! cool air has to be drawn d[n1 & ?us ! temp]ature indicat$ 9 ! pit is =c$ bel[ ! temp]ature :i* w\ld really be f\nd at t dep? if ext]nal s\rces ( *ange ( temp]ature 7 abs5t4 ,capta9 ,huyss5 rightly deem$ t ! hole :i* he _h pi]c$ pres5t$ exceptional opportunities = ! /udy ( ! important "q ( ! e>?'s int]nal temp]ature4 ,precautions _h1 ( c\rse1 to be obs]v$4 ,! hole1 z might be expect$1 0 fill$ ) wat]1 & ! wat] w\ld t5d1 if its circulation 7 p]mitt$1 to equalise ! temp]ature at diff]5t dep?s4 ,b ! +5i\s ,capta9 quickly f\nd an effici5t rem$y = ?is s\rce ( inaccuracy4 ,he devis$ an arrangem5t1 :i* ,i mu/ n delay to describe1 by :i* he c\ld place tempor>y plugs 9 ! hole at any dep?s he might desire2 he !n det]m9$ ! temp]ature ( ! wat] 9 a %ort l5g?1 s plugg$ above & bel[ t ! circulation 0 /opp$1 & accord+ly ! wat] ?us conf9$ might be reli$ on to indicate ! temp]atures ( ! /rata :i* hold x4 ,illu/ration3 ,fig4 #bb4--,,special ,,!rmomet] ,,= ,,use ,,9 ,,deep ,,bor+s4 ,! !rmomet] employ$ 9 an inve/igation ( ?is sort is +5i\s ?\gh extremely simple4 ,! ord9>y maximum !rmomet] is n f\nd to be adapt$ = ! purpose4 ,! in/rum5t 7,fig4 #bb7 employ$ 9 ! det]m9ation ( und]gr\nd temp]atures is v mu* less complicat$ & at ! same "t mu* m accurate4 ,! contrivance is inde$ s wor?y ( notice t ,i d n l to pass x by )\t a few words4 ,! !rmomet] ) :i* ! temp]ature ( ! e>? is asc]ta9$ 9 su* inve/igations is n l any ord9>y !rmomet]4 ,!re is no scale ( degrees atta*$ to x or engrav$ ^u x1 z we g5]ally f9d 9 su* in/rum5ts4 ,! in/rum5t ) :i* ! temp]ature ( ! deep hole 0 measur$ 0 m]ely a bulb ( glass ) a sl5d] capill>y /em1 ! end ( :i* 0 n clos$4 ,:5 x 0 ab\t to be l[]$ to te/ ! temp]ature ( ! rocks at ! l[e/ po9t to :i* ! drill _h p5etrat$1 ! bulb & ! tube 7 fir/ fill$ ) m]cury to ! top1 & brimm+ ov]4 ,?is simple app>atus 0 atta*$ to a long wire1 by ! aid ( :i* x c\ld be l[]$ d[n ?is deep hole4 ,d[n x w5t till at la/ ! !rmomet] rea*$ ! bottom1 :i*1 z we h expla9$1 x c\ld n d until m ?an a mile ( wire _h be5 paid out4 ,! in/rum5t 0 !n left quietly until x pres5tly assum$ ! same temp]ature z ! rocks ab\t x4 ,!re c\ld be no int]f]5ce by heat f o!r /rata1 z ! circulation ( wat] 0 prev5t$ by ! plugg+ already ref]r$ to4 ,! temp]ature to :i* ! !rmomet] _h be5 expos$ mu/1 !re=e1 h be5 precisely ! temp]ature correspond+ 9 t p>ticul> locality to t p>ticul> dep? bel[ ! e>?'s surface4 ,z ! !rmomet] desc5d$1 x pass$ ?r\gh a succession ( /rata ( ev]-increas+ temp]ature4 ,consequ5tly ! m]cury1 :i*1 x w be rememb]$1 _h completely fill$ ! in/rum5t :5 x 0 at ! surface1 began to exp& accord+ z x 0 expos$ to great] temp]atures4 ,z ! m]cury exp&$1 x mu/1 ( c\rse1 fl[ out ( ! tube & be lo/1 because ! tube _h be5 already full4 ,s long z ! m]cury 0 ga9+ 9 temp]ature1 m & m ( x escap$ f ! top ( ! tube1 & ! fl[ only ceas$ :5 ! in/rum5t 0 re/+ at ! bottom ( ! hole1 & ! m]cury became z hot z ! surr\nd+ rocks4 ,no m m]cury 0 !n expell$1 ! tube1 h[ev]1 rema9+ full to ! brim4 ,aft] all[+ a suffici5t "t = ! temp]ature to settle def9itely1 ! !rmomet] 0 rais$ to ! surface4 ,z x asc5d$ ?r\gh ! long bore ! temp]ature surr\nd+ x /eadily decl9$4 ,) ! fall 9 ! temp]ature ( ! m]cury ! volume ( t liquid began to %r9k2 b ! m]cury already expell$ c\ld n be recall$4 ,:5 at la/ ! in/rum5t _h safely rea*$ ! surface1 aft] its long j\rney d[n & up1 & :5 ! m]cury _h rega9$ ! temp]ature ( ! air1 ! less5$ quantity t rema9$ told ! tale ( ! *anges ( temp]ature4 ,x is n[ easy to see h[1 ev5 9 ! abs5ce ( an engrav$ scale on ! in/rum5t1 x is possible to det]m9e1 f ! am\nt ( m]cury rema9+1 ! temp]ature to :i* ! !rmomet] has be5 subject$ at ! bottom ( ! bor+4 ,x is only necess>y to place ?is !rmomet] 9 a bas9 ( cold wat]1 & !n gradually increase ! temp]ature by add+ hot wat]4 ,z ! temp]ature increases ! m]cury w1 ( c\rse1 rise1 & ! hott] ! wat] ! m ne>ly w ! m]cury approa* ! top ( ! tube4 ,at la/1 :5 ! m]cury has j rea*$ ! top ( ! tube1 & :5 x is j on ! po9t ( ov]fl[+1 we may feel c]ta9 t ! temp]ature ( ! wat] 9 ! bas9 has be5 rais$ to ! same temp]ature z t to :i* ! in/rum5t 0 subject$ at ! bottom ( ! bor+4 ,9 ea* case ! temp]ature is j suffici5t to exp& ! quantity ( m]cury rema9+ 9 ! in/rum5t s z to make x fill precisely bo? bulb & /em4 ,:5 ?is critical condition is rea*$1 x only rema9s to dip a /&>d !rmomet]1 furni%$ ) ! ord9>y graduation1 into ! hot wat] ( ! bas94 ,?us we le>n ! temp]ature ( ! bas91 ?us we le>n ! temp]ature ( ! m]cury 9 ! !rmomet]1 & ?us we det]m9e ! temp]ature at ! bottom ( ! bor+ ov] a mile deep4 ,i ne$ n specify ! details ( ! arrangem5ts :i* enabl$ ! skilful eng9e] also to det]m9e ! temp]ature at v>i\s po9ts ( ! hole int]m$iate betwe5 ! top & ! bottom4 ,9 fact1 tak+ e precaution to secure accuracy1 he made measurem5ts ( ! temp]ature at a succession ( po9ts ab\t a hundr$ feet di/ant ?r\gh\t ! :ole dep?4 ,9 ea* case he 0 c>eful1 z ,i h already indicat$1 to plug ! hole above & bel[ ! !rmomet]1 s z to prev5t ! circulation ( wat] 9 ! vic9ity ( ! in/rum5t4 ,! !rmomet]1 !re=e1 record$ ! temp]ature ( ! surr\nd+ rocks )\t any di/urb+ elem5t4 ,fifty-eight measurem5ts at equal di/ances f ! surface to ! greate/ dep?s 7 ?us obta9$4 ,we h n[ to discuss ! in/ructive results to :i* we h be5 conduct$ by ?is rem>kable s]ies ( measurem5ts4 ,fir/ let u notice t !re is mu* less v>iation 9 ! subt]ranean temp]atures ?an 9 ! temp]atures on ! e>?'s surface4 ,on ! surface ( ! e>? we are accu/om$ to l>ge fluctuations ( temp]ature4 ,we h1 ( c\rse1 ! diurnal fluctuations 9 temp]ature f day to night2 we h also ! great seasonal fluctuations betwe5 summ] & w9t]4 ,b bel[ a c]ta9 dep? 9 ! gr\nd ! temp]ature becomes mu* m equable4 ,:e!r ! temp]ature on ! surface be high or :e!r x be l[1 ! temp]ature ( any p>ticul> po9t f> b5ea? ! surface does n *ange to any appreciable ext5t4 ,9 ,arctic regions ! surface ( ! e>? may und]go viol5t seasonal *anges ( temp]ature1 :ile at a few feet bel[ ! surface ! temp]ature1 f "o end ( ! ye> to ! o!r1 may rema9 s5sibly unalt]$4 ,9 deep & ext5sive cav]ns ! temp]ature is sometimes f\nd to rema9 practically unaffect$ by ! *anges 9 ! seasons4 ,! ,mammo? ,cave ( ,k5tucky is a notable in/ance4 ,! uni=mity ( ! temp]ature1 z well z ! mildness & dryness ( ! air1 9 ^? wond]ful subt]ranean vaults is su* t _m ye>s ago a project 0 =m$ to utilise ! cav]n z an abode = consumptive pati5ts1 = ^: cure1 accord+ to ! belief !n prevail+1 an equable temp]ature 0 above all ?+s to be desir$4 ,h\ses 7 inde$ actually built on ! s&y floors ( ! cav]n1 & ,i believe !y 7 = "s "t t5ant$ by consumptive pati5ts will+ to try ?is desp]ate rem$y4 ,! temp]ature may h be5 uni=m & ! air may h be5 dry1 b ! intol]able gloom ( su* a resid5ce entirely neutralis$ any b5eficial effects t might o!rwise h accru$4 ,! ru9s ( ! h\ses /ill rema9 to te/ify to ! failure ( ! exp]im5t4 ,! heat receiv$ f ! sun does n p5etrate f> into ! e>?'s cru/1 & consequ5tly ! diurnal & ev5 ! seasonal *anges ( ! temp]ature at ! surface produce less & less effect ) e increase ( ! dep?4 ,all su* v>iations ( temp]ature are conf9$ to )9 #ajj feet ( ! surface4 ,at ! dep? ( ab\t #ajj feet a fix$ temp]ature ( #eb ,fahr5heit is rea*$1 & ?is is true all ov] ! e>?4 ,x matt]s n :e!r ! surface be hot or cold1 :e!r ! latitude is tropical & ! season is midsumm]1 :e!r ! latitude lie 9 ! ,arctic regions & ! season be ! awful w9t] ( iron-b\nd fro/ & total abs5ce ( sun--9 all cases we f9d t ab\t #ajj feet bel[ ! surface ! temp]ature is #eb4 ,) suffici5t accuracy we may say t ?is dep? expresses ! limit ( ! p5etration ( ! e>?'s cru/ by sunbeams4 ,! rem>kable law accord+ to :i* ! temp]ature *anges bel[ ! dep? ( #ajj feet is :olly irrespective ( ! sol> radiation4 ,! /udy ( ! int]nal heat ( ! e>? may be said to beg9 bel[ ! level ( #ajj feet1 & ! results t 7 obta9$ 9 ! great bor+ are extremely accordant4 ,! deep] ! hole1 ! hott] ! rocks2 & ,capta9 ,huyss5 f\nd t = ea* sixty-six feet 9 desc5t ! temp]ature increas$ "o degree ,fahr5heit4 ,to illu/rate ! actual obs]vations1 let u take two p>ticul> cases4 ,we h said t ! hole 0 "o mile & #aag y>ds deep4 ,let u fir/ suppose ! !rmomet] to be l[]$ #aag y>ds & !n rais$1 aft] a due obs]vance ( ! precautions requir$ to obta9 an accurate result4 ,! temp]ature ( ! rocks at ! dep? ( #aag y>ds is ?us asc]ta9$4 ,9 ! next obs]vation let ! !rmomet] be l[]$ f ! surface to ! bottom ( ! hole1 t is to say1 exactly "o mile bel[ ! position :i* x occupi$ 9 ! =m] exp]im5t4 ,! obs]vations indicate a temp]ature #hj ,fahr5heit high] 9 ! latt] case ?an 9 ! =m]4 ,we h ?us asc]ta9$ a mo/ important fact4 ,we h %[n t ! temp]ature ( ! cru/ ( ! e>? at ! dep? ( "o mile increases ab\t #hj4 ,?is is at ! rate ( "o degree e sixty-six feet4 ,i %\ld j add1 z a caution1 t if we *oose to say ! temp]ature increases "o degree p] sixty-six feet ( desc5t1 we ought to suppose t we />t f a po9t :i* is n high] ?an t level ( #ajj feet above :i* z already expla9$1 ! temp]ature ( ! rocks is m or less affect$ by sol> heat4 ,we h describ$ ^! p>ticul> obs]vations 9 "s detail because !y h be5 conduct$ "u conditions f> m fav\rable to accuracy ?an h ev] be5 available 9 any previ\s inve/igations ( ! same k9d4 ,b n[ we %all omit fur!r ref]5ce to ?is p>ticul> und]tak+ ne> ,leipzig4 ,x is n alone 9 t p>ticul> locality1 n alone 9 ,g]many1 n alone 9 ,europe1 n alone on ! surface ( any cont95t1 t ?is /atem5t may be made4 ,! /atem5t is "o univ]sally true s f> z our :ole e>? is conc]n$4 ,:]ev] we bore a hole ?r\gh ! e>?'s cru/1 :e!r t hole be made 9 ! des]t ( ,sah>a or ?r\gh ! iceb\nd coa/s ( ,gre5l&1 we %\ld f9d ! g5]al rule to obta91 t !re is an increase ( temp]ature ( ab\t #hj = a mile ( desc5t4 ,?is is true 9 e cont95t1 x is true 9 e isl&2 &1 ?\gh we _c "h g into ! evid5ce fully1 !re is n ! lea/ d\bt t x is true also "u ! floor ( ocean4 ,if b5ea? ! b$ ( ! ,atlantic a hole a mile deep 7 pi]c$1 ! temp]ature ( ! rocks at ! bottom ( t hole w\ld1 x is believ$1 exce$ by ab\t #hj ! temp]ature ( ! rocks at ! surface :]e ! hole _h its orig94 ,we le>n t at ! dep? ( a mile ! temp]ature ( ! e>? mu/ g5]ally be #hj hott] ?an x is at ! level ( con/ant temp]ature ne> ! surface4 ,x may p]haps help u to realise ! significance ( ?is /atem5t if we ?9k ( ! foll[+ illu/ration4 ,let u imag9e t ! wat]s ( ! ocean 7 remov$ f ! e>?4 ,! ocean may 9 places be five or six miles deep1 b t is q an inconsid]able quantity :5 comp>$ ) ! diamet] ( ! e>?4 ,! *ange 9 ! size ( ! e>? by ! removal ( all ! wat] w\ld n be great]1 proportionally1 ?an ! *ange produc$ 9 a wet football by simply wip+ x dry4 ,let u suppose t an out] lay] ( ! e>?'s surface1 a mile 9 ?ickness1 0 !n to be peel$ (f4 ,if we rememb] t ! diamet] ( ! e>? is #h1jjj miles1 we %all see t ?is out] lay]1 ^: removal we h suppos$1 does n be> to ! :ole ext5t ( ! e>? a ratio ev5 z great z t :i* ! sk9 ( a pea* does to ! fruit inside4 ,b ?is mu* is c]ta91 t if ! e>? 7 s peel$ !re w\ld be a wond]ful diff]5ce 9 its nature4 ,= ?\gh practically ( ! same size z x is at pres5t1 x w\ld be s hot t x w\ld be impossible to live ^u x4 ,next comes ! v int]e/+ "q z to ! temp]ature t w\ld be f\nd at ! bottom ( a hole deep] /ill ?an t we h be5 consid]+4 ,our curiosity z to ! dep?s ( ! e>? ext5ds mu* bel[ ! po9t to :i* ,capta9 ,huyss5 drove d[n 8 diamond drill4 ,! tr\ble & ! co/ ( /ill deep] exploration ( ! same k9d seem1 h[ev]1 to be actually prohibitive4 ,to bore a hole two miles deep w\ld c]ta9ly co/ a great deal m ?an twice ! sum :i* suffic$ to bore a hole "o mile deep4 ,at a great dep? ea* fur!r foot c\ld only be won ) n less difficulty & exp5se ?an a doz51 or _m doz5 feet1 at ! surface4 ,m9+ ent]prise does n at pres5t seem to contemplate actual work+s at dep?s mu* ov] a mile1 s !re does n seem mu* *ance ( any v mu* deep] bor+ be+ attempt$4 ,we d n say t a hole two miles deep w\ld be actually impossible2 x may well be wi%$ t "s millionaire c\ld be induc$ to try ! exp]im5t4 ,we %\ld greatly l to be able to l[] a !rmomet] d[n to a dep? ( two miles ?r\gh ! e>?'s cru/4 ,see+ !re is b little *ance ( our wi% = su* future exp]im5ts be+ gratifi$1 x is consolatory to f9d t actual obs]vations ( ?is k9d are n indisp5sable to ! argum5t on :i* we are to ent]4 ,our argum5t c inde$ be conduct$ a /age fur!r1 ev5 ) our pres5t in=mation4 ,! indications already obta9$ 9 ! hole "o mile deep g a long way t[>ds prov+ :at ! temp]ature ( a hole /ill deep] w\ld be4 ,we h already rem>k$ t x 0 "p ( ,capta9 ,huyss5's s*eme to obta9 c>eful read+s ( 8 !rmomet] at int]vals ( #ajj feet f ! surface to ! bottom ( ! hole4 ,a /udy ( ^! read+s %[s t ! increase ( #hj 9 a mile takes place uni=mly at ! rate ( "o degree = ea* sixty-six feet ( dep?4 ,z ! temp]ature increases uni=mly f ! surface d[n to ! l[e/ po9t :i* our !rmomet]s h rea*$1 x w\ld be unreasonable to suppose t ! rate ( increase w\ld be f\nd to suff] "s abrupt *ange if x 7 possible to g a little deep]4 ,z ! temp]ature rises #hj 9 ! fir/ mile1 & z ! rate ( increase is %[n by ! obs]vations to be q z l>ge at ! bottom ( ! hole z x is at ! top1 we c]ta9ly %all n make any v great mi/ake if we v5ture to assume t 9 ! second mile ! temp]ature w\ld also increase to an ext5t :i* w n be f> f #hj4 ,?is inf]5ce f ! obs]vations leads to ! rem>kable conclusion t at a dep? ( two miles ! temp]ature ( ! e>? mu/ be1 we w n say exactly1 b at all ev5ts n v f> f1 #afj high] ?an at ! level ( con/ant temp]ature ab\t #ajj feet d[n4 ,z 9 ! =m] case1 we ne$ n conf9e ourselves to any p>ticul> locality 9 draw+ ?is conclusion4 ,! argum5ts apply n only to ! rocks und]nea? ,leipzig1 b to ! rocks ov] e "p ( ! globe1 :e!r on cont95ts or isl&s1 or ev5 if =m+ ! base ( an ocean4 ,no "o d5ies t ! law ( increase 9 temp]ature ) ! dep? mu/ submit to "s v>iation 9 accordance ) local circum/ances4 ,9 ess5tial features x may1 h[ev]1 be conc$$ t ! law is ! same ov] all ! e>?4 ,if we take #eb to be ! temp]ature ( ! level #ajj feet d[n1 :i* limits ! seasonal v>iations1 & if we add t at two miles fur!r d[n ! temp]ature is some:]e ab\t #afj m1 we come to ! conclusion t at a dep? ( a little ov] two miles ! temp]ature ( ! rocks =m+ ! e>?'s cru/ is ab\t #bab ,fahr5heit4 ,?us we draw ! important inf]5ce t if1 ! oceans hav+ be5 remov$1 we 7 !n to remove f ! e>?'s surface a r9d two miles ?ick--a ?ickness :i*1 x is to be obs]v$1 is only ! two-?\s&? "p ( ! e>?'s radius--we %\ld trans=m ! e>? into a globe :i*1 :ile x /ill reta9$ appreciably ! same size1 w\ld h su* a temp]ature t ev5 ! coole/ spot w\ld be z hot z boil+ wat]4 ,?is is inde$ a rem>kable result4 ,& n[ t we h gone s f>1 x is impossible = u to resi/ mak+ a fur!r attempt to det]m9e :at ! temp]ature ( ! e>?'s cru/ mu/ be if we c\ld s5d a !rmomet] /ill l[]4 ,a hole "o mile deep we h se52 ,i d n ?9k we c hope to see a hole two miles deep1 b /ill x may n be absolutely impracticable2 b a hole ( ?ree or m miles deep we may safely reg>d z transc5d+ pres5t possibilities 9 eng9e]+ ent]prise4 ,are we !re=e to be depriv$ ( all in=mation z to ! condition ( our e>? at dep?s exce$+ ^? already consid]$8 ,=tunately we c le>n some?+4 ,we are assi/$ by c]ta9 laws ( heat1 &1 ?\gh ! evid5ce on :i* we believe ^? laws is necess>ily limit$ to ! exp]i5ce ( ,nature z x comes )9 our obs]vation1 yet x is impossible to refuse ass5t to ! belief t ! same laws w regulate ! transmission ( heat 9 ! cru/ ( ! e>? two miles1 ?ree miles1 or _m miles b5ea? our feet4 ,i repres5t1 9 ! diagram %[n 9 ,fig4 #bc1 ?ree consecutive b$s ( rock--,a1 ,b1 & ,c--z !y lie 9 ! e>?'s cru/1 a little m ?an a mile b5ea? our feet4 ,i %all suppose t ! b$ ,b is ! v l[e/ rock ^: temp]ature 0 det]m9$ 9 ! great bor+4 ,! drill has pass$ completely ?r\gh ,a1 x has pi]c$ to ! middle ( ,b1 b x has n ent]$ ,c4 ,! obs]vations h %[n t ! temp]ature ( ! /ratum ,b exce$s t ( ! /ratum ,a1 & we fur!r note t ?is is a p]man5t condition--t is to say1 ,b con/antly rema9s hott] ?an ,a4 ,f ?is fact alone we c le>n some?+ z reg>ds ! temp]ature ( ! /ratum ,c :i* lies 9 contact ) ,b4 ,( c\rse we are unable to obs]ve ! temp]ature ( ,c directly1 because by hypo!sis ! bor+ tool has n ent]$ t rock4 ,we c1 h[ev]1 prove1 f ! laws ( ! conduction ( heat1 t ! temp]ature ( ,c mu/ be great] ?an t ( ,b2 & ?is appe>s f ! foll[+ consid]ation4 ,illu/ration3 ,fig4 #bc4--;,,at ,,! ,,bottom ,,( ,,! ,,great ,,bore4 ,x is pla9 t ,c mu/ be ei!r j ! same temp]ature z ,b1 or x mu/ be hott] ?an ,b1 or x mu/ be cold] ?an ,b4 ,if ,c 7 ! same temp]ature z ,b1 !n ! law ( conduction ( heat tells u t no heat w\ld fl[ f "o ( ^! /rata to ! o!r4 ,! laws ( heat1 h[ev]1 assure u t :5 two bodies at diff]5t temp]atures are 9 contact ! heat w fl[ f ! hott] ( ^! bodies into ! cold]1 s long z ! inequality ( temp]ature is ma9ta9$4 ,z ,b is hott] ?an ,a1 !n heat mu/ necess>ily fl[ f ,b into ,a1 & ?is fl[ mu/ t5d to equalise ! temp]ature 9 ^! /rata1 = ,b is los+ heat :ile none is fl[+ into x f ,c4 ,!re=e ,b & ,a c\ld n cont9ue to pres]ve indef9itely ! diff]5t temp]atures :i* obs]vation %[s !m to d4 ,we are !re=e =c$ to ! conclusion t ,b & ,c _c be at ! same temp]ature4 ,next let u suppose t ! temp]ature ( ! /ratum ,b exce$$ t ( ,c4 ,!n1 z ,a is cold] ?an ,b1 x appe>s t ,b w\ld be ly+ betwe5 two /rata ea* hav+ a temp]ature l[] ?an itself4 ,b t1 ( c\rse1 _c be a p]man5t arrangem5t1 = ! heat w\ld !n escape f ,b on bo? sides4 ,! laws ( heat1 !re=e1 tell u t ,b c\ld n possibly reta9 p]man5tly a temp]ature above bo? ,a & ,c4 ,obs]vation1 h[ev]1 %[s t ! temp]atures ( ,a & ,b are p]si/5tly unequal4 ,we are !re=e oblig$ to reject ! supposition t ! temp]ature ( ,c c be less ?an t ( ,b4 ,we h ?us demon/rat$ t ! temp]ature ( ! /ratum ,c _c be ! same z t ( ,b4 ,we h also demon/rat$ t x _c be cold] ?an ,b4 ,we mu/ !re=e believe t ,c is hott] ?an ,b4 ,?is proves t ! /ratum imm$iately b5ea? t /ratum to :i* ! obs]vations h ext5d$ mu/ be hott] ?an x4 ,?us1 ?\gh ! /ratum bel[ ! bottom ( ! hole lies beyond ! rea* ( our actual obs]vation1 we h1 nev]!less1 be5 able to le>n some?+ ) reg>d to its temp]ature4 ,hav+ e/abli%$ ?is mu*1 we c cont9ue ! same argum5t fur!r2 inde$1 x w\ld seem t we c cont9ue x indef9itely1 s long z !re is a succession ( su* /rata4 ,und]nea? ! /ratum ,c mu/ lie ano!r /ratum ,d4 ,b we h %[n t ,c mu/ be hott] ?an ,b1 & precisely ! same argum5t t has prov$ ?is w prove t ,d is hott] ?an ,c4 ,und]nea? ,d comes ! /ratum ,e1 & aga9 ! same argum5t w apply4 ,inasmu* z ,d is hott] ?an ,c1 x foll[s t ,e mu/ be hott] ?an ,d4 ,^! ?ree /rata1 ,c1 ,d1 & ,e1 are all beyond ! rea* ( ! !rmomet]1 we "k no?+ ( _! temp]atures by direct obs]vation2 b none ! less is ! argum5t1 :i* we are foll[+ /rictly1 applicable4 ,?us we obta9 ! important result t 9 ! cru/ ( ! e>? ! temp]ature mu/ be always great]1 ! great] ! dep? b5ea? ! surface4 ,we h se5 t ! rate ( increase ( temp]ature ) ! dep? is ab\t #hj = ! fir/ mile1 & we deem x probable t ! rate ( increase may be ma9ta9$ at ab\t ! same = ! second mile4 ,b we d n suppose t ! rate ( increase mile aft] mile w rema9 ! same at extremely great dep?s4 ,x may p]haps be presum$ t !re mu/ be "s increase ( temp]ature all ! way to ! e>?'s c5tre2 b ! rate ( increase p] mile may *ange z ! c5tre is approa*$4 ,! po9t ( importance = our pres5t argum5t is1 t ! temp]ature ( ! e>? mu/ increase ) ! dep?1 ?\gh ! rate ( increase is q unkn[n to u at dep?s greatly beyond ^? :i* ! !rmomet] has rea*$4 ,x is easy to see t ! conditions prevail+ 9 ! e>?'s int]ior might greatly modify any conclusion we %\ld draw f obs]vations ne> ! surface4 ,our argum5t has be5 bas$ on ! laws ( heat1 z we f9d !m exi/+ 9 matt] on ! surface ( ! e>? submitt$ to su* ranges ( diff]5t physical conditions z c be dealt ) 9 our laboratories2 b at su* excessively high temp]atures z may exi/ 9 ! e>?'s int]ior ! prop]ties ( matt] may be widely diff]5t f ! prop]ties ( matt] z kn[n to u )9 ! temp]atures t we are able to produce & control4 ,! enorm\s pressure to :i* matt] 9 ! int]ior ( ! e>? mu/ be subject$ %\ld also be m5tion$ 9 ?is connection4 ,x is :olly impossible to produce pressures by any me*anical artifice :i* ev5 di/antly approa* 9 int5sity to t awful =ce to :i* matt] is subject$ 9 ! e>?'s int]ior4 ,x may be in/ructive to consid] a few facts ) respect to ?is "q ( pressure 9 ! e>?'s int]ior4 ,a column ( wat] #cd feet high gives1 z ev]ybody kn[s1 a pressure ( fifte5 p\nds on ! squ>e in*4 ,x w be q accurate en\gh = our pres5t purpose to assume t ! av]age d5sity ( rock is ?ree times t ( wat]3 ! pressure ( t5 feet ( rock w\ld !re=e produce ! same pressure z ?irty feet ( wat]1 t is to say1 fifte5 p\nds on ! squ>e in*4 ,! pressure due to ! sup]9cumb5t weight ( a mile ( rock w\ld be m ?an ?ree tons on ! squ>e in*4 ,at ! dep? ( t5 miles b5ea? ! e>?'s surface ! pressure1 am\nt+ z x does to ov] ?irty tons on ! squ>e in*1 w\ld v ne>ly equal ! pressure produc$ on ! inside ( a #ajj-ton gun :5 ! *>ge ( cordite has be5 explod$ to drive ! missile =?4 ,?is is inde$ ab\t z l>ge a pressure z c well be dealt ) artificially1 = we "k t ! #ajj-ton gun has to be enorm\sly /rong if x is to resi/ ?is pressure4 ,b t5 miles ( rock is z no?+ comp>$ ) ! ?ickness ( rock t produces ! pressures 9 ! e>?'s int]ior4 ,ev5 if a %ell ( rocks t5 miles ?ick 7 remov$ f ! surface x w\ld alt] ! diamet] ( our globe by no m ?an "o f\r-hundr$? "p4 ,at ! dep? ( ab\t ?irty miles f ! surface ! pressure 9 ! e>?'s int]ior w\ld am\nt to "s #ajj tons on ea* squ>e in*4 ,) ea* increase 9 dep? ! pressure increases enorm\sly1 ?\gh x may n be correct to say t ! pressure is proportional to ! dep?4 ,a pressure ( #a1jjj tons on ! squ>e in* mu/ exi/ at a dep? :i* is /ill q small 9 comp>ison ) ! radius ( ! e>?4 ,we h n1 & app>5tly _c h1 ! lea/ exp]im5tal k ( ! prop]ties ( matt] at ! mom5t :5 x is subject$ to pressure am\nt+ to ?\s&s ( tons p] squ>e in*2 /ill less c we det]m9e ! behavi\r ( matt] at t pressure ( scores ( ?\s&s ( tons1 to :i* mu* ( ! int]ior ( ! e>? is at ?is mom5t subject$4 ,pr(essor ,dew>1 9 8 memorable rese>*es1 has reveal$ to u ! rem>kable *anges exhibit$ 9 ! prop]ties ( matt] :5 t matt] has be5 cool$ to a temp]ature :i* lies 9 ! vic9ity ( absolute z]o4 ,we c1 h[ev]1 h>dly hope t any exp]im5ts w give u in=mation z to ! prop]ties ( matt] :5 heat$ to a temp]ature va/ly transc5d+ t :i* c\ld ev] be produc$ 9 our mo/ p[]ful electric furnaces1 & at ! same "t expos$ to a pressure hundr$s ( times1 or inde$ we may say ?\s&s ( times1 great] ?an any pressure t has ev] be5 produc$ artificially by ! action ( ! mo/ viol5t explosive ) :i* ! discov]ies ( *emi/ry h made u acqua9t$4 ,illu/ration3 ,fig4 #bd4--,,?ree ,,consecutive ,,%ells ,,( ,,! ,,e>?',s ,,cru/4 ,we really d n "k h[ f> ! laws ( heat1 :i* h be5 employ$ 9 %[+ t ! temp]ature mu/ increase z ! dep? increases1 c be consid]$ z valid "u ! extreme condition to :i* matt] is subject$ 9 ! deep int]ior ( our globe4 ,! laws may be pr(\ndly modifi$4 ,x suffices1 =tunately = our pres5t argum5t1 to say t1 s f> z obs]vations h be5 possible1 ! temp]ature does gradually increase ) ! dep?1 & t ?is increase mu/ /ill cont9ue f /ratum to /ratum z great] dep?s are rea*$1 unless x %\ld be f\nd t by ! excessive exaltation ( temp]ature & ! va/ int5sity ( pressure c]ta9 prop]ties ( matt] become s trans=m$ z to r5d] ! laws ( heat1 z we "k !m1 inapplicable4 ,9 subsequ5t *apt]s we %all h "s fur!r po9ts to consid] ) respect to ! int]ior ( ! e>? & its physical *>act]i/ics1 :i* are1 h[ev]1 n necess>y = our pres5t argum5t4 ,:at we n[ desire to prove c be d$uc$ f ! demon/rat$ fact t ! e>?'s temp]ature does /eadily increase f ! level ( con/ant temp]ature1 #ajj feet bel[ ! surface1 d[n to ! greate/ dep? to :i* !rmomet]s h ev] be5 l[]$4 ,we may presume t ! same law holds at v mu* great] dep?s1 ev5 if x does n hold all ! way to ! c5tre4 ,to make our argum5t cle>1 let u ?9k ( ?ree diff]5t /rata ( rock4 ,?is "t1 h[ev]1 we %all suppose !m to cov] ! :ole e>?1 & we %all consid] !m to lie )9 ! fir/ mile f ! surface2 !y w ?us be well )9 ! region explor$ by obs]vation 7,fig4 #bd74 ,we %all also reg>d !m z %ells ( uni=m ?ickness1 & x w be conv5i5t to ?9k ( !m z be+ s v ?9 t we may consid] any "o ( ! %ells call$ ,a to h practically a uni=m temp]ature4 ,! next %ell ,b imm$iately inside ,a w h a slightly great] temp]ature1 & be also reg>d$ z uni=m1 & ! %ell imm$iately inside t aga9 w h a temp]ature great] /ill4 ,we %all call ! inn]mo/ ( ! ?ree %ells ,c1 & ,c is hott] ?an ! next out] %ell ,b1 :ile ,b is hott] ?an ,a4 ,! laws ( heat tell u t z ,b & ,a are 9 contact1 & t z ,b is cont9ually hott] ?an ,a1 !n ,b mu/ be cont9u\sly transmitt+ heat to ,a4 ,9 fact1 ,b appe>s to be con/antly endeav\r+ to r$uce itself to ! temp]ature ( ,a by %>+ ) ,a ! excess ( temp]ature :i* x possesses4 ,b if we consid] ! relation betwe5 ! %ell ,b & ! hott] %ell ,c1 imm$iately b5ea? x1 we see t precisely ! same argum5t w %[ t ,b is con/antly receiv+ heat f ,c4 ,we ?us see t :ile ,b is cont9u\sly dis*>g+ heat f its outside surface1 x is z con/antly receiv+ heat :i* ent]s ?r\gh its inside surface4 ,heat ent]s ,b f ,c1 & heat passes f ,b into ,a1 s t ,b is 9 fact a *annel ?r\gh :i* heat passes f ,c into ,a4 ,t :i* we h %[n to take place 9 ^? ?ree consecutive lay]s 9 ! e>?'s cru/ mu/ also take place 9 e ?ree consecutive lay]s4 ,ea* lay] is cont9ually receiv+ heat f ! lay] bel[1 & is z con/antly communicat+ heat to ! lay] above4 ,no d\bt ! rocks are v bad conductors ( heat1 s t ! transmission ( heat f lay] to lay] is a v sl[ process4 ,b ev5 if ?is fl[ ( heat be sl[1 x is incessant1 s t 9 ! c\rse ( ages l>ge quantities ( heat are gradually transmitt$ f ! e>?'s int]ior1 & ultimately rea* ! level ( con/ant temp]ature4 ,!re is no?+1 h[ev]1 to imp$e _! outw>d progress1 s at la/ ! heat rea*es ! e>?'s surface4 ,:5 ! surface has be5 rea*$1 !n ano!r law ( heat decl>es :at mu/ happ5 next4 ,x is1 ( c\rse1 by conduction t ! heat passes f lay] to lay] 9 its outw>d progress1 until x ultimately ga9s ! surface4 ,at ! surface ! heat is !n absolutely remov$ f ! solid e>? ei!r by ! convection ?r\gh ! air or by direct radiation into space4 ,i may "h int]rupt ! argum5t = a mom5t to make q cle> a po9t :i* might p]haps o!rwise (f] "s difficulty to ! read]4 ,:5 ?is outw>d fl[ ( heat rea*es ! sup]ficial lay]s x becomes1 ( c\rse1 mix$ up ) ! heat :i* has be5 absorb$ by ! soil f ! direct radiation ( ! sun1 & ?is v>ies1 ( c\rse1 ) ! h\r ( ! day & ) ! season ( ! ye>4 ,! heat :i* /eadily leaks f ! int]ior has an effect on ! rocks ne> ! surface1 :i* is only inf9itesimal 9 comp>ison ) ! heat :i* !y receive f p]iodic causes4 ,we may1 h[ev]1 say t :atev] w\ld be ! temp]ature ( ! rock1 s f> z ! p]iodic causes are conc]n$1 ! actual temp]ature is always to "s m9ute ext5t increas$ by reason ( ! heat f ! e>?'s int]ior4 ,! argum5t is1 p]haps1 /ill cle>] if1 in/ead ( att5d+ to ! e>?'s surface1 we ?9k only ( t %ell1 "s #ajj feet d[n1 :i* m>ks ! limit ( ! dep? to :i* ! seasonal & diurnal v>iations ( heat ext5d4 ,! argum5t %[s h[ ! int]nal heat ( ! e>?1 pass+ f %ell to %ell 9 ! int]ior1 rea*es ?is lay] ( con/ant temp]ature1 & pass+ ?r\gh x1 ent]s into ^? sup]ficial /rata ( ! e>? :i* are expos$ to ! seasonal v>iations4 ,) :at befalls t heat ultimately we ne$ n n[ conc]n ourselves2 x suffices = our argum5t to %[ t !re is a curr5t ( heat outw>d across ?is level4 ,x is a curr5t :i* is nev] rev]s$1 & consequ5tly mu/ produce a nev]-ceas+ dra9age f ! heat ) :i* x w\ld seem t ! int]ior ( ! e>? is s copi\sly provid$4 ,calculations h be5 made to asc]ta9 h[ mu* heat passes annually f ! e>?'s int]ior1 across ?is surface ( con/ant temp]ature1 out into ! sup]ficial regions f :i* 9 due c\rse x becomes lo/ by radiation4 ,a conv5i5t way ( measur+ a quantity ( heat is by ! am\nt ( ice x w melt1 = ( c\rse a def9ite quantity ( heat is requir$ to melt a def9ite quantity ( ice4 ,x has be5 e/imat$ by ,pr(essor ,j4 ,d4 ,ev]ett1 ,f4,r4,s41 t ! am\nt ( int]nal heat escap+ f our e>? ea* ye> w\ld be suffici5t to melt a %ell ( ice "o-fif? ( an in* ?ick ov] ! :ole surface ( ! globe4 ,we _c inde$ pret5d t any det]m9ation ( ! actual loss ( heat :i* our e>? exp]i5ces c\ld be v precise4 ,suffici5t obs]vations h n yet be5 obta9$1 = ! op]ation is s sl[ t an imm5se p]iod w\ld h to elapse be=e ! total quantity ( heat lo/ w\ld be suffici5t to produce effects l>ge en\gh to be measur$ accurately4 ,b n[ let u ha/5 to add t1 = ! argum5t z to ! nebul> !ory ) :i* we are at pres5t conc]n$1 x is n really mat]ial to "k ! precise rate at :i* heat is lo/4 ,x is absolutely c]ta9 t a p]5nial leakage ( heat f ! int]ior ( ! e>? does take place4 ,?is fact1 & n ! am\nt ( t leakage1 is ! ess5tial po9t4 ,& ?is loss1 :i* is at pres5t go+ on1 has be5 go+ on cont9ually4 ,heat f ! e>? has be5 lo/ ?is ye> & la/ ye>2 x has be5 lo/ = hundr$s ( ye>s & = ?\s&s ( ye>s4 ,n alone dur+ ! p]iods ( human hi/ory has ! e>?'s heat be5 decl9+4 ,ev5 ?r\gh\t ^? p]iods1 ^? ov]:elm+ p]iods :i* geology has reveal$ to u1 has ?is e>? ( ours be5 sl[ly p>t+ ) its heat4 ,let u pursue ?is reflection to its legitimate consequ5ce4 ,:atev] may ultimately become ( t heat1 x is c]ta9 t once radiat$ into space x is lo/ = ev] s f> z ?is globe is conc]n$4 ,y mu/ n imag9e t ! w>m beams ( ! sun possess any p[] ( repl5i%m5t by :i* !y c re/ore to ! e>? ! heat :i* x has be5 squ&]+ = unlimit$ ages2 we h already expla9$ t ! effect ( ! heat radiat$ to u f ! sun is purely sup]ficial4 ,ev5 amid ! glories ( ! tropics1 ev5 9 ! burn+ heat ( ! des]t1 ! v]tical sun produces no appreciable effects at dep?s great] ?an ?is critical limit1 :i* is ab\t #ajj feet bel[ ! surface4 ,! rig\rs ( an ,arctic w9t] h z little effect 9 r$uc+ ! temp]ature ( ! rocks at t dep? z ! torrid heat at ! ,equator has 9 rais+ x4 ,! effect 9 ea* case is no?+4 ,! argum5t :i* we are "h employ+ to d$uce ! nebul\s orig9 ( our e>? f ! increase ( temp]ature ) increase 9 dep? 9 ! e>?'s cru/ mu/ be cle>$ f an objection4 ,x is necess>y to expla9 ! matt] fully1 because x t\*es on a doctr9e ( v great int]e/ & importance4 ,t a rotat+ body %\ld possess a quantity ( en]gy 9 virtue ( its rotation w be famili> to anyone :o has ev] turn$ a gr9d/one or wat*$ ! fly-:eel ( an eng9e4 ,a c]ta9 am\nt ( "w has to be exp5d$ to set ! heavy :eel into rotation1 & :5 ! ma*9e is call$ ^u to d "w x w yield up en]gy & its motion w und]go a correspond+ abatem5t4 ,! heavy fly-:eel ( ! ma*9e 9 a roll+ mill conta9s1 9 virtue ( its motion1 en\gh en]gy to ov]come ! trem5d\s resi/ance ( ! mat]ials submitt$ to x4 ,once ^u a "t ! e>? revolv$ ^u its axis 9 six h\rs1 in/ead ( 9 ! tw5ty-f\r h\rs :i* x n[ requires4 ,at t "t ! en]gy ( ! rotation mu/ h be5 sixte5fold :at x is at pres5t4 ,?is consid]ation %[s t fifte5-sixte5?s ( ! en]gy t ! e>? orig9ally possess$ 9 its rotation has disappe>$1 & we want to "k :at has become ( x4 ,we are "h ent]+ ^u a matt] ( "s difficulty4 ,x is connect$ ) t rem>kable *apt] 9 a/ronomy :i* describes ! evolution ( ! e>?-moon sy/em4 ,! moon 0 orig9ally a "p ( ! e>?1 = 9 v e>ly times1 :5 ! e>? 0 /ill 9 a pla/ic /ate1 a sep>ation w\ld seem to h tak5 place1 by :i* a small piece broke (f to =m ! moon1 :i* has be5 gradually revolv+ 9 an enl>g+ orbit until x has atta9$ ! position x n[ occupies4 ,a consid]able portion ( ! en]gy ( ! e>?'s rotation has be5 appli$ to ! purpose ( driv+ ! moon out to its pres5t pa?1 b !re is a l>ge rema9d] :i* _c be s acc\nt$ =4 ,x is well kn[n t ! evolution ( ! moon has be5 a rem>kable consequ5ce ( tidal action4 ,!re are tides :i* sway to & fro 9 ! wat]s on ! e>?'s surface2 !re are tides 9 any molt5 or visc\s matt] t ! e>? may conta91 & !re are ev5 c]ta9 small tidal displacem5ts 9 ! solid mat]ial ( our globe4 ,tides ( any k9d w g5]ate friction1 & friction produces heat1 & ! en]gy ( ! e>?'s rotation1 :i* we h n be5 able to acc\nt = o!rwise1 has be5 ?us trans=m$ into heat4 ,?r\gh\t ! :ole int]ior ( ! e>? heat has be5 produc$ by ! tidal displacem5t ( its p>ts4 ,! "q !re=e arises z to :e!r ! int]nal heat ( ! e>? may n receive an adequate explanation f ?is tidal action1 :i* is c]ta9ly suffici5t z to quantity4 ,x is easy to calculate :at ! total quantity ( ?is tidal heat may h be54 ,we "k ! en]gy :i* ! e>? _h :5 x rotat$ 9 six h\rs1 & we "k t x n[ reta9s no m ?an a sixte5? ( t am\nt4 ,we "k also precisely h[ mu* 0 absorb$ 9 ! removal ( ! moon1 & ! balance c be evaluat$ 9 heat4 ,x c be %[n1 & ! fact is a v /rik+ "o1 t ! quantity ( heat ?us aris+ w\ld be suffici5t to acc\nt _m times ov] = ! int]nal heat ( ! e>?4 ,x might !re=e be urg$ plausibly t ! int]nal heat :i* we actually f9d has _h its orig9 9 ?is way4 ,& if ?is 7 ! case ! argum5t :i* we are us+ 9 fav\r ( ! nebul> orig9 ( ! e>?1 w\ld be1 ( c\rse1 invalidat$4 ,we may /ate ! issue 9 a slightly diff]5t mann]1 z foll[s4 ,heat !re is und\bt$ly 9 ! e>?2 t heat might h come f ! primval nebula z we h suppos$1 & z 9 actual fact x did come4 ,b app>5tly x might h come f ! tidal friction4 ,:y !n are we entitl$ to reject ! latt] view1 & say t ! tidal friction w n expla9 ! int]nal heat1 & :y are we compell$ to fall back on ! only o!r explanation8 ,"l ,kelv9 sugge/$ a te/ = decid+ to :i* ( ^! two s\rces ! e>?'s int]nal heat 0 to be attribut$4 ,pr(essor ,g4 ,h4 ,d>w9 appli$ ! te/ & decid$ ! issue4 ,we h dwelt ^u ! rate at :i* ! heat increases ) ! desc5t1 ?is rate be+ ab\t "o degree e sixty-six feet4 ,n[ ! di/ribution ( ! heat1 if x _h come f ! tidal action1 w\ld be q diff]5t f ! di/ribution :i* w\ld result f ! gradual efflux ( heat f ! c5tre 9 ! process ( cool+4 ,&1 speak+ q g5]ally1 we may surmise t ! heat produc$ by tidal friction w\ld be di/ribut$ r m t[>ds ! ext]ior ( ! e>? ?an at its c5tre4 ,we might !re=e reasonably expect t if ! int]nal heat ( ! e>? arose f tidal friction x w\ld be m uni=mly di/ribut$ ?r\gh\t ! globe1 & !re w\ld n be s great a contra/ betwe5 ! high temp]ature ( ! int]ior & ! less] temp]atures ne> ! surface z !re is :5 ! heat di/ribution is m]ely ! result ( cool+4 ,x has be5 prov$ t if ! int]nal heat _h its orig9 f ! tidal friction1 ! rate ( increase ) ! dep? w\ld be totally diff]5t f :at x is actually f\nd to be4 ,x w\ld be necess>y to g d[n #b1jjj feet to obta9 an increase ( "o degree1 in/ead ( only sixty-six feet1 z is actually ! case4 ,h5ce we conclude t ! increas+ heat met ) 9 desc5d+ ?r\gh ! e>?'s cru/ is n acc\nt$ = by tidal friction2 x has its orig9 9 ! o!r alt]native1 namely1 f ! cool+ ( ! primval nebula4 ,! heat :i* 0 und\bt$ly produc$ by ! tidal friction has gradually become bl5d$ ) ! heat f ! o!r1 &1 z we mu/ n[ say1 ! pr9cipal s\rce4 ,! facts ) reg>d to ! rate ( increase ) dep? ?us %[ t1 :atev] ! tides may h done 9 produc+ int]nal heat1 !re has be5 ano!r & a /ill m pot5t cause 9 op]ation4 ,! important conclusion = our pres5t purpose is t our argum5t may ju/ly proce$ )\t tak+ acc\nt ( ! effect ( tidal friction4 ,we are l$ by ^! consid]ations to a k ( a great trans=mation 9 ! nature ( our globe :i* mu/ h occurr$ 9 ! c\rse ( ages4 ,we h se5 t ?is e>? is gradually los+ heat f its int]ior1 & we h se5 t ?is loss ( heat is incessant4 ,f ! f\nta9s ( heat1 /ill s copi\s1 9 ! int]ior ! supply is gradually dissipat+4 ,n[ heat is only a =m ( en]gy1 & en]gy1 l matt]1 _c itself be creat$ out ( no?+4 ,!re c be no creation ( heat 9 our e>? )\t a correspond+ exp5diture ( en]gy4 ,if1 !re=e1 ! e>? is radiat+ heat1 !n1 z !re is no kn[n or1 inde$1 conceivable s\rce ( en]gy by :i* an equival5t c be re/or$1 x foll[s t ! e>? mu/ h less int]nal heat n[ ?an x _h at any e>li] p]iod4 ,no d\bt ! process ( cool+ is excessively sl[4 ,! e>? has less int]nal heat at pres5t ?an x _h a hundr$ ye>s ago1 b ,i d n suppose t ev5 9 a ?\s& ye>s1 or p]haps 9 t5 ?\s& ye>s1 !re w\ld be any appreciable decl9e 9 ! quantity ( heat1 s f> z any obvi\s manife/ations ( t heat are conc]n$4 ,x is1 h[ev]1 c]ta9 t ! e>? mu/ h be5 hott]1 ev5 ?\gh !re are n any obs]vations to :i* we c appeal to v]ify ! /atem5t2 & z our retrospect ext5ds fur!r & /ill fur!r ?r\gh ! ages we see t ! globe mu/ h be5 ev] hott] & ev] /ill hott]4 ,:atev] be ! heat conta9$ 9 our e>? n[1 x mu/ h conta9$ va/ly m heat t5 million ye>s ago2 h[ o!rwise c\ld ! daily leakage ( heat = all ^? t5 million ye>s h be5 suppli$8 ,x foll[s t !re mu/ h be5 mu* m heat some:]e 9 our e>? t5 million ye>s ago ?an !re is at pres5t1 & ! fur!r our retrospect ext5ds ! hott] d we f9d ! e>? to h be54 ,!re 0 a "t :5 ! temp]ature ( ! e>?'s surface mu/ h be5 w>m$ n alone by su* sunbeams z fell ^u x1 b by ! passage ( ! heat f ! int]ior4 ,no matt] h[ e>ly be ! p]iod :i* we consid]1 we f9d ! same causes to be 9 op]ation4 ,!re 0 a "t :51 ow+ to ! int]nal heat1 ! surface ( ! e>? mu/ h be5 z hot z boil+ wat]4 ,! loss ( heat by radiation mu/ !n h tak5 place mu* m copi\sly ?an x does at pres5t4 ,! argum5t we are pursu+ mu/ !re=e h appli$ ) ev5 great] =ce 9 ^? e>ly days4 ,!re 0 a "t :5 ! mat]ials at ! surface ( ! e>? mu/ h be5 int5sely heat$1 :5 !y mu/ h ev5 be5 r$-hot4 ,!re 0 a "t :5 ! e>?'s surface mu/ h _h a temp]ature l t ( ! lava z x issues f a volcano4 ,!re mu/ h be5 a "t :5 ! surface ( ! e>? 0 n ev5 solid1 :5 inde$ x 0 a viscid liquid1 & e>li] /ill ! liquid mu/ h be5 m & m inc&esc5t4 ,f t brilliant surface heat 0 vehem5tly radiat$4 ,ea* day ! globe 0 hott] ?an on ! succe$+ day4 ,!re is no break 9 ! argum5t4 ,we h to ?9k ( ?is gl[+ globe pass+ ?r\gh ^? phases ?r\gh :i* we "k t all matt] w pass if only we apply to x suffici5t heat4 ,! globe assum$ ! liquid /ate f t /ate :i* is dem&$ by a temp]ature /ill high]1 ! /ate 9 :i* ! matt] is actually 9 ! =m ( vap\r4 ,ev5 ! mo/ refractory sub/ances w take ! =m ( vap\r at a v high temp]ature4 ,?us we are conduct$ to a rem>kable conception ( ! condition 9 :i* ! mat]ials n[ =m+ our solid e>? mu/ h be5 9 ! exce$+ly remote pa/4 ,:at is n[ our e>? mu/ once h be5 a great quantity ( heat$ vap\r4 ,x ne$ h>dly be said t 9 t =m ! volume ( ! e>? 0 mu* l>g] ?an ! volume :i* ! e>? has at pres5t1 :ile no d\bt ! mass ( ! e>? !n 0 ev5 less ?an ! mass ( ! e>? n[1 by reason ( ! meteoric matt] :i* has be5 drawn 9 by our globe4 ,b ev5 :5 our e>? 0 9 ?is inflat$ /ate ( vap\r our argum5t c be /ill ma9ta9$4 ,?us we see t ! e>?1 or r ! cl\d ( vap\r :i* 0 ultimately to =m ! e>?1 is ev] gr[+ l>g] & l>g] 9 our retrospect1 ev] becom+ m & m r>efi$2 & x may well h be5 t !re 0 a "t :5 ! mat]ials ( ?is e>? occupi$ a volume ?\s&s ( times great] ?an !y d at pres5t4 ,9 a previ\s *apt] we h se5 h[ ! sun 0 at "o "t 9 ! nebul\s /ate1 & n[ we h be5 l$ to a simil> conclusion ) reg>d to ! e>?4 ,at t "t1 ( c\rse1 ! sun 0 greatly 9 excess ( its pres5t dim5sions1 & ! e>? 0 also greatly swoll54 ,! nebula :i* =m$ our sun1 & ! nebula :i* =m$ our e>?1 7 bo? s va/ z to be conflu5t2 !y 7 inde$ bo? "p ( ! same va/ nebula4 ,su* has be5 ! ,e>?'s ,beg9n+ s f> z mod]n sci5ce c make x cle> to u4 ,we h at lea/ indicat$ ! c\rse :i* ev5ts mu/ h tak5 accord+ to ! laws ( nature z we und]/& !m4 ,_m ( ! details ( ! great evolution are no d\bt unkn[n at pres5t1 & p]haps mu/ ev] rema9 s4 ,t ! ev5ts :i* we h endeav\r$ to describe d sub/antially repres5t ! actual evolution ( our sy/em is ! fam\s ,nebul> ,!ory4 ---------------------------------------- -------------------------------- ,,*apt] ,,ix4 ,,e>?quakes ,,& ,,volcanoes4 ,int]ior ( ! ,e>?--,illu/ration f ,norway--,solids & ,liquids--,rigidity ( ! ,int]ior ( ! ,e>?--,e>?quakes1 h[ caus$--,_! ,te/imony z to ! ,rigidity ( ! ,e>?--,delicate ,in/rum5t = ,measur+ ,e>?quake ,tremors--,! ,seismomet]--,pr(essor ,milne's ,"w 9 ! ,isle ( ,wight--,diff]5t ,e>?quake ,gr\ps--,precursors & ,e*oes--,vibrations transmitt$ ?r\gh ! ,e>?'s ,c5tre--,e>?quakes 9 ,engl&--,o!r ,evid5ce ( ! ,e>?'s ,rigidity--,krakatoa1 ,augu/ #bg?1 #ahhc--,! ,s\nds f ,krakatoa--,! ,div]g+ ,waves--,! ,krakatoa ,du/--,! ,hurricane ,ov]head--,/range ,signs 9 ! ,heav5s--,! ,blood-r$ ,skies4 ,,9 ?is *apt] we %all le>n :at we c z to ! physical condition ( ! int]ior ( our e>? s f> z x may be reasonably inf]r$ f ! facts ( obs]vation4 ,we h already expla9$ 9 ! la/ *apt] t a v high temp]ature mu/ be f\nd at ! dep? ( ev5 a small fraction ( ! e>?'s radius1 & we h po9t$ out t ! excessively high pressure *>act]i/ic ( ! e>?'s int]ior mu/ be borne 9 m9d 9 any consid]ation z to ! condition ( ! matt] !re f\nd4 ,let u take1 = in/ance1 t prim>y "q 9 t]re/rial physics1 z to :e!r ! int]ior ( ! e>? is liquid or solid4 ,if we 7 to judge m]ely f ! temp]atures reasonably believ$ to exi/ at a dep? ( "s tw5ty miles1 & if we might ov]look ! "q ( pressure1 we %\ld c]ta9ly say t ! e>?'s int]ior mu/ be 9 a fluid /ate4 ,x seems at lea/ c]ta9 t ! temp]atures to be f\nd at dep?s ( two score miles1 & /ill m at great] dep?s1 mu/ be s high t ! mo/ refractory solids1 :e!r metals or m9]als1 w\ld at once yield if we c\ld subject !m to su* temp]atures 9 our laboratories4 ,at su* temp]atures e metal w\ld become fluid1 ev5 if x 7 n trans=m$ into a cl\d ( vap\r4 ,b none ( our laboratory exp]im5ts c tell u :e!r1 "u ! pressure ( ?\s&s ( tons on ! squ>e in*1 ! application ( any heat :atev] w\ld be adequate to trans=m solids into liquids4 ,x may inde$ be reasonably d\bt$ :e!r ! t]ms solids & liquids are applicable1 9 ! s5se 9 :i* we und]/& !m1 to ! mat]ials =m+ ! int]ior ( ! e>?4 ,x 0 my good =tune "s ye>s ago to enjoy a mo/ int]e/+ trip to ,norway1 9 company ) a di/+ui%$ geologi/4 ,"u 8 guidance ,i !re saw evid5ce :i* demon/rates conclusively t1 :5 subject$ to great pressure1 solids1 z we %\ld call !m1 behave 9 a mann] :i*1 if n t ( actual liquids1 resembles at all ev5ts 9 "s ( its *>act]i/ics ! behavi\r ( liquids4 ,^! rocks 9 "s places are conglom]ates1 ( :i* ! lead+ con/itu5ts are wat]-worn pebbles ( granite4 ,^! pebbles are ( v>i\s sizes1 f m>bles to pav+-/ones4 ,9 "s p>ts ( ! c\ntry ^! granite pebbles rema9 9 ! =m :i* !y acquir$ on ! bea* on :i* !y 7 roll$ by ! primval ocean2 9 o!r p>ts ( ! same int]e/+ region ! =m ( ! pebbles has be5 greatly *ang$ f :at x 0 orig9ally4 ,= 9 ! c\rse ( geological p]iods1 & aft] ! pebbles _h become consolidat$ into ! conglom]ate1 ! rock s =m$ _h be5 9 "s cases submitt$ to enorm\s pressure4 ,?is may h be5 lat]al pressure1 su* z is f\nd to h occurr$ 9 _m o!r places1 :]e x has produc$ ! well-kn[n geological ph5om5on ( /rata crumpl$ into folds4 ,9 ! pres5t case1 h[ev]1 x seem$ m probable t x 0 ! actual weight ( ! sup]9cumb5t rocks1 :i* once lay ov] ^! b$s ( conglom]ate1 :i* produc$ ! surpris+ trans=mation4 ,x seems to be n at all improbable t at "o "t ^! b$s ( conglom]ate mu/ h be5 cov]$ ) /rata ( :i* ! ?ickness is s great t x may actually be e/imat$ by miles4 ,!re has1 h[ev]1 be5 imm5se d5udation ( ! sup]ficial rocks 9 ?is "p1 at all ev5ts1 ( ,norway1 s t 9 ! c\rse ( ages ^! /rata1 ov]ly+ ! conglom]ate = ages1 h be5 s f> worn away1 & inde$ remov$1 by ! action ( ice & ! action ( wat] t ! conglom]ate is n[ expos$ to view4 ,x (f]s = our exam9ation /rik+ indications ( ! enorm\s pressure to :i* x 0 subject$ dur+ ! incalculable ages ( geological "t4 ,! effect ( ?is long cont9uance ( great pressure ^u ! pebbles ( ! conglom]ate 9 c]ta9 p>ts ( ! c\ntry has be5 mo/ a/oni%+4 ,! granite 9 ! pebbles /ill reta9s its *>act]i/ic cry/all9e /ructure2 x has obvi\sly n und]gone any?+ t c\ld be describ$ z fusion2 yet "u ! influ5ce ( ! two factors ( t pressure1 namely1 its int5sity & its long cont9uance1 ! granite pebbles h yield$4 ,9 "s cases !y are slightly elongat$1 9 o!rs !y are mu* elongat$1 :ile 9 yet o!rs !y are ev5 roll$ out flat4 ,at diff]5t places along ! valley ! v>i\s phases ( ! trans=mation c be /udi$4 ,we c f9d places :]e ! pebbles seem little alt]$1 & !n we c trace ea* /age until ! solid granite pebbles h1 by ! application ( excessive pressure1 be5 compress$ into ?9 %eets ^: "* x w\ld n h be5 easy to div9e if x _h n be5 possible to trace out _! hi/ory4 ,^! %eets lie close & p>allel1 s t ! mat]ial ?us produc$ acquires "s ( ! *>act]i/ics ( slate4 ,x splits easily along ! flatt5$ %eets1 & ?is roll$-out conglom]ate is inde$ actually us$ z a sub/itute = slate1 & 9 "s places !re are h\ses ro($ ) ! conglom]ate :i* has be5 treat$ 9 ?is extraord9>y fa%ion4 ,?is fact w illu/rate a pr9ciple1 already well kn[n 9 ! arts1 t _m1 if n all1 solids may be made to fl[ l liquids if only adequate pressure be appli$4 ,! mak+ ( lead tubes is a well-kn[n practical illu/ration ( ! same pr9ciple1 = ^! tubes are simply =m$ by =c+ solid lead by ! hydraulic press ?r\gh a m\ld :i* imp>ts ! desir$ =m4 ,if !n a solid c be made to behave l a liquid1 ev5 ) su* pressures z are )9 our control1 h[ are we to suppose t ! solids w\ld behave ) su* pressures z ^? to :i* !y are subject$ 9 ! int]ior ( ! e>?8 ,! fact is t ! t]ms solid & liquid1 at lea/ z we und]/& !m1 appe> to h no physical mean+ ) reg>d to bodies subject$ to ^! /up5d\s pressures1 & ?is mu/ be c>efully borne 9 m9d :5 we are discuss+ ! nature ( ! int]ior ( ! e>?4 ,x mu/1 h[ev]1 be admitt$ t ! int]ior ( ! e>? 9 its actual physical /ate seems to possess at lea/ "o ( ! mo/ important *>act]i/ics ( a solid1 = x seems to be int5sely rigid4 ,we mean by ?is1 t ! mat]ial ( ! e>?1 or r ea* p>ticle ( t mat]ial1 is v little incl9$ to move f its position ) ref]5ce to ! adjac5t p>ticles by ! application ( =ce4 ,possibly a liquid1 su* z wat]1 might n behave v diff]5tly 9 ?is respect f a solid su* z ca/ iron1 if ea* ( !m 7 expos$ to a pressure ( scores ( ?\s&s ( tons p] squ>e in*1 z are ! mat]ials :i* =m ! great bulk ( ! e>?4 ,b1 )\t speculat+ on ^! po9ts1 we are able to demon/rate t ! e>?1 z a :ole1 does exhibit extreme rigidity4 ,?is is "o ( ! mo/ rem>kable discov]ies :i* has ev] be5 made ) reg>d to ! physics ( our e>?4 ,! discov]y t ! e>? is s rigid is ma9ly due to ,"l ,kelv94 ,we %all n[ m5tion ! l9e ( evid5ce :i* appe>s to prove1 9 ! simple/ & mo/ direct mann]1 ! excessive rigidity ( our e>?4 ,x is d]iv$ f ! /udy ( e>?quake ph5om5a1 & we mu/ endeav\r to set x =? ) ! complet5ess its importance des]ves4 ,z to ! imm$iate cause ( e>?quakes1 !re is no d\bt consid]able diff]5ce ( op9ion4 ,b ,i ?9k x w n be d\bt$ t an e>?quake is "o ( ! consequ5ces1 ?\gh p]haps a remote "o1 ( ! gradual loss ( int]nal heat f ! e>?4 ,z ?is t]re/rial heat is gradually decl9+1 x foll[s f ! law t we h already s (t5 _h occasion to use t ! bulk ( ! e>? mu/ be %r9k+4 ,no d\bt ! dim9ution 9 ! e>?'s diamet]1 due to ! loss ( heat mu/ be excessively small1 ev5 9 a long p]iod ( "t4 ,! cause1 h[ev]1 is cont9ually 9 op]ation1 & accord+ly ! cru/ ( ! e>? has1 f "t to "t1 to be accommodat$ to ! fact t ! :ole globe is less5+4 ,! circumf]5ce ( our e>? at ! ,equator mu/ be gradually decl9+2 a c]ta9 l5g? 9 t circumf]5ce is lo/ ea* ye>4 ,we may admit t loss to be a quantity f> too small to be measur$ by any obs]vations z yet obta9able1 b1 nev]!less1 x is productive ( ph5om5a s important t x _c be ov]look$4 ,x foll[s f ^! consid]ations t ! rocks :i* =m ! e>?'s cru/ ov] ! surface ( ! cont95ts & ! isl&s1 or b5ea? ! b$s ( ocean1 mu/ h a less5+ acreage ye> by ye>4 ,^! rocks mu/ !re=e submit to compression1 ei!r cont9u\sly or f "t to "t1 & ! necess>y yield+ ( ! rocks w 9 g5]al take place 9 ^? regions :]e ! mat]ials ( ! e>?'s cru/ happ5 to h comp>atively small p[]s ( resi/ance4 ,! acts ( compression w (t51 & p]haps g5]ally1 n proce$ ) uni=mity1 b r ) small successive %ifts1 & ev5 ?\gh ! displacem5ts ( ! rocks 9 ^! %ifts be actually v small1 yet ! pressures to :i* ! rocks are subject$ are s va/ t a v small %ift may correspond to a v great t]re/rial di/urbance4 ,suppose1 = in/ance1 t !re is a slight %ift 9 ! rocks on ea* side ( a crack1 or fault1 at a dep? ( t5 miles4 ,x mu/ be rememb]$ t ! pressure t5 miles d[n w\ld be ab\t ?irty-five tons on ! squ>e in*4 ,ev5 a slight displacem5t ( "o ext5sive surface ov] ano!r1 ! sides be+ press$ toge!r ) a =ce ( ?irty-five tons on ! squ>e in*1 w\ld be an op]ation necess>ily accompani$ by viol5ce greatly exce$+ t :i* we might expect f s small a displacem5t if ! =ces conc]n$ _h be5 only ( m ord9>y magnitude4 ,on acc\nt ( ?is great multiplication ( ! int5sity ( ! ph5om5on1 m]ely a small re>rangem5t ( ! rocks 9 ! cru/ ( ! e>?1 9 pursuance ( ! necess>y "w ( accommodat+ its volume to ! p]petual %r9kage1 might produce an excessively viol5t %ock ext5d+ f> & wide4 ,! effect ( su* a %ock w\ld be propagat$ 9 ! =m ( waves ?r\gh ! globe1 j z a viol5t bl[ giv5 at "o end ( a b> ( iron by a hamm] is propagat$ ?r\gh ! b> 9 ! =m ( waves4 ,:5 ! effect ( ?is int]nal adju/m5t rea*es ! e>?'s surface1 x w sometimes be great en\gh to be p]ceptible 9 ! %ak+ x gives t surface4 ,! %ak+ may be s viol5t t build+s may n be able to )/& x4 ,su* is ! ph5om5on ( an e>?quake4 ,e>?quakes h be5 made to yield te/imony ( ! mo/ /rik+ "* ) reg>d to ! rigidity ( ! e>?4 ,! rese>*es we are n[ to describe are ma9ly due to ,pr(essor ,milne1 :o1 hav+ enjoy$ ! advantage ( /udy+ e>?quakes 9 _! natural home 9 ,japan1 :]e are to be f\nd "s ( ! mo/ e>?quake-%ak5 regions ( ?is e>?1 has n[ transf]r$ 8 obs]vations ( ^! ph5om5a to ! m peaceful regions ( ! ,isle ( ,wight4 ,b ?\gh ! ,isle ( ,wight is p]haps "o ( ! la/ places 9 ! _w to :i* anyone :o desir$ to exp]i5ce viol5t e>?quake %ocks w\ld be likely to g1 yet by ! help ( a beautiful app>atus ,pr(essor ,milne is actually able to witness important e>?quakes t are happ5+ all ov] ! _w4 ,he has a demon/ration ( ^! e>?quakes 9 ! indications ( an extremely s5sitive in/rum5t :i* he has erect$ 9 8 home at ,%ide4 ,:5 our e>? is %ak5 by "o ( ^? occasional adju/m5ts ( ! cru/ :i* ,i h describ$1 ! wave t spreads l a pulsation f ! c5tre ( agitation ext5ds all ov] our globe &1 inde$ ,i may say1 is transmitt$ "r ?r\gh x4 ,at ! surface ly+ imm$iately ov] ! c5tre ( di/urbance !re w be a viol5t %ock4 ,9 ! surr\nd+ c\ntry1 & (t5 ov] great di/ances1 ! e>?quake may also be p[]ful en\gh to produce de/ructive effects4 ,! convulsion may also be manife/$ ov] a f> l>g] area ( c\ntry 9 a way :i* makes ! %ock to be felt1 ?\gh ! damage wr\ght may n be appreciable4 ,b beyond a limit$ di/ance f ! c5tre ( ! agitation ! e>?quake w produce no de/ructive effects ^u build+s1 & w n ev5 cause vibrations t w\ld be appreciable to ord9>y obs]vation4 ,?is e>? ( ours may transmit f an e>?quake pulses ( a v di/9ct & def9ite "*1 :i* are too weak to be p]ceiv$ by our unaid$ s5ses2 b1 j z ! microscope w r5d] objects visible :i* are too m9ute to be p]ceiv$ )\t ?is aid to ! ord9>y vision1 s ^! fa9t e>?-pulses may be r5d]$ p]ceptible by ! delicate indications ( an in/rum5t :i* p]ceives & records tremors t w\ld pass unnotic$ by our ord9>y obs]vations4 ,! +5i\s in/rum5t = /udy+ e>?quakes is call$ a seismomet]4 ,x m>ks on a revolv+ drum ( pap] ! p>ticul>s ( ^? inf9itesimal tremors by :i* ! e>? is almo/ daily agitat$ 9 "o place or ano!r4 ,let u suppose1 = example1 t an e>?quake occurs 9 ,japan1 9 :i* mu* agitat$ c\ntry x is1 ,i believe1 e/imat$ t no few] ?an "o ?\s& e>?quakes ( v>y+ degrees ( int5sity occur annually 9 "o di/rict or ano!r4 ,let u suppose t ?is e>?quake behaves z s]i\s e>?quakes usually d2 t x knocks d[n build+s & monum5ts1 causes l&slips1 raises great waves 9 ! sea & hurls !m z inundations on ! l&4 ,we may also suppose t x issues tragically 9 ! loss ( _m lives & t !re is a de/ruction ( mu* prop]ty1 & t its en]gies 9 ! acutely viol5t =m ext5d ov]1 let u say1 an area ( a hundr$ squ>e miles4 ,beyond t area ( greate/ de/ruction su* an e>?quake w\ld be felt ov] a great ext5t ( c\ntry z a %ak+ m or less vehem5t1 & *>act]i/ic rumbl+ s\nds w\ld be he>d4 ,b ! int5sity decl9es ) ! di/ance1 & we may feel confid5t t n ev5 ! fa9te/ indications ( ! e>?quake w\ld be p]ceptible by ! unaid$ s5ses at a ?\s& miles f its orig94 ,a ?\s& miles is1 h[ev]1 less ?an a fif? ( ! di/ance betwe5 ,tokio & ,%ide1 9 ! ,isle ( ,wight1 measur$ 9 a great circle r\nd ! e>?'s surface4 ,! acute/ s5se c\ld n p]ceive ! slighte/ indication ( ! convulsion 9 ,japan at ev5 half ! di/ance betwe5 ^! two places4 ,b ! e>? transmits s fai?fully ! undulations committ$ to its c>e t ?\gh ! int5sity may h decl9$ s z to be no long] p]ceptible to ! unaid$ s5se1 x is /ill possible t !y may be %[n di/9ctly on ! seismomet] 9 ,pr(essor ,milne's laboratory1 ev5 aft] a j\rney ( five ?\s& miles4 ,?is in/rum5t n only ann\nces t an e>?quake has be5 9 progress "s little "t previ\sly1 b ! record+ p5cil reproduces ) m>vell\s fidelity "s actual details ( ! vibration4 ,! movem5ts ( ! l9e up & d[n on ! revolv+ drum ( pap] %[ h[ ! convulsions succe$ ea* o!r1 & _! v>y+ int5sity4 ,?us ,pr(essor ,milne is enabl$ to set d[n "s features ( ! e>?quake long be=e ! po/ br+s an acc\nt ( ! convulsion f ! unhappy locality4 ,pr(essor ,milne's acc\nt ( "w 9 /udy+ e>?quakes has ! *>m ( a romance1 ev5 :ile x fai?fully sets out ! facts ( ,nature4 ,i h suppos$ ! e>?quake to take place 9 ,japan2 b we mu/ obs]ve t ! seismomet] at ,%ide w also take acc\nt ( consid]able e>?quakes 9 :atev] "p ( ! _w ! di/urbance may arise4 ,!re are1 = example1 localities 9 ! ,we/ ,indies 9 :i* e>?quakes are by no means infrequ5t1 ?\gh !y may n be ph5om5a ( almo/ daily occurr5ce1 z !y are 9 ,japan4 ,e consid]able e>?quake1 no matt] :]e its c5tre may lie1 produces 9 our :ole globe a vibration or a t+le :i* is suffici5t to be manife/$ by ! delicate indications ( ! seismomet] at ,%ide4 ,?us ?is in/rum5t1 :i* 9 ! morn+ may record an e>?quake f ,japan1 w 9 ! aft]noon ( ! same day del9eate ) equal fidelity an e>?quake f ! opposite hemisph]e 9 ! neighb\rhood ( ! ,c>ibbean ,sea4 ,9 ea* locality 9 :i* e>?quakes are *ronic x w\ld seem z if !re mu/ be "s p>ticul>ly weak spot 9 ! e>? "s miles bel[ ! surface4 ,a %r9kage ( ! e>?1 9 ! c\rse ( ! incessant adju/m5t betwe5 ! int]ior & ! ext]ior1 w take place by occasional little jumps at ?is p>ticul> c5tre4 ,! fact t !re is ?is weak spot at :i* small adju/m5ts are possible may provide1 z x 71 a safety-valve = o!r places 9 ! same "p ( ! _w4 ,in/ead ( a g5]al %r9k+1 ! mat]ials w\ld be suffici5tly ela/ic & flexible to all[ ! %r9k+ = a v l>ge area to be done at ?is p>ticul> locality4 ,9 ?is way we may expla9 ! fact t imm5se tracts on ! e>? are practically free f e>?quakes ( a s]i\s "*1 :ile 9 ! less =tunate regions ! e>?quakes are m or less p]5nial4 ,! *>act]i/ics ( an e>?quake record1 a seismogram1 if we give x ! correct designation1 dep5d on ! di/ance ( ! orig9 f ! locality :]e ! record is made4 ,! l5g? ( ! j\rney1 z might be expect$1 tells on ! "* ( ! inscription :i* ! e>?quake waves make on ! drum4 ,if1 = in/ance1 ! fir/ intimation ( a l>ge e>?quake receiv$ at ,%ide prec$es ! second by ab\t ?irty-five m9utes1 x may be conclud$ t ! e>?quake has come f ,japan4 ,9 l mann] ! %ocks1 ) _! orig9 9 ! ,we/ ,indies1 w proce$ f _! p>ticul> e>?quake c5tre1 & consequ5tly all ! e>?quakes f ?is s\rce w possess a *>act]i/ic resemblance4 ,! ,japan gr\p ( e>?quakes w h1 s to speak1 a family resemblance2 & ! ,tr9idad gr\p ( e>?quakes1 ?\gh q diff]5t f ! ,japan gr\p1 w also possess a family resemblance4 ,^! features are fai?fully transmitt$ by undulations ?r\gh ! e>? & r\nd ! e>?2 ?us 9 due c\rse !y rea* ! ,isle ( ,wight1 & !y are reproduc$ by ! p5cil ( ! seismomet]4 ,! diff]5t e>?quakes ( a family may diff] 9 size1 9 int5sity1 & undulation1 b !y w h ! features appropriate to ! p>ticul> gr\p f :i* !y come4 ,f long exp]i5ce ,pr(essor ,milne has become s famili> ) ! l9eam5ts ( ^! e>?quake families1 t 9 8 /udy at ,%ide1 z he looks at ! indications ( 8 in/rum5t1 he is able to say1 = example1 8,"h is an e>?quake1 & x is a little e>?quake f ,japan20 !n a little lat]1 :5 a new e>?quake beg9s1 he w say1 8,& "h is a big e>?quake f ,tr9idad40 ,pr(essor ,milne's app>atus has br\ght u rem>kable in=mation ) reg>d to ! int]ior ( ! e>?4 ,! /ory :i* we h to tell is really "o ( ! mo/ a/oni%+ 9 physical sci5ce4 ,let u suppose t an e>?quake orig9ates 9 ,japan4 ,we %all assume t ! e>?quake is a vigor\s "o1 capable ( produc+ bold & def9ite indications on ! seismomet] ev5 9 ! ,isle ( ,wight4 ,x is to be not$ t ?is in/rum5t is n cont5t m]ely ) a s+le v]sion ( ! /ory ( t e>?quake2 x w inde$ repeat t /ory twice m4 ,fir/ ( all1 ab\t a qu>t] ( an h\r aft] a %ock has tak5 place 9 ,japan1 ! p5cil ( ! seismomet] comm5ces to record4 ,b ?is record1 ?\gh q di/9ct1 is n s boldly indicat$ z ! subsequ5t records ( ! same ev5t :i* w pres5tly be receiv$4 ,x is to be reg>d$ z a precursor4 ,aft] ! fir/ record is complet$ !re is a pause ( p]haps ?ree-qu>t]s ( an h\r1 & !n ! p5cil ( ! seismomet] comm5ces aga94 ,x comm5ces to give an e>?quake record1 b x is obvi\sly only a second v]sion ( ! same e>?quake4 ,= ! ups & d[ns trac$ by ! p5cil are j ! same relatively z be=e4 ,! picture giv5 ( ! e>?quake is1 h[ev]1 on a mu* l>g] scale ?an ! "o t is fir/ s5t4 ,! ext5t ( ! %ak+ ( ! in/rum5t 9 ?is second record is great] ?an 9 ! fir/1 & all ! details are m boldly drawn4 ,aft] ! second diagram has be5 receiv$1 !re is yet ano!r pause1 :i* may be p]haps = half an h\r4 ,!n1 by ! same p5cil1 a ?ird & la/ v]sion is convey$ to ! seismomet]4 ,?is diagram is n q s /rong z ! la/1 ?\gh /rong] ?an ! fir/2 9 x aga91 h[ev]1 ! fai?ful p5cil tells1 ) _m a detail1 :at happ5$ 9 ?is e>?quake at ,japan4 ,we h fir/ to expla9 h[ x occurs t !re are ?ree v]sions ( ! ev5t1 = x ne$ h>dly be said t ! same e>?quake did n take place ?ree diff]5t times ov]4 ,! po9t is inde$ a beautiful "o4 ,! explanation is s a/oni%+ t we %\ld h>dly cr$it x 7 x n e/abli%$ ^u evid5ce t does n admit ( a mom5t's "q4 ,illu/ration3 ,fig4 #be4--;,,e>?quake ,,r\tes ,,f ,,japan ,,to ,,! ,,isle ,,( ,,wight4 ,9 ! adjo9+ diagram we repres5t ! position ( ,japan at "o side ( ! e>?1 & ! ,isle ( ,wight at ! o!r4 ,:5 ! e>?quake takes place at ,japan x orig9ates1 z we h said1 a s]ies ( vibrations ?r\gh our globe4 ,we mu/ "h di/+ui% betwe5 ! rocks--,i might almo/ say ! comp>atively pliant rocks--:i* =m ! e>?'s cru/1 & ^? :i* =m ! int5sely rigid core ( ! int]ior ( our globe4 ,! vibrations :i* c>ry ! tid+s ( ! e>?quake spread ?r\gh ! rocks on ! surface1 f ! c5tre ( ! di/urbance1 9 gradually enl>g+ circles4 ,we may lik5 ! spread ( ^! vibrations to ! ripples 9 a pool ( wat] :i* div]ge f ! spot :]e a ra9drop has fall51 or to ! rem>kable air-waves f ,krakatoa1 to :i* we %all pres5tly ref]4 ,! vibrations transmitt$ by ! rocks on ! surface1 or on ! floor ( ! ocean1 w c>ry ! message all ov] ! e>?4 ,z ^! rocks are flexible1 at all ev5ts by comp>ison ) ! e>?'s int]ior1 ! vibrations w be correspond+ly l>ge1 & w travel ) vig\r ov] l& & "u sea4 ,9 due "t !y rea* ! ,isle ( ,wight1 :]e !y set ! p5cil ( ! seismomet] at "w4 ,b !re are diff]5t ways r\nd ! e>? f ,japan to ! ,isle ( ,wight4 ,!re is ! mo/ direct r\te across ,asia & ,europe2 !re is also ! r\te across ! ,pacific1 ,am]ica1 & ! ,atlantic4 ,! vibrations w travel by bo? r\tes1 & ! =m] is ! %ort] ( ! two4 ,! vibrations :i* take ! fir/ r\te ?r\gh ! cru/ ( ! e>?'s surface are travell+ by ! %ort] di/ance2 !y consequ5tly rea* ,%ide fir/1 & r5d] _! v]sion ( :at has happ5$4 ,b ! vibrations :i*1 />t+ f ! c5tre ( ! di/urbance1 move ?r\gh ! e>?'s cru/ 9 an opposite direction w also 9 _! due c\rse ( expansion rea* ! ,isle ( ,wight4 ,!y w h _h a long] j\rney1 & w consequ5tly be some:at enfeebl$1 ?\gh !y w /ill reta9 ! *>act]i/ics m>k+ ! p>ticul> e>?quake c5tre f :i* !y arose4 ,we ?us acc\nt = bo? ! second & ! ?ird ( ! diff]5t v]sions ( ! e>?quake :i* are receiv$ at ,%ide4 ,& n[ = ! fir/ ( ! ?ree v]sions4 ,?is is ! "o :i* is ( special int]e/ to u at pres5t4 ,! orig9al subt]ranean impulse 01 z we h se51 propagat$ ?r\gh ! rocks =m+ ! e>?'s cru/4 ,"p ( x1 h[ev]1 ent]$ into ! core =m+ ! e>?'s int]ior4 ,! e>?quake _h ! p[] n only ( %ak+ ! e>?'s cru/ all ov]1 b x produc$ ! a/oni%+ effect ( sett+ ! :ole int]ior ( our globe into a tremble4 ,!re 0 n a s+le p>ticle ( our e>?1 f c5tre to surface1 :i* 0 n made to vibrate1 9 "s degree1 9 consequ5ce ( ! e>?quake4 ,c]ta9 ( ^! vibrations1 spread+ f ! c5tre ( di/urbance1 took a direct c\rse to ! ,isle ( ,wight1 "r ?r\gh ! globe4 ,!y consequ5tly _h a %ort] j\rney 9 travell+ f ,tokio to ,%ide ?an ^? :i* w5t r\nd ! e>?'s cru/4 ,! =m] travell$ ne> ! *ord1 :ile ! latt] travell$ on ! arc4 ,ev5 = ?is reason alone ! int]nal vibrations might be expect$ to accompli% _! j\rney m rapidly ?an ! sup]ficial movem5ts4 ,) ! same velocity !y w\ld take a %ort] "t = ! j\rney4 ,!re is1 h[ev]1 ano!r reason = ! less] "t tak5 by ! int]nal vibrations4 ,n only is ! j\rney %ort]1 b ! spe$ ) :i* ^! vibrations travel ?r\gh ! solid e>? is mu* great] ?an ! spe$ ) :i* sup]ficial vibrations travel ?r\gh ! cru/4 ,x has be5 %[n t ! av]age velocity ( ^! vibrations :5 travell+ ?r\gh ! c5tre ( ! e>? is r m ?an t5 miles a second4 ,! velocity v>ies ) ! squ>e root ( ! dep?1 & ne> ! surface x is sc>cely two miles a second4 ,!re are two po9ts to be specially notic$4 ,! vibrations1 :i*1 pass+ ?r\gh ! e>?'s int]ior ) a high velocity1 arrive z precursors1 make a fai?ful diagram1 b only on a v small scale4 ,we say t ^! vibrations h b small amplitude4 ,?is %[s t ! p>ticles 9 ! e>?'s int]ior are n mu* displac$ by ! e>?quake1 z comp>$ ) ^? on ! e>?'s cru/1 & ?is is "o indication ( ! effective rigidity ( ! e>?4 ,x is also to be not$ t ! great spe$ ) :i* ! vibrations trav]se ! solid e>? is a consequ5ce ( ! extreme rigidity ( our globe4 ,^! vibrations travel m rapidly ?r\gh ! e>? ?an !y w\ld d ?r\gh a b> ( solid /eel4 ,9 o!r words1 we h "h a pro( t1 "u ! influ5ce ( ! trem5d\s pressures *>act]i/ic ( ! e>?'s int]ior1 ! mat]ial ( :i* t e>? is compos$1 not)/&+ ! high temp]ature to :i* x is rais$1 possesses a rigidity :i* is practically great] ?an t ( /eel itself4 ,illu/ration3 ,,%[+ ,,localities ,,( ,,e>?quakes ,?is is p]haps ! mo/ /rik+ te/imony t c be borne to ! rigidity ( our globe2 b we mu/ n imag9e t we are dep5d5t solely ^u ! ph5om5a ( e>?quakes = ! demon/ration ( ?is important po9t2 !re are o!r pro(s4 ,x c be %[n t ! ebb & fl[ ( ! tides on our coa/s w\ld be v diff]5t f t :i* !y actually are 7 x n t ! e>? behaves z a rigid globe4 ,x has also be5 demon/rat$ t c]ta9 a/ronomical ph5om5a connect$ ) ! way 9 :i* ! e>? turns r\nd on its axis w\ld n be ! same z we actually f9d !m to be if ! e>? 7 n solid 9 its int]ior4 ,! result ( ^! inve/igations is to %[ t1 ?\gh ?is globe ( ours mu/ be excessively hot inside1 s hot inde$ t at ord9>y pressures ev5 ! mo/ refractory solids w\ld be liquefi$ or vaporis$1 yet "u ! influ5ce ( ! pressure to :i* its mat]ials are subject$ ! behavi\r ( t globe is z t ( ! mo/ rigidly solid body4 ,happily 9 ?is c\ntry we d n (t5 exp]i5ce e>?quakes o!r ?an delicate movem5ts %[n by ! record ( ! seismomet]4 ,b ?\gh mo/ ( u live our lives )\t ev] hav+ felt an e>?quake %ock1 yet e>?quakes d sometimes make !mselves felt 9 ,great ,brita94 ,! map we "h give1 :i* 0 drawn by ,pr(essor ,j4 ,p4 ,o',reilly1 indicates ! localities 9 ,engl& 9 :i* f "t to "t e>?quake %ocks h be5 exp]i5c$4 ,! int]nal heat ( ! e>?1 d]iv$ f ! primval nebula1 is 9 no way m /rik+ly illu/rat$ ?an by ! ph5om5a ( volcanoes4 ,we h %[n 9 ?is *apt] t !re is no long] any reason to believe t ! e>? is fluid 9 its int]ior4 ,! evid5ce has prov$ t1 "u ! extraord9>y pressure :i* prevails 9 ! e>?1 ! mat]ials 9 ! c5tral portions ( our globe behave ) ! *>act]i/ics ( solids r ?an ( liquids4 ,b ?\gh ?is applies to ! deep-seat$ regions ( our globe1 x ne$ n univ]sally apply at ! surface or )9 a mod]ate dep? f ! surface4 ,:5 ! circum/ances are su* t ! pressure is relax$1 !n ! heat is p]mitt$ to ex]cise its prop]ty ( trans=m+ ! solids into liquids4 ,masses ( matt] ne> ! e>?'s cru/ are ?us1 9 c]ta9 circum/ances1 & 9 c]ta9 localities1 trans=m$ into ! fluid or viscid =m4 ,9 t /ate !y may issue f a volcano & fl[ 9 sluggi% curr5ts z lava4 ,!re has be5 mu* diff]5ce ( op9ion z to ! imm$iate cause ( volcanic action1 b !re c be little d\bt t ! en]gy :i* is manife/$ 9 a volcanic eruption has be5 orig9ally d]iv$ 9 "s way f ! contraction ( ! primval nebula4 ,! extraord9>y vehem5ce t a volcanic eruption sometimes atta9s may be specially illu/rat$ by ! case ( ! great eruption ( ,krakatoa4 ,x is1 inde$1 believ$ t 9 ! annals ( our e>? !re has be5 no record ( a volcanic eruption s va/ z t :i* be>s ! "n ( ?is little isl& 9 f> ,ea/]n seas1 t5 ?\s& miles f our %ores4 ,until ! ye> #ahhc few _h ev] he>d ( ,krakatoa4 ,x 0 unkn[n to fame1 z are hundr$s ( o!r gems ( glori\s vegetation set 9 tropical wat]s4 ,x 0 n inhabit$1 b ! natives f ! surr\nd+ %ores ( ,sumatra & ,java us$ occasionally to draw _! canoes up on its bea*1 :ile !y roam$ ?r\gh ! jungle 9 se>* ( ! wild fruits t !re ab\nd$4 ,geograph]s 9 e>ly days h>dly condesc5d$ to notice ,krakatoa2 ! "n ( ! isl& on _! maps w\ld h be5 f> long] ?an ! isl& itself4 ,x 0 kn[n to ! m>9] :o navigat$ ! ,/raits ( ,sunda1 = x 0 m>k$ on 8 *>ts z "o ( ! p]ils ( ! intricate navigation 9 ^? wat]s4 ,x 0 no d\bt record$ t ! locality _h be5 once1 or m ?an once1 ! seat ( an active volcano4 ,9 fact1 ! isl& seem$ to owe its exi/5ce to "s frightful eruption ( bygone days2 b = a c\ple ( c5turies !re _h be5 no fre% outbreak4 ,x almo/ seem$ z if ,krakatoa might be reg>d$ z a volcano t _h become ext9ct4 ,9 ?is respect x w\ld only be l _m o!r simil> objects all ov] ! globe1 or ! c\ntless ext9ct volcanoes all ov] ! moon4 ,9 #ahhc ,krakatoa sudd5ly sprang into notoriety4 ,insignificant ?\gh x _h hi!rto seem$1 ! little isl& 0 soon to compel by its tones ( ?und] ! :ole _w to pay x in/ant att5tion4 ,x 0 to become ! sc5e ( a volcanic outbreak s appall+ t x is de/9$ to be rememb]$ ?r\gh\t ! ages4 ,9 ! spr+ ( t ye> !re 7 symptoms t ! volcanic p[]s 9 ,krakatoa 7 once m ab\t to awake f ! slumb] t _h endur$ = _m g5]ations4 ,notable w>n+s 7 giv54 ,e>?quakes 7 felt1 & deep rumbl+s proce$$ f ! e>?1 %[+ t "s di/urbance 0 9 prep>ation1 & t ! old volcano 0 aga9 to bur/ =? aft] its long p]iod ( re/4 ,at fir/ ! eruption did n ?reat5 to be ( any s]i\s type2 9 fact1 ! good p ( ,batavia1 s f> f be+ t]rifi$ at :at 0 9 progress 9 ,krakatoa1 ?\ght ! display 0 su* an attraction t !y *>t]$ a /eam] & w5t =? = a pleasant picnic to ! isl&4 ,_m ( u1 ,i am sure1 w\ld h be5 delight$ to h be5 able to jo9 ! p>ty :o 7 to witness s int]e/+ a spectacle4 ,) cauti\s /eps ! m v5turesome ( ! excursion p>ty clamb]$ up ! sides ( ! volcano1 guid$ by ! s\nds :i* 7 issu+ f its summit4 ,!re !y beheld a va/ column ( /eam p\r+ =? ) t]rific noise f a pr(\nd op5+ ab\t ?irty y>ds 9 wid?4 ,z ! summ] ( ?is dread ye> advanc$ ! vig\r ( ,krakatoa /eadily increas$1 ! noises became m & m vehem5t2 ^! 7 pres5tly audible on %ores t5 miles di/ant1 & !n tw5ty miles di/ant2 & /ill ^? noises wax$ l\d] & l\d]1 until ! great ?und]s ( ! volcano1 n[ s rapidly develop+1 a/oni%$ ! inhabitants t dwelt ov] an area at lea/ z l>ge z ,great ,brita94 ,& !re 7 o!r symptoms ( ! approa*+ cata/rophe4 ,) ea* successive convulsion a quantity ( f9e du/ 0 project$ al(t into ! cl\ds4 ,! w9d c\ld n c>ry ?is du/ away z rapidly z x 0 hurl$ upw>ds by ,krakatoa1 & accord+ly ! atmosph]e became heavily *>g$ ) susp5d$ p>ticles4 ,a pall ( d>kness ?us hung ov] ! adjo9+ seas & isl&s4 ,su* 0 ! ?ickness & ! d5sity ( ^! atmosph]ic volumes ( ,krakatoa du/ t1 = a hundr$ miles ar\nd1 ! d>kness ( midnight prevail$ at midday4 ,!n ! awful trag$y ( ,krakatoa took place4 ,_m ?\s&s ( ! un=tunate inhabitants ( ! adjac5t %ores ( ,sumatra & ,java 7 de/9$ nev] to behold ! sun aga94 ,!y 7 pres5tly swept away to de/ruction 9 an invasion ( ! %ore by ! trem5d\s waves ) :i* ! seas surr\nd+ ,krakatoa 7 agitat$4 ,gradually ! developm5t ( ! volcanic en]gy proce$$1 & gradually ! t]ror ( ! inhabitants ( ! surr\nd+ coa/s rose to a climax4 ,july _h end$ be=e ! manife/ations ( ,krakatoa _h atta9$ _! full viol5ce4 ,z ! days ( ,augu/ pass$ by ! spasms ( ,krakatoa wax$ m & m vehem5t4 ,by ! middle ( t mon? ! panic 0 widespread1 = ! supreme cata/rophe 0 at h&4 ,illu/ration3 ,fig4 #bf4--,,%[+ ,,coa/s ,,invad$ ,,by ,,! ,,great ,,sea-,,waves ,,f ,,krakatoa4 7,f ! ,royal ,society's ,reports47 ,on ! night ( ,sunday1 ,augu/ #bf?1 #ahhc1 ! blackness ( ! du/-cl\ds1 n[ mu* ?ick] ?an ev] 9 ! ,/raits ( ,sunda & adjac5t p>ts ( ,sumatra & ,java1 0 only occasionally illum9$ by lurid fla%es f ! volcano4 ,! ,krakatoan ?und]s 7 on ! po9t ( atta9+ _! complete developm5t4 ,at ! t[n ( ,batavia1 a hundr$ miles di/ant1 !re 0 no quiet t night4 ,! h\ses trembl$ ) ! subt]ranean viol5ce1 & ! w9d[s rattl$ z if heavy artill]y 7 be+ dis*>g$ 9 ! /reets4 ,& /ill ^! ef=ts seem$ to be only rehe>s+ = ! supreme display4 ,by t5 o'clock on ! morn+ ( ,monday1 ,augu/ #bg?1 #ahhc1 ! rehe>sals 7 ov] & ! p]=mance began4 ,an ov]ture1 consi/+ ( two or ?ree introductory explosions1 0 succe$$ by a frightful convulsion :i* tore away a l>ge "p ( ! isl& ( ,krakatoa & scatt]$ x to ! w9ds ( heav54 ,9 t f9al ef=t all records ( previ\s explosions on ?is e>? 7 completely brok54 ,?is supreme ef=t x 0 :i* produc$ ! mightie/ noise t1 s f> z we c asc]ta91 has ev] be5 he>d on ?is globe4 ,x mu/ h be5 inde$ a l\d noise :i* c\ld travel f ,krakatoa to ,batavia & pres]ve its vehem5ce ov] s great a di/ance2 b we %\ld =m a v inadequate conception ( ! en]gy ( ! eruption ( ,krakatoa if we ?\ght t its s\nds 7 he>d by ^? m]ely a hundr$ miles (f4 ,?is w\ld be little inde$ comp>$ ) :at is record$1 on te/imony :i* x is impossible to d\bt4 ,illu/ration3 ,,! ,,e>ly ,,/age ,,( ,,! ,,eruption ,,( ,,krakatoa4 7,f a ,photograph tak5 on ,may #bg?1 #ahhc47 ,we/w>d f ,krakatoa /ret*es ! wide expanse ( ! ,indian ,ocean4 ,on ! opposite side f ! ,/raits ( ,sunda lies ! isl& ( ,rodriguez1 ! di/ance f ,krakatoa be+ almo/ ?ree ?\s& miles4 ,x has be5 prov$ by evid5ce :i* _c be d\bt$ t ! boom+ ( ! great volcano attract$ ! att5tion ( an intellig5t coa/gu>d on ,rodriguez1 :o c>efully not$ ! "* ( ! s\nds & ! "t ( _! occurr5ce4 ,he _h he>d !m j f\r h\rs aft] ! actual explosion1 = ?is is ! "t ! s\nd occupi$ on its j\rney4 ,we %all bett] realise ! extraord9>y vehem5ce ( ?is trem5d\s noise if we imag9e a simil> ev5t to take place 9 localities m kn[n to mo/ ( u ?an are ! f> ,ea/]n seas4 ,if ,vesuvius 7 vigor\s en\gh to ?und] =? l ,krakatoa1 h[ great w\ld be ! con/]nation ( ! _w6 ,su* a report might be he>d by ,k+ ,edw>d at ,w9dsor1 & by ! ,cz> ( all ! ,russias at ,mosc[4 ,x w\ld a/oni% ! ,g]man ,emp]or & all 8 subjects4 ,x w\ld p5etrate to ! seclusion ( ! ,sultan at ,con/ant9ople4 ,nans5 w\ld /ill h be5 )9 its rea* :5 he 0 fur!/ nor?1 ne> ! ,pole4 ,x w\ld h ext5d$ to ! s\rces ( ! ,nile1 ne> ! ,equator4 ,x w\ld h be5 he>d by ,mohamm$an pilgrims at ,mecca4 ,x w\ld h rea*$ ! e>s ( exiles 9 ,sib]ia4 ,no inhabitant ( ,p]sia w\ld h be5 beyond its range1 :ile pass5g]s on half ! l9]s cross+ ! ,atlantic w\ld also cat* ! mighty rev]b]ation4 ,! subject is ( su* exceptional int]e/ t ,i may v5ture on ano!r illu/ration4 ,let u suppose t a simil> e>?-%ak+ ev5t took place 9 a c5tral position 9 ! ,unit$ ,/ates4 ,let u say1 = example1 t an explosion occurr$ at ,pike's ,peak z resonant z t f ,krakatoa4 ,x w\ld c]ta9ly />tle n a little ! inhabitants ( ,colorado f> & wide4 ,! e>s ( dwell]s 9 ! neighb\r+ ,/ates w\ld receive a consid]able %ock4 ,) less5+ int5sity ! s\nd w\ld spread mu* fur!r ar\nd--inde$1 x might be he>d all ov] ! ,unit$ ,/ates4 ,! sonor\s waves w\ld roll ov] to ! ,atlantic coa/1 !y w\ld be he>d on ! %ores ( ! ,pacific4 ,florida w\ld n be too f> to ! s\?1 nor ,alaska too remote to ! nor?4 ,if1 inde$1 we c\ld believe t ! s\nd w\ld travel z freely ov] ! great cont95t z x did across ! ,indian ,ocean1 !n we may boldly ass]t t e e> 9 ,nor? ,am]ica might li/5 to ! ?und] f ,pike's ,peak1 if x rivall$ ,krakatoa4 ,! rev]b]ation might ev5 be audible by sk9-clad ,eskimos amid ! sn[s ( ,gre5l&1 & by nak$ ,indians swelt]+ on ! ,or9oco4 ,c we d\bt t ,krakatoa made ! greate/ noise t has ev] be5 record$8 ,illu/ration3 ,fig4 #bg4--,,spread ,,( ,,! ,,air-,,wave ,,f ,,krakatoa ,,to ,,! ,,antipodes4 7,f ! ,royal ,society's ,reports47 ,among ! _m o!r incid5ts connect$ ) ?is explosion1 ,i may specially m5tion ! wond]ful sy/em ( div]g5t ripples t />t$ 9 our atmosph]e f ! po9t at :i* ! eruption took place4 ,i h call$ !m ripples1 f ! obvi\s resemblance :i* !y be> to ! circul> exp&+ ripples produc$ by ra9drops :i* fall ^u ! /ill surface ( wat]4 ,b x w\ld be m correct to say t ^! objects 7 a s]ies ( great undulations :i* />t$ f ,krakatoa & spread =? 9 ev]-enl>g+ circles ?r\gh our atmosph]e4 ,! initial impetus 0 s trem5d\s t ^! waves spread = hundr$s & ?\s&s ( miles4 ,!y div]g$1 9 fact1 until !y put a mighty girdle r\nd ! e>?1 on a great circle ( :i* ,krakatoa 0 ! pole4 ,! atmosph]ic waves1 ) ! :ole e>? n[ well 9 _! grasp1 advanc$ into ! opposite hemisph]e4 ,9 _! fur!r progress !y _h necess>ily to =m gradually contract+ circles1 until at la/ !y conv]g$ to a po9t 9 ,c5tral ,am]ica1 at ! v opposite po9t ( ! diamet] ( our e>?1 eight ?\s& miles f ,krakatoa4 ,?us ! waves completely embrac$ ! e>?4 ,e "p ( our atmosph]e _h be5 set into a t+le by ! great eruption4 ,9 ,great ,brita9 ! waves pass$ ov] our heads1 ! air 9 our /reets1 ! air 9 our h\ses1 trembl$ f ! volcanic impulse4 ,! v oxyg5 supply+ our lungs 0 respond+ also to ! supreme convulsion :i* took place t5 ?\s& miles away4 ,x is ne$less to object t ?is c\ld n h tak5 place because we did n feel x4 ,self-regi/]+ b>omet]s h enabl$ ^! waves to be foll[$ unmi/akably all ov] ! globe4 ,su* 0 ! en]gy ) :i* ^! vibrations 7 initiat$ at ,krakatoa1 t ev5 :5 ! waves ?us aris+ _h conv]g$ to ! po9t diametrically opposite 9 ,s\? ,am]ica _! vig\r 0 n yet exhau/$4 ,! waves 7 !n1 /range to say1 reflect$ back f _! po9t ( conv]g5ce to retrace _! /eps to ,krakatoa4 ,/>t+ f ,c5tral ,am]ica1 !y aga9 describ$ a s]ies ( enl>g+ circles1 until !y embrac$ ! :ole e>?4 ,!n1 advanc+ into ! opposite hemisph]e1 !y gradually contract$ until !y _h rega9$ ! ,/raits ( ,sunda1 f :i* !y _h set =? ab\t ?irty-six h\rs previ\sly4 ,"h 01 inde$1 a unique exp]i5ce4 ,! air-waves _h twice gone f end to end ( ?is globe ( ours4 ,ev5 !n ! atmosph]e did n subside until1 aft] "s m oscillations ( gradually fad+ int5sity1 at la/ !y became evanesc5t4 ,b1 besides ^! ph5om5al undulations1 ?is mighty incid5t at ,krakatoa has taught u o!r lessons on ! con/itution ( our atmosph]e4 ,we previ\sly knew little1 or ,i might almo/ say no?+1 z to ! conditions prevail+ above ! height ( t5 miles ov]head4 ,we 7 almo/ altoge!r ignorant ( :at ! w9d might be at an altitude (1 let u say1 tw5ty miles4 ,x 0 ,krakatoa :i* fir/ gave u a little in=mation :i* 0 greatly want$4 ,h[ c\ld we le>n :at w9ds 7 bl[+ at a height f\r times z great z ! l(tie/ m\nta9 on ! e>?1 & twice z great z ! l(tie/ altitude to :i* a balloon has ev] so>$8 ,we c\ld nei!r see ^! w9ds nor feel !m4 ,h[1 !n1 c\ld we le>n :e!r !y really exi/$8 ,no d\bt a /raw w %[ ! way ! w9d bl[s1 b !re are no /raws up !re4 ,!re 0 no?+ to r5d] ! w9ds p]ceptible until ,krakatoa came to our aid4 ,krakatoa drove into ^? w9ds prodigi\s quantities ( du/4 ,hundr$s ( cubic miles ( air 7 ?us depriv$ ( t invisibility :i* !y _h hi!rto ma9ta9$4 ,!y 7 ?us compell$ to disclose ^? movem5ts ab\t :i*1 nei!r be=e nor s9ce1 h we _h any opportunity ( le>n+4 ,) eyes full ( a/oni%m5t m5 wat*$ ^? va/ volumes ( ,krakatoa du/ />t on a trem5d\s j\rney4 ,we/w>d ! du/ ( ,krakatoa took its way4 ,( c\rse1 ev]yone kn[s ! s-call$ tradew9ds on our e>?'s surface1 :i* bl[ /eadily 9 fix$ directions1 & :i* are ( su* s]vice to ! m>9]4 ,b !re is yet ano!r con/ant w9d4 ,we _c call x a trade-w9d1 = x nev] has r5d]$1 & nev] w r5d]1 any s]vice to navigation4 ,x 0 fir/ disclos$ by ,krakatoa4 ,be=e ! occurr5ce ( t eruption no "o _h ! slighte/ suspicion t f> up al(t1 tw5ty miles ov] our heads1 a mighty tempe/ is incessantly hurry+ ) a spe$ mu* great] ?an t ( ! awful hurricane :i* once laid s l>ge a "p ( ,calcutta on ! gr\nd1 & slew s _m ( its inhabitants4 ,=tunately = humanity1 ?is new trade-w9d does n come )9 less ?an tw5ty miles ( ! e>?'s surface4 ,we are ?us pres]v$ f ! fe>ful de/ruction t its un9t]mitt5t bla/s w\ld produce1 bla/s aga9/ :i* no tree c\ld /&1 & :i* w\ld1 9 t5 m9utes1 d z mu* damage to a city z w\ld ! mo/ viol5t e>?quake4 ,:5 ?is great w9d _h become *>g$ ) ! du/ ( ,krakatoa1 !n1 = ! fir/ &1 ,i may add1 = ! only "t1 x /ood reveal$ to human vision4 ,!n x 0 se5 t ?is w9d circl$ r\nd ! e>? 9 ! vic9ity ( ! ,equator1 & complet$ its circuit 9 ab\t ?irte5 days4 ,please obs]ve ! contra/ betwe5 ?is w9d ( :i* we are n[ speak+ & ! waves to :i* we h j ref]r$4 ,! waves 7 m]ely undulations or vibrations produc$ by ! bl[ :i* our atmosph]e receiv$ f ! explosion ( ,krakatoa1 & ^! waves 7 propagat$ ?r\gh ! atmosph]e mu* 9 ! same way z s\nd waves are propagat$4 ,inde$1 ^! waves mov$ ) ! same velocity z s\nd4 ,b ! curr5t ( air ( :i* we are n[ speak+ 0 n produc$ by ,krakatoa2 x exi/$ f all "t1 be=e ,krakatoa 0 ev] he>d (1 & x exi/s at ! pres5t mom5t1 & w d\btless exi/ z long z ! e>?'s meteorological arrangem5ts rema9 z !y are at pres5t4 ,all t ,krakatoa did 0 simply to provide ! *>ges ( du/ by :i* = "o brief p]iod ?is w9d 0 made visible4 ,9 ! autumn ( #ahhc ! newspap]s 7 full ( acc\nts ( /range appe>ances 9 ! heav5s4 ,! lett]s conta9+ ^! acc\nts p\r$ 9 ^u u f resid5ts 9 ,ceylon2 !y came f resid5ts 9 ! ,we/ ,indies1 & f o!r tropical places4 ,all _h ! same tale to tell4 ,sometimes exp]i5c$ obs]v]s assur$ u t ! sun look$ blue2 sometimes we 7 told ( ! amazem5t ) :i* p beheld ! moon drap$ 9 vivid gre54 ,o!r acc\nts told ( curi\s halos1 &1 9 %ort1 ( ! signs 9 ! sun1 ! moon1 & ! />s1 :i* 7 exce$+ly unusual1 ev5 if we d n say t !y 7 absolutely unprec$5t$4 ,^? :o wrote to tell ( ! /range hues t ! sun manife/$ to travell]s 9 ,ceylon1 or to plant]s 9 ,jamaica1 nev] dreamt ( attribut+ ! ph5om5a to ,krakatoa1 _m ?\s&s ( miles away4 ,9 fact1 ^! obs]v]s knew no?+ at ! "t ( ! ,krakatoa eruption1 & probably few ( !m1 if any1 _h ev] he>d t su* a place exi/$4 ,x 0 only gradually t ! belief grew t ^!1 ph5om5a 7 due to ,krakatoa4 ,b :5 ! acc\nts 7 c>efully comp>$1 & :5 ! dates 7 /udi$ at :i* ! ph5om5a 7 witness$ 9 ! v>i\s localities1 x 0 demon/rat$ t ^! ph5om5a1 not)/&+ _! worldwide di/ribution1 _h c]ta9ly aris5 f ! eruption 9 ?is little isl& 9 ! ,/raits ( ,sunda4 ,x 0 mo/ assur$ly ,krakatoa t pa9t$ ! sun & ! moon1 & produc$ ! o!r /range & weird ph5om5a 9 ! tropics4 ,aft] a little "t we le>n$ :at _h actually happ5$4 ,! du/ manufactur$ by ! supreme convulsion 0 :irl$ r\nd ! e>? 9 ! mighty atmosph]ic curr5t into :i* ! volcano dis*>g$ x4 ,z ! du/-cl\d 0 swept along by ?is incomp>able hurricane1 x %[$ its pres5ce 9 ! mo/ glori\s mann] by deck+ ! sun & ! moon 9 hues ( unaccu/om$ spl5d\r & beauty4 ,! blue col\r 9 ! sky "u ord9>y circum/ances is due to p>ticles 9 ! air1 & :5 ! ord9>y motes ( ! sunbeam 7 re9=c$ by ! introduction ( ! myriads ( motes produc$ by ,krakatoa1 ev5 ! sun itself sometimes %[$ a blue t9t4 ,?us ! progress ( ! great du/-cl\d 0 trac$ out by ! extraord9>y sky effects x produc$1 & f ! progress ( ! du/-cl\d we inf]r$ ! movem5ts ( ! invisible air curr5t :i* c>ri$ x along4 ,nor ne$ x be ?\ght t ! quantity ( mat]ial project$ f ,krakatoa %\ld h be5 inadequate to produce effects ( ?is worldwide description4 ,imag9e t ! mat]ial :i* 0 bl[n to ! w9ds ( heav5 by ! supreme convulsion ( ,krakatoa c\ld be all recov]$ & swept into "o va/ heap4 ,imag9e t ! heap 7 to h its bulk measur$ by a vessel consi/+ ( a cube "o mile long1 "o mile broad1 & "o mile deep2 x has be5 e/imat$ t ev5 ?is prodigi\s vessel w\ld h to be fill$ to ! brim at lea/ t5 times be=e all ! products ( ,krakatoa _h be5 measur$4 ,x 0 9 ! late autumn ( #ahhc t ! m>vell\s s]ies ( cele/ial ph5om5a connect$ ) ! great eruption began to be display$ 9 ,great ,brita94 ,!n x 0 t ! glory ( ! ord9>y sunsets 0 enhanc$ by a spl5d\r :i* has dwelt 9 ! memory ( all ^? :o 7 p]mitt$ to see !m4 ,! frontispiece ( ?is volume conta9s a view ( ! sunset z se5 at ,*elsea at #d4dj p4m4 on ,novemb] #bf?1 #ahhc4 ,! picture 0 pa9t$ f nature by ,mr4 ,w4 ,ascr(t1 & is giv5 9 ! great "w on ,krakatoa :i* 0 publi%$ by ! ,royal ,society4 ,!re is n ! lea/ d\bt t x 0 ! du/ f ,krakatoa :i* produc$ ! beauty ( ^? sunsets1 & s long z t du/ rema9$ susp5d$ 9 our atmosph]e1 s long 7 /range signs to be witness$ 9 ! heav5ly bodies4 ,b ! du/ :i* _h be5 borne ) unp>allel$ viol5ce f ! int]ior ( ! volcano1 ! du/ :i* _h be5 %ot al(t by ! vehem5ce ( ! eruption to an altitude ( tw5ty miles1 ! du/ :i* _h ?us be5 :irl$ r\nd & r\nd our e>? = p]haps a doz5 times or m 9 ?is air curr5t1 :i* c>ri$ x r\nd 9 less ?an a =tnight1 0 end[$ ) no p[] to resi/ = ev] ! law ( gravitation :i* bids x fall to ! e>?4 ,x !re=e gradually sank d[nw>ds4 ,ow+1 h[ev]1 to ! great height to :i* x _h be5 driv51 ow+ to ! impetu\s nature ( ! curr5t by :i* x 0 hurri$ along1 & ow+ to ! exce$+ly m9ute p>ticles ( :i* x 0 compos$1 ! act ( s9k+ 0 greatly protract$4 ,n until two ye>s aft] ! orig9al explosion _h all ! p>ticles ) :i* ! air 0 *>g$ by ! great eruption f9ally subsid$ on ! e>?4 ,at fir/ !re 7 "s :o refus$ to believe t ! glory ( ! sunsets 9 ,london c\ld possibly be due to a volcano 9 ! ,/raits ( ,sunda1 at a di/ance f ,engl& :i* 0 b little %ort ( t ( ,au/ralia4 ,b ! gorge\s ph5om5a 9 ,engl& 7 f\nd to be simultane\s ) l ph5om5a 9 o!r places all r\nd ! e>?4 ,once aga9 ! comp>ison ( dates & o!r circum/ances prov$ t ,krakatoa 0 ! cause ( ^! exceptional & mo/ int]e/+ appe>ances4 ,nor 0 ! incid5t )\t a hi/orical p>allel1 = has n ,t5nyson told u ( ! call to ,/4 ,telema*us-- 8,_h ! fi]ce a%es ( "s fi]y peak ,be5 hurl'd s high !y rang$ ab\t ! globe8 ,= day by day1 ?ro' _m a blood-r$ eve1 ,9 t f\r-hundr$? summ] aft] ,*ri/1 ,! wra?ful sunset gl>$44440 ---------------------------------------- -------------------------------- ,,*apt] ,x4 ,,spiral ,,& ,,planet>y ,,nebul4 ,a ,sub/itute = ,hi/ory--,photograph ( ! ,great ,spiral tak5 at ! ,lick ,obs]vatory--,sol> ,sy/em ,relations ,unimportant--,*aotic ,nebul--,"l ,rosse's ,great ,discov]y--,dr4 ,rob]ts' ,photographs--,! ,a/oni%+ ,discov]y ( ,pr(essor ,keel]--,! ,p]spective ( ! ,spirals--,! ,spiral ,nebul are n ,gase\s--,! ,spiral is a ,nebula 9 an advanc$ ,/age ( ,developm5t--,"* ( ! ,great ,nebula 9 ,&rom$a4 ,,9 a great college 9 ,am]ica a new educational exp]im5t has be5 tri$ ) "s success4 ,in/ead ( ! in/ruction 9 hi/ory :i* /ud5ts receive 9 mo/ o!r in/itutions1 an attempt has be5 made 9 ?is college to give in/ruction 9 a v diff]5t mann]1 :i* x is believ$ w n be ( less educational value ?an ! m ord9>y processes ( tea*+4 ,9 ! c\rse ( /udy to :i* ,i am n[ ref]r+ ! /ud5t is invit$ to consid]1 n s mu* ! hi/ory ( ! developm5t ( ! ,con/itution ( "o p>ticul> c\ntry1 z to make a broad survey ( ! diff]5t ,con/itutions "u :i* ! sev]al c\ntries ( ! _w are at ?is mom5t gov]n$4 ,! promot]s ( ?is s*eme believe t _m ( ! intellectual advantages :i* are ord9>ily expect$ to be ga9$ by ! /udy ( ! hi/ory ( "o c\ntry may be secur$ equally well by /udy+ only exi/+ conditions1 provid$ t att5tion is giv5 to sev]al c\ntries :i* h arriv$ at diff]5t /ages ( civilisation4 ,)\t attempt+ to say h[ f> ! /udy ( ! exi/+ ,con/itutions ( ,france & ,g]many1 ,am]ica & ,au/ralia1 ,turkey & ,india1 ,morocco & ,fiji1 might be ju/ly us$ to sup]s$e ! /udy ( ,engli% hi/ory1 x may at lea/ be urg$ t if we _h no annals f :i* hi/ory c\ld be compil$ x might be in/ructive to employ su* a sub/itute = hi/orical /udies z is "h sugge/$4 ,?is is1 inde$1 ! c\rse :i* we are compell$ to take 9 our /udy ( t great *apt] 9 e>?-hi/ory :i* we are discuss+ 9 ^! pages4 ,x is obvi\s f ! nature ( ! case t x c nev] be possible = u to obta9 direct te/imony z to :at occurr$ 9 ! br++ toge!r ( ! mat]ials ( ?is globe4 ,we mu/1 !re=e1 look abroad ?r\gh ! univ]se1 & see :e!r we c f9d1 f ! /udy ( o!r sy/ems at pres5t 9 v>i\s /ages ( _! evolution1 illu/rations ( ! incid5ts :i* we may presume to h occurr$ 9 ! e>ly /ages ( our own hi/ory4 ,if ,kant _h nev] liv$1 if ,laplace _h nev] ann\nc$ 8 ,nebul> ,!ory1 if ! discov]ies ( ,sir ,william ,h]s*el _h n be5 made1 ,i /ill v5ture to ?9k t a due consid]ation ( ! rem>kable photograph ( ! fam\s ,great ,spiral1 :i* 0 obta9$ at ! fam\s ,lick ,obs]vatory 9 ,cali=nia1 w\ld h sugge/$ ! high probability ( t doctr9e :i* we describe z ! ,nebul> ,!ory4 ,illu/ration3 ,fig4 #bh4--,,! ,,great ,,spiral ,,nebula 7,lick ,obs]vatory74 7,f ! ,royal ,a/ronomical ,s]ies47 ,if an arti/ ?or\ghly v]s$ 9 ! great facts ( a/ronomy _h be5 commission$ to repres5t ! nebul> orig9 ( our sy/em z p]fectly z a highly cultivat$ yet discipl9$ imag9ation w\ld p]mit1 ,i d n ?9k he c\ld h design$ any?+ :i* c\ld answ] ! purpose m p]fectly ?an does t picture :i* is n[ be=e u4 ,we might wi% inde$ t ,kant & ,laplace & ,h]s*el c\ld h liv$ to see ?is m>vell\s natural illu/ration ( _! views1 = photographs 7 ( c\rse un?\ght ( 9 ^? days1 &1 ,i ne$ h>dly say1 t = any "o cele/ial nebula t c\ld h be5 kn[n 9 ! times ( ,laplace1 hundr$s are n[ )9 ! rea* ( a/ronom]s4 ,we entreat special att5tion to ?is picture :i* ,nature has h]self giv5 u1 & :i* repres5ts :at we may n unreasonably conclude to be a sy/em 9 a /ate ( =mation4 ,let me say at once t our sol> sy/em1 h[ev] impos+ x may be f our po9t ( view1 is b ( inf9itesimal importance z comp>$ ) ! sy/em :i* is "h 9 ! c\rse ( developm5t4 ,x is sometimes urg$ t x is difficult to imag9e h[ a sy/em s l>ge z ours c\ld h be5 produc$ by cond5sation f a primval nebula4 ,! be/ answ] is f\nd 9 ! fact t ! ,great ,spiral n[ be=e u may be consid]$ to exhibit at ?is v mom5t a sy/em 9 actual evolution1 ! c5tral body ( :i* is c]ta9ly ?\s&s ( times1 & n improbably millions ( times1 great] ?an ! sun1 & ( :i* ! att5d+ planets or o!r revolv+ bodies1 are fram$ on a scale imm5sely transc5d+ t ( ev5 ,jupit] himself4 ,! details ( ?is rem>kable nebula seem to illu/rate ^? p>ticul> features :i* _h be5 previ\sly assign$ to ! primval nebula ( our sy/em1 long be=e any photograph 0 available = ! purpose ( _! /udy4 ,9 ! ,great ,nebula 9 ,orion1 to :i* we h already ref]r$1 z well z 9 _m o!r simil> objects :i* we might also h adduc$1 ! nebul\s mat]ial f :i* aft] long ages new sy/ems may be ! result1 0 %[n 9 an extremely *aotic /ate4 ,x 0 little m ?an an irregul> /a9 ( light on ! sky4 ,b 9 ! picture ( ! ,great ,spiral :i* is be=e u 7,fig4 #bh7 x is manife/ t ! evolution ( ! sy/em has rea*$ an advanc$ /age2 su* consid]able progress has be5 made 9 ! actual =mation t ! f9al =m seems to be %ad[$ =?4 ,! lum9osity is no long] diffus$ 9 a *aotic condition2 x has =m$ into spirals1 & become mu* cond5s$ at ! c5tre & some:at cond5s$ 9 o!r regions4 ,z we n[ see x1 ! object seems to repres5t a sy/em mu* m advanc$ 9 its =mation ?an any ( ! o!r great nebul ) :i* we h comp>$ x4 ,9 comp>ison ) x ! evolution ( su* an object z ! ,great ,nebula 9 ,orion c h>dly be said to h begun4 ,b 9 ! ,great ,spiral _m portions ( ! nebula h already become outl9$ into masses :i*1 ?\gh /ill f> f resembl+ ! planets 9 ! sol> sy/em1 h at lea/ made "s approa* !reto :ile ! c5tral portions are be+ drawn toge!r1 j z we may conceive ! great primval fire-mi/ to h drawn toge!r 9 ! actual =mation ( ! sun4 ,! fam\s nebula :i* we are discuss+1 & :i* is g5]ally kn[n z ! ,great ,spiral1 is f\nd 9 ! con/ellation ( ,canes ,v5atici1 v ne> ! end /> 9 ! tail ( ! ,great ,be>1 & "o-f\r? ( ! way f x to ,cor ,c>oli4 ,x w be easy to f9d x f ! indication giv5 9 ! adjo9+ ,fig4 #bi4 ,z a nebul\s spot x is an object :i* c be se5 ) any mod]ately good telescope1 b to detect ^? details :i* indicate ! spiral /ructure dem&s an in/rum5t ( fir/-class p[]4 ,?is object _h inde$ be5 /udi$ by _m a/ronom]s be=e ,"l ,rosse turn$ 8 colossal reflector ^u x4 ,!n x 0 t ! wond]ful :irlpool /ructure 0 fir/ discov]$1 & ?us ! e>lie/ spiral nebula became kn[n4 ,illu/ration3 ,fig4 #bi4--;,,h[ ,,to ,,f9d ,,! ,,great ,,spiral ,,nebula4 ,9 ^? days !re 7 few telescopes ( great p[]1 & none ( ^? in/rum5ts appe>$ able to deal ) ?is nebula suffici5tly to reveal its spiral "*4 ,! ann\ncem5t ( ! discov]y ( ! spiral con/itution ( ?is object 0 !re=e receiv$ ) incr$ulity by "s a/ronom]s1 :o believ$1 or pr(ess$ to believe1 t ! spiral l9es ( nebul\s matt] :i* ,"l ,rosse describ$ s fai?fully1 exi/$ only 9 ! imag9ation ( ! a/ronom]4 ,inde$1 9 "o notable in/ance1 x 0 alleg$ t ^! features 7 to be attribut$ to actual imp]fections 9 ! unrivall$ telescope4 ,! incr$ulity widely preval5t 9 ! middle ( ! la/ c5tury ab\t ! exi/5ce ( ! spiral nebul may be p>allel$ by ! incr$ulity ab\t o!r discov]ies 9 m rec5t ye>s4 ,:5 a highly skill$ obs]v]1 us+ an in/rum5t ( adequate p[]1 &1 x may be1 enjoy+ unequall$ opportunities = good "w1 te/ifies to c]ta9 discov]ies2 :5 he has employ$ 9 ! v]ification ( 8 obs]vations ! skill & exp]i5ce t ye>s ( practice h procur$ = him1 x is futile = ^? :o h n ! l opportunities1 ei!r f ! want ( in/rum5ts ( adequate p[] or f climatic difficulties1 to d5y ! tru? ( discov]ies because !y are n able to v]ify !m4 ,x 0 absurd = a/ronom]s to refuse ass5t to ! great discov]ies ( ,"l ,rosse simply because in/rum5ts inf]ior to 8 w\ld n %[ ! spiral /ructure4 ,9 due "t1 "o a/ronom] aft] ano!r began to admit t possibly ! rem>kable =m :i* ,"l ,rosse ann\nc$ z *>act]i/ic ( "s nebul might n be a m]e figm5t ( ! imag9ation4 ,! complete v9dication ( ,"l ,rosse's great discov]y 0 n1 h[ev]1 atta9$ until t wond]ful advance 9 ! arts ( a/ronomy :5 ! photographic plate 0 call$ 9 to supplem5t1 or r va/ly to ext5d1 ! p[]s ( ! eye4 ,dr4 ,isaac ,rob]ts n only %[$ by a magnific5t photograph t ! ,great ,spiral discov]$ by ,"l ,rosse 0 j z ,"l ,rosse _h describ$ x1 he n only %[$ t ! o!r spirals ann\nc$ by ,"l ,rosse 7 equally entitl$ to ! "n1 b1 ) ! newly acquir$ p[]s t ! photographic plate plac$ at 8 disposal1 he 0 able to %[ t _m o!r nebul1 :i* _h be5 frequ5tly obs]v$ & _h ev5 be5 sket*$1 possess$ fur!r features too fa9t & delicate to be se5 by any human eye1 ev5 ) ! help ( ! mo/ p[]ful telescope4 ,^! fur!r features 7 discov]$ because !y came )9 ! k5 ( ! int5sely acute p]ception ( ! photographic plate4 ,on ! plate ^! features :i* ! cam]a %[$1 7 add$ to ^? :i* ! eye _h already p]ceiv$1 & :5 ^! additions 7 made x 0 n infrequ5tly f\nd t ! nebula assum$ ! =m ( a spiral4 ,b ! mo/ rem>kable circum/ance has /ill to be add$4 ,"s ( ! plates expos$ by ,dr4 ,rob]ts %[ cle> & unmi/akable photographs ( spiral nebul z exquisite 9 detail z ! ,great ,spiral itself1 b yet s fa9t t !y h nev] be5 se5 by ! eye 9 any telescope :atev]1 ?\gh !y c\ld n elude ! photographic plate4 ,?us1 ,dr4 ,rob]ts n only confirm$ 9 ! mo/ spl5did mann] t really great discov]y ( ! spiral nebul ( :i* ! hon\r belongs to ,"l ,rosse1 b ! em95t photographic a/ronom] add$ _m o!r spirals ( ! greate/ int]e/ to ! li/ ( ^? objects :i* ,"l ,rosse _h himself giv54 ,?\gh ^! discov]ies plac$ ! fact ( ! exi/5ce ( spiral nebul 9 an impregnable position1 & ?\gh !y greatly increas$ ! int]e/ ) :i* a/ronom]s /udy su* objects1 yet ano!r /op _h to be tak5 be=e ! spiral nebula atta9$ ! position ( extraord9>y importance z a cele/ial object :i* mu/ n[ be ackn[l$g$ to be its due4 ,illu/ration3 ,fig4 #cj4--;,a ,,gr\p ,,( ,,nebul 7,"l ,rosse74 7#cddj1 #cdde 9 n4g4c47 7,f ! ,sci5tific ,transactions ( ! ,royal ,dubl9 ,society47 ,we h already _h occasion 7page #fg7 to m5tion ! m>vell\s discov]ies ( nebul :i* ! lam5t$ ,pr(essor ,keel] made ) ! ,crossley ,reflector at ! ,lick ,obs]vatory4 ,we h expla9$ t 8 discov]ies h %[n ! numb] ( nebul 9 ! heav5s to be probably at lea/ tw5ty times t :i* previ\s obs]vations w\ld h au?oris$ u 9 ass]t+4 ,! m]e ann\ncem5t t #abj1jjj new nebul 7 )9 ! rea* ( a photographic plate atta*$ to ! ,crossley ,reflector1 w\ld1 by itself1 h be5 a /atem5t s rem>kable z to comm& ! imm$iate att5tion ( ! sci5tific _w4 ,b ! int]e/ ( ev5 ?is /atem5t %r9ks to unimportance relatively to ! fur!r fact :i* ,pr(essor ,keel] has add$4 ,i d n "k1 9 ! annals ( a/ronomy1 a pron\ncem5t ( great] int]e/1 c]ta9ly none ( m importance = our pres5t purpose1 ?an ! /atem5t t ( ! #abj1jjj new nebul1 at lea/ half are spirals4 ,"h is inde$ a /up5d\s revolution 9 our k ( ! cele/ial objects4 ,fifty ye>s ago ,"l ,rosse ann\nc$ ! discov]y ( a spiral nebula1 & ! exi/5ce ( ?is spiral 0 d\bt$ at fir/1 ?\gh x 0 gradually conc$$ at la/4 ,n[ we h ! ann\ncem5t1 on ! un*all5g$ evid5ce ( ! photographic plate itself1 t to all appe>ances !re are at lea/ #fj1jjj spiral nebul 9 ! heav5s4 ,x is1 alas6 too true t ,pr(essor ,keel] did n live long en\gh to enum]ate all ^? nebul himself1 &1 inde$1 !y h n s f> be5 actually c\nt$1 b to ^? :o w /udy ,pr(essor ,keel]'s pap]s1 ! evid5ce ( ! sub/antial accuracy ( ! /atem5t is inconte/able4 ,illu/ration3 ,fig4 #ca4--;,a ,,ray ,,nebula 7,"l ,rosse74 7#cfbh 9 n4g4c47 7,f ! ,sci5tific ,transactions ( ! ,royal ,dubl9 ,society47 ,& a/oni%+ z ?is /atem5t may be1 we h /ill to add t1 9 face ( ! actual facts1 x may be reg>d$ z ev5 a mod]ate e/imate ( ! abundance ( spirals 9 ! univ]se4 ,we mu/ rememb] t a spiral nebula is a flat object ) long arms ext5d+ f x :i* lie ne>ly 9 ! same plane4 ,if we are actually to see t su* an object is spiral1 x is necess>y = x to be turn$ squ>ely t[>ds ! e>?4 ,if ! object be too mu* =e%ort5$1 x is q pla9 t we c h>dly expect to detect its spiral "*4 ,x is also obvi\s if ! spiral happ5s to be turn$ edgeways t[>ds u1 t !n its spiral =m _c be se52 x w\ld m]ely appe> z :at a/ronom]s (t5 call a ray4 ,9 ! enum]ation ( ! spirals x is !re=e only possible = u to include ^? :i* happ5 to be s f> squ>ely turn$ t[>ds ! e>? z to make _! spiral "* unmi/akable4 ,we might1 !re=e1 reasonably expect t ! numb]s ( spiral nebul actually c\nt$ w\ld fall %ort ( ! reality4 ,we "k t !re are _m nebul ( a some:at elliptical %ape 7,fig4 #ca74 ,!re are also _m nebul t look l long rays 7,fig4 #cj74 ,^? :o are famili> ) ! appe>ance ( nebul 9 great telescopes w recall at once ! num]\s sp9dle-%ap$ objects ( ?is class4 ,x c h>dly be d\bt$ t _m ( ! nebul1 m or less oval 9 =m1 & also ^! rays or ! sp9dle-%ap$ objects s frequ5tly se5 9 good telescopes 7,fig4 #cc7 are 9 reality spiral nebul1 :i* are turn$ n squ>ely t[>ds u1 b :i* we are m]ely look+ at m or less edgewise1 s t !y h be5 =e%ort5$ en\gh to hide _! peculi> /ructure 7,figs4 #cd1 #ce74 ,tak+ ^! consid]ations into acc\nt1 x becomes obvi\s t ! e/imate ( ,pr(essor ,keel] z to ! numb] ( spiral nebul 9 ! heav5s1 va/ z t e/imate seems1 may /ill fall %ort ( ! tru?4 ,?us we are l$ to "o ( ! mo/ rem>kable conclusions ( mod]n a/ronomy1 viz4 t ! spiral nebula1 next to a /> itself1 is ! mo/ *>act]i/ic object 9 ! sid]eal heav5s4 ,9 treat+ ( ! nebul 9 ,*apt] ,,iv4 we expla9$ ^? fundam5tal features ( ! diff]5t spectra :i* make x possible to discrim9ate ) confid5ce betwe5 a nebula :i* is purely gase\s & a nebula :i* _c be s describ$4 ,z ! spiral nebul =m a class *>act]is$ among all ! o!r nebul by ! possession ( a v p>ticul> /ructure1 x is int]e/+ to enquire :at evid5ce ! spectrum gives ) reg>d to ! nature ( ! mat]ial :i* ent]s into ! con/itution ( ! nebul :i* belong to ?is /rongly-m>k$ gr\p4 ,i d n mean to say t all ! #fj1jjj spirals h be5 exam9$ ) ! spectroscope1 b1 z already expla9$ on page #fg1 a suffici5t numb] h be5 exam9$ to decide ! "q4 ,we le>n f ,pr(essor ,s*e9]1 a well-kn[n au?ority on a/ronomical spectroscopy1 t ! spectra ( spirals are g5]ally f\nd to be cont9u\s2 9 o!r words1 we le>n t a spiral nebula is n gase\s4 ,x does n consi/1 l1 = example1 ! nebula 9 ,orion1 ( vapor\s matt] 9 a /ate ( inc&esc5ce4 ,a nebula or a nebul\s-look+ object :i* does n give a spectrum ( bright l9es1 b :i* does give a cont9u\s spectrum1 is n infrequ5tly set d[n z be+ m]ely a clu/] ( />s4 ,?is is und\bt$ly a true /atem5t ) reg>d to "s ( ^! nebul\s objects1 b x is n true ) reg>d to all4 ,x is mu* m reasonable to suppose t ! great] "p ( ! mat]ials ( ! spiral nebul1 ?\gh c]ta9ly n 9 ! =m ( gas1 are /ill n cond5s$ into objects l>ge en\gh to entitle !m to be call$ />s4 ,x mu/ be rememb]$ t :5 an object ( a gase\s nature has lo/ heat by radiation1 & has begun to draw itself toge!r1 ! gas cond5ses into p>ticles :i* con/itute small portions ( liquid or solid1 j z ! vap\r ( wat] 9 ! atmosph]e cond5ses into ! beads ( wat] t =m ! cl\ds 9 our own sky4 ,^! small objects1 ev5 if inc&esc5t1 w\ld no long] radiate light ) ! *>act]i/ics ( a gase\s nebula4 ,! light !y w\ld emit w\ld be ( ! same "* z t disp5s$ f ! p>ticles ( c>bon 9 ! sol> photosph]e to :i* ! sun owes its light4 ,radiation f su* a s\rce w\ld give light ) a cont9u\s spectrum1 l t f ! sun or a />4 ,f ! fact t ! spectra ( ! spiral nebul are cont9u\s1 we may inf] t1 ?\gh ^! nebul h rea*$ an advanc$ /age 9 _! developm5t1 !y h n always1 &1 p]haps1 n g5]ally1 atta9$ to ! /age 9 :i* cond5sation trans=m$ !m into a clu/] ( actual />s4 ,!y h1 h[ev]1 rea*$ a /age 9 _! progress t[>ds ^? sy/ems ( l>ge bodies t !y are ultimately to become4 ,! "* ( its spectrum may %[ u t ! spiral nebula is n v "y1 t x has atta9$ a consid]able age 9 its evolution z comp>$ ) o!r nebul :i* d n %[ ! spiral "* & :i* h a gase\s spectrum4 ,! importance ( ?is consid]ation w be made app>5t 9 ! next *apt]1 :5 we discuss ! dynamical conditions to :i* a spiral nebula mu/ submit4 ,b !re is no reason to d\bt t "s ( ! spiral nebul may be 9 reality />-clu/]s1 9 :i* !re are aggregations ( myriads ( po9ts1 ea* ju/ly entitl$ by its dim5sions & its lu/re to be reg>d$ z a real />4 ,! great nebula 9 ,&rom$a seems to be a greatly =e%ort5$ spiral4 ,?is1 at lea/1 is ! int]pretation :i* may p]haps be mo/ reasonably giv5 to ,dr4 ,rob]ts' fam\s photograph ( ?is spl5did object4 ,! spectrum ( ! ,&rom$a nebula has be5 photograph$ by ,s*e9] aft] a protract$ exposure ( sev5 & a half h\rs4 ,t spectrum %[$ no trace ( bright l9es1 ?us prov+ t !re is no disc]nible inc&esc5t gas 9 ! nebula ( ,&rom$a4 ,x gives practically a cont9u\s spectrum1 across :i* "s broad b&s c be recognis$4 ,x 0 int]e/+ to comp>e ?is spectrum ( ! great nebula 9 ,&rom$a ) ! sol> spectrum se5 by ! same app>atus & "u ! same conditions4 ,pr(essor ,s*e9] ann\nces t !re 0 a rem>kable co9cid5ce betwe5 ! two1 & he draws ! inf]5ce t ! />s :i* ent] into ! nebula 9 ,&rom$a are />s ( t p>ticul> type to :i* ! sun belongs4 ,illu/ration3 ,fig4 #cb4--,,portion ,,( ,,! ,,milky ,,way 7,,ne> ,,messi] ,,ii474 7,photograph$ by ,pr(essor ,e4 ,e4 ,b>n>d47 7,f ! ,royal ,a/ronomical ,society ,s]ies47 ,b we h n[ to po9t out h[ ! rec5t /udy ( nebul has af=d$ a yet m /rik+ confirmation ( ! nebul> !ory4 ,laplace %[$ h[ a gradually cond5s+ nebula might h =m$ a sun & a sy/em ( planets4 ,_h ,laplace kn[n ( ! spiral nebul he w\ld1 ,i d\bt n1 h f\nd 9 !m ! mo/ /rik+ illu/ration ( ! op]ation ( evolution on a gigantic scale4 ,!y w\ld h provid$ him ) admirable argum5ts 9 support ( ! nebul> !ory4 ,x is possible t !y might also h provid$ sugge/ions z to ! details ( ! evolution1 :i* he _h n anticipat$4 ,b ,laplace did n "k ( su* objects1 & we c only deplore ! loss ( ! in/ructive lessons :i* 8 incomp>able g5ius w\ld h d]iv$ f !m4 ,we mu/1 h[ev]1 admit t ! lessons z to ! orig9 ( ! sol> sy/em1 d]iv$ f ! spiral nebul1 mu/ be receiv$ ) due limitation4 ,we may say at once t ! great spiral nebul d n appe> to be evolv+ into sy/ems l ! sun & planets2 _! "w is ( a high] ord] ( magnitude altoge!r4 ,! great spiral nebul seem to be m analog\s to galaxies1 l ! ,milky ,way 7,fig4 #cb71 ?an to sol> sy/ems4 ,! spiral nebula in/ead ( be+ describ$ z a sy/em1 %\ld p]haps be describ$ z a sy/em ( sy/ems4 ,if ! sol> sy/em 7 drawn to scale on ! photograph ( ! ,great ,spiral 7,fig4 #bh7 ! orbit ( ,neptune w\ld n be l>g] ?an ! smalle/ recognisable dot4 ---------------------------------------- -------------------------------- ,,*apt] ,,xi4 ,,! ,,un]r+ ,,guide4 ,! ,sol> ,sy/em--,orbits ne>ly ,plane--,satellites1 ,saturn's ,r+1 ,spiral ,nebul--,an ,explanation ( ?is ,t5d5cy ( a ,sy/em t[>ds ,flatness--,! ,en]gy ( a ,sy/em--,loss ( ,en]gy by ,collision & ,tidal ,action--,a ,sy/em )9 a ,sy/em--,movem5ts ( ,translation & ,movem5ts ( ,rotation--,! ,g5]al ,law ( ,cons]vation ( ,mom5t ( ,mom5tum--,illu/rations ( ! ,pr9ciple--,! ,conception ( ! ,pr9cipal ,plane--,! ,utility ( ?is pr9ciple arises f its indep5d5ce ( ,collisions or ,friction--,nature does n d ,?+s inf9itely ,improbable--,! ,decl9e ( ,en]gy & ! ,pres]vation ( ,mom5t ( ,mom5tum--,explanation ( ! ,motions 9 "o ,plane & 9 ! same ,direction--,! ,satellites ( ,uranus--,! ,rotation ( ,uranus--,:y ! ,orbits are n exactly 9 ! same ,plane--,! ,evolution ( a ,nebula--,! ,inevitable ,t5d5cy t[>ds ! ,spiral--,! ,explanation ( ! ,spiral4 ,,we h to consid] 9 ?is *apt] ! light :i* ! laws ( ma!matics ?r[ ^u c]ta9 features :i* are possess$ by a v l>ge numb] ( cele/ial objects4 ,let u fir/ describe1 z cle>ly z ! circum/ances w p]mit1 ! nature ( ^! common features to :i* we n[ ref]1 & ( :i* ma!matics w sugge/ ! explanation4 ,we %all beg9 ) our sol> sy/em1 9 :i* ! e>? describes an orbit ar\nd ! sun4 ,t orbit is conta9$ )9 a plane1 :i* plane passes ?r\gh ! c5tre ( ! sun4 ,we may neglect = ! pres5t ! e>?'s occasional slight deviations f ?is plane :i* are caus$ by ! attractions ( ! o!r planets4 ,if we consid] ! o!r bodies ( our sy/em1 su*1 = in/ance1 z ,v5us or ,jupit]1 we f9d t ! orbit ( ,v5us also lies 9 a plane1 & t plane also passes ?r\gh ! c5tre ( ! sun4 ,! orbit ( ,jupit] is f\nd to be conta9$ )9 a plane1 & x1 too1 passes ?r\gh ! sun's c5tre4 ,ea* ( ! rema9+ planets 9 l mann] is f\nd to revolve 9 an orbit :i* is conta9$ 9 a plane1 & all ^! planes h "o common po9t1 t po9t be+ ! c5tre ( ! sun4 ,x is a rem>kable fact t ! mutual incl9ations are v small1 s t ! sev]al planes are ne>ly co9cid5t4 ,if we take ! plane ( our e>?'s orbit1 :i* we call ! ecliptic1 z ! /&>d1 !n ! greate/ incl9ation ( ! orbit ( any o!r important planet is sev5 degrees1 :i* is f\nd 9 ! case ( ,m]cury4 ,! incl9ations to ! ecliptic ( ! planes ( ! orbits ( a few ( ! a/]oids are mu* m consid]able2 to take an extreme case1 ! orbit ( ,pallas is incl9$ at an angle ( no less ?an ?irty-f\r degrees4 ,x mu/1 h[ev]1 be rememb]$ t ! a/]oids are v small objects1 z ! collective masses ( ! five hundr$ :i* are at pres5t kn[n w\ld am\nt to no m ?an an unimportant fraction ( ! mass ( "o ( ! great planets ( our sy/em4 ,?ree-f\r?s ( ! a/]oids h incl9ations "u t5 degrees4 ,we may1 !re=e1 leave ^! bodies out ( consid]ation = ! pres5t1 ?\gh we may f9d occasion to ref] to !m aga9 lat] on4 ,/ill less ne$ we pay att5tion at pres5t to ! comets1 = ?\gh ^! bodies belong to our sy/em1 & ?\gh !y move 9 plane orbits1 :i* l ! orbits ( ! planets pass ?r\gh ! c5tre ( ! sun1 yet _! orbits are incl9$ at angles ( v v>y+ magnitudes4 ,inde$1 we _c detect any t5d5cy 9 ! orbits ( comets to approximate to ! plane ( ! ecliptic4 ,! masses ( comets are1 h[ev]1 inconsid]able 9 comp>ison ) ! robu/ globes :i* =m ! planets1 :ile ! orig9 ( comets has be5 app>5tly s diff]5t f t ( ! planets1 t we may leave !m out ( consid]ation 9 our pres5t argum5t4 ,!re is no?+ 9 ! motion ( ei!r a/]oids or comets to invalidate ! g5]al proposition :i* affirms1 t ! planes ( ! orbits ( ! heavie/ & mo/ important bodies 9 ! sol> sy/em are v ne>ly co9cid5t4 ,_m ( ! planets are accompani$ by satellites1 & ^! satellites revolve r\nd ! planets1 j z ! planet accompani$ by its satellites revolves r\nd ! sun4 ,! orbit ( ea* satellite is conta9$ )9 a plane1 & t plane passes ?r\gh ! c5tre ( ! planet to :i* x is app5d$4 ,we ?us h a sy/em ( planes appropriate to ! satellites1 j z !re is a sy/em ( planes appropriate to ! planets4 ,! orbits ( ! satellites ( ea* planet are v ne>ly 9 ! same plane1 ) notable exceptions 9 ! cases ( ,uranus & ,neptune1 :i* x w be necess>y to consid] at full l5g? lat] on4 ,?is plane is v ne>ly co9cid5t ) ! planes 9 :i* ! planets !mselves move4 ,omitt+ ! exceptions1 :i* are unimportant z to magnitude1 ?\gh o!rwise extremely int]e/+ & in/ructive1 ! fundam5tal *>act]i/ic ( ! movem5ts ( ! pr9cipal bodies 9 our sy/em is t _! orbits are ne>ly p>allel to ! same plane4 ,we draw an av]age plane ?r\gh ^! closely adjac5t planes & we t]m x ! pr9cipal plane ( our sy/em4 ,x is n1 inde$1 co9cid5t ) ! plane ( ! orbit ( any "o planet1 yet ! actual plane ( ! orbit ( e important planet1 & ( ! important satellites1 lies exce$+ly close to ?is pr9cipal plane4 ,?is is a notewor?y circum/ance 9 ! arrangem5t ( ! planet>y sy/em1 & we expect t x mu/ admit ( "s physical explanation4 ,:5 we look into ! details ( ! planet>y gr\ps compos+ ! sol> sy/em1 we f9d /rik+ indications ( ! t5d5cy ( ! orbits ( ! bodies 9 ea* subord9ate sy/em to become adju/$ to a plane4 ,! mo/ /rik+ in/ance is t exhibit$ by ! ,r+s ( ,saturn4 ,x has be5 demon/rat$ t ^! wond]ful r+s are compos$ ( myriads ( sep>ate p>ticles4 ,ea* ( ^! p>ticles foll[s an indep5d5t orbit r\nd ,saturn4 ,ea* su* orbit is conta9$ 9 a plane1 & all ^! planes appe>1 s f> z our obs]vations g1 to be absolutely co9cid5t4 ,x is fur!r to be not$ t ! plane1 ?us rem>kably relat$ to ! sy/em ( r+s revolv+ ar\nd ,saturn1 is sub/antially id5tical ) ! plane 9 :i* ! satellites ( ,saturn !mselves revolve1 & ?is plane aga9 is incl9$ at an angle no great] ?an tw5ty-eight degrees to ! plane ( ! ecliptic1 & close to t 9 :i* ,saturn itself revolves ar\nd ! sun4 ,ov]look+1 z we may = ! pres5t1 ! v>ieties 9 detail :i* su* natural ph5om5a pres5t1 we may say t ! mo/ noticeable *>act]i/ic ( ! revolutions 9 ! sol> sy/em is express$ by ! /atem5t t !y lie approximately 9 ! same plane4 ,illu/ration3 ,fig4 #cc4--;,a ,,spiral ,,nebula ,,se5 ,,edgewise 7n4g4c4 #cfbh2 9 ,leo74 7,photograph$ by ,dr4 ,isaac ,rob]ts1 ,f4,r4,s47 ,we %all also f9d t ?is t5d5cy ( ! movem5ts 9 a sy/em to range !mselves 9 orbits :i* lie 9 ! same plane1 is exhibit$ 9 o!r p>ts ( ! univ]se4 ,let u consid] f ?is po9t ( view ! spiral nebul1 ^? rem>kable objects :i*1 9 ! la/ *apt]1 we h se5 to be s num]\s & s *>act]i/ic4 ,x is obvi\s t a spiral nebula mu/ be a flat object4 ,its ?ickness is small 9 comp>ison ) its diamet]4 ,:5 a spiral nebula is look$ at edgewise 7,fig4 #de71 !n x seems long & ?91 s mu* s t x pres5ts ! appe>ance ( a ray su* z we h %[n 9 ,fig4 #cc1 :i* repres5ts a type ( object v famili> to ^? a/ronom]s :o are acqua9t$ ) nebul4 ,! *>act]i/ics ( ^! objects seem consi/5t only ) ! supposition t !re is a t5d5cy 9 ! mat]ials :i* ent] into a spiral nebula to adapt _! movem5ts to a p>ticul> plane1 j z !re is a t5d5cy = ! objects 9 ,saturn's r+ to rema9 9 a p>ticul> plane1 & j z !re has be5 a t5d5cy among ! bodies belong+ to ! sol> sy/em !mselves to revolve 9 a p>ticul> plane4 ,rememb]+ also t !re seems excell5t reason to believe t spiral nebul exhibit+ ?is *>act]i/ic are to be reckon$ 9 scores ( ?\s&s1 x is evid5t t ! fundam5tal feature 9 :i* !y all agree mu/ be "o ( v great importance 9 ! univ]se4 ,illu/ration3 ,fig4 #cd4--;,a ,,=e%ort5$ ,,spiral 7n4g4c4 #caih2 9 ,ursa ,major74 7,photograph$ by ,dr4 ,isaac ,rob]ts1 ,f4,r4,s47 ,illu/ration3 ,fig4 #ce4--;,,edge ,,view ,,( ,a ,,spiral ,,boldly ,,%[n 7n4g4c4 #defe2 9 ,coma ,b]5ices74 7,photograph$ by ,dr4 ,isaac ,rob]ts1 ,f4,r4,s47 ,we may m5tion yet "o m illu/ration ( ! rem>kable t5d5cy1 s frequ5tly exhibit$ by an organis$ sy/em 9 space1 to place its p>ts ultimately 9 or ne> ! same plane1 or at all ev5ts1 to assume a %ape ( :i* "o dim5sion is small 9 comp>ison ) ! two o!rs4 ,we h1 9 ! la/ *apt]1 ref]r$ to ! ,milky ,way1 & we h allud$ to ! significance ( ! obvi\s fact t1 h[ev] ! mass ( />s :i* =m ! ,milky ,way may be arrang$1 !y are s dispos$ t ! ?ickness ( ! mass is c]ta9ly mu* less ?an its two o!r dim5sions4 ,h]s*el's fam\s illu/ration ( a gr9d/one to repres5t ! %ape ( ! ,milky ,way w s]ve to illu/rate ! =m we are n[ consid]+4 ,:5 we meet ) a *>act]i/ic =m s widely diffus$ ?r\gh ! univ]se1 exhibit$ n only 9 ! sy/ems att5d+ on ! s+le planets1 n only 9 ! sy/ems ( planets :i* revolve r\nd a s+le sun1 b also 9 t m>vell\s aggregation ( innum]able suns :i* we f9d 9 ! ,milky ,way1 & 9 scores ( ?\s&s ( nebul 9 all directions1 at all di/ances1 & app>5tly ( e grade ( importance1 we are tempt$ to ask :e!r !re may n be "s physical explanation ( a *>act]i/ic s univ]sal & s rem>kable4 ,let u see :e!r ma!matics c provide any sugge/ion z to ! cause ( ?is t5d5cy t[>ds flatness :i* seems to affect ^? sy/ems 9 ! univ]se :i* are suffici5tly isolat$ to escape f any l>ge di/urbance ( _! p>ts by outside int]f]5ce4 ,we mu/ beg9 by putt+1 z x 71 ! problem into %ape1 & by enum]at+ c]ta9 conditions :i*1 ?\gh !y may n be absolutely fulfill$ 9 nature1 are (t5 s v ne>ly fulfill$ t we make no appreciable error by suppos+ !m to be s4 ,let u suppose t a myriad bodies ( v>i\s sizes1 %apes1 mat]ials & masses1 are laun*$ 9 space 9 any ord] :atev]1 at any di/ances f ea* o!r1 & t !y are />t$ ) v diff]5t movem5ts4 ,"s may be go+ v fa/1 "s go+ sl[ly1 or n at all2 "s may be mov+ up or d[n or to ! "r or to ! left--!re may be1 9 fact1 e v>iety 9 _! di/ances & _! velocities1 & 9 ! directions 9 :i* !y are />t$4 ,we assume t ea* pair ( masses attract ea* o!r by ! well-kn[n law ( gravitation1 :i* expresses t ! =ce betwe5 any two bodies is proportional directly to ! product ( _! masses & inv]sely to ! squ>e ( _! di/ance4 ,we h "o fur!r supposition to make1 & x is an important "o4 ,we %all assume t ?\gh ea* "o ( ! bodies :i* we are consid]+ is affect+ all ! o!rs1 & is 9 turn affect$ by !m1 yet t !y are subject$ to no appreciable di/urb+ influ5ce f o!r bodies n includ$ 9 ! sy/em to :i* !y belong4 ,?is may seem at fir/ to make ! problem we are ab\t to consid] a purely imag9>y "o1 su* z c\ld only be applicable to sy/ems diff]5t f ^? :i* are actually pres5t$ to u 9 nature4 ,x mu/ be admitt$ t ! condition we h inf]r$ c only be approximately fulfill$4 ,b a little consid]ation w %[ t ! supposition is n an unreasonable "o4 ,take1 = in/ance1 ! sol> sy/em1 consi/+ ( ! sun1 ! planets1 & _! satellites4 ,e "o ( ^! bodies attracts e o!r body1 & ! movem5t ( ea* ( ! bodies is produc$ by ! jo9t effects ( ! =ces ex]t$ ^u x by all ! o!rs4 ,assur$ly ?is gives a problem q difficult en\gh = all ! res\rces t are at our comm&4 ,b 9 su* inve/igations we omit altoge!r ! influ5ce ( ! />s4 ,sirius1 = example1 does ex]cise "s attraction on ! bodies ( our sy/em1 b ow+ to its enorm\s di/ance1 9 comp>ison ) ! di/ances 9 our sol> sy/em1 ! effect ( ! di/urbance ( ,sirius on ! relative movem5ts ( ! planets is :olly inappreciable4 ,inde$1 we may add t ! di/urbances 9 ! sol> sy/em produc$ by all ! />s1 ev5 includ+ ! myriads ( ! ,milky ,way1 are absolutely negligible4 ,! movem5ts 9 our sol> sy/em1 s f> z our obs]vations reveal !m1 are p]=m$ precisely z if all bodies ( ! univ]se =eign to ! sol> sy/em 7 non-exi/5t4 ,?is consid]ation %[s t 9 ! problem we are n[ to consid]1 we are introduc+ no unreasonable elem5t :5 we premise t ! sy/em ^: movem5ts we are to inve/igate is to be reg>d$ z free f appreciable di/urbance by any =eign influ5ce4 ,to foll[ ! =tunes ( a sy/em ( bodies1 l>ge or small1 />t+ "u any arbitr>y conditions at ! comm5cem5t1 & !n ab&on$ to _! mutual attractions1 is a problem = ! ma!matician4 ,x c]ta9ly pres5ts to him que/ions ( v great difficulty1 & _m ( ^! he has to confess are insoluble2 !re are1 h[ev]1 c]ta9 important laws :i* mu/ be obey$ 9 all ! vicissitudes ( ! motion4 ,!re are c]ta9 !orems kn[n to ! ma!matician :i* apply to su* a sy/em1 & x is ^! !orems :i* af=d u mo/ int]e/+ & in/ructive in=mation4 ,i am well aw>e t ! subject ^u :i* ,i am ab\t to ent] is n a v easy "o1 b its importance is su* t ,i mu/ make ! ef=t to expla9 x4 ,let me comm5ce by describ+ :at is meant :5 we speak ( ! en]gy ( a sy/em4 ,take1 fir/1 ! case ( m]ely two bodies1 & let u suppose t !y 7 initially at re/4 ,! en]gy ( a sy/em ( ?is v simple type is repres5t$ by ! quantity ( "w :i* c\ld be done by all[+ ^! two bodies to come toge!r4 ,if1 in/ead ( be+ 9 ! beg9n+ simply at re/1 ! bodies _h ea* be5 9 motion1 ! en]gy ( ! sy/em w\ld be correspond+ly great]4 ,! en]gy ( a mov+ body1 or its capacity ( do+ "w 9 virtue ( its movem5t1 is proportional jo9tly to its mass & to ! squ>e ( its velocity4 ,! en]gy ( ! two mov+ bodies w !re=e be repres5t$ by ?ree p>ts2 fir/1 !re w be t due to _! di/ance ap>t2 secondly1 !re w be t due to ! velocity ( "o ( !m2 &1 ?irdly1 !re is t due to ! velocity ( ! o!r4 ,9 ! case ( a numb] ( bodies1 ! en]gy w consi/ 9 ! fir/ place ( a "p :i* is due to ! sep>ation ( ! bodies1 & measur$ by ! quantity ( "w t w\ld be produc$ if1 9 ob$i5ce to _! mutual attraction1 all ! bodies 7 all[$ to come toge!r into "o mass4 ,9 ! second place1 ! bodies are to be suppos$ to h be5 orig9ally />t$ ) c]ta9 velocities1 & ! en]gy ( ea* ( ! bodies1 9 virtue ( its motion1 is to be measur$ by ! product ( "o-half its mass into ! squ>e ( its velocity4 ,! total en]gy ( ! sy/em consi/s1 !re=e1 ( ! sum ( ! p>ts due to ! velocities ( ! bodies1 & t :i* is due to _! mutual sep>ation4 ,if ! bodies c\ld really be p]fectly rigid1 unyield+ masses1 s t !y h no movem5ts analog\s to tides1 & if _! movem5ts be su* t collisions w n take place among !m1 !n ! laws ( me*anics tell u t ! quantity ( en]gy 9 t sy/em w rema9 = ev] unalt]$4 ,! velocities ( ! p>ticles may v>y1 & ! mutual di/ances ( ! p>ticles may v>y1 b ^? v>iations w be always conduct$1 subject to ! fundam5tal condition t if we multiply ! squ>e ( ! velocity ( ea* body by "o-half its mass1 & add all ^? quantities toge!r1 & if we increase ! sum ?us obta9$ by ! quantity ( en]gy equival5t to ! sep>ation ( ! p>ticles1 ! total am\nt ?us obta9$ is con/ant4 ,?is is ! fundam5tal law ( me*anics kn[n z ! cons]vation ( en]gy4 ,= su* mat]ial sy/ems z ! univ]se pres5ts to u1 ! cons]vation ( en]gy1 9 ! s5se 9 :i* ,i h "h express$ x1 w n be ma9ta9$2 = ! necess>y conditions _c be fulfill$4 ,let u suppose t ! incessant movem5ts ( ! bodies 9 ! sy/em1 ru%+ ab\t "u ! influ5ce ( _! mutual attractions1 has at la/ be5 productive ( a collision betwe5 two ( ! bodies4 ,we h already expla9$ 9 ,*apt] ,,vi4 h[ 9 ! collision ( two masses ! en]gy :i* !y possess 9 virtue ( _! movem5ts may be to a l>ge ext5t trans=m$ into heat2 !re is consequ5tly an imm$iate increase 9 ! temp]ature ( ! bodies conc]n$1 & !n foll[s ! op]ation ( t fundam5tal law ( heat1 by :i* ! excess ( heat s aris+ w be radiat$ away4 ,"s ( x w1 no d\bt1 be int]cept$ by fall+ on o!r bodies 9 ! sy/em1 & ! am\nt t might be ?us possibly reta9$ w\ld1 ( c\rse1 n be lo/ to ! sy/em4 ,! bodies ( ! sol> sy/em at lea/ are s widely scatt]$1 t ! great] "p ( ! heat w\ld c]ta9ly escape into space1 & ! correspond+ quantity ( en]gy w\ld be totally lo/ to ! sy/em4 ,we may g5]ally assume t a collision among ! bodies w\ld be mo/ c]ta9ly productive ( a loss ( en]gy f ! sy/em4 ,no d\bt collisions c h>dly be expect$ to occur 9 a sy/em consi/+ ( l>ge1 isolat$ bodies l ! planets4 ,ev5 9 any sy/em ( solid bodies collisions may be presum$ to be infrequ5t 9 comp>ison ) ! numb]s ( ! bodies4 ,b if1 in/ead ( a sy/em ( few bodies ( l>ge mass1 we h a gas or nebula compos$ ( innum]able atoms or molecules1 ! collisions w\ld be by no means infrequ5t1 & e collision1 9 s f> z x l$ to ! production ( heat1 w\ld be productive ( loss ( en]gy by radiation f ! sy/em4 ,x %\ld also be add$ t1 ev5 indep5d5tly ( actual collisions1 !re is1 & mu/ be1 loss ( en]gy 9 ! sy/em f o!r causes4 ,!re are no absolutely rigid bodies kn[n 9 nature1 = ! h>de/ m9]al or ! t\ghe/ /eel mu/ yield to "s ext5t :5 l>ge =ces are appli$ to x1 & z ! bodies 9 ! sy/em are n m]e po9ts or p>ticles ( inconsid]able dim5sions1 !y w exp]i5ce /resses some?+ l ^? to :i* our e>? is subject$ 9 t action ( ! moon & sun :i* produces ! tides4 ,9 consequ5ce ( ! influ5ces ( ea* body on ! re/1 !re w be c]ta9 relative *anges 9 ! p>ts ( ea* body2 !re w be1 z x 71 tidal movem5ts 9 _! liquid p>ts & ev5 9 _! solid sub/ance4 ,^! tides w produce friction1 & ?is w produce heat4 ,?is heat w be radiat$ f ! sy/em1 b ! heat radiat$ corresponds to a c]ta9 am\nt ( en]gy2 ! en]gy is !re=e lo/ to ! sy/em1 s t ev5 )\t actual collisions we /ill f9d t en]gy mu/ be gradually lo/ to ! sy/em4 ,?us we h be5 conduct$ to an important conclusion1 :i* may be /at$ 9 ! foll[+ way4 ,let !re be any sy/em ( bodies1 subject to _! mutual attractions1 & suffici5tly isolat$ f ! di/urb+ influ5ce ( all bodies :i* d n belong to ! sy/em1 !n ! orig9al en]gy ) :i* t sy/em is />t$ mu/ be und]go+ a cont9ual decl9e4 ,x mu/ at lea/ decl9e until su* a condition ( ! sy/em has be5 rea*$ t collisions are no long] possible & t tidal influ5ces h ceas$4 ,^! conditions might be fulfill$ if all ! bodies ( ! sy/em coalesc$ into a s+le mass4 ,z illu/rations ( ! sy/ems we are n[ consid]+1 we may take ! sun & planets z a :ole4 ,a spiral nebula is a sy/em 9 ! pres5t s5se1 :ile p]haps ! gr&e/ illu/ration ( all is provid$ by ! ,milky ,way4 ,x w be not$ t we may h a sy/em :i* is isolat$ s f> z our pres5t argum5t is conc]n$1 ev5 :ile x =ms a "p ( ano!r sy/em ( a high] ord] ( magnitude4 ,= in/ance1 ,saturn ) 8 r+s & satellites is suffici5tly isolat$ f ! re/ ( ! sol> sy/em & ! re/ ( ! univ]se1 to enable u to trace ! consequ5ces ( ! gradual decl9e ( en]gy 9 8 att5dant sy/em4 ,! sol> sy/em 9 :i* ,saturn appe>s m]ely z a unit1 is itself suffici5tly isolat$ f ! />s 9 ! ,milky ,way to p]mit u to /udy ! decl9e ( en]gy 9 ! sol> sy/em1 )\t consid]+ ! action ( ^? />s4 ,?is g5]al law ( ! decl9e ( en]gy 9 an isolat$ sy/em1 is supplem5t$ by ano!r law (t5 kn[n z ! cons]vation ( mom5t ( mom5tum4 ,x may at fir/ seem difficult to grasp ! notion :i* ?is law involves4 ,! ef=t is1 h[ev]1 wor? mak+1 = ! law 9 "q is ( fundam5tal importance 9 ! /udy ( ! me*anics ( ! univ]se4 ,9 ! ,app5dix w be f\nd an inve/igation by elem5t>y geometry ( ! important me*anical pr9ciples :i* are involv$ 9 ?is subject4 ,:atev] may h be5 ! orig9 ( ! primval nebula1 & :atev] may h be5 ! =ces conc]n$ 9 its production we may feel confid5t t x 0 n orig9ally at re/4 ,we d n inde$ "k any object :i* is at re/4 ,n "o ( ! heav5ly bodies is at re/1 no?+ on e>? is at re/1 = ev5 ! molecules ( rigid matt] are 9 rapid motion4 ,re/ seems unkn[n 9 ! univ]se4 ,x w\ld be1 !re=e1 inf9itely improbable t a primval nebula1 :atev] may h be5 ! ag5cy by :i* x 0 />t$ on t c>e] :i* we are consid]+1 0 initially 9 a condition ( absolute re/4 ,we assume )\t hesitation t ! nebula 0 to "s ext5t 9 motion1 & we may feel assur$ t ! motions 7 ( a highly complicat$ description4 ,x is =tunate = u t our argum5t does n require u to "k ! precise "* ( ! movem5ts1 z su* k w\ld obvi\sly be q unatta9able4 ,we c1 h[ev]1 invoke ! laws ( me*anics z an un]r+ guide4 ,!y w tell u n inde$ ev]y?+ ab\t ^? motions1 b !y w set =? c]ta9 *>act]i/ics :i* ! movem5ts mu/ h _h1 & ^! *>act]i/ics suffice = our argum5t4 ,to illu/rate ! important pr9ciple on :i* we are n[ ent]+ ,i mu/ m5tion ! fam\s problem ( ?ree bodies :i* has engag$ ! att5tion ( ! greate/ ma!maticians4 ,let !re be a body ,a1 & ano!r ,b1 & ano!r ,c4 ,we %all suppose t ^! bodies are s small t !y may be reg>d$ m]ely z po9ts 9 comp>ison ) ! di/ances by :i* !y are sep>at$4 ,we %all suppose t !y are all mov+ 9 ! same plane1 & we %all suppose t ea* ( !m attracts ! o!rs1 b t except ^! attractions !re are no o!r =ces 9 ! sy/em4 ,to discov] all ab\t ! motions ( ^! bodies is s difficult a problem t ma!maticians h nev] be5 able to solve x4 ,b ?\gh we are n able to solve ! problem completely1 we c le>n some?+ ) reg>d to x4 ,we repres5t by arr[s 9 ,fig4 #cf ! directions 9 :i* ,a1 ,b1 & ,c are mov+ at ! mom5t4 ,we *oose any po9t ,o 9 ! plane1 & = simplicity we h s drawn ! figure t ,a1 ,b1 & ,c are =ces t5d+ to turn r\nd ,o 9 ! same direction4 ,! velocity ( a body multipli$ into its mass is t]m$ ! mom5tum ( ! body4 ,draw ! p]p5dicul> f ,o to ! direction 9 :i* ! body ,a is mov+1 !n ! product ( ?is p]p5dicul> & ! mom5tum ( ,a is call$ ! mom5t ( mom5tum ( ,a ar\nd ,o4 ,9 l mann] we =m ! mom5t ( mom5tum ( ,b & ,c1 & if we add !m toge!r we obta9 ! total mom5t ( mom5tum ( ! sy/em4 ,we c n[ give expression to a great discov]y :i* ma!maticians h made4 ,no matt] h[ complicat$ may be ! movem5ts ( ,a1 ,b1 & ,c2 no matt] to :at ext5t ^! p>ticles approximate or h[ widely !y sep>ate2 no matt] :at *anges may occur 9 _! velocities1 or ev5 :at actual collision may take place1 ! sum ( ! mom5ts ( mom5tum mu/ rema9 = ev] unalt]$4 ,?is mo/ important pr9ciple 9 dynamics is kn[n z ! cons]vation ( mom5t ( mom5tum4 ,?\gh ,i h only m5tion$ ?ree p>ticles1 yet ! same pr9ciple w be true = any numb]4 ,if x %\ld happ5 t any ( !m are turn+ r\nd ,o 9 ! opposite direction1 !n _! mom5ts ( mom5tum are to be tak5 z negative4 ,9 ?is case we add ! mom5ts t5d+ 9 "o direction toge!r2 & !n subtract all ! opposite mom5ts4 ,! rema9d] is ! quantity :i* rema9s con/ant4 ,illu/ration3 ,fig4 #cf4--,,to ,,illu/rate ,,mom5t ,,( ,,mom5tum4 ,we may /ate ?is pr9ciple 9 a some:at diff]5t mann] z foll[s3 ,let u consid] a multitude ( p>ticles 9 a plane2 let !m be sev]ally />t$ 9 any directions 9 ! plane1 & !n be ab&on$ to _! mutual attractions1 x be+ und]/ood t !re are no =ces produc$ by bodies ext]nal to ! sy/em2 if we !n *oose any po9t 9 ! plane1 & measure ! areas describ$ r\nd t po9t by ! sev]al mov+ bodies 9 "o second1 & if we multiply ea* (1 ^? areas by ! mass ( ! correspond+ body1 !n1 if all ! bodies are mov+ 9 ! same direction r\nd ! po9t1 ! sum ( ! quantities s obta9$ is con/ant4 ,x w be ! same a hundr$ or a ?\s& ye>s h5ce z x is at ! pres5t mom5t1 or z x 0 a hundr$ or a ?\s& ye>s ago4 ,if any ( ! p>ticles _h be5 turn+ r\nd ! po9t 9 ! opposite direction1 !n ! products belong+ to su* p>ticles are to be subtract$ f ! o!rs in/ead ( add$4 ,we h n[ to express 9 a /ill m g5]al mann] ! important pr9ciple t is "h involv$4 ,let u consid] any sy/em ( attract+ p>ticles1 no matt] :at _! masses or :e!r _! movem5ts be re/rict$ to a plane or n4 ,let u />t !m into motion 9 any directions & ) any initial velocities1 & !n ab&on !m to ! influ5ce ( _! mutual attractions1 )hold+ at ! same "t ! int]f]5ce ( any =ces f bodies ext]ior to ! sy/em4 ,draw any plane :atev]1 & let fall p]p5dicul>s ^u ?is plane f ! diff]5t p>ticles ( ! sy/em4 ,x w be obvi\s t z ! p>ticles move ! feet ( ! p]p5dicul>s mu/ move 9 correspond5ce ) ! p>ticles f :i* ! p]p5dicul>s 7 let fall4 ,we may reg>d ! foot ( e p]p5dicul> z ! actual position ( a mov+ po9t1 & x c be prov$ t if ! mass ( ea* p>ticle be multipli$ into ! area :i* ! foot ( its p]p5dicul> describes 9 a second r\nd any po9t 9 ! plane1 & !n be add$ to ! simil> products f all ! o!r p>ticles1 only obs]v+ ! prop] precautions z to sign1 ! sum w rema9 con/ant1 i4e41 9 any o!r second ! total quantity arriv$ at w be exactly ! same4 ,?is is a g5]al law ( dynamics4 ,x is n a law ( m]ely approximate tru?1 x is a law true ) absolute accuracy dur+ unlimit$ p]iods ( "t4 ,! actual value ( ! con/ant w dep5d bo? on ! sy/em & on ! plane4 ,= a giv5 sy/em ! con/ant w diff] = ! diff]5t planes :i* may be drawn1 & !re w be "s planes 9 :i* t sum w be z]o4 ,9 o!r words1 9 ^? planes ! areas describ$ by ! feet ( ! p]p5dicul>s1 multipli$ by ! masses ( ! p>ticles :i* are mov+ 9 "o way1 w be precisely equal to ! simil> sum obta9$ f ! p>ticles mov+ 9 ! opposite direction4 ,b among all possible planes !re is "o ( special significance 9 its relation to ! sy/em4 ,x is call$ ! 8pr9cipal plane10 & x is *>act]is$ by ! fact t ! sum 7) due att5tion to sign7 ( ! areas describ$ ea* second by ! feet ( ! p]p5dicul>s1 multipli$ into ! masses ( ! correspond+ p>ticle1 is great] ?an ! l magnitude = any o!r plane1 & is ?us a maximum4 ,= all planes p>allel to ?is pr9cipal plane1 ! result w be1 ( c\rse1 ! same2 x is ! direction ( ! plane & n its absolute situation t is mat]ial4 ,we ?us see t :ile ?is rem>kable quantity is con/ant 9 any plane1 = all "t1 yet ! actual value ( t con/ant dep5ds ^u ! aspect ( ! plane2 = "s planes x is z]o1 = o!rs ! con/ant has int]m$iate values1 & !re is "o plane = :i* ! con/ant is a maximum4 ,?is is ! pr9cipal plane1 & a k ( x is ( vital importance 9 endeav\r+ to und]/& ! nebul> !ory4 ,nor are ! pr9ciples "u consid]ation limit$ only to a sy/em consi/+ ( sun & planets2 !y apply1 ) suitable modifications1 to _m o!r cele/ial sy/ems z well4 ,! in/ructive "* ( ?is dynamical pr9ciple w be se5 :5 we d$uce its consequ5ces4 ,! t]m 8mom5t ( mom5tum0 ( a p>ticle1 ) ref]5ce to a c]ta9 po9t 9 a plane1 expresses d\ble ! product ( ! rate at :i* ! area is describ$ by ! foot ( ! p]p5dicul> to ?is plane1 multipli$ by ! mass ( ! p>ticle4 ,! mom5t ( mom5tum ( ! sy/em1 ) ref]5ce to ! pr9cipal plane1 is a maximum 9 comp>ison ) all o!r planes2 t mom5t ( mom5tum reta9s precisely ! same value ?r\gh\t all "t1 f ! fir/ in/ant ! sy/em 0 />t$ onw>ds4 ,& x reta9s ?is value1 no matt] :at *anges or di/urbances may happ5 9 ! sy/em1 provid$ only t ! influ5ce ( ext]nal =ces is )held4 ,subject to ?is condition1 ! trans=mations ( ! sy/em may be any :atev]4 ,! sev]al bodies may be =c$ into wide *anges ( _! orbits1 s t !re may ev5 be collisions among !m2 yet1 not)/&+ ^? collisions1 & not)/&+ ! viol5t alt]ations :i* may be ?us produc$ 9 ! movem5ts ( ! bodies1 ! mom5t ( mom5tum w n alt]4 ,no matt] :at tides may be produc$1 ev5 if ^? tides be s great z to produce disruption 9 ! masses & =ce ! orbits to *ange _! "* radically1 yet ! mom5t ( mom5tum w be cons]v$ )\t alt]ation4 ,x is ess5tial to notice ! fundam5tal diff]5ce betwe5 ! pr9ciple :i* has be5 call$ ! cons]vation ( en]gy 9 ! sy/em1 & ! cons]vation ( mom5t ( mom5tum4 ,we h po9t$ out t :5 collisions take place1 "p ( ! en]gy due to motion is trans=m$ into heat1 & en]gy 9 t =m admits ( radiation ?r\gh space1 & ?us becomes lo/ to ! sy/em1 ) ! result t ! total en]gy decl9es4 ,ev5 )\t actual collision1 we h %[n h[ c]ta9 effects ( tides1 or o!r consequ5ces ( friction1 necess>ily involve ! squ&]+ ( en]gy ) :i* ! sy/em 0 orig9ally end[$4 ,a sy/em />t$ ) a c]ta9 end[m5t ( en]gy may cons]ve t en]gy indef9itely1 if all su* actions z collisions or frictions are abs5t4 ,if collisions or frictions are pres5t ! sy/em w gradually dissipate en]gy4 ,our int]pretation ( ! future ( su* a sy/em mu/ always take acc\nt ( ?is fundam5tal fact4 ,x is1 ( c\rse1 conceivable t ! mom5t ( mom5tum ) :i* a sy/em 0 orig9ally end[$ might h happ5$ to be z]o4 ,a sy/em ( p>ticles c\ld be s con/ruct$ & s />t$ on _! movem5ts t _! mom5t ( mom5tum ) reg>d to a c]ta9 plane %\ld be z]o4 ,x might happ5 t ! mom5t ( mom5tum ( ! sy/em ) reg>d to a second plane1 p]p5dicul> to ! =m] "o1 %\ld be also z]o2 &1 f9ally1 t ! mom5t ( mom5tum ( ! sy/em ) reg>d to a ?ird plane p]p5dicul> to ea* ( ! o!r two1 %\ld be also z]o4 ,if ^! ?ree conditions 7 f\nd to prevail at ! comm5cem5t1 !y w\ld prevail ?r\gh\t ! movem5t1 &1 m g5]ally /ill1 we may /ate t 9 su* circum/ances ! mom5t ( mom5tum ( ! sy/em w\ld be z]o ab\t any plane :atev]4 ,!re w\ld be no pr9cipal plane 9 su* a sy/em4 ,we ?us note t ?\gh x is inconceivable t a gr\p ( mutually attract+ bodies %\ld be />t$ into movem5t )\t a suitable end[m5t ( en]gy1 x is yet q conceivable t a sy/em c\ld be />t$ )\t hav+ any mom5t ( mom5tum4 ,& if at ! beg9n+ ! sy/em _h no mom5t ( mom5tum1 !n no matt] :at may be ! future vicissitudes ( its motion1 no mom5t ( mom5tum c ev] be acquir$ by x to all et]nity1 s long z ! int]f]5ce ( ext]nal =ces is exclud$4 ,b hav+ said ?is mu* z to ! conceivability ( ! initiation ( a sy/em ) no mom5t ( mom5tum1 we n[ ha/5 to add t1 s f> z ,nature is actually conc]n$1 ?is b>e possibility may be set aside z "o :i* is inf9itely improbable4 ,nature does n d ?+s :i* are inf9itely improbable1 &1 !re=e1 we may affirm t all mat]ial sy/ems1 ) :i* we %all h to deal1 d possess mom5t ( mom5tum4 ,h[ev] ! sy/em may h orig9at$1 :atev] may h be5 ! actions ( =ces by :i* x 0 br\ght into be+1 we may feel assur$ t ! sy/em receiv$ at its initiation "s end[m5t ( mom5t ( mom5tum1 z well z ( en]gy4 ,h5ce we may conclude t e su* sy/em z is pres5t$ to u 9 ! inf9ite v>iety ( ,nature1 mu/ /& 9 intimate relation to "s p>ticul> plane1 be+ t :i* is kn[n z ! pr9cipal plane ( mom5t ( mom5tum4 ,9 our ef=t to int]pret ,nature1 ! physical importance ( ?is fact c h>dly be ov]-e/imat$4 ,9 a future *apt] we %all make "s attempt to sket* ! natural op]ations by :i* individual sy/ems h be5 />t$ on _! c>e]s4 ,po/pon+1 !n1 su* que/ions1 we propose to deal n[ ) ! ph5om5a :i* ! pr9ciples ( dynamics decl>e mu/ accompany ! evolution ( a sy/em "u ! action ( ! exclusive attraction ( ! v>i\s p>ts ( t sy/em = ea* o!r4 ,! sy/em comm5ces its c>e] ) a c]ta9 end[m5t ( en]gy1 ) a c]ta9 end[m5t ( mom5t ( mom5tum1 & ) a c]ta9 pr9cipal plane to :i* t mom5t ( mom5tum is specially relat$4 ,9 ! c\rse ( ! evolution ?r\gh :i*1 9 myriads ( ages1 ! sy/em is de/9$ to pass1 ! en]gy t x conta9s w und]go va/ loss by dissipation4 ,on ! o!r h&1 ! mom5t ( mom5tum w nev] v>y1 & ! position ( ! pr9cipal plane w rema9 ! same = all "t4 ,we h to consid] :at features1 connect$ ) ! evolution1 may be attribut$ to ! op]ation ( ^! dynamical laws4 ,we h1 9 fact1 to d$uce ! consequ5ces :i* seem to foll[ f ! fact t1 9 consequ5ce ( collisions1 & 9 consequ5ce ( friction1 an isolat$ sy/em 9 space mu/ gradually "p ) its initial /ore ( en]gy1 b t1 not)/&+ any collisions & any friction1 ! total mom5t ( mom5tum ( ! sy/em suff]s no abatem5t4 ,z ! sy/em advances 9 developm5t1 we h to deal ) a gradual decl9e 9 ! ratio ( ! orig9al /ore ( en]gy to ! orig9al /ore ( mom5t ( mom5tum4 ,& h5ce we mu/ expect t a sy/em w ultimately t5d t[>ds a =m 9 :i*1 :ile pres]v+ its mom5t ( mom5tum1 x %all d s ) su* a di/ribution ( ! bodies ( :i* x consi/s z %all be compatible ) a dim9i%+ quantity ( en]gy4 ,x is n h>d to see t 9 ! c\rse ( ages ?is t5ds1 z "o consequ5ce1 to make ! movem5ts ( ea* ( ! bodies 9 ! sy/em ultimately approximate to movem5ts 9 a plane4 ,let u1 = simplicity1 beg9 ) ! case ( ?ree attract+ p>ticles1 ,a1 ,b & ,c4 ,let ,b be />t$ 9 any direction 9 ! plane ,l1 & let ,a be />t$ 9 an orbit r\nd x1 & 9 ! same plane ,l4 ,n[ let ,c be />t$ into motion1 9 any direction1 f "s po9t also 9 ,l4 ,x is c]ta9 t ! sum ( ! areas project$ p>allel to any plane1 :i* are describ$ 9 a second by ^! ?ree bodies1 mu/ be con/ant1 ea* ( ! areas be+1 z usual1 multipli$ by ! mass ( ! correspond+ body4 ,let u specially consid] ! plane ,l 9 :i* ! motions ( ,a & ,b already lie4 ,x is on ?is plane t ! area describ$ by ,c has to be project$4 ,! ess5tial po9t n[ to rememb] is t ! project$ area is less ?an ! actual area4 ,x is pla9 t if ,c has to describe a c]ta9 project$ area 9 a c]ta9 "t1 ! velocity ) :i* ,c has to move mu/ be great] :5 ,c />ts (f at an incl9ation to ! plane ?an w\ld h be5 necess>y if ,c _h />t$ 9 ! plane1 o!r ?+s be+ ! same4 ,?us we see t1 if ! ?ree bodies 7 all mov+ 9 ! same plane1 !y c\ld1 speak+ g5]ally1 ma9ta9 m easily ! requisite description ( areas1 t is1 ! requisite mom5t ( mom5tum ) small] velocities ?an if !y 7 mov+ 9 directions :i* 7 n s regulat$2 t is to say1 ! mom5t ( mom5tum c be kept up ) less en]gy :5 ! p>ticles move 9 ! same plane4 ,9 a m g5]al mann] we see t any sy/em 9 :i* ! bodies are mov+ 9 ! same plane w1 = equal mom5t ( mom5tum1 require less en]gy ?an x w\ld h done _h ! bodies be5 mov+ 9 directions :i* 7 n limit$ to a plane4 ,?us we are l$ to ! conclusion t ! ultimate result ( ! collisions & ! friction & ! tides1 :i* are caus$ by ! action ( "o p>ticle on ano!r1 is to make ! movem5ts t5d t[>ds ! same plane4 ,9 ?is dynamical pr9ciple we h 9 all probability a physical explanation ( t rem>kable *>act]i/ic ( cele/ial movem5ts to :i* we h ref]r$4 ,! sol> sy/em possesses less en]gy 9 proportion to its mom5t ( mom5tum ?an x w\ld require to h if ! orbits ( ! important planets1 in/ead ( ly+ practically 9 ! same plane1 7 incl9$ at v>i\s angles4 ,:atev] may h be5 ! orig9al disposition ( ! mat]ials =m+ ! sol> sy/em1 !y mu/ once h conta9$ mu* m en]gy ?an !y h at pres5t4 ,! mom5t ( mom5tum 9 ! pr9cipal plane1 at ! beg9n+1 0 n1 h[ev]1 diff]5t f ! mom5t ( mom5tum t ! sy/em n[ possesses4 ,z ! en]gy ( ! sy/em gradually decl9$1 ! sy/em has gradually be5 compell$ to adju/ itself 9 su* a mann] t1 ) ! r$uc$ quantity ( en]gy1 ! requisite mom5t ( mom5tum %all /ill be pres]v$4 ,?is is ! reason :y1 9 ! c\rse ( ! myriads ( ages dur+ :i* ! sol> sy/em has be5 acquir+ its pres5t =m1 ! movem5ts h gradually become ne>ly con=m$ to a plane4 ,! op]ation ( ! pr9ciple1 n[ be=e u1 may be se5 9 a /rik+ mann] 9 ,saturn's r+4 7,fig4 #cg47 ,! p>ticles con/itut+ ?is exquisite object1 s f> z obs]vations h reveal$ !m1 seem to pres5t to u an almo/ absolutely plane movem5t4 ,! fact t ! movem5ts ( ! con/itu5ts ( ,saturn's r+ lie 9 a plane is d\btless to be acc\nt$ = by ! op]ation ( ! fundam5tal dynamical pr9ciple to :i* we h ref]r$4 ,saturn1 9 its great motion r\nd ! lum9>y1 is1 ( c\rse1 controll$ by ! sun1 yet ! sy/em atta*$ to ,saturn is s close to t globe z to be attract$ by ! sun 9 a mann] :i* ne$ n "h be di/+ui%$ f ! sol> attraction on ,saturn itself4 ,x foll[s t ! diff]5tial action1 s to speak1 ( ! sun on ,saturn1 & on ! myriad objects :i* con/itute its r+1 may be disreg>d$4 ,we are !re=e entitl$1 z already m5tion$1 to view ,saturn & its sy/em z an isolat$ gr\p1 n act$ ^u by any =ces ext]ior to ! sy/em4 ,x is !re=e subject to ! laws :i* decl>e t1 ?\gh ! en]gy decl9es1 ! mom5t ( mom5tum is to rema9 unalt]$4 ,?is x is :i* has app>5tly caus$ ! extreme flatness ( ,saturn's r+4 ,! en]gy ( ! rotation ( t sy/em has be5 exp5d$ until x might seem t no m en]gy has be5 left ?an j suffices to pres]ve ! unalt]able mom5t ( mom5tum1 "u ! mo/ economical conditions1 s f> z en]gy is conc]n$4 ,illu/ration3 ,fig4 #cg4--,,saturn4 ,drawn by ,e4 ,m4 ,antoniadi4 7,july #cj?1 #ahii47 ,let u suppose t "o ( ! innum]able myriads ( p>ticles :i* con/itute ! r+ ( ,saturn 7 to =sake ! plane 9 :i* x n[ revolves1 & move 9 an orbit incl9$ to ! pres5t plane4 ,we %all suppose t ! orig9al track ( ! orbit 0 a circle1 & we %all assume t 9 ! new plane to :i* ! motion is transf]r$ ! motion is also circul>4 ,t p>ticle w h /ill to d its %>e ( pres]v+ ! requisite total mom5t ( mom5tum1 = we are to suppose t ea* ( ! o!r p>ticles rema9s unalt]$ 9 its pace & 9 ! o!r circum/ances ( its motion4 ,! ab]rant p>ticle w describe1 9 a second1 an area :i*1 = ! purpose ( ! pres5t calculation1 mu/ be project$ ^u ! plane conta9+ ! o!r p>ticles4 ,! area1 :5 project$1 mu/ /ill be z l>ge z ! area t ! p>ticle w\ld h describ$ if x _h rema9$ 9 ! plane4 ,x is !re=e necess>y t ! area swept ov] by ! p>ticle 9 ! incl9$ plane1 9 "o second1 %all be great] ?an ! area :i* suffic$ 9 ! orig9al plane4 ,?is requires ! circle 9 :i* ! p>ticle revolves to be enl>g$1 & ?is necessitates t its en]gy %\ld be increas$4 ,9 o!r words1 :ile ! mom5t ( mom5tum 0 no great] ?an be=e1 ! en]gy ( ! sy/em w\ld h to be great]4 ,we ?us see t inasmu* z ! p>ticles =m+ ! r+s ( ,saturn move 9 circles 9 ! same plane1 !y require a small] am\nt ( en]gy 9 ! sy/em to pres]ve ! requisite mom5t ( mom5tum ?an w\ld be requir$ if !y mov$ 9 circul> orbits :i* 7 n 9 ! same plane4 ,9 su* a sy/em z ,saturn's r+1 9 :i* ! p>ticles are excessively num]\s & excessively close toge!r1 x may be presum$ t !re may once h be5 suffici5t collisions & frictions among ! p>ticles to cause ! exhau/ion ( en]gy to ! l[e/ po9t at :i* ! mom5t ( mom5tum w\ld be su/a9$4 ,9 ! c\rse ( ages ?is has be5 accompli%$ by ! rem>kable adju/m5t ( ! movem5ts to t plane 9 :i* we n[ f9d !m4 ,! importance ( ?is subject is s great t we %all pres5t ! matt] 9 a some:at diff]5t mann] z foll[s3 ,we %all simplify ! matt] by reg>d+ ! orbits ( ! planets or o!r bodies z circles ,! fact t ^! orbits are ellipses1 :i* are1 h[ev]1 v ne>ly circles1 w n appreciably affect ! argum5t4 ,let u1 !n1 suppose a s+le planet revolv+ r\nd a fix$ sun1 9 ! c5tre4 ,! en]gy ( ?is sy/em has two p>ts4 ,!re is fir/ ! en]gy due to ! velocity ( ! planet1 & ?is is f\nd by tak+ half ! product ( ! mass ( ! planet & ! squ>e ( its velocity4 ,! second "p ( ! en]gy dep5ds1 z we h already expla9$1 on ! di/ance ( ! planet f ! sun4 ,! planet possesses en]gy on acc\nt ( its situation1 = ! attraction ( ! sun on ! planet is capable ( do+ "w4 ,! fur!r ! planet is f ! sun ! l>g] is ! quantity ( en]gy t x possesses f ?is cause4 ,on ! o!r h&1 ! fur!r ! planet is f ! sun ! small] is its velocity1 & ! less is ! quantity ( en]gy t x possesses ( ! fir/ k9d4 ,we unite ! two p>ts1 & we f9d t ! net result may be express$ 9 ! foll[+ mann]3 ,if a planet be revolv+ 9 a circul> pa? r\nd ! sun1 !n ! total en]gy ( t sy/em 7ap>t f any rotation ( ! sun & planet on _! axes71 :5 add$ to ! reciprocal ( ! di/ance betwe5 ! two bodies1 measur$ ) a prop] unit ( l5g?1 is ! same = all di/ances ( ! same two bodies4 ,?is %[s ! connection betwe5 ! en]gy & ! di/ance ( ! planet f ! sun4 ,?us we see t if ! circle is enl>g$ ! en]gy ( ! sy/em increases4 ,! mom5t ( mom5tum ( ! sy/em is proportional to ! squ>e root ( ! di/ance ( ! two bodies4 ,if1 !re=e1 ! di/ance ( ! two bodies is increas$1 ! mom5t ( mom5tum increases also4 ,x w illu/rate ! application ( ! argum5t to take a p>ticul> case 9 :i* a sy/em ( p>ticles is revolv+ r\nd a c5tral sun 9 circul> orbits1 all ( :i* lie 9 ! same plane4 ,let u suppose t1 :ile ! mom5t ( mom5tum ( ! sy/em ( p>ticles is to rema9 unalt]$1 "o ( ! p>ticles is to be %ift$ into a plane :i* is incl9$ at an angle ( #fj to ! plane ( ! o!r orbits2 x c easily be se5 t an area 9 ! new plane1 :5 project$ d[n into ! orig9al plane1 w be r$uc$ to half its am\nt4 ,h5ce1 z ! mom5t ( mom5tum ( ! :ole sy/em is to be kept up1 x w be necess>y = ! p>ticle to h a mom5t ( mom5tum 9 ! circle :i* x describes 9 ! new plane :i* is d\ble t :i* x _h 9 ! orig9al plane4 ,x foll[s t ! radius ( ! circle 9 ! new plane mu/ be f\r times ! radius ( ! circle :i* def9$ ! orbit ( ! p>ticle 9 ! old plane4 ,! en]gy ( ! p>ticle 9 ?is orbit is !re=e correspond+ly great]1 & ?us ! en]gy ( ! :ole sy/em is increas$4 ,?is illu/rates h[ a sy/em1 9 :i* ! circul> orbits are 9 diff]5t planes1 requires m en]gy = a giv5 mom5t ( mom5tum ?an w\ld suffice if ! circul> orbits _h all be5 9 ! same plane4 ,s long z ! orbits are 9 diff]5t planes !re w /ill rema9 a res]ve ( en]gy = possible dissipation4 ,b ! dissipation is always 9 progress1 & h5ce !re is an incessant t5d5cy t[>ds a flatt5+ ( ! sy/em by ! mutual actions ( its p>ts4 ,x may help to elucidate ?is subject to /ate ! matt] z foll[s3 ,! m ! sy/em contracts1 ! fa/] x mu/ g5]ally revolve2 ?is is ! univ]sal law :5 di/urb+ influ5ces are exclud$4 ,take1 = in/ance1 ! sun1 :i* is at ?is mom5t contract+ on acc\nt ( its loss ( heat4 ,9 consequ5ce ( t contraction x is ess5tial t ! sun %all gradually turn fa/] r\nd on its axis4 ,at pres5t ! sun requires tw5ty-five days1 f\r h\rs & tw5ty-n9e m9utes = ea* rotation4 ,t p]iod mu/ c]ta9ly be dim9i%+1 al?\gh no d\bt ! rate ( dim9ution is v sl[4 ,inde$1 x is too sl[ = u to obs]ve2 nev]!less1 "s dim9ution mu/ be 9 progress4 ,apply+ ! same pr9ciple to ! primitive nebula1 we see1 t z ! contraction ( ! orig9al volume proce$s1 ! spe$ ) :i* ! sev]al p>ts w rotate mu/ increase4 ,! p]iodic times ( ! planets are "h in/ructive4 ,! mat]ials n[ =m+ ,jupit] 7 situat$ t[>ds ! ext]ior ( ! nebula1 s t1 z ! nebula contract$1 x t5d$ to leave ,jupit] beh9d4 ,! p]iod 9 :i* ,jupit] n[ revolves r\nd ! sun may give "s notion ( ! p]iod ( ! rotation ( ! nebula at ! "t t x ext5d$ s f> z ,jupit]4 ,subsequ5tly to ! =mation1 & ! deta*m5t ( ,jupit]1 a body :i* 0 h5ce=? no long] 9 contact ) ! nebula1 ! latt] proce$$ fur!r 9 its contraction4 ,pass+ ov] ! int]m$iate /ages1 we f9d ! nebula contract+ until x ext5d$ no fur!r ?an ! l9e n[ m>k$ by ! e>?'s orbit2 ! spe$ ) :i* ! nebula 0 rotat+ mu/ h be5 increas+ all ! "t1 s t ?\gh ! nebula requir$ sev]al ye>s to g r\nd :5 x ext5d$ z f> z ,jupit]1 only a fraction ( t p]iod 0 necess>y :5 x _h rea*$ ! position indicat$ by ! e>?'s track at ! pres5t "t4 ,leav+ ! e>? beh9d x1 j z x _h previ\sly left ,jupit]1 ! nebula />t$ on a /ill fur!r cond5sation4 ,x drew 91 until at la/ x rea*$ a fur!r /age by contraction into ! sun1 :i* rotates 9 less ?an a mon?4 ,?us ! p]iod ( ,jupit] namely1 twelve ye>s1 ! p]iod ( ! e>?1 namely1 "o ye>1 & ! p]iod ( ! sun1 namely1 tw5ty-five days1 illu/rate ! successive accel]ations ( ! rotation ( ! nebula 9 ! process ( contraction4 ,no d\bt ^! /atem5ts mu/ be receiv$ ) mu* qualification1 b !y w illu/rate ! nature ( ! argum5t4 ,we may also "h m5tion ! satellites ( ,uranus1 all ! m s because x has be5 frequ5tly urg$ z an objection to ! nebul> !ory t ! orbits ( ! satellites ( ,uranus lie 9 a plane :i* is incl9$ at a v l>ge angle2 no less ?an #hb to ! g5]al plane ( ! sol> sy/em4 ,i %all ref] 9 a lat] *apt] to ?is subject1 & consid] :at explanation c be (f]$ ) reg>d to ! great incl9ation ( ?is plane1 :i* is "o ( ! anomalies ( our sy/em4 ,= ! pres5t ,i m]ely draw att5tion to ! fact t ! movem5ts ( all f\r satellites ( ,uranus d actually lie 9 ! same plane1 ?\gh1 z already indicat$1 x /&s ne>ly at "r angles to ! ecliptic4 ,pr(essor ,newcomb has %[n t ! f\r satellites ( ,uranus revolve 9 orbits :i* are almo/ exactly circul>1 & :i*1 s f> z obs]vation %[s1 are absolutely 9 ! same plane4 ,f our pres5t po9t ( view ?is is a matt] ( mu* int]e/4 ,:atev] may h be5 ! influ5ce by :i* ?is plane dep>ts s widely f ! plane ( ! ecliptic1 x seems c]ta9 t x mu/ be reg>d$ z hav+ act$ at a v e>ly p]iod 9 ! evolution ( ! ,uranian sy/em2 & :5 ?is sy/em _h once />t$ on its c\rse ( evolution1 ! op]ation ( t dynamical pr9ciple to :i* we h s (t5 ref]r$ 0 gradually br\ght to be> on ! orbits ( ! satellites4 ,we h "h ano!r isolat$ case resembl+ t ( ,saturn & its r+s4 ,! fundam5tal law orda9$ t ! mom5t ( mom5tum ( ,uranus & its moons mu/ rema9 con/ant1 ?\gh ! total quantity ( en]gy 9 t sy/em %\ld decl9e4 ,9 ! c\rse ( ages ?is has l$ to ! adju/m5t ( ! orbits ( ! f\r satellites into ! same plane4 ,i ought "h to m5tion t ! rotation ( ,uranus on its axis pres5ts a problem :i* has n yet be5 solv$ by telescopic obs]vation4 ,x is extremely int]e/+ to note t1 z a rule1 ! axes on :i* ! important planets rotate are incl9$ at no great angles to ! pr9cipal plane ( ! sol> sy/em4 ,! great di/ance ( ,uranus has1 h[ev]1 prev5t$ a/ronom]s f /udy+ ! rotation ( t planet 9 ! ord9>y mann]1 by obs]vation ( ! displacem5t ( m>ks on its surface4 ,s f> z telescopic obs]vations are conc]n$1 we are !re=e 9 ignorance z to ! axis ab\t :i* ,uranus revolves4 ,if1 foll[+ ! analogy ( ,jupit]1 or ,saturn1 or ,m>s1 or ! e>?1 ! rotation ( ,uranus 0 conduct$ ab\t an axis1 n greatly incl9$ f ! p]p5dicul> to ! ecliptic1 !n ! rotation ( ,uranus w\ld be ab\t an axis v f> f p]p5dicul> to ! plane 9 :i* its satellites revolve4 ,! analogy ( ! o!r planets seems to sugge/ t ! rotation ( a planet %\ld be ne>ly p]p5dicul> to ! plane 9 :i* its satellites revolve4 ,z ! "q is "o :i* does n admit ( be+ decid$ by obs]vation1 we may v5ture to rem>k t ! necessity = a decl9+ ratio ( en]gy to mom5t ( mom5tum 9 ! ,uranian sy/em provides a sugge/ion4 ,! mom5t ( mom5tum ( a sy/em1 su* z t ( ,uranus & its satellites1 is d]iv$ p>tly f ! movem5ts ( ! satellites & p>tly f ! rotation ( ! planet itself4 ,f ! illu/rations we h already giv51 x is pla9 t ! requisite mom5t ( mom5tum is compatible ) a comp>atively small en]gy only :5 ! sy/em is s adju/$ t ! axis ( rotation ( ! planet is p]p5dicul> to ! plane 9 :i* ! satellites revolve1 or 9 o!r words :5 ! satellites revolve 9 ! plane ( ! equator ( ! planet4 ,we d n expect t ?is condition w be compli$ ) to ! fulle/ ext5t 9 any memb]s ( ! sol> sy/em4 ,!re is inde$ an obvi\s exception2 = ! moon1 9 its revolution ab\t ! e>?1 does n revolve exactly 9 ! e>?'s equator4 ,we might1 h[ev]1 expect t ! t5d5cy w\ld be = ! movem5ts to adju/ !mselves 9 ?is mann]4 ,x seems !re=e likely t ! direction ( ! axis ( ,uranus is p]p5dicul>1 or ne>ly s1 to ! plane ( ! movem5ts ( its satellites4 ,at ?is po9t we take occasion to answ] an objection :i* may p]haps be urg$ aga9/ ! doctr9e ( mom5t ( mom5tum z "h appli$4 ,i h %[n t ! t5d5cy ( ?is dynamical pr9ciple is to r$uce ! movem5ts t[>ds "o plane4 ,x may be object$ t if !re is ?is t5d5cy1 :y is x t ! movem5ts h n all be5 br\ght into ! same plane exactly8 ,?is has be5 accompli%$ 9 ! case ( ! bodies =m+ ,saturn's r+1 & p]haps 9 ! satellites ( ,uranus4 ,b :y is x t all ! great planets ( our sol> sy/em h n be5 br\ght to revolve absolutely 9 ! same plane8 ,we answ] t ! op]ations ( ! =ces by :i* ?is adju/m5t is effect$ are necess>ily extremely sl[4 ,! process is /ill go+ on1 & x may ultimately rea* completion4 ,b x is to be p>ticul>ly obs]v$ t ! ne>] ! approa* is made to ! f9al adju/m5t1 ! sl[] mu/ be ! process ( adju/m5t1 & ! less effici5t are ! =ces t5d+ to br+ x ab\t4 ,= ! purpose ( illu/rat+ ?is1 we may e/imate ! effici5cy ( ! =ces 9 flatt5+ d[n ! sy/em 9 ! foll[+ mann]4 ,suppose t !re are two circul> orbits at "r angles to ea* o!r1 & t we measure ! effici5cy ( ! action t5d+ to br+ ! planes to co9cide by #ajj4 ,:5 ! planes are at an angle ( ?irty degrees ! effici5cy is repres5t$ by #ej1 & :5 ! incl9ation is only five degrees ! effici5cy is no m ?an #i1 & ! effici5cy gradually less5s z ! angle decl9es4 ,z ! angles ( incl9ation ( ! planes 9 ! sol> sy/em are s small1 we see t ! effici5cy ( ! flatt5+ op]ation 9 ! sol> sy/em mu/ h dw9dl$ correspond+ly4 ,h5ce we ne$ n be surpris$ t ! f9al r$uction ( ! orbits into ! same plane has n yet be5 absolutely complet$4 ,c]ta9ly ! mo/ num]\s1 & p]haps ! gr&e/1 illu/rations ( ! op]ation ( ! great natural pr9ciples we h be5 consid]+ are to be f\nd 9 ! case ( ! spiral nebul4 ,! *>act]i/ic appe>ance ( ^! objects dem&s special explanation1 & x is to dynamics we mu/ look = t explanation4 ,z to ! orig9al cause ( a nebula we %all h some?+ to say 9 a future *apt]4 ,at pres5t we are only consid]+ h[1 :5 a nebula has come into exi/5ce1 ! action ( kn[n dynamical pr9ciples w m\ld t nebula into =m4 ,z an illu/ration ( a nebula1 9 :at we may describe z its comp>atively primitive %ape1 we may take ! ,great ,nebula 9 ,orion4 ,?is /up5d\s mass ( vaguely diffus$ vap\r may probably be reg>d$ z 9 an e>ly /age :5 contra/$ ) ! spirals4 ,we h already %[n h[ ! spectroscopic evid5ce demon/rates t ! fam\s nebula is actually a gase\s object4 ,x /&s ?us 9 m>k$ contra/ ) _m o!r nebul :i*1 by n yield+ a gase\s spectrum1 seem to in=m u t !y are objects :i* h advanc$ to a fur!r /age 9 _! developm5t ?an su* masses ( m]e gl[+ gas z are f\nd 9 ! spl5did object 9 ,orion4 ,! developm5t ( a nebula mu/ f dynamical pr9ciples proce$ along ! l9es t we h already indicat$4 ,we %all assume t ! nebula is suffici5tly isolat$ f surr\nd+ objects 9 space z to be practically free f di/urb+ influ5ces produc$ by ^! objects4 ,we %all !re=e suppose t ! evolution ( ! nebula proce$s solely 9 consequ5ce ( ! mutual attractions ( its v>i\s p>ts4 ,9 its orig9al =mation ! nebula receives a c]ta9 end[m5t ( en]gy & a c]ta9 end[m5t ( mom5t ( mom5tum2 ! m]e fact t we see ! nebula1 ! fact t x radiates light1 %[s t x mu/ be exp5d+ en]gy1 & ! decl9e ( ! en]gy w proce$ cont9u\sly f ! =mation ( ! object4 ,! laws ( dynamics assure u t no matt] :at may be ! losses ( en]gy :i* ! nebula suff]s ?r\gh radiation or ?r\gh ! collisions ( its p>ticles1 or ?r\gh _! tidal actions1 or 9 any way :atev] f _! mutual actions1 ! mom5t ( mom5tum mu/ rema9 un*ang$4 ,z ! ages roll by1 ! nebula mu/ gradually come to dispose itself1 s t ! mom5t ( mom5tum %all be ma9ta9$1 not)/&+ t ! en]gy may h wa/$ away to no m ?an a fraction ( its orig9al am\nt4 ,orig9ally !re 01 ( c\rse1 "o plane1 9 :i* ! mom5t ( mom5tum 0 a maximum4 ,x is :at we h call$ ! pr9cipal plane ( ! sy/em1 & ! evolution t5ds 9 ! direction ( mak+ ! nebula gradually settle d[n t[>ds ?is plane4 ,we h se5 t ! mom5t ( mom5tum c be su/a9$ ) ! utmo/ economy ( en]gy by adju/+ ! movem5ts ( ! p>ticles s t !y all take place 9 orbits p>allel to ?is plane1 & ! mutual attractions ( ! sev]al p>ts w gradually t5d to br+ ! planes ( ! diff]5t orbits into co9cid5ce4 ,e collision betwe5 two atoms1 e ray ( light s5t =?1 conduce to ! f9al result4 ,h5ce x is t ! nebula gradually t5ds to ! =m ( a flat plane4 ,?is is ! fir/ po9t to be notic$ 9 ! =mation ( a spiral nebula4 ,b !re is a fur!r consid]ation4 ,z ! nebula radiates its light & its heat1 & ?us loses its en]gy1 x mu/ be und]go+ cont9ual contraction4 ,concurr5tly ) its gradual assumption ( a flat =m1 ! nebula is also becom+ small]4 ,"h aga9 t fundam5tal conception ( ! cons]vation ( mom5t ( mom5tum w give u important in=mation4 ,if ! nebula contracts1 t is to say1 if ea* ( its p>ticles draws 9 clos] to ! c5tre1 ! orbits ( ea* ( its p>ticles w be r$uc$4 ,b ! quantity ( areas to be describ$ ea* second mu/ be kept up4 ,we h po9t$ out t x is inf9itely improbable ! sy/em %\ld h be5 />t$ )\t any mom5t ( mom5tum1 & ?is condition ( affairs be+ inf9itely improbable1 we dismiss any ?\ght ( its occurr5ce4 ,z ! p>ticles settle t[>ds ! plane1 ! areas swept out by ! movem5ts to ! "r1 & ^? areas swept out by ! movem5ts to ! left1 w n be id5tical2 !re w !re=e be a balance on "o side1 & t balance mu/ be ma9ta9$ )\t ! slighte/ alt]ation ?r\gh\t all "t4 ,z ! p>ticles get clos] toge!r1 & z _! orbits less51 x w necess>ily happ5 t ! velocities ( ! p>ticles mu/ increase1 = n o!rwise c ! fundam5tal pr9ciple ( ! con/ant mom5t ( mom5tum be ma9ta9$4 ,& z ! sy/em gets small] & small]1 by contraction f an orig9al widely diffus$ nebulosity1 l1 p]haps1 ! nebula 9 ,orion1 d[n to a spiral nebula :i* may occupy n a ?\s&? or a million? "p ( ! orig9al volume1 ! areas w be kept up by curr5ts ( p>ticles mov+ 9 ! two opposite ways ar\nd a c5tral po9t4 ,z ! contraction proce$s1 ! oppos+ p>ticles w occasionally collide1 & consequ5tly ! t5d5cy w be = ! pr$om9ant side to ass]t itself m & m1 until at la/ we may expect a condition to be rea*$ 9 :i* all ! movem5ts w take place 9 "o direction1 & :5 ! sum ( ! areas describ$ 9 a second1 by ea* ( ! p>ticles1 multipli$ by _! respective masses1 w repres5t ! orig9al end[m5t ( mom5t ( mom5tum4 ,?us we f9d t ! :ole object becomes ultimately possess$ ( a movem5t ( rotation4 ,! same argum5t w %[ t ! inn] p>ts ( ! nebula w revolve m rapidly ?an ^? 9 ! ext]ior4 ,?us we f9d ! :irlpool /ructure produc$1 & ?us we obta9 an explanation1 n only ( ! flatness ( ! nebula1 b also ( ! spiral =m :i* x possesses4 ,x is n too mu* to say t ! op]ation ( ! causes we h specifi$1 if ext]nal influ5ce be )held1 t5ds ultimately to produce ! spiral1 :atev] may h be5 ! orig9al =m ( ! object4 ,no long]1 !re=e1 ne$ we feel any hesitation 9 believ+ ! assurance ( ,pr(essor ,keel] t out ( ! "o hundr$ & tw5ty ?\s& nebul1 at lea/ "o-half mu/ be spirals4 ,we h f\nd 9 dynamics an explanation ( t rem>kable type ( object :i* we h n[ reason to ?9k is "o ( ! great fundam5tal =ms ( nature4 ---------------------------------------- -------------------------------- ,,*apt] ,,xii4 ,,! ,,evolution ,,( ,,! ,,sol> ,,sy/em4 ,! ,primval ,nebula--,a ,planet>y ,nebula--,! ,progress ( its ,evolution--,unsymmetrical ,contraction--,c5tres ( ,cond5sation--,! ,=m ultimately assum$--,diff]5ce betwe5 ,small ,bodies & ,l>ge--,e>? & ,sun--,accel]ation ( ,velocities--,=mation ( ! ,subord9ate ,sy/ems--,special ,circum/ances 9 ! case ( ! ,e>? & ,moon--,va/ ,scale ( ! ,spirals--,spectra ( ! ,spiral ,nebul4 ,,we %all consid] 9 ?is *apt] :at we believe to h be5 ! hi/ory ( t spl5did sy/em1 =m$ by ! planets "u ! presid+ control ( ! sun4 ,! gr\nd ov] :i* we h already pass$ w prep>e u = ! fam\s doctr9e t ! sun1 ! planets & _! satellites1 toge!r ) ! o!r bodies :i* =m ! gr\p we call ! sol> sy/em1 h orig9at$ f ! contraction ( a primval nebula4 ,z ! ages roll$ by1 ?is great primval nebula began to und]go modification4 ,9 accordance ) ! univ]sal law :i* we f9d obey$ 9 our laboratories1 & :i* we h reason to believe mu/ be equally obey$ ?r\gh\t ! :ole ext5t ( space1 ?is nebula1 if w>m] ?an ! surr\nd+ space1 mu/ beg9 to radiate =? its heat4 ,we are to assume t ! nebula does n receive heat f o!r bodies1 adequate to comp5sate = t :i* x dissipates by radiation4 ,!re is ?us a loss ( heat & consequ5tly ! nebula mu/ beg9 to contract4 ,its mat]ial mu/ gradually draw toge!r1 & mu/ d s "u ! op]ation ( ^? fundam5tal laws :i* we h expla9$ 9 ! la/ *apt]4 ,! contraction1 or r ! cond5sation1 ( ! mat]ial w\ld ( c\rse g5]ally be greate/ at ! c5tral portion ( ! nebula4 ,?is is especially noticeable 9 ! photograph ( ! great spiral already ref]r$ to4 ,b 9 addition to ?is special cond5sation at ! c5tre1 ! conc5tration takes place also1 ?\gh 9 a less] degree1 at _m o!r po9ts ?r\gh\t ! :ole ext5t ( ! gl[+ mass4 ,ea* c5tre ( cond5sation :i* 9 ?is way becomes e/abli%$ t5ds cont9ually to increase4 ,9 consequ5ce ( ?is law1 z ! great nebula contract$ & z ! great bulk ( ! mat]ial drew 9 t[>ds ! c5tre1 !re 7 isolat$ regions 9 ! nebula :i* became subord9ate c5tres ( cond5sation4 ,p]haps 9 ! primval nebula1 f :i* ! sol> sy/em orig9at$1 !re 7 half-a-doz5 or m ( ^! c5tres t 7 ( conspicu\s importance1 :ile a mu* l>g] numb] ( small po9ts 7 also di/+ui%$ f ! surr\nd+ nebula4 7,figs4 #dj & #da47 ,& /ill ! contraction w5t on4 ,! heat1 or r ! en]gy ) :i* ! nebula _h be5 orig9ally *>g$1 0 /ill be+ dissipat$ by radiation4 ,we give no e/imate ( ! myriads ( ye>s t ea* /age ( ! mighty process mu/ h occupi$4 ,! t5d5cy ( ! trans=mation 01 h[ev]1 always 9 "o direction4 ,x did at la/ result 9 a great increase ( ! d5sity ( ! sub/ance ( ! nebula1 bo? 9 ! c5tral regions z well z 9 ! subord9ate p>ts4 ,9 due "t ?is increase 9 d5sity _h rea*$ su* a po9t t ! mat]ials 9 ! cond5s+ c5tres c\ld be no long] describ$ z reta9+ ! gase\s =m4 ,b ?\gh heat 0 incessantly be+ radiat$ f ! great nebula1 x did n necess>ily foll[ t ! nebula 0 itself los+ temp]ature4 ,?is is a seem+ p>adox to :i* we h already _h occasion to ref] 9 ,*apt] ,,vi4 ,we ne$ n n[ fur!r ref] to x ?an to rememb] t1 9 speak+ ( ! loss ( heat f ! nebula1 x w\ld sometimes n be correct to describe ! op]ation z t ( cool+4 ,up to a c]ta9 /age 9 ! cond5sation1 ! loss ( heat leads r to an augm5tation ( temp]ature ?an to its decl9e4 ,we are ?us l$ to see h[ ! laws ( heat1 aft] be+ 9 action on ! primitive nebula = a p]iod ( illimitable ages1 h at la/ effect$ a m>vell\s trans=mation4 ,t nebula has cond5s$ into a va/ c5tral mass ) a numb] ( associat$ subord9ate portions4 ,we may suppose t ! orig9al nebula 9 ! c\rse ( "t does practically disappe>4 ,x is absorb$ by ! attraction ( ^? pond]\s c5tres :i* h gradually develop$ ?r\gh\t its ext5t4 ,! l>ge c5tral body1 & p]haps "s ( ! o!r bodies ?us evolv$1 are at fir/ ( s high a temp]ature t a copi\s radiation ( heat /ill goes =? f ! sy/em4 ,z !y dis*>ge _! /ores ( heat1 ! small] bodies %[ ! effects ( loss ( heat m rapidly ?an ^? :i* are l>g]4 ,x is inde$ obvi\s t a small body mu/ cool m rapidly ?an a big "o4 ,x is suffici5t to note t ! cool+ takes place f ! surface1 & t ! bigg] ! body ! l>g] ! quantity ( mat]ial t x conta9s = ea* unit ( sup]ficial area4 ,if ! radius ( a sph]e be d\bl$1 its volume is increas$ eightfold1 :ile its surface is only increas$ f\rfold4 ,illu/ration3 ,fig4 #ch4--,,! ,,r+ ,,nebula ,,9 ,,lyra 7,lick ,obs]vatory74 7,f ! ,royal ,a/ronomical ,society ,s]ies47 ,let u n[ conc5trate our att5tion on two ( ! bodies :i*1 aft] imm5se ages1 h be5 =m$ f ! cond5sation ( ! primval nebula4 ,let "o ( ! two bodies be t c5tral object1 :i* prepond]ates s enorm\sly t its mass is a ?\s&fold t ( all ! o!rs tak5 toge!r4 ,let ! o!r be "o ( ! small] bodies4 ,z x p>ts ) its heat1 ! small] body1 :i* has orig9ally cond5s$ f ! nebula1 w assume "s ( ! features ( a mass ( molt5 liquid4 ,f ! liquid condition1 ! body w pass ) comp>ative rapidity into a solid /ate1 at lea/ on its out] p>ts4 ,! ext]ior ( ?is body w !re=e become solid :ile ! int]ior is /ill at an excessively high temp]ature4 ,! out] mat]ial1 :i* has assum$ ! solid =m1 is con/itut$ ( ! elem5ts ) :i* we are acqua9t$1 & is 9 ! =m ( :at ! geologi/ w\ld class z ! igne\s rocks1 ( :i* granite is ! be/ kn[n example4 ,! %ell ( h>d rocks outside encloses ! mat]ial :i* is /ill heat$ & molt5 inside4 ,su* a cru/ w\ld c]ta9ly be an extremely bad conductor ( heat4 ,! int]nal heat is !re=e greatly ob/ruct$ 9 its passage outw>ds to ! surface4 ,! int]nal heat may consequ5tly be pres]v$ 9 ! int]ior ( ! body = an enorm\sly protract$ p]iod1 a p]iod p]haps comp>able ) ^? imm5se ages :i* ! evolution ( ! body f ! primval nebula has dem&$4 ,! small] body may h ?us atta9$ a condition 9 :i* ! temp]ature reign+ on its surface is regulat$ *iefly by ! ext]nal conditions ( ! space ar\nd1 :ile ! int]nal p>ts are /ill highly *>g$ ) ! primitive heat f ! orig9al nebula4 ,! great c5tral mass1 :i* we may reg>d z ?\s&s ( times great] ?an t ( ! subord9ate body1 cools mu* m sl[ly4 ,! cool+ ( ?is great mass is s enorm\sly protract$ 9 comp>ison ) t ( ! small] body t x is q conceivable ! c5tral mass may cont9ue to gl[ ) int5se f]v\r = imm5se ages aft] ! small] body has become cov]$ ) h>d rock4 ,x w1 ,i hope1 be cle> t ! two bodies to :i* ,i am "h allud+ are n m]ely imag9>y objects4 ,! small body1 :i* has s f> cool$ d[n t its surface has lo/ all indication ( int]nal heat1 is ( c\rse our e>?4 ,! great c5tral mass :i* /ill gl[s ) int5se f]v\r is ! sun4 ,su* is 9 outl9e ! orig9 ( ! sun & ! e>? z sugge/$ by ! nebul> !ory4 ,:at we h said ( ! =mation ( ! e>? w equally apply to ! evolution ( o!r deta*$ portions ( ! primitive nebula4 ,!re may be sev]al ( ^!1 & !y may v>y greatly 9 size4 ,! small] !y are ! m rapidly 9 g5]al w ! sup]abundant heat be radiat$ away1 & ! soon] w ! surface ( t planet acquire ! temp]ature :i* is det]m9$ by ! surr\nd+ conditions4 ,!re are1 h[ev]1 _m modify+ circum/ances4 ,x is ess5tial to notice t ! primval nebula mu/ h _h "s initial mom5t ( mom5tum1 unless we are to assume ! occurr5ce ( t :i* is inf9itely improbable4 ,x w\ld h be5 inf9itely improbable = ! sy/em n to h _h "s mom5t ( mom5tum orig9ally4 ,z ! evolution proce$s1 & z ! en]gy is exp5d$1 :ile ?is orig9al end[m5t ( mom5t ( mom5tum is pres]v$1 we f9d1 z expla9$ 9 ! la/ *apt]1 ! sy/em gradually settl+ d[n into proximity to a plane1 & gradually acquir+ a uni=m direction ( revolution4 ,h5ce we see t ea* ( ! subord9ate masses :i* ultimately consolidate to =m a planet h a motion ( revolution ar\nd ! c5tral body4 ,9 l mann] ! c5tral body itself rotates1 & all ^! motions are p]=m$ 9 ! same direction4 ,9 addition to ! revolutions ( ! planets ar\nd ! sun1 !re are o!r motions :i* c be acc\nt$ = z consequ5ces ( ! contraction ( ! nebula4 ,we n[ ref] to t c5tral portion :i* is to =m ! sun1 & consid]1 9 ! fir/ in/ance1 only "o ( ! subord9ate portions :i* is to =m a planet4 ,z ^! two bodies =m "p ( ! same nebul\s mass !y w to a c]ta9 ext5t rotate toge!r z "o piece4 ,if any body is rotat+ z a :ole1 e "p ( t body is also 9 actual rotation4 ,we %all ref] to ?is aga9 lat] on2 b = ! pres5t x is suffici5t to obs]ve t z ! planet 0 orig9ally cont9u\s ) ! sun1 x _h a motion ( rotation besides its motion ( revolution1 & x revolv$ r\nd its own axis 9 a p]iod equal to t ( its revolution r\nd ! sun4 ,9 ! beg9n+ ! rotation ( ! planet 0 !re=e an exce$+ly sl[ movem5t4 ,b x became subsequ5tly accel]at$4 ,= we h already expla9$ t ea* planet is by itself subject$ to ! law ( ! cons]vation ( mom5t ( mom5tum4 ,z ea* planet assumes a sep>ate exi/5ce1 x draws to itself its %>e ( ! mom5t ( mom5tum1 & t mu/ be /rictly pres]v$4 ,b ! planet1 or r ! mat]ials :i* are to =m ! future planet1 are all ! "t %r9k+2 !y are draw+ m closely toge!r4 ,if1 !re=e1 ! area :i* ea* p>ticle ( ! planet describes :5 multipli$ by ! mass ( t p>ticle & add$ to ! simil> products aris+ f all ! o!r p>ticles1 is to rema9 con/ant1 x becomes necess>y t j z ! orbits ( ^! p>ticles dim9i% 9 size1 s mu/ ! spe$ at :i* !y revolve increase4 ,we ?us f9d t !re is a t5d5cy 9 ! planet to accel]ate its rotation4 ,& ?us we see t a "t w come :5 ! planet1 hav+ assum$ an indep5d5t exi/5ce1 w be f\nd rotat+ r\nd its axis ) a velocity :i* mu/ be consid]$ high 9 comp>ison ) ! angul> velocity :i* ! planet _h :ile x /ill =m$ "p ( ! orig9al nebula4 ,z ! planets h be5 evolv$ s z to describe _! sev]al orbits ar\nd ! sun1 s 9 l mann] ! small] sy/ems ( satellites h be5 s evolv$ z to describe _! orbits r\nd ! sev]al planets t are _! respective prim>ies4 ,:5 a planet1 or r ! mat]ials :i* 7 draw+ toge!r to =m a planet1 _h acquir$ a pr$om9ant attraction = ! p>ts ( ! primval nebula 9 _! locality1 a portion ( ! nebul\s mat]ial became specially associat$ ) ! planet4 ,z ! planet ) ?is nebul\s mat]ial became sep>at$ f ! c5tral contract+ sun1 or became1 z x 71 left beh9d :ile ! sun 0 draw+ into itself ! mat]ial :i* surr\nd$ x ! planet & its associat$ nebula und]w5t on a m9iature scale an evolution simil> to t :i* _h already tak5 place 9 ! =mation ( ! sun & ! planets z a :ole4 ,9 ?is mann] second>y sy/ems seem sometimes to h _h _! orig94 ,we %\ld1 h[ev]1 say t ?\gh :at we h "h indicat$ appe>s to expla9 fully ! evolution ( "s ( ! sy/ems1 su*1 = in/ance1 z t ( ,jupit] & 8 f\r moons1 or ,saturn & 8 eight or n9e1 ! circum/ances ) reg>d to ! e>? & ! moon are su* z to require a v diff]5t explanation ( ! orig9 ( our satellite4 ,9 ! fir/ place we may notice t ! great mass ( ! moon1 9 comp>ison ) ! e>?1 is a :olly exceptional feature 9 ! relations betwe5 ! planets & _! satellites 9 ! o!r p>ts ( ! sy/em4 ,9 no o!r in/ance does ! mass ( a satellite be> to ! mass ( ! planet a ratio any?+ l s great z ! ratio ( our moon to ! e>?4 ,! moon has a mass :i* is ab\t "o-eightie? ( ! mass ( ! e>?1 :ile ev5 ! l>ge/ ( ,jupit]'s satellites has n "o t5-?\s&? "p ( ! mass ( ! planet itself4 ,! evolution ( ! e>? & moon sy/em has be5 br\ght ab\t 9 a mann] v diff]5t f t ( ! evolution ( ! o!r sy/ems ( satellites4 ,we d n "h ent] into any discussion ( ! matt]4 ,we m]ely rem9d ! read] t x is n[ kn[n1 ma9ly by ! rese>*es ( ,pr(essor ,g4 ,h4 ,d>w91 t 9 all probability ! moon 0 orig9ally "p ( ! e>?1 & t a p>tition hav+ occurr$ :ile ! mat]ials ( ! e>? & moon 7 /ill 9 a pla/ic /ate1 a small portion broke away to =m ! moon1 leav+ beh9d ! great] mass to =m ! e>?4 ,!n1 "u ! influ5ce ( tides1 :i* may agitate a mass ( molt5 rock1 z ! moon 0 once 7,fig4 #ci71 j z !y may agitate an ocean1 ! moon 0 =c$ away1 & 0 ultimately conduct$ to its pres5t orbit4 ,illu/ration3 ,fig4 #ci4--,,lun> ,,crat]s3 ,,hyg9us ,,& ,,albategnius4 7,photograph$ by ,,mm4 ,loewy & ,puiseux47 ,x 0 at fir/ tempt+ to imag9e t a !ory :i* acc\nt$ s satisfactorily = ! evolution ( ! moon f ! e>? might also acc\nt 9 a simil> mann] = ! evolution ( ! e>? f ! sun4 ,_h ?is be5 ! case1 x is ne$less to say t ! pr9ciples we n[ accept 9 ! nebul> !ory w\ld h ne$$ l>ge modification1 if n actual ab&onm5t4 ,a close exam9ation into ! actual /ati/ics br+s =cibly be=e u ! exceptional "* ( ! e>?-moon sy/em4 ,x c be demon/rat$ t ! e>? c\ld n h be5 evolv$ f ! sun 9 ! same mann] z !re is e reason to believe t ! moon has be5 evolv$ f ! e>?4 ,! evolution ( ! satellites ( ,jupit] has proce$$ along l9es q diff]5t f ^? ( ! evolution ( ! moon f ! e>?1 s t we may1 p]haps1 f9d 9 ! evolution ( ! satellites ( ,jupit] an illu/ration 9 m9iature ( ! way 9 :i* ! planets !mselves h be5 evolv$ 9 relation to ! sun4 ,we mu/ n =get t ! only spiral nebul :i* lie )9 ! rea* ( our p[]s ( obs]vation1 :e!r telescopic or photographic1 appe> to be objects ( enorm\sly great] cosmical magnific5ce ?an 0 t primval nebula f :i* s insignificant an object z ! sol> sy/em has sprung4 ,! great spirals1 s f> z we c tell at pres5t1 appe> to be ?\s&s ( times1 or ev5 millions ( times1 great] 9 area ?an ! sol> sy/em4 ,at ?is po9t1 h[ev]1 we mu/ speak ) special caution1 hav+ due reg>d to ! paucity ( our k ( a mo/ important elem5t4 ,a/ronom]s mu/ confess t no ef=ts :i* h yet be5 made to det]m9e ! dim5sions ( a nebula h be5 cr[n$ ) success4 ,we h n any precise idea z to :at ! di/ance ( ! great spiral might be4 ,we g5]ally take = grant$ t ^! nebul are at di/ances comp>able ) ! di/ances ( ! />s4 ,on ?is assumption we e/imate t ! spiral nebul mu/ transc5d enorm\sly ! dim5sions ( ! primval nebula f :i* ! sol> sy/em has sprung4 ,! spiral nebul t h s f> come )9 our obs]vation seem to be objects ( an ord] ( magnitude altoge!r high] ?an a sol> sy/em4 ,!y seem to be engag$ on ! maje/ic function ( evolv+ sy/ems ( />s l ! ,milky ,way1 r ?an on ! inconsid]able task ( produc+ a sy/em :i* conc]ns only a s+le /> & n a galaxy4 ,illu/ration3 ,fig4 #dj4--;,a ,,rem>kable ,,spiral 7n4g4c4 #fbh2 9 ,pisces74 7,photograph$ by ,dr4 ,isaac ,rob]ts1 ,f4,r4,s47 ,! spiral =m ( /ructure is "o 9 :i* ,nature seems to delight4 ,we f9d x 9 ! organic _w alli$ ) objects ( ! greate/ int]e/ & beauty4 ,! ammonite1 a magnific5t spiral %ell sometimes exce$+ ?ree feet 9 diamet]1 belongs to a type :i* dom9at$ ! wat]s ( ! globe 9 second>y times1 & :i* /ill survives 9 ! nautilus4 ,! same =m is reproduc$ 9 m9ute creations totally diff]5t f ammonites 9 _! zoological relations4 ,among ! exquisite =am9if]a :i* ! microscopi/ kn[s s well may be f\nd mo/ delicate & beautiful spirals4 ,j z we see e range ( spiral 9 ! animal _w1 f an organism invisible to ! nak$ eye1 up to an ammonite a y>d or m across1 s x w\ld seem t !re are spiral nebul rang+ f su* va/ objects z ! great spiral 9 ,canes ,v5atici d[n to su* relatively m9ute spirals z ^? ^: humble function x is to develop a sol> sy/em4 ,x is no m ?an a reasonable supposition t ! great spirals 9 ! heav5s are probably only ! m maje/ic objects ( an extremely num]\s class4 ,! small] objects ( ?is type--among :i* we might expect to f9d nebul l1 9 size & importance1 to ! primval nebula ( our sy/em--are s small t !y h n yet be5 recognis$4 ,x %\ld at ?is /age be m5tion$ t sev]al curi\s small planet>y nebul h 9 ^! mod]n days be5 discov]$ by _! peculi> spectra4 ,if ! nebul\s "* ( ^! mo/ int]e/+ objects _h n be5 accid5tally disclos$ by *>act]i/ic l9es 9 _! spectra1 ^! und\bt$ nebul w\ld ea* h be5 classifi$ m]ely z />s4 ,?is fact w lead u to ! surmise t !re mu/ be myriads ( nebul 9 ! heav5s1 too small to come )9 ! range ( our telescopes or ( our mo/ s5sitive photographic plates4 ,suppose t a facsimile ( ! primval nebula ( our sy/em1 precisely correspond+ ) x 9 size & id5tical ) x 9 e detail1 7 at ! pres5t mom5t locat$ 9 space1 b at a di/ance f our /&po9t1 z great z ! di/ance (1 let u say1 ! great spiral2 x seems c]ta9 t ?is nebula1 ev5 ?\gh x conta9$ ! mat]ials = a huge sun & a pot5tial sy/em ( mighty planets1 if n actually invisible to u "h1 w\ld 9 all probability dem& ! be/ p[]s ( our in/rum5ts to reveal x1 & !n x w\ld be class$ n z a nebula at all b z a /> ( p]haps ! #ab? or #ae?1 or ev5 small] magnitude4 ,illu/ration3 ,fig4 #da4--;,a ,,cle>ly ,,cut ,,spiral 7n4g4c4 #dcba2 9 ,coma ,b]5ices74 7,photograph$ by ,dr4 ,isaac ,rob]ts1 ,f4,r4,s47 ,x is to be rememb]$ t ! class ( m9ute planet>y nebul make !mselves kn[n solely by ! fact t !y exhibit ! bright l9e indicative ( gase\s spectra4 ,if ^! objects 7?\gh /ill nebul7 _h n display$ gase\s spectra1 x is c]ta9 !y w\ld h escap$ detection1 at lea/ by ! process :i* has actually prov$ s successful4 ,! cont9u\s b& ( light :i* !y w\ld !n h pres5t$ c\ld n be discrim9at$ f ! b& ( light f a />4 ,x is !re=e n improbable t among ! />-l bodies :i* h be5 repres5t$ on our photographs1 !re may be "s :i* are really m9ute spiral nebul4 ,9 g5]al a /> is a m9ute po9t ( light :i* no augm5tation ( telescopic p[] & no magnification w %[ o!rwise ?an z a po9t1 grant$ only good optical conditions & good opportunity s f> z ! atmosph]e is conc]n$4 ,x has1 h[ev]1 be5 occasionally not$ t c]ta9 s-call$ />s are n m]e po9ts ( light2 !y d possess :at is describ$ z a disc4 ,x is n at all impossible t ! objects s ref]r$ to are spiral nebul4 ,we may describe !m z =m$ on a small scale 9 comp>ison ) ! great spiral or ! nebula 9 ,&rom$a4 ,b ! smallness "h ref]r$ to is only relative4 ,!y are 9 all probability q z va/ z ! primval spiral nebula f :i* ! sol> sy/em has be5 evolv$1 ?\gh n s l>ge z ^? curi\s r+-%ap$ nebul ( :i* ! mo/ celebrat$ example lies 9 ! con/ellation ,lyra 7,fig4 #ch74 ,su* is an outl9e ( :at we believe to h be5 ! hi/ory ( our sol> sy/em4 ,we h already giv5 ! evid5ce d]iv$ f ! laws ( heat4 ,we h n[ to consid] ! evid5ce :i* has be5 d]iv$ f ! con/itution ( ! sy/em itself4 ,we %all see h[ /rongly x supports ! belief t ! orig9 ( sun & planets has be5 su* z ! nebul> !ory sugge/s4 ---------------------------------------- -------------------------------- ,,*apt] ,,xiii4 ,,! ,,unity ,,( ,,mat]ial ,,9 ,,! ,,heav5s ,,& ,,! ,,e>?4 ,cl\ds--,fire-,mi/--,vap\r ( ,plat9um--,compon5ts ( ,*alk--,con/itu5ts ( ! ,primval ,fire-,mi/--,objections--,orig9 ( ! ,mi/--,rem>kable ,discov]y ( ! ,c5tury--,analysis ( ! ,sun--,spectroscopic ,analysis--,simplicity ( ,sol> ,*emi/ry--,potassium--,a ,drop ( ,wat]--,! ,sol> ,elem5ts--,calcium--,! ,mo/ ,important ,l9es 9 ! ,sol> ,spectrum--,photograph ( ! ,sun--,c>bon 9 ! ,sol> ,cl\ds--,function ( ,c>bon--,buns5's ,burn] ,illu/rates ,c>bon 9 ! ,sun--,c>bon ,vap\rs 9 ! ,sun--,! ,suppos$ ,limit to our ,k ( ! ,heav5s--,*>act]i/ics ( ,spectroscopic ,"w--,be>+ on ! ,nebul> ,!ory4 ,,9 consid]+ h[ ! =mation ( our sol> sy/em 0 br\ght ab\t1 we naturally fir/ enquire z to ! mat]ial ( :i* ?is sup]b s*eme is con/ruct$4 ,:at 7 ! mat]ials already to h& f :i*1 9 pursuance ( ! laws ( ,nature1 ! sol> sy/em 0 evolv$8 ,see ! robu/ & solid nature ( ?is e>? ( ours1 & ! robu/ & solid nature ( ! moon & ! planets4 ,x might at fir/ sight be conclud$ t ! primitive mat]ials ( our e>? _h also be5 9 ! solid /ate4 ,b su* is n ! case4 ,! primitive mat]ial ( ! sol> sy/em 0 n solid1 x 0 n ev5 liquid4 ,:at we may describe z ! "m-sub/ance ( ! univ]se mu/ h be5 ( q a diff]5t nature2 we c give an illu/ration ( ! physical "* ( t sub/ance4 ,! lov] ( ,nature delights to look at ! m\nta9s & ! trees1 ! lakes & ! riv]s4 ,b he w n conf9e 8 reg>d m]ely to ! objects on ! e>?'s surface4 ,he1 no less ?an ! arti/ & ! poet1 delights to gaze at t en*ant+ sc5]y :i*1 day by day1 is display$ 9 inf9ite beauty ov]head2 t sc5]y :i* is n :olly )held ev5 f obs]v]s ^: lives may be pass$ amid ! busy haunts ( m51 t sc5]y :i* is s (t5 display$ on f9e days at all seasons4 ,we are allud+ to ^? cl\ds :i* add ! *>m ( inf9ite v>iety to ! sky above u4 ,x is necess>y = u n[ to ?9k ( matt] :5 x possesses nei!r ! d5sity ( a solid1 nor ! qualities ( a liquid1 b r :5 x has t delicate texture :i* ! cl\ds exhibit4 ,! primval mat]ial f :i* ! sol> sy/em has be5 evolv$ is ( a texture some:at simil> to t ( ! cl\ds4 ,?is primval mat]ial is nei!r solid nor liquid2 x is :at we may describe z vap\r4 ,b hav+ po9t$ to ! cl\ds 9 our own sky z illu/rat+1 9 a s5se1 ! texture ( ?is orig9al "m-sub/ance ( ! sol> sy/em1 we c c>ry ! analogy no fur!r4 ,^? d>k & ?reat5+ masses :i* =bode ! ?und]/orm1 or ^? beautiful fleecy cl\ds :i* enhance ! lovel9ess ( a summ]'s day1 are1 ( c\rse1 m]ely ! vap\rs ( wat]4 ,b ! vap\rs 9 ! "m-sub/ance f :i* sy/ems h be5 evolv$ 7 by no means ! vap\rs ( wat]4 ,!y 7 vap\rs ( a v diff]5t "*--vap\rs t sugge/ ! abodes ( ,pluto r ?an ! g5tle ra9 t blesses ! e>?4 ,9 ! "m-sub/ance ( ! sol> sy/em vap\rs ( a great v>iety ( sub/ances 7 bl5d$4 ,= 9 ! pot5t laboratory ( ,nature e sub/ance1 be x a metal or any o!r elem5t1 or any comp\nd1 no matt] h[ refractory1 w1 "u suitable circum/ances1 be dissolv$ into vap\r4 ,take1 = in/ance1 su* a mat]ial z plat9um4 ,c\ld any?+ be less l a vap\r ?an ?is silv]y metal8 ,we "k t plat9um is ! d5se/ ( all ! elem5ts4 ,we "k t plat9um1 m effectually ?an o!r metals1 resi/s liquefaction f ! application ( heat4 ,no ord9>y furnace c fuse plat9um2 yet 9 ano!r way we c ov]come ! resi/ance ( ?is metal4 ,! electric arc1 :5 suitably manag$1 yields a temp]ature high] ?an t ( any furnace4 ,let ! electric curr5t spr+ f "o pole ( plat9um to ano!r1 & a brilliant arc ( light is produc$ by ! gl[+ gas1 :i* is *>act]i/ic ( plat9um4 ,! light disp5s$ f t arc is diff]5t f ! light t w\ld be radiat$ if ! poles 7 ( any mat]ial o!r ?an plat9um4 ,"s ( ! plat9um has n alone be5 melt$1 x has actually be5 turn$ into vap\r by ! ov]p[]+ heat to :i* x has be5 subject$4 ,?us ! solidity ( ?is sub/ance1 :i* resi/s s /ubbornly ! action ( l[] temp]atures1 c be ov]come1 & ! v d5se/ ( all metals is dissolv$ into wisps ( vap\r4 ,we *oose ! case ( plat9um z an illu/ration because x is a sub/ance exceptionally d5se & exceptionally refractory4 ,if plat9um c be vaporis$1 !re is n mu* difficulty 9 see+ t o!r elem5ts mu/ be capable ( be+ vaporis$ also4 ,9 fact1 giv5 su* heat z is f\nd abundantly 9 natural s\rces1 !re is no kn[n elem5t1 or comb9ation ( elem5ts1 :i* w n assume ! =m ( gas or vap\r or cl\d4 ,at ! temp]ature ( ! sun a drop ( wat] w\ld be =?) resolv$ into its compon5t gases ( oxyg5 & hydrog54 ,9 l mann] a piece ( *alk1 if expos$ to ! sun1 w\ld be spe$ily trans=m$2 x w\ld fir/ be heat$ r$-hot & !n :ite-hot2 x is1 inde$1 :ite-hot *alk t gives u t limelight :i* we "k s well4 ,b ! heat ( ! sun is f> great] ?an ! temp]ature ( ! inc&esc5t lime4 ,! lime w\ld n only be heat$ :ite-hot by contact ) sol> heat1 b /ill fur!r /ages w\ld be rea*$4 ,x w\ld suff] decomposition4 ,x w\ld break up into ?ree diff]5t elem5ts3 !re w\ld be ! metal :i* we call calcium1 !re w\ld be oxyg51 & !re w\ld be c>bon4 ,ow+ to ! trem5d\s temp]ature ( ! sun ! metal w\ld n rema9 9 ! metallic =m2 x w\ld n be ev5 9 a liquid =m2 x w\ld become a gas4 ,! elem5ts :i* unite to =m ?is *alk w\ld be n only decompos$1 b !y w\ld be vaporis$4 ,:at is ?us /at$ ab\t ! drop ( wat] & ! *alk may1 s f> z we "k1 be /at$ equally ) reg>d to any o!r comp\nds4 ,x matt]s n h[ close may be ! *emical association 9 :i* ! elem5ts are jo9$3 no matt] h[ successfully ^? comp\nds may resi/ ! decomposition "u ! conditions ord9>ily prevail+ on e>?1 !y h to yield "u ! ov]:elm+ trial to :i* ! sun w\ld subject !m4 ,?\gh !re are _m elem5ts 9 ! sol> *emi/ry1 !re are no comp\nds4 ,at ! exalt$ temp]ature to :i* !y are expos$ 9 ! sun ! elem5ts are indispos$ = union ) ! o!r elem5ts !re met )1 & :i* are at ! same temp]ature4 ,9 ^! circum/ances1 !y successfully resi/ all alliances4 ,until ! la/ few ye>s no elem5ts 7 kn[n 9 our t]re/rial exp]i5ce :i* possess$ at ord9>y temp]atures ! same qualities ( resolute isolation :i* all elem5ts seem to display at extreme temp]atures4 ,! fam\s discov]y ( argon1 & ( o!r /range gases associat$ ) argon 9 ! atmosph]e & else:]e1 has reveal$1 to ! a/oni%m5t ( *emi/s & to ! great ext5sion ( k1 t we h ) u "h elem5ts :i* resi/ all solicitations to ent] into *emical union ) o!r sub/ances4 ,x is d\btless 9 consequ5ce ( ?is absolute refusal to unite t1 9 spite ( _! abundance & _! wide di/ribution1 ^! elem5ts h elud$ detection = c5turies4 ,to ! a/ronom] argon is bo? int]e/+ & in/ructive4 ,x %[s u an elem5t :i* possesses1 at ! ord9>y temp]atures ( ! surface ( ! e>?1 a prop]ty :i* is true ( all elem5ts :5 subject$ to su* temp]atures z are f\nd 9 ! sun4 ,?9k ( ! rocks :i* =m ! e>?'s cru/ & ( ! m9]als :i* lie f> bel[4 ,?9k ( ! soil :i* lies on its surface1 ( ! =e/s :i* t soil supports1 & ! crops :i* x br+s =?4 ,?9k ( ! wat]s ( ! ocean1 & ! ice ( ! ,poles4 ,?9k ( ! objects ( e k9d on ?is globe4 ,?9k ( ! /one walls ( a great build+1 ( ! iron us$ to give x /r5g?1 ( ! slates :i* cov] x1 & ( ! timb] :i* =ms its floors2 ?9k ( ! innum]able o!r mat]ials :i* h gone t[>ds its con/ruction2 ?9k ev5 ( ! elem5t>y sub/ances :i* g to =m ! bodies ( animals1 ( ! lime 9 _! bones1 & ( ! c>bon :i* is s intimately associat$ ) life itself4 ,! nebul> !ory decl>es t ^? mat]ials h n always be5 9 ! condition 9 :i* we n[ see !m2 t !re 0 a "t 9 :i* !y 7 s hot t !y 7 n 9 ! solid /ate2 !y 7 n ev5 9 ! fluid /ate1 b 7 all 9 roll+ volumes ( gl[+ vap\r :i* =m$ ! great primval fire-cl\d4 ,we mu/ und]/& ! composite nature ( ! primitive fire-mi/ f :i* our sol> sy/em orig9at$4 ,let me illu/rate ! matt] ?us3 ,we %all suppose t a het]og5e\s collection ( sub/ances is br\ght toge!r1 ! items ( :i* may be some:at z foll[s3 let !re be _m tons ( iron & b>rels ( lime1 "s pieces ( timb]1 & c>goes ( fl9t2 let !re be lead & t9 & z9c1 & _m o!r metals1 f :i* copp] & silv] & sev]al ( ! r>e/ metals mu/ n be exclud$2 let !re be innum]able loads ( clay1 :i* %all repres5t alum9ium & silicon1 & hog%eads ( sea-wat] to supply oxyg51 hydrog51 & sodium4 ,!re %\ld be also1 ,i ne$ h>dly add1 _m o!r elem5ts2 b !re is no occasion to m5tion m2 inde$1 x w\ld be impossible to give a li/ :i* w\ld be complete4 ,suppose t ?is div]se mat]ial is submitt$ to a heat z int5se z ! mo/ p]fect furnace c make x4 ,let ! heat be inde$ z great z t :i* we c get f ! electric arc1 or ev5 great] /ill4 ,let u suppose ?is heat to be rais$ to su* a po9t t1 n only h ! mo/ refractory metals be5 trans=m$ into vap\r1 b ! elem5ts :i* 7 closely 9 comb9ation h also be5 r5t asund]4 ,?is we "k w happ5 :5 comp\nd sub/ances are rais$ to a v high temp]ature4 ,we %all suppose t ! heat has be5 suffici5t to sep>ate ea* p>ticle ( wat] into its con/itu5t atoms ( oxyg5 & hydrog52 we %all suppose t ! heat has be5 suffici5t to decompose ev5 lime itself into its con/itu5t p>ts1 & exhibit !m 9 ! =m ( vap\r4 ,! heat is to be s great t ev5 c>bon itself1 ! mo/ refractory ( sub/ances1 has _h to yield1 s t aft] pass+ ?r\gh a /age ( dazzl+ inc&esc5ce x has melt$ & ultimately dissolv$ into vap\r4 ,next let u suppose t ^! sev]al vap\rs are bl5d$1 ?\gh we ne$ n assume t ! sep>ate elem5ts are diffus$ uni=mly ?r\gh\t all p>ts ( ! cl\d4 ,let u suppose t ^! bodies1 :i* contribut$ to =m ! nebula1 h be5 employ$ 9 am\nts1 n to be measur$ 9 tons1 or 9 hundr$s ( tons1 b 9 a ?\s& millions ( millions ( millions ( millions ( tons4 ,let ! mass ( vap\r ?us aris+ be exp&$ freely ?r\gh op5 space4 ,let x ext5d ov] a region :i* is to measure hundr$s ( ?\s&s ( millions ( miles 9 l5g? & bread? & dep?4 ,!n ! doctr9e ( ! e>?'s beg9n+1 :i* we are /riv+ to unfold 9 ^! lectures1 decl>es t 9 a fire-mi/ su* z is "h outl9$ ! sol> sy/em _h its orig94 ,v>i\s objections may occur to ! ?\ghtful read] :5 ask$ to accept su* /atem5ts4 ,we mu/ d our be/ to meet ^! objections4 ,! evid5ce we submit mu/ be ( an indirect or circum/antial k9d4 ,direct te/imony on su* a subject is f ! nature ( ! case impossible4 ,! actual fire-mi/ 9 :i* our sy/em _h its orig9 is a mi/ no long]4 ,! mat]ial t =ms ! solid e>? b5ea? our feet did once1 we v]ily believe1 float 9 ! great primval fire-mi/4 ,( c\rse we _c %[ y t mi/4 ,d>w9 c\ld n %[ ! orig9al monkeys f :i* x w\ld seem ! human race has desc5d$2 none ! less d mo/ ( u believe t our desc5t has really tak5 ! l9e t ,d>w9's !ory indicates4 ,9 connection ) ?is subject1 z ) mo/ o!rs1 x is easy to ask que/ions :i*1 ,i ?9k we may say1 no "o c answ] ) any confid5ce4 ,x may1 = in/ance1 be ask$ h[ ?is va/ fire-mi/ came into exi/5ce4 ,if x arose f heat1 h[ did t heat happ5 to be pres5t8 ,:y 0 all ! mat]ial 9 ! /ate ( vap\r8 ,:at1 9 %ort1 0 ! orig9 ( t great primval nebula8 ,"h we mu/ admit t we h propos$ que/ions to :i* x is impossible = u to d m ?an sugge/ answ]s4 ,z to :at br\ght ! mi/ into exi/5ce1 z to :5ce ! mat]ials came1 & z to :5ce ! en]gy 0 d]iv$ :i* has be5 gradually exp5d$ ev] s9ce1 we d n "k any?+1 &1 s f> z ,i c see1 we h no means ( kn[+4 ,conjectures on ! subject are n want+1 ( c\rse1 & 9 a lat] *apt] we %all discuss :at may be said on ?is matt]4 ,i h %[n y to "s ext5t our reasons = believ+ t our sol> sy/em did orig9ate 9 a fire-mi/ ,& ev5 if we are n able to expla9 h[ ! mi/ itself arose1 yet we d n admit t our argum5t z to ! orig9 ( our sy/em is !reby invalidat$4 ,t su* a fire-mi/ z ! sol> sy/em requir$ did once exi/1 mu/ surely be reg>d$ z n at all improbable s long z we c po9t to ! analog\s nebul or fire-mi/s :i* exi/ at ! pres5t mom5t1 & :i* we see ) our telescopes4 ,_m ( ^! are millions ( times z great z ! comp>atively small fire-mi/ t w\ld h evolv$ into our sol> sy/em4 ,a "q has sometimes be5 ask$ z to ! mo/ important discov]y 9 a/ronomy :i* has be5 made 9 ! c5tury t has j clos$4 ,if1 by ! mo/ important discov]y1 we mean t :i* has mo/ widely ext5d$ our k ( ! ,univ]se1 ,i d n ?9k !re ne$ be mu* hesitation 9 /at+ ! answ]4 ,x seems to me beyond d\bt t ! mo/ a/oni%+ discov]y ( ! la/ c5tury 9 reg>d to ! heav5ly bodies is t :i* has reveal$ ! elem5t>y sub/ances ( :i* ! orbs ( heav5 are compos$4 ,?is discov]y is ! m int]e/+ & in/ructive because x has taught u t ! mat]ials ( ! sun1 ( ! />s1 & ( ! nebul are ess5tially ! elem5ts ( :i* our own e>? is =m$1 & ) :i* *emi/s _h already become well acqua9t$4 ,we "k1 ( c\rse1 t ?is e>?1 no matt] h[ v>i\s may be ! rocks & m9]als :i* =m its cru/1 & h[ inf9ite ! v>iety ( objects1 organic & inorganic1 :i* div]sify its surface1 is really =m$ f diff]5t comb9ations ( ab\t eighty diff]5t elem5ts4 ,!re are gases l oxyg5 & hydrog51 !re are o!r sub/ances l c>bon & sulphur1 & !re are metals l iron & copp]4 ,^! elem5ts are sometimes met ) 9 _! free or uncomb9$ /ate1 l oxyg5 9 ! atmosph]e1 or l gold 9 ,klondike4 ,m frequ5tly !y are f\nd 9 comb9ation1 & 9 su* comb9ations ! *>act]s ( ! con/itu5t elem5ts are sometimes completely trans=m$4 ,a deadly gas & a curi\s metal1 :i* burns z x floats on wat]1 mo/ c]ta9ly r5\nce _! special *>act]s :5 !y unite to =m ! salt on our breakfa/-table4 ,:o w\ld h guess$1 if ! *emi/ _h n told him1 t 9 e :eelb>r[ful ( ord9>y e>? !re are p\nds ( silv]y alum9ium1 & t m>ble is l>gely compos$ ( an extremely r>e metal1 :i* b few p h ev] se58 ,until ! middle ( ! c5tury j complet$ x seem$ utt]ly impossible to =m any notion z to ! sub/ances actually pres5t 9 ! sun4 ,h[ c\ld anyone possibly disc]n !m by ! res\rces ( ! old] *emi/s8 ,x might well h be5 d\bt$ :e!r ! elem5ts ( :i* ! sun 0 made 7 ! elem5ts ( :i* our e>? 0 =m$1 & ) :i* ord9>y *emi/ry _h made u famili>4 ,j z ! animals & plants :i* met ! gaze ( ! discov]]s :5 !y l&$ 9 ! ,new ,_w 7 ess5tially diff]5t f ^? 9 ! ,old ,_w1 s x might h be5 suppos$1 ) good %>e ( reason1 t ?is great sol> orb1 n9ety-?ree million miles di/ant1 w\ld be compos$ ( elem5ts totally diff]5t f ^? ) :i* dwell]s on ! e>? _h be5 p]mitt$ to become acqua9t$4 ,?is great discov]y ( ! la/ c5tury reveal$ to u ! "* ( ! elem5ts :i* con/itute ! sun4 ,x also add$ ! a/oni%+ in=mation t !y are ess5tially ! same elem5ts z ^? ( :i* our e>? itself & all :i* x conta9s are =m$4 ,if any "o _h ask$ 9 ! e>ly ye>s ( ! c5tury :at ^? elem5ts 7 :i* ent]$ into ! composition ( ! sun1 ! "q w\ld h be5 deem$ a silly "o2 x w\ld h be5 reg>d$ z hopelessly beyond ! possibility ( solution1 & x w\ld h be5 z little likely to receive an answ] z ! que/ions p sometimes ask n[ z to ! possible inhabitants on ,m>s4 ,b ab\t ! middle ( ! c5tury a new era dawn$2 ! wond]ful me?od ( spectroscopic analysis 0 discov]$1 & x became possible to exam9e ! *emi/ry ( ! sun4 ,! mo/ important result 0 to %[ t ! elem5ts :i* ent] into ! composition ( ! sun are ! same elem5ts :i* ent] into ! composition ( ! e>?4 ,! /ud5t ( ! sol> *emi/ry enjoys1 h[ev]1 "o advantage ov] ! t]re/rial *emi/1 if x be an advantage to h 8 sci5ce simplifi$ to ! utmo/ ext5t4 ,*emi/ry w\ld1 h[ev]1 lose its *ief int]e/ if all ! elem5ts rema9$ z ob/9ately neutral z argon1 & disda9$ alliance ) all o!r elem5ts4 ,x w\ld seem t ^? elem5ts :i* mo/ eag]ly ent] into comb9ation "h1 & :i* resi/ ) su* vehem5ce our ef=ts to divorce !m1 mu/ r5\nce all *emical union :5 expos$ to ! trem5d\s temp]ature ( ! sun4 ,^? elem5ts :i* unite ) ! utmo/ eag]ness at ord9>y temp]atures1 seem to become indiff]5t to ea* o!r :5 subject$ to ! extremes ( heat & cold4 ,potassium unites fi]cely ) oxyg5 9 ! mo/ famili> ( all *emical exp]im5ts4 ,potassium is inde$ a /range metal1 = x is ( su* small d5sity t a piece ca/ on a bas9 ( wat] w float l a *ip ( wood4 ,x has su* avidity = oxyg5 t x w decompose ! wat] to wr5* ! molecules ( oxyg5 f ^? ( hydrog54 ,! union ( ! metal ) ! gas g5]ates su* heat t ! /range sub/ance bur/s into flame4 ,?is is :at takes place at ! ord9>y temp]atures 9 ! well-kn[n exp]im5t ( ! *emical lecture-table4 ,b at extreme temp]atures ! gre$ ( potassium = oxyg5 abates1 if x does n vani% altoge!r4 ,9 ^? excessively l[ temp]atures at :i* ,pr(essor ,dew> exp]im5ts *emical aff9ities langui%4 ,he has r$uc$ oxyg5 to a liquid1 & he tells u t 8a b]g ( silv]y potassium might float = ev] unt>ni%$ on an ocean ( liquid oxyg540 ,at ! excessively high temp]ature ( ! electric arc ! oxyg5 & ! potassium1 ^: union has be5 accompli%$ ) su* vehem5ce1 cease to possess aff9ity1 & !y sep>ate aga94 ,! sol> *emi/ry seems to "k no comb9ation4 ,if a drop ( wat] 7 transf]r$ to ! sun & subject$ to ! heat ( ! sol> surface1 x mu/ imm$iately und]go decomposition4 ,t :i* 0 a drop ( wat] "h w\ld n rema9 a drop ( wat] !re2 x w\ld be at once resolv$ into its compon5t elem5ts ( oxyg5 & hydrog54 ,! consid]ations j giv5 greatly simplify ! se>* = ! p>ticul> bodies :i* are at pres5t 9 ! sun4 ,we h only to te/ = ! pres5ce ( ea* ( eighty elem5ts4 ,we h n to take acc\nt ( ! ?\s&s ( *emical comb9ations ( :i* ^! elem5ts are susceptible "u t]re/rial conditions4 ,we are specially indebt$ to ! late ,pr(essor ,h5ry ,r[l&1 ( ,baltimore1 = a pr(\nd /udy ( ! sol> spectrum4 ,9 8 great "w he enum]ates ?irty-six elem5ts pres5t 9 ! sun1 & ! numb] may be increas$ n[ by at lea/ two4 ,eight elem5ts he classes z d\btful1 fifte5 are set d[n z abs5t f ! sol> spectrum1 & sev]al _h n be5 tri$4 ,iron /&s =emo/ among all ! sol> elem5ts1 s f> z ! numb] ( its l9es are conc]n$4 ,no few] ?an #b1jjj l9es 9 ! spectrum ( ! sun are attribut$ to ?is elem5t4 ,at ! o!r end ( ! li/ lead is f\nd4 ,!re is only "o l9e app>5tly due to ?is metal4 ,c>bon is repres5t$ by ab\t #bjj l9es1 & calcium by ab\t #ge4 ,if1 h[ev]1 we te/ ! significance ( l9es n by _! numb]1 b by _! int5sity1 !n iron no long] heads ! li/1 its place be+ tak5 by calcium 7,fig4 #db74 ,among ! elem5ts :i* ,r[l& sets d[n z n contribut+ any recognisable l9es to ! sol> spectrum we may m5tion ars5ic & sulphur1 phosphorus1 m]cury1 & gold4 ,( ! m prom95t sol> elem5ts !re are two or ?ree ( su* special importance t we pause to give !m a little consid]ation4 ,:o does n rememb] ! delight ( ! fir/ occasion 9 *ildhood :5 he 0 p]mitt$ to peep into a bird's-ne/ & !re see a gr\p ( eggs1 (t5 s exquisitely m>k$ or s delicately t9t$8 ,h[ beautiful !y seem$ z !y lay 9 _! cosy receptacle conceal$ ) s mu* cunn+6 ,among o!r delightful recollections ( e>ly y\? _m w recall a ramble by ! sea-%ore4 ,we may suppose ! tide _h retreat$1 & ) o!r objects left by ! sea on ! gleam+ s& a little c[rie %ell is f\nd4 ,h[ en*ant$ we 7 ) our prize6 ,h[ we look$ at ! curi\s m>ks on its lips1 & ! inimitable beauty ( its t9ts6 ,! %ell ( ! h$ge-sp>r[ & ! %ell ca/ up by ! sea h ano!r quality 9 common besides _! beauty4 ,!y h bo? be5 fabricat$ f ! same mat]ial4 ,lime is ( c\rse ! sub/ance f :i* ! bird1 by "s subtle art ( physiology1 =ms ^? exquisite walls by :i* ! vital "p ( ! egg is protect$4 ,! s(t organism t once dwelt 9 ! c[rie 0 end[$ ) "s p[] by :i* x extract$ f ! wat]s ( ! ocean ! lime ) :i* x gradually built an inimitable %ell4 ,is x an exagg]ation to say t ?is p>ticul> elem5t calcium1 ?is elem5t s excessively abundant & s r>ely se51 seems to enjoy "s peculi> di/9ction by association ) exquisite grace & beauty8 ,! :ite m>ble wr\ght to an unp>allel$ lovel9ess by ! g5ius ( a ,phidias or a ,canova is b a =m ( lime4 ,s is ! ivory on :i* ! ,japanese arti/ works ) su* delicacy & ref9em5t4 ,:e!r z coral 9 a ,pacific isl&1 z a pe>l 9 a necklace or z a /one 9 ! ,p>!non1 lime seems (t5 privileg$ to =m ! mat]ial basis ( beauty 9 nature & beauty 9 art4 ,?\gh lime 9 its diff]5t =ms1 9 ! rocks ( ! e>? or ! wat]s ( ! ocean1 is "o ( ! mo/ ord9>y sub/ances met ) on our globe1 yet calcium1 ! ess5tial elem5t :i* goes to ! composition ( lime1 is1 z we h already said1 n by any means a famili> body1 & n _m ( u1 ,i imag9e1 c ev] h se5 x4 ,*emi/ry tea*es t lime is ! result ( a union 9 def9ite proportions betwe5 oxyg5 gas & ! v %y metal1 calcium4 ,?is metal is nev] f\nd 9 nature unless 9 su* intimate *emical union ) "s o!r elem5t l oxyg5 or *lor9e1 t its *>act]i/ic features are altoge!r obscur$1 & w\ld inde$ nev] be suspect$ f ! m]e appe>ance ( ! results ( ! union4 ,to see ! metal calcium y mu/ visit a *emical laboratory :]e1 by electrical decomposition or o!r +5i\s process1 ?is elusive elem5t c be induc$ to "p tempor>ily f its union ) ! oxyg5 or o!r body = :i* x has s eag] an aff9ity1 & to :i* x returns ) su* alacrity4 ,?\gh calcium is c]ta9ly a metal1 x is v unlike ! m famili> metals su* z gold or silv]1 copp] or iron4 ,a co9 might conceivably be =m$ out ( calcium1 b x w\ld h no /ability l ! co9s ( ! well-kn[n metals4 ,calcium has su* an unconqu]able desire to unite ) oxyg5 t ! un/able metal w spe$ily grasp f ! surr\nd+ air ! vital elem5t4 ,unless special precautions are tak5 to )hold f ! calcium ! air1 or o!r s\rce f :5ce x c\ld obta9 oxyg51 ! union w mo/ c]ta9ly take place1 & ! calcium w resume ! /able =m ( lime4 ,?us x happ5s t ?\gh ?is e>? conta9s incalculable billions ( tons ( calcium 9 its v>i\s comb9ations1 yet calcium itself is almo/ unkn[n except to ! *emi/4 ,x is pla9 t calcium plays a "p ( trem5d\s significance on ?is e>?4 ,i d n say t x is ! mo/ important ( all ! elem5ts4 ,x w\ld inde$ seem impossible to assign t di/9ction to any p>ticul> elem5t4 ,_m are1 ( c\rse1 ( vital importance1 ?\gh !re are1 no d\bt1 c]ta9 ( ! r>] elem5ts ) :i* ?is e>? c\ld p]haps disp5se )\t be+ to any appreciable ext5t diff]5t f :at x is at pres5t4 ,i d n "k t we %\ld be specially inconv5i5c$ or feel any appreciable want unsatisfi$1 if1 let u say1 ! elem5t lan?anum 7 to be /ruck out ( exi/5ce2 & !re are p]haps c]ta9 o!r r>e bodies among ! kn[n eighty elem5ts1 ab\t :i* ! same rem>k might be made4 ,illu/ration3 ,fig4 #db4--,,! ,h4 ,,& ,k4 ,,l9es ,,9 ,,! ,,photographic ,,sol> ,,spectrum 7,higgs74 ,b )\t calcium !re w\ld nei!r be f]tile soil = plants nor bones = animals1 & consequ5tly a _w1 inhabit$ 9 ! same mann] z our pres5t globe1 w\ld be cle>ly impossible4 ,!re may be l[ly organisms on ?is e>? to :i* calcium is ( no appreciable consequ5ce1 & x is ( c\rse conceivable t a _w ( liv+ types c\ld be con/ruct$ )\t ! aid ( t p>ticul> elem5t :i* is to u s indisp5sable4 ,b a _w )\t calcium w\ld be radically diff]5t f t _w :i* we "k1 s t we are dispos$ to feel special int]e/ 9 ! important mod]n discov]y t ?is same elem5t1 calcium1 is abundantly di/ribut$ ?r\gh\t ! univ]se4 ,! bolde/ & mo/ /rik+ features 9 ! photograph ( ! sol> spectrum are ^? due to calcium 7,figs4 #db & #dd74 ,9 ! sol> spectrum are two v broad1 v d>k1 & v conspicu\s l9es1 kn[n z ,h & ,k4 ,9 e photograph ( t portion ( ! sol> spectrum :i*1 ly+ beyond ! extreme violet1 is invisible to our eyes1 ?\gh int5sely active on ! photographic plate1 ^! l9es /& =? s boldly z to arre/ ! att5tion m ?an any o!r features ( ! spectrum4 ,x _h be5 kn[n t ^! l9es 7 due to calcium1 b !re 7 c]ta9 difficulties connect$ ) _! int]pretation4 ,"s rec5t beautiful rese>*es by ,sir ,william & ,lady ,hugg9s h cle>$ away all d\bt4 ,x is n[ c]ta9 t ! pres5ce ( ^! l9es 9 ! spectrum demon/rates t t rem>kable elem5t :i* is ! ess5tial feature ( lime on ?is e>? is also f\nd 9 ! sun4 ,we h also to note t ^! same l9es h be5 detect$ 9 ! photographic spectra ( _m o!r bodies 9 widely diff]5t regions ( space4 ,?us we e/abli% ! int]e/+ result t ?is p>ticul> elem5t :i* plays a "p s rem>kable on our e>? is n re/rict$ to our globe1 b is diffus$ f> & wide ?r\gh\t ! univ]se4 ,p]haps ! mo/ a/oni%+ discov]y made 9 mod]n times ab\t ! sun is connect$ ) ! wond]ful elem5t1 helium4 ,s long ago z #ahfh ,sir ,norman ,locky] discov]$1 dur+ an eclipse1 t ! light ( ! sun conta9$ evid5ce ( ! pres5ce 9 t orb ( "s elem5t :i* 0 !n totally unkn[n to *emi/s4 ,?is new body 0 n unnaturally nam$ ! sun-elem5t1 or helium4 ,b m ?an a qu>t] ( a c5tury _h to elapse be=e any *emi/ c\ld enjoy ! opportunity ( exp]im5t+ directly ^u helium4 ,no lab\r c\ld prep>e ! smalle/ p>ticle ( ?is sub/ance1 no money c\ld pur*ase x1 = at t "t no specim5 ( ! elem5t 0 kn[n to exi/ ne>] ?an ! sun1 n9ety-?ree million miles di/ant4 ,b 9 #ahie an a/oni%+ discov]y 0 made by ,pr(essor ,ramsay4 ,he 0 exam9+ a r>e piece ( m9]al f ,norway4 ,f ?is m9]al1 clevite1 ! ,pr(essor extract$ a little gas :i* 0 to him & to all o!r *emi/s q unkn[n4 ,b on apply+ ! spectroscope to exam9e ! "* ( ! light :i* ?is gas emitt$ :5 submitt$ to ! electric curr5t1 x yield$1 to _! amazem5t1 ! *>act]i/ic light ( helium4 ,?us 0 ! sun-elem5t at la/ %[n to be a t]re/rial body1 ?\gh no d\bt a r>e "o4 ,! circum/ances t ,i h m5tion$ make helium = ev] fam\s among ! con/itu5ts ( ! univ]se4 ,x w nev] be =gott5 t ?\gh f h5ce=? x may be reg>d$ z a t]re/rial body1 yet x 0 fir/ discov]$1 n 9 ! e>? b5ea? our feet1 b 9 ! f>-di/ant sun4 ,9 a previ\s picture 7,fig4 #ad7 we %[$ a photograph ( a "p ( ! sun's surface2 ?is /rik+ view displays ^? gl[+ cl\ds f :i* ! sun disp5ses its light & heat4 ,^! cl\ds =m a comp>atively ?9 /ratum ar\nd ! sun1 ! int]ior ( :i* is v mu* d>k]4 ,! lay] ( cl\ds is s ?9 t x may p]haps be lik5$ to ! delicate sk9 ( a pea* 9 comp>ison ) ! lusci\s int]ior4 ,x is 9 ^! dazzl+ :ite cl\ds t we f9d ! s\rce ( ! sun's brightness4 ,7 ^? cl\ds remov$1 ?\gh ! sun's diamet] w\ld n be appreciably r$uc$1 yet its unp>allel$ lu/re w\ld be at once less5$4 ,we use ! expression 8cl\ds0 9 speak+ ( ^! objects1 = cl\ds !y c]ta9ly are1 9 ! s5se ( be+ aggregates ( innum]able myriads ( m9ute beads ( "s sub/ance2 b ^? sol> cl\ds are v unlike ! cl\ds ( our own sky1 9 s f> z ! mat]ial ( :i* !y are made is conc]n$4 ,! sol> cl\ds are n little beads ( wat]2 !y are little beads ( :ite-hot mat]ial s dazzl+ly bright z to radiate =? ! *>act]i/ic brilliance & spl5d\r ( ! sun4 ,! sol> cl\ds drift to & fro2 !y are occasionally ! sport ( t]rific hurricanes2 !y are sometimes driv5 away f limit$ areas1 & 9 _! abs5ce we see m]ely ! black int]ior ( ! sol> globe1 :i* we call a sun-spot4 ,n[ comes ! important "q z to ! mat]ial pres5t 9 ^! cl\ds :i* conf]s on ! sun its ability to radiate =? su* abundant light & heat4 ,! pr(\nd tru? already /at$1 t ! sol> elem5ts are ! same z ! t]re/rial elem5ts1 greatly simplifies ! se>* = t p>ticul> elem5t :i* =ms ^? sol> cl\ds4 ,z ! sun is made ( sub/ances already kn[n to u by t]re/rial *emi/ry1 & z !re are no *emical comp\nds to emb>rass u1 ! *oice ( ! possible con/itu5ts ( ^? sol> cl\ds becomes n>r[$ to ! li/ ( elem5ts exp]im5t$ on 9 our laboratories4 ,we owe to ,dr4 ,g4 ,john/one ,/oney1 ,f4,r4,s41 ! discov]y ( ! p>ticul> elem5t :i* =ms ^? fire-cl\ds 9 ! sun1 & conf]s on ! presid+ body ( ! sol> sy/em ! p[] ( be+ s useful to ! planets :i* owe x allegiance4 ,c>bon is ! elem5t 9 "q4 ,i ne$ h>dly add t c>bon is well kn[n z "o ( ! mo/ commonplace & "o ( ! mo/ rem>kable sub/ances 9 ,nature4 ,a piece ( coke diff]s f a piece ( pure c>bon only by ! a% :i* ! coke leaves beh9d :5 burn$4 ,timb] is pr9cipally compos$ ( ?is same elem5t1 & :5 ! timb] is trans=m$ into *>coal b little m ?an ! c>bon rema9s4 ,c>bon is inde$ ev]y:]e pres5t4 ,x is1 z we h m5tion$1 "o ( ! elem5ts :i* ent] into ! composition ( a piece ( *alk4 ,c>bon is 9 ! e>? b5ea? our feet2 x is 9 ! air above u4 ,c>bon is "o ( ! *ief +r$i5ts 9 our food1 & x is by c>bon t ! heat ( ! body is su/a9$4 ,inde$1 ?is rem>kable elem5t is intimately connect$ ) life 9 e phase4 ,e organic sub/ance conta9s c>bon1 & x c\rses ) ! blood 9 our ve9s4 ,x assumes ! wide/ v>iety ( =ms1 r5d]s ! greate/ div]sity ( s]vices1 & appe>s 9 ! mo/ widely diff]5t places4 ,c>bon is inde$ ( a protean "*1 & !re is a beautiful symbol ( ! unique position :i* x occupies 9 ! s*eme ( ,nature 7,fig4 #dc74 ,c>bon is associat$ n alone ) articles ( daily utility & ( pl5te\s abundance1 b x is c>bon :i* =ms ! mo/ exquisite gems 8( pure/ ray s]5e40 ,! diamond is1 ( c\rse1 m]ely a specim5 ( c>bon ( absolute purity & 9 cry/all9e =m4 ,great z is ! importance ( c>bon on ?is e>?1 x is spread f> m widely2 x is n conf9$ m]ely to ! e>?1 = c>bon ab\nds on o!r bodies 9 space4 ,! mo/ important functions ( c>bon 9 ! univ]se are n ^? x r5d]s on ?is e>?4 ,x 0 %[n by ,dr4 ,/oney t ?is same wond]ful sub/ance is inde$ a sol> elem5t ( va/ utility4 ,x is c>bon :i* =ms ! gl[+ sol> cl\ds to :i* our v life owes its orig94 ,9 ! inc&esc5t lamp ! brilliant light is produc$ by a gl[+ filam5t ( c>bon1 & "o reason :y we employ ?is elem5t 9 ! electric lamp1 in/ead ( any o!r1 may be easily /at$4 ,if we tri$ to make "o ( ^! lamps ) an iron wire1 we %\ld f9d t :5 ! electric curr5t is turn$ on & beg9s to fl[ ?r\gh ! wire1 ! wire w1 9 accordance ) a well-kn[n law1 become w>m1 !n hot1 r$-hot1 & :ite-hot2 b ev5 :5 :ite-hot ! wire w n gl[ ) ! brightness t we expect f "o ( ^! lamps4 ,ere a suffici5t temp]ature c be rea*$ ! iron w h yield$1 x w h melt$ into drops ( liquid1 cont9uity w be brok51 ! circuit w be int]rupt$1 & ! lamp de/roy$4 ,we %\ld n h be5 mu* m successful if in/ead ( iron we _h tri$ any o!r metal4 ,ev5 a plat9um wire1 ?\gh x w admit ( be+ rais$ to a mu* high] temp]ature ?an a wire ( iron or a wire ( /eel1 _c rema9 9 ! solid condition at ! temp]ature :i* w\ld be necess>y if ! requisite inc&esc5ce is to be produc$4 ,!re is no kn[n metal1 & p]haps no sub/ance :atev]1 :i* has s high a temp]ature ( fusion z c>bon4 ,a filam5t ( c>bon1 alone among ! available elem5ts1 w rema9 cont9u\s & unfus$ :ile transmitt+ a curr5t int5se en\gh to produce t dazzl+ brilliance :i* is expect$ f ! inc&esc5t lamp4 ,?is is ! reason :y ?is p>ticul> elem5t c>bon is an indisp5sable mat]ial = ! electrician4 ,mod]n rese>* has n[ demon/rat$ t j z we employ c>bon z ! imm$iate ag5t = produc+ our beautiful artificial light1 s ! sun uses precisely ! same elem5t z ! ag5t ( its light & heat-giv+ p[]4 ,9 ! extraord9>y f]v\r :i* prevails 9 ! int]ior ( ! sun all sub/ances ( e description mu/ submit to be melt$1 nay1 ev5 to be driv5 into vap\r4 ,an iron pok]1 = in/ance1 w\ld vani% into iron vap\r if submitt$ to ?is appall+ sol> furnace4 ,ev5 c>bon itself is unable to rema9 solid :5 subject$ to ! int5se heat prevail+ 9 ! inn] p>ts ( ! sun4 ,at t heat c>bon mu/ assume ! =m ( gas or vap\r1 j z iron or ! o!r sub/ances :i* yield m readily to ! application ( heat4 ,by ! help ( a simple exp]im5t we may illu/rate ! significance ( ! c>bon vap\rs 9 ! sol> economy4 ,let u take a ,buns5 burn]1 9 :i* ! air & gas are freely m+l$ be=e !y ent] into combu/ion4 ,if ! air & ! gas be prop]ly proportion$1 ! combu/ion is s p]fect t ?\gh a great deal ( heat is produc$ !re is b little light4 ,! gas burn$ 9 ?is exp]im5t ought to be ! ord9>y gas ( our ma9s1 :i* dep5ds = its illum9at+ p[] on ! circum/ance t ! hydrog51 ( :i* ! gas is *iefly compos$1 is l>gely *>g$ ) c>bon4 ,! illum9at+ p[] ( ! gas may inde$ be measur$ by its available ri*ness 9 c>bon4 ,z x ent]s ! burn] ! c>bon is itself 9 a gase\s =m4 ,?is is n1 ( c\rse1 on acc\nt ( a high temp]ature4 ,! c>bon ( ! coal-gas is 9 *emical union ) hydrog51 & ! result is 9 ! =m ( invisible gases4 ,x is ^! composite gases1 bl5d$ ) l>ge volumes ( ord9>y hydrog51 :i* =m ! illum9at+ gas ( our ma9s4 ,9 ! ,buns5 burn] ! admission ( a prop] proportion ( air1 :i* becomes ?or\ghly mix$ ) ! coal gas1 produces p]fect combu/ion4 ,9 ! act ( burn+1 ! oxyg5 ( ! air unites imm$iately ) ! gas2 x comb9es ) ! hydrog5 to =m wat]y vap\r1 & x comb9es ) ! c>bon to =m gases :i* are ! well-und]/ood products ( combu/ion4 ,suppose1 n[1 we cut (f ! supply ( air f ! ,buns5 burn]1 :i* c be done 9 a mom5t by plac+ ! h& ov] ! r+ ( holes at ! bottom at :i* ! air is admitt$4 ,imm$iately a *ange takes place 9 ! combu/ion4 ,9 place ( ! /eady1 h>dly visible1 b int5sely hot flame :i* we _h be=e1 we h n[ a v mu* l>g] flame :i* makes a bright & flick]+ fl>e t lights up ! room4 ,if we re-admit ! air at ! bottom ( ! burn] ! light goes d[n in/antly2 ! small1 pale flame replaces x1 & aga9 ! p]fect combu/ion gives out int5se heat at ! exp5se ( ! light4 ,! rem>kable *ange 9 ! "* ( a gas-flame produc$ by admitt+ air to mix ) ! gas be=e combu/ion is1 ( c\rse1 easily expla9$4 ,! *emical action takes place ) mu* great] facility "u ^! circum/ances4 ,! union ( ! c>bon 9 ! coal gas ) ! oxyg5 !n takes place s ?or\ghly & in/antane\sly t ! c>bon nev] seems to h ab&on$ ! gase\s =m ev5 = a mom5t 9 ! c\rse ( ! trans=mation4 ,b 9 ! case :]e air is n p]mitt$ to m+le ) ! gas1 ! supply ( oxyg5 to unite ) ! inc&esc5t gases c only be obta9$ f ! ext]ior ( ! flame4 ,! consequ5ce is t ! gl[+ gas *>g$ ) c>bon vap\r is *ill$ to "s ext5t by contact ) ! cold air4 ,x !re=e seems z if ! union ( ! hydrog5 ) ! oxyg5 p]mitt$ ! p>ticles ( c>bon 9 ! flame to resume _! solid =m = a mom5t4 ,b 9 t solid =m ^! p>ticles1 be+ at a high temp]ature1 h a wond]ful effici5cy = radiation1 & consequ5tly brilliance is conf]r$ ^u ! light4 ,mo/ ( ! p>ticles ( c>bon spe$ily unite ) ! surr\nd+ oxyg51 & re-ent] ! gase\s /ate 9 a diff]5t comb9ation4 ,"s ( !m1 h[ev]1 may escape ?is fate1 9 :i* case !y assume ! undesirable =m ( smoke4 ,! ,buns5 lamp c ?us be made to give an illu/ration ( ! fact t :5 c>bon vap\rs receive a *ill1 ! imm$iate effect ( ! *ill is to trans=m ! c>bon f ! gase\s =m to myriads ( p>ticles 9 ! liquid1 or m probably 9 ! solid =m4 ,9 ! latt] /ate ! c>bon possesses a p[] ( radiation greatly 9 excess ( t :i* x possess$ 9 ! gase\s /ate1 ev5 ?\gh ! gas may h be5 at a mu* high] temp]ature ?an ! :ite-hot solid p>ticles4 ,we c n[ apply ^! pr9ciples to ! explanation ( ! m>vell\s radiation ( light & heat f ! great orb ( day4 ,! buoyancy ( ! c>bon vap\rs is "o ( _! mo/ rem>kable *>act]i/ics2 !y t5d to so> upw>ds ?r\gh ! sol> atmosph]e until !y atta9 an elevation consid]ably ov] t ( _m ( ! o!r mat]ials 9 ! heat$ vap\rs surr\nd+ ! great lum9>y4 ,we may illu/rate :at happ5s to ^! c>bon vap\rs by consid]+ ! analog\s case pres5t$ 9 ! =mation ( ord9>y cl\ds 9 our own sk9s4 ,x is true1 no d\bt1 t t]re/rial cl\ds are compos$ ( mat]ial v diff]5t f t :i* ent]s into ! sol> cl\ds4 ,t]re/rial cl\ds ( c\rse arise 9 ?is way2 ! g5]\s w>m? ( ! sun evaporates wat] f ! great oceans1 & trans=ms x into vap\r4 ,?is vap\r asc5ds ?r\gh our atmosph]e1 n at fir/ z a visible cl\d1 b 9 ! =m ( an invisible vap\r4 ,x is gradually diffus$ ?r\gh\t ! upp] air1 until at la/ p>ticles ( wat]1 b rec5tly )drawn f ! oceans1 atta9 an altitude ( a mile or m above ! surface ( ! e>?4 ,a trans=mation !n awaits ?is aque\s vap\r4 ,9 ! coldness ( ^? elevat$ regions ! wat] c no long] rema9 9 ! =m ( vap\r4 ,! laws ( heat require t x %all rev]t to ! liquid /ate4 ,9 ob$i5ce to ?is law ! vap\r collects into liquid beads1 & x is ^! liquid beads1 associat$ 9 c\ntless myriads1 :i* =m ! cl\ds we "k s well4 ,! same ph5om5on ( cl\d-production is witness$ on a small] scale 9 ! =mation ( ! visible puffs :i* issue f ! funnel ( a locomotive4 ,we g5]ally describe ^! roll+ :ite volumes z /eam2 b ?is language is h>dly correct4 ,/eam1 prop]ly s call$1 is truly z invisible z ! air itself2 x is only aft] ! /eam has done its "w & is dis*>g$ into ! atmosph]e1 & !re receives a *ill1 t x becomes sudd5ly trans=m$ f ! purely gase\s /ate into clu/]+ masses ( microscopic sph]es ( wat]1 & ?us becomes visible4 ,we c n[ und]/& ! trans=mation ( ^! buoyant c>bon vap\rs :i* so> upw>ds 9 ! sun4 ,!y atta9 an elevation at :i* ! fe>ful int5sity ( ! sol> heat has be5 s f> abat$ by ! cold ( out] space t ! c>bon gas is n p]mitt$ to rema9 any long] 9 ! =m ( gas2 x mu/ return to ! liquid or to ! solid /ate4 ,9 ! fir/ /age on ?is return ! c>bon gas becomes trans=m$1 j 9 ! same way z wat]y vap\r asc5d+ f ! e>? becomes trans=m$ into ! fleecy cl\d4 ,"u ! influ5ce ( its fall 9 temp]ature ! c>bon vap\r collects into a clu/]+ ho/ ( little beads ( c>bon4 ,?is is ! orig9 ( ! glori\s sol> cl\ds4 ,ea* p>ticle ( c>bon 9 t magnific5t radiant surface has a temp]ature1 & consequ5tly a p[] ( radiation1 probably exce$+ t ) :i* ! filam5t ( c>bon gl[s 9 ! inc&esc5t electric arc4 ,:5 we consid] t millions ( millions ( squ>e miles on our lum9>y are cov]$ ) cl\ds1 ( :i* e p>ticle is s int5sely bright1 we %all p]haps be able to =m "s idea ( t inimitable spl5d\r :i* ev5 across ! awful gulf ( n9ety-?ree million miles transmits ! indescribable glory ( daylight4 ,we are p]haps at pres5t liv+ r too close to ! p]iod itself to be able to appreciate to its full ext5t ! greatness ( t *>act]i/ic discov]y made 9 a/ronomy dur+ ! c5tury j clos$1 to :i* ! pres5t *apt] relates4 ,9 ! e>ly "p ( ! la/ c5tury x might h be5 said--inde$1 by a c]ta9 v di/+ui%$ philosoph] x actually 0 said--t a limit c\ld be laid d[n b\nd+ ! possibilities ( our k ( ! heav5ly bodies4 ,x 0 admitt$ t we might /udy ! movem5ts ( ! diff]5t orbs 9 va/ly great] detail ?an _h be5 hi!rto attempt$1 & t we might calculate ! =ces to :i* ^? orbs 7 submitt$4 ,) ! help ( ma!matical analysis we might pursue ! consequ5ces ( ^! =ces to _! remote ramifications2 we might det]m9e :]e ! v>i\s orbs 7 situat$ at inimitably remote p]iods 9 ! pa/4 ,we might calculate ! positions :i* !y %all atta9 at epo*s to be rea*$ 9 ! illimitably remote future2 we might discov] innum]able new />s & worlds2 & we might map d[n & survey ! di/ant p>ts ( ! univ]se4 ,we might ev5 s\nd ! dep?s ( space & det]m9e ! di/ances ( ! m remote cele/ial bodies1 mu* m di/ant ?an any ( ^? :i* h already yield$ _! secrets2 we might measure ! dim5sions ( ^? bodies & det]m9e _! weights2 we might add scores or hundr$s to ! li/ ( ! kn[n planets2 we might multiply _m times ! numb] ( kn[n nebul & />-clu/]s2 we might make measurem5ts ( _m ?\s&s ( d\ble />s2 we might essay ! sublime task ( =m+ an inv5tory ( ! />s ( ! univ]se & compil+ a catalogue 9 :i* ! />s & _! positions w\ld be record$ 9 _! millions2 b1 said ! philosoph] to :om ,i h ref]r$1 ?\gh y might accompli% all ?is1 & mu* m 9 ! same direction1 yet !re is a well-m>k$ limit to y\r possible a*ievem5ts2 y c1 he said1 nev] expect to discov] ! actual *emical elem5ts ( :i* ! heav5ly bodies are compos$4 ,nobody c\ld dispute ! reasonabl5ess ( ?is /atem5t at ! "t he made x2 inde$1 x seem$ to be a necess>y d$uction f our k ( ! arts ( *emi/ry1 z ^? arts 7 und]/ood be=e ! middle ( ! la/ c5tury4 ,9 ! prosecution ( 8 rese>*es by ! old] me?od1 ! *emi/ c\ld no d\bt discov] ! diff]5t elem5ts ( :i* ! body 0 =m$4 ,t is to say1 8 art enabl$ him to accompli% ?is task1 provid$ "o v ess5tial & fundam5tal condition c\ld be compli$ )4 ,h[ev] accompli%$ ! *emi/ ( fifty ye>s ago might h be51 he w\ld assur$ly h ?\ght t he 0 be+ mock$ if ask$ to det]m9e ! composition ( a body :i* 0 #ic1jjj1jjj miles away f him4 ,! v idea ( =m+ an analysis "u su* conditions w\ld h be5 sc\t$ z prepo/]\s4 ,he w\ld naturally ask t a specim5 ( ! body %\ld be deliv]$ into 8 h&s1 a specim5 :i* he c\ld take into 8 laboratory1 pulv]ise 9 8 mort>s1 place 9 8 te/-tubes1 treat ) 8 re-ag5ts1 or exam9e ) 8 bl[pipe4 ,only by su* me?ods 0 x !n ?\ght possible to obta9 an analysis & discov] ! elem5ts f :i* any giv5 sub/ance 0 =m$4 ,= 9 ! e>ly "p ( ?is c5tury ! spl5did me?od ( spectrum analysis1 t me?od :i* has reveal$ to u s _m ( ! secrets ( ,nature1 _h n yet come into be+4 ,:5 t memorable ev5t took place x 0 at once p]ceiv$ t ! spectroscope requir$ no actual contact ) ! object to be te/$1 b only ask$ to receive "s ( ! rays ( light :i* t object disp]s$ :5 suffici5tly heat$4 ,x 0 obvi\s t ?is new me?od mu/ be capable ( an enorm\sly enl>g$ application4 ,! flame produc+ ! vap\r might be at "o end ( ! room1 :ile ! spectroscope te/+ ! elem5ts 9 t vap\r might be at ! o!r end4 ,?is new & beautiful optical in/rum5t c\ld analyse an object at a di/ance ( a hundr$ feet4 ,b if applicable at a di/ance ( a hundr$ feet1 :y n at a hundr$ y>ds1 or a hundr$ miles1 or a hundr$ million miles8 ,:y might ! me?od n be us$ if ! s\rce ( light 7 z f> z ! sun1 or z f> z a />1 or ev5 z f> z ! remote/ nebula1 ^: fa9t gleam on ! sky is all t ! mightie/ telescope c %[4 ,pres5tly ano!r great advance 0 record$4 ,z ! /udy ( ?is subject progress$1 x 0 soon f\nd t a spectrum visible to ! human eye 0 n always indisp5sable = ! success ( ! analysis4 ,! photographic plate1 :i* s frequ5tly replaces ! eye 9 o!r classes ( obs]vation1 has also be5 us$ to replace ! eye 9 ! use ( ! spectroscope4 ,a picture has ?us be5 obta9$ %[+ ! *>act]i/ic l9es 9 ! spectrum ( a cele/ial object4 ,t object may h be5 sunk 9 space to a di/ance s trem5d\s t ev5 ?\gh ! light travell$ at a pace suffici5t to complete sev5 circuits ( our e>? 9 ea* second ( "t1 yet ! rays f ! object 9 "q may h be5 travell+ = c5turies be=e !y rea*$ our in/rum5t4 ,h[ev] ! rays ( light may h become weak5$ 9 ! c\rse ( t j\rney1 !y /ill fai?fully pres]ve ! cr$5tials ( _! orig94 ,at la/ ! light is decompos$ 9 ! spectroscope1 & ! sev]al rays1 :i* h be5 s closely comm+l$ 9 _! long voyage ( myriads ( miles1 are n[ = ! fir/ "t =c$ to pursue diff]5t tracks2 !y ?us rea* _! diff]5t de/9ations on ! photographic plate1 & !y !re engrave _! *>act]i/ic inscriptions4 ,nature 9 ?is op]ation imp>ts = our in/ruction a message :i* x is our bus9ess to int]pret4 ,x is true t ^! inscriptions are n always easily deciph]$2 _m ( !m h n yet be5 und]/ood4 ,a portion ( ! sol> spectrum %[+ _m ( ! l9es 9 ! visible region is repres5t$ 9 ! accompany+ plate4 ,illu/ration3 ,fig4 #dc4--,,spectrum ,,( ,,comet ,,%[+ ,,c>bon ,,l9es4 7,sir ,w4 ,hugg9s1 ,k4,c4,b47 ,consid]+ ! insignificance ( our e>? :5 view$ 9 comp>ison ) ! millions ( o!r orbs 9 ! univ]se1 consid]+ also ! /up5d\s di/ances by :i* ! e>? is sep>at$ f innum]able globes :i* are v mu* great]1 x is c]ta9ly n a little a/oni%+ to le>n t ! elem5ts f :i* ! v>i\s bodies 9 ! univ]se h be5 compos$ are practically ! same elem5ts z ^? ( :i* our e>? is built4 ,is n ?is a weighty piece ( evid5ce 9 fav\r ( ! !ory t e>?1 sun1 & planets are all portions ( ! same primval nebula 9 :i* ^! elem5ts 7 bl5d$8 ,illu/ration3 ,,! ,,sol> ,,spectrum4 ,we d n1 ( c\rse1 mean to affirm t ! great primval nebula 0 homog5e\s ?r\gh\t its va/ ext5t4 ,! wat]s ( ocean are n /rictly ! same 9 all places2 ev5 ! atmosph]e is n absolutely uni=m4 ,nature does n l homog5eity4 ,! orig9al nebula1 we may well believe1 0 irregul> 9 =m1 & d5s] 9 "s places ?an 9 o!rs4 ,we d n suppose t if we c\ld procure a sample ( nebula 9 "o place & ano!r sample f ! same nebula1 b 9 a diff]5t place1 say a hundr$ million miles di/ant1 ! two w\ld %[ an id5tity ( *emical composition2 two samples ( rock f diff]5t p>ts ( ! same qu>ry w n always be id5tical4 ,b we may be assur$ t1 9 g5]al1 :atev] elem5ts are pres5t 9 ! nebula w be widely disp]s$ ?r\gh its ext5t4 ,if f diff]5t p>ts ( ! nebula two globes are =m$ by cond5sation1 ?\gh we %\ld n affirm1 & ?\gh 9 fact we c\ld n believe1 t ^? globes w\ld be ( id5tical composition1 yet we %\ld reasonably expect t ! elem5t>y bodies :i* ent]$ into _! composition w\ld be 9 sub/antial agreem5t4 ,if "o elem5t1 say iron1 0 abundant 9 "o globe1 we %\ld expect t iron w\ld n be abs5t f ! o!r4 ,?us ! elem5ts repres5t$ 9 "o body %\ld be ess5tially ^? :i* 7 repres5t$ 9 ! o!r4 ,illu/ration3 ,fig4 #dd4--,,spectrum ,,( ,,sun ,,dur+ ,,eclipse4 ,,! ,,two ,,*ief ,,l9es ,,are ,,due ,,to ,,calcium4 7,ev]%$47 ,x is obvi\s t if ! sun & ! e>?--to conf9e our att5tion solely to ^? two bodies--_h orig9at$ f ! primval nebula1 !y w\ld be> ) !m1 z a m>k ( _! common orig91 a resemblance 9 ! elem5t>y bodies ( :i* !y 7 compos$4 ,:5 ,laplace fram$ 8 !ory1 he _h n1 he c\ld n h _h1 ! slighte/ notion z to ! p>ticul> elem5ts 9 ! sun4 ,= any?+ he c\ld tell1 ^? elem5ts might be absolutely diff]5t f ! elem5ts 9 ! e>?4 ,yet1 ev5 )\t in=mation on ?is critical po9t1 ! evid5ce = ! nebul> !ory appe>$ to him s cog5t t he gave x ! sanction ( 8 "n4 ,x _c be d5i$ t if spectroscopic analysis _h demon/rat$ t ! elem5ts 9 ! sun 7 totally diff]5t f ! elem5ts 9 ! e>? a s]i\s bl[ w\ld h be5 dealt to ! nebul> !ory4 ,! collat]al evid5ce1 /rong z x und\bt$ly is1 might h>dly h )/ood s damag+ an admission4 ,if1 on ! o!r h&1 we f9d1 z we actually h f\nd1 t ! elem5ts 9 ! sun & ! elem5ts 9 ! e>? are practically id5tical1 we obta9 ! mo/ /rik+ corroboration ( ! tru? ( ! nebul> !ory4 ,_h ,kant & ,laplace be5 aw>e ( ?is mo/ significant fact1 !y w\ld probably h cit$ x z mo/ important te/imony4 ,!y w\ld h po9t$ out t ! iron s abundant 9 ! e>? b5ea? our feet is also abundant 9 ! sun ov]head4 ,!y w\ld1 ,i d\bt n1 if !y _h kn[n x1 h dwelt ^u ! circum/ance t ) t elem5t1 c>bon1 :i* ent]s into e organic body on ?is e>?1 our sun is also ri*ly suppli$1 & !y w\ld h h>dly fail$ to allude to ! wide di/ribution 9 space ( calcium1 hydrog51 & _m o!r well-kn[n elem5ts4 ,laplace ma9ly bas$ 8 belief 9 ! nebul> !ory on "s rem>kable d$uctions f ! !ory ( probabilities4 ,to ! consid]ation ( ^! we proce$ 9 ! next ?ree *apt]s4 ,we may1 h[ev]1 rem>k at ! outset t if ! evid5ce d]iv$ f probabilities seem$ satisfactory to ,laplace "o hundr$ ye>s ago1 ?is same l9e ( evid5ce1 /r5g!n$ z x has be5 by rec5t discov]ies1 is enorm\sly m weighty1 at ! pres5t day4 ---------------------------------------- -------------------------------- ,,*apt] ,,xiv4 ,,! ,,fir/ ,,concord4 ,c]ta9 ,rem>kable ,co9cid5ces--,! ,plane ( ,movem5t ( a ,planet--,consid]ation ( ,planes ( ,sev]al ,planet>y ,orbits--,a ,*>act]i/ic ( ! ,actual ,planet>y ,motions n to be ,expla9$ by ,*ance--,! ,fir/ ,concord--,! ,planes n at ,r&om--,a ,division ( ! ,"r ,angle--,/atem5t ( ! ,co9cid5ces--,an ,illu/ration by ,p>able--,! ,cause ( ! ,co9cid5ces--,! ,argum5t ,/r5g!n$ by ! ,a/]oids--,an ,explanation by ! ,nebul> ,!ory4 ,,9 ! pres5t *apt]1 & 9 ! two *apt]s :i* are to foll[1 ,i propose to give an outl9e ( ^? argum5ts 9 fav\r ( ! nebul> !ory :i* are pres5t$ by c]ta9 rem>kable co9cid5ces obs]v$ 9 ! movem5ts ( ! bodies ( our sol> sy/em4 ,!re are1 inde$1 c]ta9 features 9 ! movem5ts ( ! planets :i* w\ld seem s inexplicable if ! arrangem5t ( ! sy/em _h tak5 place by *ance1 t x is impossible n to seek = "s physical explanation4 ,we h already _h occasion to ref] 9 previ\s *apt]s to ! movem5ts ( ! bodies ( our sy/em4 ,x w be our object at pres5t to %[ t x is h>dly conceivable t ! movem5ts c\ld h acquir$ ! peculi> *>act]i/ics !y possess unless ! sol> sy/em has itself _h an orig9 su* z t :i* ! nebul> !ory assigns4 ,! argum5t on :i* we are to ent] is1 x mu/ be confess$1 some:at subtle1 b its cog5cy is irresi/ible4 ,= ?is argum5t we are indebt$ to "o ( ! great f\nd]s ( ! nebul> !ory4 ,x 0 giv5 by ,kant himself 9 8 fam\s essay4 ,we w comm5ce ) a prelim9>y po9t :i* relates to elem5t>y me*anics4 ,x may1 h[ev]1 help to cle> up a difficult po9t 9 our argum5t if ,i n[ /ate "s well-kn[n pr9ciples 9 a mann] specially adapt$ = our pres5t purpose4 ,let u ?9k ( two bodies1 ,a & ,s1 &1 = ! sake ( cle>ness1 we may suppose t ea* ( ^! bodies is a p]fect sph]e4 ,we might ?9k ( !m z billi>d balls1 or balls ( /one1 or balls ( iron4 ,we %all1 h[ev]1 suppose !m to be =m$ ( mat]ial :i* is p]fectly rigid4 ,!y may be ( any size :atev]1 l>ge or small1 equal or unequal4 ,"o ( !m may be no great] ?an a gra9 ( mu/>d-se$1 & ! o!r may be z l>ge z ! moon or ! e>? or ! sun4 ,let u fur!r suppose t !re is no o!r body 9 ! univ]se by :i* ! mutual attraction ( ! two bodies we are consid]+ c be int]f]$ )4 ,if ^! two bodies are ab&on$ to _! mutual attraction1 let u n[ see :at ! laws ( me*anics assure u mu/ necess>ily happ54 ,illu/ration3 ,fig4 #de4--;,a ,,spiral ,,pres5t$ ,,edgewise 7n4g4c4 #dfca2 9 ,coma ,b]5ices74 7,photograph$ by ,dr4 ,isaac ,rob]ts1 ,f4,r4,s47 ,let ,a & ,s be simply releas$ f initial positions ( absolute re/4 ,9 ^! circum/ances1 ! two po9ts w />t (f t[>ds ea* o!r4 ,! "t t mu/ elapse be=e ! two bodies collide w dep5d ^u circum/ances4 ,! great] ! initial di/ance betwe5 ! two balls1 _! sizes be+ ! same1 ! long] mu/ be ! int]val be=e !y come toge!r4 ,! relation betwe5 ! di/ance sep>at+ ! bodies & ! "t t mu/ elapse be=e !y meet may be illu/rat$ 9 ?is way4 ,suppose t two balls1 bo? />t+ f re/ at a c]ta9 di/ance1 %\ld take a ye> to come toge!r by _! mutual attraction1 !n we "k t if ! di/ance ( ! two balls _h be5 f\r times z great eight ye>s w\ld h to elapse be=e ! two balls collid$4 ,if ! di/ances 7 n9e times z great !n tw5ty-sev5 ye>s w\ld elapse be=e ! balls collid$1 & g5]ally ! squ>es ( ! times w\ld increase z ! cubes ( ! di/ances4 ,9 su* /atem5ts we are suppos+ t ! radii ( ! balls are inconsid]able 9 comp>ison ) ! di/ances ap>t f :i* !y are />t$4 ,! "t occupi$ 9 ! j\rney mu/ also g5]ally dep5d on ! masses ( ! two bodies1 or1 to speak m precisely1 on ! sum ( ! masses ( ! two bodies4 ,if ! two balls ea* weigh$ five hundr$ tons1 !n !y w\ld take precisely ! same "t to ru% toge!r z w\ld two balls ( "o ton & n9e hundr$ & n9ety-n9e tons respectively1 provid$ ! di/ances betwe5 ! c5tres ( ! two balls _h be5 ! same 9 ea* case4 ,if ! unit$ masses ( ! two bodies am\nt$ to f\r ?\s& tons1 !n !y w\ld meet 9 half ! "t t w\ld h be5 requir$ if _! unit$ masses 7 "o ?\s& tons1 x be+ und]/ood t 9 ea* case !y />t$ ) ! same initial di/ance betwe5 ! c5tres4 ,in/ead ( simply releas+ ! two bodies ,a & ,s s t nei!r ( !m %all h any impulse t5d+ to make x sw]ve f ! l9e directly jo9+ !m1 let u n[ suppose t we give "o ( ! bodies4 ,a1 a slight pu% sideways4 ,! "q w be some:at simpl] if we ?9k ( ,s z v massive1 :ile ,a is relatively small4 ,if1 = in/ance1 ,s be z heavy z a cannon-ball1 :ile ,a is no heavi] ?an a gra9 ( %ot1 !n we may consid] t ,s rema9s practically at re/ dur+ ! movem5t4 ,! small pull :i* ,a is able to give w produce no m ?an an inappreciable effect on ,s4 ,if ! two bodies come toge!r1 ,a w practically d all ! mov+4 ,illu/ration3 ,fig4 #df4--,,! ,,plane ,,( ,a ,,planet',s ,,orbit4 ,we repres5t ! movem5t 9 ! adjo9+ figure4 ,if ,a is />t$ (f ) an initial velocity 9 ! direction ,a ,t1 ! attraction ( ,s w1 h[ev]1 make itself felt1 ev5 ?\gh ,a _c move directly t[>ds ,s4 ,! body w n be all[$ to travel along ,a ,t2 x w be =c$ to sw]ve by ! attraction ( ,s2 x w move f ,p to ,q1 gradually gett+ ne>] to ,s4 ,to ent] into ! details ( ! movem5t w\ld require r m calculation ?an x w\ld be conv5i5t to give "h4 ,ev5 ?\gh ,s is mu* m massive ?an ,a1 we may suppose t ! pa? :i* ,a foll[s is s great t ! diamet] ( ! globe ,s is q insignificant 9 comp>ison ) ! diamet] ( ! orbit :i* ! small] body describes4 ,we %all ?us reg>d bo? ,a & ,s z p>ticles1 & ,kepl]'s well-kn[n law1 to :i* we s (t5 ref]1 tells u t ,a w revolve ar\nd ,s 9 t beautiful figure :i* ! ma!matician calls an ellipse4 ,= our pres5t purpose we are p>ticul>ly to obs]ve t ! movem5t is re/rict$ to a plane4 ,! plane 9 :i* ,a moves dep5ds entirely on ! direction 9 :i* x 0 fir/ />t$4 ,! body w always cont9ue to move 9 ! same plane z t 9 :i* its motion orig9ally comm5c$4 ,?is plane is det]m9$ by ! po9t ,s & ! /raight l9e 9 :i* ,a 0 orig9ally project$4 ,x is ess5tial = our argum5t to note t ,a w nev] sw]ve f its plane s long z !re are n o!r =ces 9 action beside ^? aris+ f ! mutual attractions ( ,a & ,s4 ,! ord9>y p]turbations ( "o body by ! action ( o!rs ne$ n "h conc]n u4 ,! case we h suppos$ w1 ( c\rse1 include t ( ! movem5t ( a planet r\nd ! sun4 ,! planet is small & repres5t$ by ! body ,a1 :i* revolves r\nd ! great body ,s1 :i* /&s = ! sun4 ,h[ev] ! motion ( ! planet may actually h orig9at$1 x moves j z if x _h receiv$ a c]ta9 initial impulse1 9 consequ5ce ( :i* x />t$ into motion1 & ?us def9$ a c]ta9 plane1 to :i* = all "t its motion w\ld be re/rict$4 ,s f> we h spok5 ( only a s+le planet2 let u n[ suppose t a second planet1 ,b1 is also to move 9 revolution ab\t ! same sun4 ,?is planet may be z great z ,a1 or bigg]1 or small]1 b we %all /ill assume t bo? planets are inconsid]able 9 comp>ison ) ,s4 ,we may assume t ,b revolves at ! same di/ance z ,a1 or x may be ne>]1 or fur!r4 ,! orbit ( ,b might also h be5 9 ! same plane z ,a1 or--& "h is ! important po9t--x might h be5 9 a plane incl9$ at any angle :atev] to ! orbit ( ,a4 ,! two planes might1 inde$1 h be5 p]p5dicul>4 ,no matt] h[ v>i$ may be ! circum/ances ( ! two planets1 ! sun w\ld accept ! control ( ea* ( !m2 ea* w\ld be guid$ 9 its own orbit1 :e!r t orbit be a circle1 or :e!r x be an ellipse ( any ecc5tricity :atev]4 ,s f> z ! attraction ( ! sun is conc]n$1 ea* ( ^! planets w\ld rema9 = ev] 9 ! same plane z t 9 :i* x orig9ally />t$4 ,let u n[ suppose a ?ird planet to be add$4 ,"h aga9 we may assume e v>iety 9 ! conditions ( mass & di/ance4 ,we may also assume t ! plane :i* conta9s ! orbit ( ?is ?ird planet is incl9$ at any angle :atev] to ! planes ( ! prec$+ planets4 ,9 ! same way we may add a f\r? planet1 & a fif?2 & 9 ord] to p>allel ! actual circum/ance ( our sol> sy/em1 s f> z its m important memb]s are conc]n$1 we may add a six?1 & a sev5?1 & an eigh?4 ,! planes ( ^! orbits are subject$ to a s+le condition only4 ,ea* "o ( !m passes ?r\gh ! c5tre ( ! sun4 ,if ?is requirem5t is fulfill$1 ! planes may be 9 o!r respects z diff]5t z possible4 ,9 ! actual sol> sy/em ! circum/ances are1 h[ev]1 v diff]5t f :at we h repres5t$ 9 ?is imag9>y sol> sy/em4 ,x is ! mo/ obvi\s *>act]i/ic ( ! tracks ( ,jupit] & ,v5us1 & ! o!r planets belong+ to ! sun1 t ! planes 9 :i* !y respectively move co9cide v ne>ly ) ! plane 9 :i* ! e>? revolves4 ,we mu/ suppose all ! orbits ( our imag9>y sy/em to be flatt5$ d[n1 ne>ly into a plane1 be=e we c trans=m ! imag9>y sy/em ( planets ,i h describ$ into ! semblance ( an actual sol> sy/em4 ,if ! orbits ( ! planets _h be5 arrang$ 9 planes :i* 7 plac$ at r&om1 we may presume !y w\ld h be5 incl9$ at v v>i$ angles4 ,z !y are n s dispos$1 we may conclude t ! planes h n be5 put d[n at r&om2 we mu/ conclude t !re has be5 "s cause 9 action :i*1 if we may s describe x1 has sup]9t5d$ ! planes ( ^! orbits & orda9$ t !y %\ld be plac$ 9 a v p>ticul> mann]4 ,two planets' orbits might conceivably co9cide or be p]p5dicul>1 or !y might conta9 any int]m$iate angle4 ,! plane ( ! second planet might be incl9$ to ! fir/ at an angle conta9+ any numb] ( degrees4 ,to make "s num]ical e/imate ( ! matt]1 we proce$ z foll[s3 ,if we divide ! "r angle into t5 p>ts ( n9e degrees ea* 7,fig4 #dg71 !n ! incl9ation ( ! two planes might1 = example1 lie betwe5 ,o & #i1 or betwe5 #ah & #bg1 or betwe5 #de & #ed1 or betwe5 #ha & #ij1 or 9 any "o ( ! t5 divisions4 ,let u ?9k ( ! orbit ( ,jupit]4 ,!n ! incl9ation ( ! plane 9 :i* x moves to ! plane 9 :i* ! e>? moves mu/ fall into "o ( ! t5 divisions4 ,z a matt] ( fact1 x does fall into ! angle betwe5 #j & #i4 ,illu/ration3 ,fig4 #dg4--;,a ,,"r ,,angle ,,divid$ ,,into ,,t5 ,,p>ts4 ,b n[ let u consid] a second planet1 = example ,v5us4 ,if ! orbit ( ,v5us 7 to be plac$ at r&om1 its incl9ation might ) equal probability lie 9 any "o ( ! t5 divisions1 ea* ( n9e degrees1 into :i* we h divid$ ! "r angle4 ,x w\ld be j z likely to lie betwe5 =ty-five & fifty-f\r1 or betwe5 sev5ty-two & eighty-"o1 z 9 any o!r division4 ,b we f9d ano!r curi\s co9cid5ce4 ,x 0 already rem>kable t ! plane ( ,jupit]'s orbit %\ld h be5 includ$ 9 ! fir/ angle ( n9e degrees f ! orbit ( ! e>?4 ,x is !re=e specially notewor?y to f9d t ! planet ,v5us foll[s ! same law1 ?\gh ea* "o ( ! t5 angul> divisions 0 equally available4 ,! co9cid5ces we h m5tion$1 rem>kable z !y are1 repres5t only ! fir/ ( ! s]ies4 ,:at has be5 said ) respect to ! positions ( ! orbits ( ,jupit] & ,v5us may be repeat$ ) reg>d to ! orbits ( ,m]cury & ,m>s1 ,saturn1 ,uranus1 & ,neptune4 ,if ! tracks ( ^! planets _h be5 plac$ m]ely at r&om1 _! incl9ations w\ld h be5 equally likely to fall into any ( ! t5 divisions4 ,z a matt] ( fact1 !y all agree 9 *oos+ t "o p>ticul> division :i* is adjac5t to ! track ( ! e>?4 ,if ! orbits ( ! planets _h inde$ be5 arrang$ =tuit\sly1 x is almo/ inconceivable t su* co9cid5ces c\ld h occurr$4 ,let me illu/rate ! matt] by ! foll[+ little p>able4 ,!re 7 sev5 classes 9 a s*ool1 & !re 7 t5 boys 9 ea* class4 ,!re 0 "o boy nam$ ,smi? 9 ! fir/ class1 b only "o4 ,!re 0 also "o ,smi?1 b only "o1 9 ea* ( ! o!r classes4 ,! o!rs 7 nam$ ,br[n1 ,jones1 ,rob9son1 etc4 ,an old boy1 nam$ ,capta9 ,smi?1 :o _h gone out to ,au/ralia _m ye>s be=e1 came back to visit 8 old s*ool4 ,he _h succe$$ well 9 ! _w1 & he want$ to d some?+ g5]\s = ! boys at ! place ( :i* he _h su* k9dly recollections4 ,he det]m9$ to give a plum-cake to "o boy 9 ea* class2 & ! =tunate boy 0 to be *os5 by lot4 ,! t5 boys 9 ea* class 7 to draw1 & ea* successful boy 0 to be s5t 9 to ,capta9 ,smi? to receive 8 cake4 ,! ,capta9 sat at a table1 & ! sev5 w9n]s 7 %[n 9 to receive _! prizes4 8,:at is y\r "n80 he said to ! boy 9 ! fir/ class1 z he %ook h&s ) him4 8,smi?10 repli$ ! boy4 8,de> me10 said ! ,capta91 8h[ odd t our names %\ld be ! same4 ,nev] m9d1 x's a good "n4 ,"h's y\r cake4 ,good-bye1 ,smi?40 ,!n up came ! boy f ! second class4 8,:at is y\r "n80 said ! ,capta94 8,smi?1 sir10 0 ! reply4 8,de> me10 said ! visitor4 8,?is is v s+ul>4 ,x is inde$ a v curi\s co9cid5ce t two ,smi?s %\ld h succe$$4 ,7 y really *os5 by draw+ lots80 8,yes1 sir10 said ! boy4 8,!n are all ! boys 9 y\r class nam$ ,smi?80 8,no1 sir2 ,i'm ! only "o ( t "n 9 ! t540 8,well10 said ! ,capta91 8x really is mo/ curi\s4 ,i nev] he>d any?+ s extraord9>y z t two namesakes ( my own %\ld happ5 to be ! w9n]s4 ,n[ !n = ! boy f class ?ree40 ,a *e]ful y\? advanc$ ) a smile4 8,well1 at all ev5ts10 said ! good-natur$ old boy1 8y\r "n is n ,smi?80 8,oh1 b x is10 said ! y\?4 ,! gallant ,capta9 jump$ up1 & decl>$ t !re mu/ h be5 "s trem5d\s imposition4 ,ei!r ! :ole s*ool consi/$ ( ,smi?s1 or !y call$ !mselves ,smi?s1 or !y _h pick$ out ! ,smi?s4 ,! f\r rema9+ boys1 /ill expect+ _! cakes1 "h bur/ out laugh+4 8,:at are y\r names80 %\t$ ! donor4 8,smi?60 8,smi?660 8,smi?6660 8,smi?66660 7 ! a/\nd+ replies4 ,! good man c\ld /& ?is no long]4 ,he s5t = ! s*oolma/]1 & said1 8,i p>ticul>ly reque/$ t y w\ld *oose a boy drawn by lot f ea* ( y\r sev5 classes1 b y h n done s4 ,y h m]ely pick$ out my namesakes & s5t !m up = ! cakes40 ,b ! ma/] repli$1 8,no1 ,i assure y1 !y h be5 hone/ly *os5 by lot4 ,n9e black beans & "o :ite bean 7 plac$ 9 a bag2 ea* class ( t5 !n drew 9 succession1 & 9 ea* class x happ5$ t ! boy nam$ ,smi? drew ! :ite bean40 8,b10 said ! visitor1 8?is is n cr$ible4 ,only once 9 t5 million times w\ld all ! sev5 ,smi?s h drawn ! :ite beans if left solely to *ance4 ,& d y mean to tell me t :at c happ5 only once out ( t5 million times did actually happ5 on ?is occasion--! only occasion 9 my life on :i* ,i h attempt$ su* a ?+8 ,i don't believe ! draw+ 0 made fairly by lot4 ,!re mu/ h be5 "s int]f]5ce ) ! op]ation ( *ance4 ,i insi/ on hav+ ! lots drawn aga9 "u my own inspection40 8,yes1 yes10 %\t$ all ! o!r boys4 ,b all ! successful ,smi?s ro>$ out1 8,no40 ,!y did n feel at all desir\s ( ano!r trial4 ,!y knew en\gh ( ! !ory ( probabilities to be aw>e t !y might wait till ano!r t5 million =tunate old boys came back to ! s*ool be=e !y w\ld h su* luck aga94 ,! situation came to a deadlock4 ,! ,capta9 prote/$ t "s fraud _h be5 p]petrat$1 & 9 spite ( _! assurances he w\ld n believe !m4 ,! sev5 ,smi?s decl>$ !y _h won _! cakes hone/ly1 & t !y w\ld n surr5d] !m4 ,! ,capta9 0 gett+ furi\s1 ! boys 7 on ! po9t ( rebellion1 :5 ! s*oolma/]'s wife1 al>m$ by ! tumult1 came on ! sc5e4 ,%e ask$ :at 0 ! cause ( ! di/urbance4 ,x 0 expla9$ to h]1 & !n ,capta9 ,smi? add$ t by ma!matical probabilities x 0 almo/ inconceivable t ! only sev5 ,smi?s 9 ! s*ool %\ld h be5 *os54 ,! graci\s lady repli$ t %e knew no?+1 & c>$ z little1 ab\t ! !ory ( probabilities1 b %e did c>e greatly t ! s*ool %\ld n be ?r[n into tumult4 8,!re is only "o solution ( ?is difficulty10 %e add$4 8,x is t y =?) provide cakes1 n only = ! sev5 ,smi?s1 b = e "o ( ! boys 9 ! s*ool40 ,?is resolute pron\ncem5t 0 receiv$ ) %\ts ( approval4 ,! ,capta91 ) a some:at rueful c\nt5ance1 ackn[l$g$ t x only rema9$ = him to comply4 ,he return$1 %ortly aft]w>ds1 to 8 gold-digg+s 9 ,au/ralia1 !re to m$itate dur+ 8 leisure on ?is rem>kable illu/ration ( ! !ory ( probabilities4 ,?is p>able illu/rates ! improbability ( su* arrangem5ts z we f9d 9 ! planets hav+ orig9at$ by *ance4 ,! *ances aga9/ _! hav+ ?us occurr$ are #aj1jjj1jjj to #a4 ,h5ce we f9d x reasonable to come to ! conclusion t ! arrangem5t1 by :i* ! planets move r\nd ! sun 9 planes :i* are ne>ly co9cid5t1 _c h orig9at$ by *ance4 ,!re mu/ h be5 "s cause :i* produc$ ?is special disposition4 ,we h1 !re=e1 to se>* = "s common cause :i* mu/ h op]at$ on all ! planets4 ,z ! planets are at pres5t absolutely sep>at$ f ea* o!r1 x is impossible = u to conceive a common cause act+ ^u !m 9 _! pres5t condition4 ,! cause mu/ h op]at$ at "s primval "t1 be=e ! planets assum$ ! sep>ate individual exi/5ce t !y n[ h4 ,we h spok5 s f> ( ! great planets only1 & we h se5 h[ ! probability /&s4 ,we %\ld also rem>k t !re are also ne>ly #ejj small planets1 or a/]oids1 z !y are m g5]ally call$4 ,among !m are1 no d\bt1 a few ^: orbits h incl9ations to ! ecliptic l>g] ?an ^? ( ! great planets4 ,! great majority ( ! a/]oids revolve1 h[ev]1 v close to t rem>kable plane ) :i* ! orbits ( ! great planets s ne>ly co9cide4 ,e "o ( ^! a/]oids increases ! improbability t ! planes ( ! orbits c\ld h be5 arrang$ z we f9d !m1 )\t "s special dispos+ cause4 ,x is n possible or necess>y to write d[n ! exact figures4 ,! probability is absolutely ov]:elm+ aga9/ su* an arrangem5t be+ f\nd if ! orbits ( ! planets _h be5 decid$ by *ance1 & *ance alone4 ,we may feel confid5t t !re mu/ h be5 "s p>ticul> circum/ances accompany+ ! =mation ( ! sol> sy/em :i* r5d]$ x absolutely necess>y = ! orbits ( ! planets to possess ?is p>ticul> *>act]i/ic4 ,we h po9t$ out 9 ,*apt] ,,xii4 t ! nebul> !ory (f]s su* an explanation1 & we d n "k ( any o!r natural explanation :i* w\ld be wor?y ( s]i\s att5tion4 ,inde$1 we may say t no o!r su* explanation has ev] be5 (f]$4 ---------------------------------------- -------------------------------- ,,*apt] ,,xv4 ,,! ,,second ,,concord4 ,ano!r ,rem>kable ,co9cid5ce 9 ! ,sol> ,sy/em--,! ,second ,concord--,! ,direction ( ! ,movem5ts ( ! ,great ,planets--,! ,movem5t ( ,c]es--,yet ,ano!r ,planet--,discov]y ( ,eros--,! ,ne>e/ ,neighb\r ( ! ,e>?--,?r[+ ,heads & ,tails--,a ,calculation ( ! ,*ances--,! ,num]ical ,/r5g? ( ! ,argum5t--,an ,illu/ration ( ! ,probability ( ! ,orig9 ( ! ,sol> ,sy/em f ! ,nebula--,! ,explanation ( ! ,second ,concord (f]$ by ! ,nebul> ,!ory--,! ,relation ( ,en]gy & ,mom5t ( ,mom5tum--,diff]5t ,sy/ems ,illu/rat$--,t all ! ,movem5ts %\ld be 9 ! same ,direction is a ,consequ5ce ( ,evolution f ! ,primval ,nebula4 ,,we h se5 9 ! la/ *apt] t !re is a v rem>kable concordance 9 ! positions ( ! planes ( ! orbits ( ! planets1 & we h %[n t ?is concordance f9ds a natural hi/orical explanation 9 ! nebul> orig9 ( our sy/em4 ,we h n[ to consid] ano!r /rik+ concord 9 ! movem5ts ( ! planets 9 _! sev]al orbits1 & ?is also furni%es u ) important evid5ce z to ! tru? ( ! nebul> !ory4 ,! argum5t on :i* we are n[ to ent] is "o :i* specially appeal$ to ,laplace1 & 0 put =w>d by him z ! ma9 f\ndation ( ! nebul> !ory4 ,illu/ration3 ,fig4 #dh4--;,,illu/ration ,,( ,,! ,,second ,,concord4 ,9 ! adjo9+ ,fig4 #dh we h a diagram ( a portion ( ! sol> sy/em4 ,we %all reg>d ! movem5ts z some:at simplifi$4 ,! sun is suppos$ to be at ! c5tre1 turn+ r\nd once e tw5ty-five days1 on an axis :i* is suppos$ to be p]p5dicul> to ! plane ( ! pap]4 ,we may also = our pres5t purpose assume t ! orbits ( ! e>? & ! o!r planets lie 9 ?is same plane4 ,9 ! fir/ place we obs]ve t ! e>? might h gone r\nd its track 9 ei!r direction s f> z ! welf>e ( mank9d is conc]n$4 ,! succession ( day & night1 & ! due *anges ( ! seasons1 c\ld h be5 equally well secur$ :i*ev] be ! direction 9 :i* ! e>? revolves4 ,we d1 h[ev]1 mo/ c]ta9ly f9d t ! direction 9 :i* ! e>? revolves r\nd ! sun is ! same z ! direction 9 :i* ! sun rotates on its axis4 ,?is is ! fir/ co9cid5ce4 ,we may n[ consid] o!r planets4 ,look1 = in/ance1 at ! orbit ( ,jupit]4 ,x seems obvi\s t ,jupit] might h be5 made to revolve r\nd ! sun ei!r "o way or ! o!r2 inde$1 x w be rememb]$ t ?\gh ,kepl]'s laws indicate s p>ticul>ly ! %ape ( ! track 9 :i* ! planet revolves1 & prescribe s beautifully ! way 9 :i* ! planet mu/ mod]ate or accel]ate its velocity at ! diff]5t p>ts ( its track1 yet !y are q sil5t z to ! direction 9 :i* ! planets %all revolve 9 t track4 ,if we c\ld imag9e a planet to be /opp$ to h its velocity rev]s$1 & !n to be />t$ 9 a precisely opposite direction1 x w\ld /ill cont9ue to describe precisely ! same pa?2 x w\ld /ill obey ,kepl]'s laws ) unfail+ accuracy1 s f> z our pres5t argum5t is conc]n$1 & ! velocity :i* x w\ld h at ea* po9t ( ! track w\ld be q ! same :e!r ! planet 7 go+ "o way or :e!r x 0 go+ ! o!r4 ,x is !re=e equally possible = ,jupit] to pursue 8 actual track by go+ r\nd ! sun 9 ! same direction z ! e>?1 or by go+ 9 ! opposite direction4 ,b we actually f9d t ,jupit] does take ! same direction z ! e>?1 & ?is1 z we h already se51 is ! direction 9 :i* ! sun rotates4 ,"h we h ! second co9cid5ce4 ,we n[ take ano!r planet2 = example1 ,m>s4 ,aga9 we affirm t ,m>s c\ld h mov$ 9 ei!r direction1 b1 z a matt] ( fact1 x pursues ! same direction z ,jupit] & ! e>?4 ,9 ! orbital movem5t ( ,saturn we h ! f\r? co9cid5ce ( ! same k9d1 & we h a fif? 9 ! case ( ,m]cury1 & a six? 9 ,v5us1 a sev5? 9 ,uranus1 & an eigh? 9 ,neptune4 ,! sev5 great planets & ! e>? all revolve ar\nd ! sun1 n only 9 orbits :i* are v ne>ly 9 ! same plane1 b !y also revolve 9 ! same direction4 ,! co9cid5ces we h po9t$ out ) reg>d to ! movem5ts ( ! great planets ( our sy/em may be also obs]v$ ) reg>d to ! num]\s bodies ( a/]oids4 ,on ! fir/ night ( ! c5tury j clos$1 ! #a/ ( ,janu>y1 #ahja1 ! fir/ ( ! a/]oids1 n[ kn[n z ,c]es1 0 discov]$4 ,?is 0 a small planet1 n a ?\s&? "p ( ! bulk ( "o ( ! old] planets1 & visible1 ( c\rse1 only 9 ! telescope4 ,l ! old] planets1 x 0 f\nd to obey ,kepl]'s laws2 b ?is we might h =ese51 because ,kepl]'s laws dep5d ^u ! attraction ( gravitation1 & mu/ apply to any planet1 :atev] its size4 ,:51 !re=e1 ! new planet 0 f\nd1 & its track 0 kn[n1 x 0 ( mu* int]e/ to see :e!r ! planet 9 mov+ r\nd t track obs]v$ ! same direction 9 :i* all ! old] planets _h agre$ to travel1 or :e!r x mov$ 9 ! opposite direction4 ,9 ! orbit ( ,c]es we h a repetition ( ! co9cid5ce :i* has be5 notic$ 9 ea* ( ! o!r planets4 ,! new planets1 l all ! re/1 move r\nd ! sun 9 ! same direction z ! sun rotates on its axis4 ,! discov]y ( ?is fir/ a/]oid 0 quickly foll[$ by o!r simil> discov]ies2 ea* ( ! new planets describ$1 ( c\rse1 an ellipse1 & ! directions :i* ^! planets foll[$ 9 _! movem5ts r\nd ! sun 7 9 absolute h>mony ) ^? ( ! old] planets4 ,b1 besides ! great planets & ! a/]oids prop]ly s call$1 !re is yet ano!r planet1 ,eros4 ,its te/imony is ( special value1 inasmu* z x seems to /& ap>t f all o!r bodies 9 ! sol> sy/em1 & )1 ( c\rse1 ! exception ( ! moon1 x is ! e>?'s ne>e/ neighb\r4 ,b :atev] may be ! exceptional features ( ,eros1 h[ev] x may diff] f ! great planets & ! a/]oids already kn[n1 yet ,eros makes no exception to ! law :i* we h f\nd to be obey$ by all ! o!r planets4 ,x also revolves r\nd ! sun 9 ! same direction z all ! planets revolve1 9 ! same direction z ! rotation ( ! sun 7,fig4 #di74 ,we may pause at ?is mom5t to make a calculation z to ! improbability t ! sun1 ! e>?1 ! sev5 great planets1 & ,c]es1 numb]+ altoge!r t51 %\ld move r\nd 9 ! same direction if _! movem5ts _h be5 left to *ance4 ,?is w %[ :at we c reasonably inf] f ?is concord 9 _! movem5ts4 ,! !ory ( probabilities w aga9 enlight5 a difficult subject4 ,!re are only two possible directions = ! motion ( a planet 9 its orbit4 ,x mu/ move l ! h&s ( a wat*1 or x mu/ move 9 ! opposite direction4 ,! planet mu/ move "o way or ! o!r1 j z a p5ny mu/ always fall head or tail4 ,illu/ration3 ,fig4 #di4--,,orbits ,,( ,,e>?1 ,,eros ,,& ,,m>s4 ,we may illu/rate ?is rem>kable co9cid5ce 9 ! foll[+ mann]3 ,suppose we take t5 co9s 9 ! h&1 & toss !m all up toge!r & let !m fall on ! table2 9 ! va/ majority ( cases 9 :i* ! exp]im5t may be tri$1 !re w\ld be "s heads & "s tails2 !y w\ld n all be heads4 ,b x is1 ( c\rse1 n impossible t ! co9s %\ld all turn up heads4 ,we %\ld1 h[ev]1 deem x a v rem>kable circum/ance if x happ5$3 yet x w\ld c]ta9ly n be m rem>kable ?an t ! t5 cele/ial movem5ts %\ld all take place 9 ! same direction1 unless1 inde$1 x %\ld turn out t !re is "s s\nd physical cause :i* imposes on ! planets ( ! sol> sy/em an obligation1 re/rict+ _! movem5ts r\nd ! sun to ! same direction z t 9 :i* ! sun itself rotates4 ,x w be useful to /udy ! matt] num]ically2 & ! rules ( probabilities w enable u to d s1 z we may see by ! foll[+ illu/ration3 ,we deem ! capta9 ( a cricket team =tunate :5 he w9s ! toss = inn+s4 ,we %\ld deem him lucky inde$ if he won x ?ree times 9 successive mat*es4 ,if he won x five times runn+1 8 luck w\ld be ph5om5al2 :ile1 if x 0 /at$ t he won x t5 times consecutively1 we %\ld consid] ! /atem5t well-nigh incr$ible4 ,= x is easy to calculate t ! *ances aga9/ su* an occurr5ce are "o ?\s& & tw5ty-f\r to "o4 ,9 l mann] we may say1 t = n9e planets & ! sun all to g r\nd 9 ! same direction w\ld be inde$ surpris+ if ! arrangem5t ( ! planets _h be5 det]m9$ by *ance2 !re are m ?an a ?\s& *ances to "o aga9/ su* an occurr5ce4 ,b ,c]es 0 only ! e>lie/ ( _m o!r simil> discov]ies4 ,& z ea* a/]oid 0 successively br\ght to light1 x became mo/ int]e/+ to te/ :e!r x foll[$ ! re/ ( ! planets 9 t wond]ful unanimity 9 ! direction ( _! movem5ts ( revolution1 or :e!r x made a new dep>ture by go+ 9 ! opposite direction4 ,no su* exception has ev] yet be5 obs]v$4 ,let u take1 !n1 t5 m planets1 9 addition to ^? we h already consid]$1 s t we h n[ n9ete5 planets all revolv+ 9 ! same direction z ! sun rotates4 ,x is easy to compute ! improbability t ^! tw5ty movem5ts %\ld all be 9 ! same direction1 if1 inde$1 x 7 by *ance t _! directions _h be5 det]m9$4 ,x is ! same problem z ! foll[+3 ,:at is ! *ance t tw5ty co9s1 tak5 toge!r 9 ! h& & toss$ into ! air at once1 %all all alight ) _! heads upp]mo/8 ,we h se5 t ! *ances aga9/ ?is occurr5ce1 if !re 7 t5 co9s1 is ab\t a ?\s& to "o4 ,x c easily be %[n t if !re 7 tw5ty co9s ! *ances aga9/ ! occurr5ce w\ld be a million to "o4 ,we ?us see t1 ev5 ) no m ?an n9ete5 planets & ! sun1 !re is a million to "o aga9/ a unanimity 9 ! directions ( ! movem5ts1 if ! det]m9ation ( ! motions 0 made by *ance4 ,we may1 h[ev]1 express ! result 9 a diff]5t mann]1 :i* is m to ! purpose ( our argum5t4 ,!re are a million *ances to "o 9 fav\r ( ! supposition t ! disposition ( ! movem5ts ( ! planets has n be5 ! result ( *ance2 or we may say t !re are a million *ances to "o 9 fav\r ( ! supposition t "s physical ag5t has caus$ ! unanimity4 ,we c add almo/ any desir$ am\nt ( num]ical /r5g? to ! argum5t4 ,! discov]ies ( m9or planets w5t on ) ev]-increas+ success ?r\gh ! :ole ( ! la/ c5tury4 ,:5 t5 m _h be5 f\nd1 & :5 ea* "o 0 %[n to obey ! same invisible guide z to ! direction 9 :i* x %\ld pursue its elliptic orbit1 ! *ances 9 fav\r ( "s physical cause = ! unanimity became multipli$ by yet ano!r ?\s&4 ,! probability !n /ood at a ?\s& millions to "o4 ,z ! ye>s roll$ by1 a/]oids 7 f\nd 9 ev]-increas+ abundance4 ,sometimes a s+le a/ronom] discov]$ two1 & sometimes ev5 m ?an two1 on a s+le night4 ,9 ! c\rse ( a lifetime a dilig5t a/ronom] has plac$ fifty discov]ies ( a/]oids1 or ev5 m ?an fifty1 on 8 record4 ,by comb9$ ef=ts ! tale ( ! a/]oids has n[ approa*$ five hundr$1 & out ( t huge numb] ( indep5d5t planet>y bodies !re is n "o s+le diss5ti5t 9 ! direction ( its motion4 ,)\t any exception :atev]1 !y all p]=m _! revolutions 9 ! same direction z ! sun rotates at ! c5tre4 ,:5 ?is great ho/ is consid]$1 ! num]ical /r5g? ( ! argum5t w\ld require ab\t #aej figures = expression4 ,ea* new a/]oid simply d\bl$ ! /r5g? ( ! argum5t z x /ood be=e4 ,pr(essor ,j4 ,j4 ,?omson rec5tly discov]$ t !re are corpuscles ( matt] v mu* small] ?an atoms4 ,let u ?9k ( "o ( ^! corpuscles1 ( :i* _m millions w\ld be requir$ to make ! smalle/ gra9 ( s& :i* w\ld j be visible "u a microscope4 ,?9k1 on ! o!r h&1 ( a sph]e ext5d+ ?r\gh space to s va/ a di/ance t e /> 9 ! ,milky ,way w be conta9$ )9 its compass4 ,!n ! numb] ( ^? corpuscles :i* w\ld be requir$ to fill t sph]e is /ill f> too small to repres5t ! hug5ess ( ! improbability t all ! five hundr$ planet>y bodies %\ld revolve 9 ! same direction1 if *ance1 & *ance alone1 _h guid$ ! direction :i* ea* planet 0 to pursue 9 mov+ r\nd its orbit4 ,! m]e /atem5t ( ^! facts is suffici5t to %[ t "s physical ag5t mu/ h caus$ ?is m>vell\s concord 9 ! movem5ts ( ! sol> sy/em4 ,h[ ! argum5t w\ld h /ood if !re _h be5 ev5 a s+le diss5ti5t x is n necess>y to consid]1 = !re is no diss5ti5t ,no reasonable p]son w d5y t ^! facts impose an obligation to se>* = ! physical explanation ( ?is feature 9 ! planet>y movem5ts4 ,z 9 ! la/ *apt]1 :]e we 7 deal+ ) ! positions ( ! planes ( ! orbits1 !re c "h be no hesitation z to ! true cause ( ?is mo/ /rik+ *>act]i/ic ( ! planet>y movem5ts4 ,! nebul> !ory is at once ready ) an explanation1 z has be5 already indicat$ 9 ,*apt] ,,xi4 ,! primval nebula1 end[$ 9 ! beg9n+ ) a c]ta9 am\nt ( mom5t ( mom5tum1 has be5 gradually contract+4 ,x has be5 gradually exp5d+ its en]gy1 z we h already _h occasion to expla92 b ! mom5t ( mom5tum has rema9$ undim9i%$4 ,& f ?is x c be %[n t ! dynamical pr9ciples guid+ ! evolution ( ! nebula mu/ ultimately refuse p]mission = any planet to revolve 9 opposition to ! g5]al movem5t4 ,?is po9t is a v int]e/+ "o1 & z x is ( v great importance 9 connection ) our sy/em1 ,i mu/ give x "s fur!r illu/ration & explanation4 ,! two figures t are %[n 9 ,fig4 #ej repres5t two imag9>y sy/ems4 ,we h a sun 9 ea*1 & we h two planets 9 ea*4 ,! sun is m>k$ ) ! lett] ,s1 & ! two planets are designat$ by ,a & ,b4 ,= simplicity ,i h repres5t$ ! orbits z circles1 & = ! same reason ,i h left out ! re/ ( ! planets2 we %all also suppose ! orbits ( ! two planets t are involv$ to lie exactly 9 ! same plane4 ,9 ! two sy/ems t ,i h "h suppos$1 ! two suns are to be ( ! same weight1 ! planet ,a 9 "o sy/em is ( equal mass to ! planet ,a 9 ! o!r2 & ! planets ,b 9 ! two sy/ems are also equal4 ,x is also assum$ t ! orbit ( ,a 9 "o diagram %all be ! same z ! orbit ( ,a 9 ! o!r1 & t ! orbit ( ,b 9 "o %all be precisely ! same z ! orbit ( ,b 9 ! o!r4 ,! sun rotates 9 precisely ! same mann] 9 bo?1 & takes ! same "t = ea* rotation4 ,a1 9 "o sy/em1 goes r\nd 9 ! same "t t ,a does 9 ! o!r2 & ,b1 9 "o sy/em1 goes r\nd 9 ! same "t t ,b does 9 ! o!r4 ,!re is1 !re=e1 a p]fect resemblance betwe5 ! two sy/ems ,i h "h suppos$ 9 e po9t b "o4 ,i h indicat$1 z usual1 ! movem5ts ( ! bodies by arr[s1 &1 :ile 9 "o ( ! sy/ems ! sun & ,a & ,b all g r\nd 9 ! same direction1 9 ! o!r sy/em ! sun & ,a g r\nd1 no d\bt1 9 ! same direction1 b ! direction ( ,b is opposite4 ,we are n1 9 ?is illu/ration1 consid]+ ! rotations ( ! planets on _! axes4 ,t w be dealt ) 9 ! next *apt]4 ,illu/ration3 ,fig4 #ej4--;,i4 ,a ,,natural ,,sy/em ,,on ,,! ,,left4 ,,ii4 ,,an ,,unnatural ,,sy/em ,,on ,,! ,,"r4 ,!re c be no d\bt t ei!r ( ^! two sy/ems w\ld be possible = ?\s&s ( revolutions4 ,!re is no?+ :atev] to prev5t ,a & ,b f be+ />t$ 9 ! same direction r\nd ! sun z 9 ! fir/ figure1 or ) ,a 9 "o direction & ,b 9 ! opposite direction1 z 9 ! second figure4 ,x is equally conceivable t1 :ile ,a & ,b revolve 9 ! same direction1 bo? %\ld be opposite to t ( ! sun4 ,b "o sy/em is p]man5t1 & ! o!r is n4 ,=1 z a matt] ( fact1 we d n f9d 9 ,nature su* an arrangem5t z t 9 ! second figure1 or z t 9 :i* bo? ! planets revolve 9 opposite directions to ! sun's rotation2 :at we d f9d is1 t ! planets g r\nd 9 ! same direction z ! sun4 ,& ! explanation is und\bt$ly connect$ ) ! important pr9ciple already illu/rat$1 namely1 t natural sy/ems are 9 a condition 9 :i* ! total quantity ( en]gy und]goes cont9u\s r$uction 9 comp>ison ) ! mom5t ( mom5tum4 ,9 ! arrangem5ts made 9 ! two figures1 x w be recollect$ t ! masses ( ! ?ree bodies 7 respectively ! same1 & also _! di/ances ap>t1 & _! velocities4 ,z ! en]gy dep5ds only on ! masses1 ! di/ances1 & ! velocities1 ! en]gies ( ! two sy/ems mu/ be id5tical4 ,b ! mom5t ( mom5tum ( ! two sy/ems is v diff]5t1 = :ile 9 ! "o case ! sum ( ! mom5ts ( mom5tum ( ! sun's rotation & t ( ! planet ,a1 :i* is go+ 9 ! same direction1 are to be increas$ by ! mom5t ( mom5tum ( ,b1 ! same is n ! case 9 ! o!r sy/em4 ,! mom5t ( mom5tum ( ! sun & ( ,a conspire1 no d\bt1 & mu/ be add$ toge!r2 b z ,b is revolv+ 9 ! opposite direction1 ! mom5t ( mom5tum ( ?is planet has to be subtract$ be=e we obta9 ! nett mom5t ( mom5tum ( ! sy/em4 ,h5ce1 we p]ceive a rem>kable diff]5ce betwe5 ! two sy/ems2 =1 ?\gh 9 ea* ! total en]gy is ! same1 yet 9 ! latt] case ! mom5t ( mom5tum is small] ?an 9 ! =m]4 ,x has be5 po9t$ out t ! effect ( ! mutual actions ( ! diff]5t bodies ( a sy/em is to less51 9 c\rse ( "t1 ! total quantity ( en]gy t !y receive 9 ! beg9n+1 :ile x is n 9 ! p[] ( ! mutual actions ( ! p>ticles ( ! sy/em to affect ! sum total ( ! mom5t ( mom5tum4 ,h5ce we see t1 s long z ! sy/em is isolat$ f ext]nal int]f]5ce1 ! t5d5cy mu/ ev] be t[>ds ! r$uction ( ! quantity ( en]gy to z l[ a po9t z may be compatible ) ! pres]vation ( ! necess>y am\nt ( mom5t ( mom5tum4 ,! fir/ ( ! two sy/ems giv5 9 ,fig4 #ej is mu* m 9 con=mity ) ?is pr9ciple ?an ! second4 ,! mom5t ( mom5tum 9 ! =m] case mu/ be ne>ly z l>ge z c\ld be obta9$ by any o!r disposition ( ! matt] =m+ x1 ) ! same am\nt ( en]gy4 ,b 9 ! second diagram ! mom5t ( mom5tum is mu* less1 ?\gh ! en]gy is ! same4 ,x foll[s t ! en]gy ( ?is sy/em might be l>gely r$uc$1 = if accompani$ by a suitable re>rangem5t ( ! planets ! r$uc$ am\nt ( mom5t ( mom5tum might be easily provid$ =4 ,we ?us see t ?is sy/em is n "o to :i* ! evolution ( a mat]ial arrangem5t w\ld ultimately t5d4 ,x is1 !re=e1 n to be expect$ 9 ,nature1 & we d n f9d x4 ,( c\rse1 ! same w\ld be equally true if1 in/ead ( hav+ m]ely two planets1 z ,i h "h suppos$ = ! sake ( illu/ration1 ! planets 7 mu* m num]\s4 ,! op]ation ( ! causes we h be5 consid]+ w %[ t1 9 ! evolution ( su* a sy/em1 !re w be a t5d5cy = ! planets to revolve 9 ! same direction4 ,x is easy to see h[1 9 ! contraction ( ! orig9al nebula1 !re mu/ h be5 a /rong influ5ce to *eck & efface any movem5ts antagoni/ic to ! g5]al direction ( ! rotation ( ! nebula4 ,if p>ticles revolve 9 a direction opposite to ! curr5t pursu$ by ! majority ( p>ticles1 !re w\ld be collisions & frictions1 & ^! collisions & frictions w1 ( c\rse1 f9d expression 9 ! production ( equival5t quantities ( heat4 ,t heat w1 9 due c\rse1 be radiat$ away at ! exp5se ( ! en]gy ( ! sy/em1 & consequ5tly1 s long z any contr>y movem5ts exi/1 !re w be an exceptional loss ( en]gy f ?is cause4 ,?us ! en]gy w\ld incessantly t5d to decl9e4 ,z ! %r9k+ ( ! body proce$$ :ile ! mom5t ( mom5tum w\ld h to be su/a9$1 ?is w\ld incessantly t5d m & m to require f all ! p>ticles a movem5t 9 ! same direction4 ,! second concord ( ! planet>y sy/em1 :i* is impli$ 9 ! fact t all ! planets g r\nd 9 ! same direction1 ne$ n !re=e surprise u4 ,x is a consequ5ce1 an inevitable consequ5ce1 ( ! evolution ( t sy/em f ! great primval nebula4 ,we h se5 t x w\ld be excessively improbable t ev5 n9e or t5 planets %\ld revolve r\nd ! sun 9 ! same direction1 if ! directions ( _! movem5ts _h be5 m]ely decid$ by *ance4 ,we h se5 t ! movem5ts ( ! ho/s ( planets1 :i* actually =m our sy/em1 w\ld be inconceivable1 unless !re 7 "s reason = ^? movem5ts4 ,! *ances aga9/ su* an arrangem5t hav+ aris5 )\t "s pr$ispos+ cause is s va/ t1 ev5 if ! *ances 7 inf9ite1 ! case w\ld be h>dly /r5g!n$4 ,b once we grant t ! sy/em orig9at$ f ! contraction ( ! primval nebula1 dynamics (f]s ready aid1 & ! difficulty vani%es4 ,n only d we see mo/ excell5t reasons :y all ! planets %\ld revolve 9 ! same direction2 we are also provid$ ) illu/rations ( simil> evolutions 9 progress 9 o!r p>ts ( ! univ]se2 we le>n t ! evolv+ nebula1 h[ev] erratic may h be5 its primitive motion1 :atev] cross curr5ts may h agitat$ x 9 ! e>ly phases ( a possibly viol5t orig91 w ultimately atta9 a rotation uni=m 9 direction4 ,z ! evolution proce$s1 ! v>i\s p>ts ( ! nebula draw toge!r to =m ! planets ( ! future sy/em1 & ! planets reta9 ! movem5t possess$ by _! compon5t p>ticles4 ,?us we see t ! nebul> !ory n only extricates u f ! difficulty ( try+ to expla9 some?+ :i* seem$ almo/ inf9itely improbable1 b x also %[s :y no o!r disposition ( ! motions ?an t :i* we actually f9d c\ld be expect$4 ,! nebul> !ory expla9s to u :y !re is no exception to t fundam5tal law 9 ! sol> sy/em :i* decl>es t ! orbits ( ! planets %all all be foll[$ 9 ! same direction4 ,?is wond]ful agreem5t 9 ! movem5ts ( ! planets1 :i* we h call$ ! second concord1 ?us af=ds u /rik+ evid5ce ( ! g5]al tru? ( ! nebul> !ory4 ,b !re is yet a ?ird concord 9 ! sol> sy/em :i*1 l ! o!r two1 l5ds wond]ful corroboration to ! sublime doctr9e ( ,kant & ,laplace4 ,?is we %all consid] 9 ! next *apt]4 ---------------------------------------- -------------------------------- ,,*apt] ,,xvi4 ,,! ,,?ird ,,concord4 ,rotations ( ! ,planets on _! ,axes4--,! ,old] ,planets--,no ,in=mation ab\t ,uranus or ,neptune or ! ,a/]oids--,! ,spe$ ( ,rotation is ,arbitr>y s f> z ,kepl]'s ,laws are conc]n$--,! ,?ird ,concord--,a ,rem>kable ,unanimity--,kant's ,argum5t--,illu/ration ( ! ,rotation ( ! ,moon on its ,axis--,h[ ! ,nebul> ,!ory expla9s ! ,rotation--,! ,moon's ,evolution--,special ,action ( ,tides--,! ,evolution ( ! o!r ,satellites--,! case ( ,m>s--,jupit] & ,saturn z ,m9iatures ( ! ,sol> ,sy/em--,uranus & ,neptune (f] ,difficulties4 ,,we h se5 9 ! la/ *apt] h[ ! rotation ( ! sun beat "t1 z x 71 = ! planets1 by giv+ to !m an indication ( ! direction 9 :i* ! revolutions r\nd ! sun %\ld be p]=m$1 & we h obs]v$ ) :at m>vell\s unanimity ! planets foll[ ! precept ?us giv54 ,we h n[ to consid] yet ano!r concord1 :i* has p]haps n ! great num]ical /r5g? ( t la/ consid]$1 b is1 nev]!less1 wor?y ( our mo/ special att5tion4 ,! e>? revolves ab\t an axis :i* is n v f> f be+ p]p5dicul> to ! pr9cipal plane to :i* ! movem5ts ( ! sol> sy/em are relat$4 ,f a dynamical po9t ( view x w\ld1 ( c\rse1 h be5 equally possible = ! e>? to revolve on its axis 9 ! same direction z ! rotation ( ! sun1 or 9 ! opposite direction4 ,!re is no?+ s f> z ! welf>e ( man is conc]n$ to make "o direction ( rotation pref]able to ! o!r1 b1 z a matt] ( fact1 ! e>? does turn r\nd 9 ! same way z ! sun turns4 ,jupit] also turns on its axis1 & ,jupit] aga91 l ! e>?1 might turn ei!r ) ! sun or x might turn 9 ! opposite direction4 ,"h1 aga91 we f9d a unanimity betwe5 ! e>? & ,jupit]2 !y bo? turn 9 ! same direction1 & t is ! direction 9 :i* ! sun rotates4 ,! same may be said ( ,m>s1 & ! same may be said ( ,saturn4 ,9 ! case ( ! planets ,m]cury & ,v5us we _c speak ) equal def9it5ess on ! subject ( _! rotations ab\t _! axes4 ,! circum/ances ( ^! planets are su* t !re are great difficulties att5d+ ! exact telescopic det]m9ation ( _! p]iods ( rotation4 ,! wide/ v>iations appe> 9 ! p]iods :i* h be5 assign$4 ,x has1 = in/ance1 be5 believ$ t ,v5us rotates 9 a p]iod n greatly diff]+ f ! p]iod ( tw5ty-f\r h\rs 9 :i* our e>? revolves4 ,b x has be5 lately suppos$ t ! p]iod ( ,v5us is v mu* long]1 & is 9 fact no less ?an sev5 mon?s1 :i* is1 inde$1 t ( ! revolution ( ,v5us ab\t ! sun4 ,accord+ to ?is view1 ,v5us rotates r\nd ! sun 9 a p]iod equal to its revolution4 ,if ?is be s1 !n ,v5us con/antly turns ! same face to ! sun1 & ! movem5t ( ! planet w\ld ?us resemble ! movem5t ( ! moon ar\nd ! e>?4 ,z a matt] ( obs]vation1 ! "q mu/ /ill be consid]$ unsettl$1 ?\gh !re are s\nd dynamical reasons = believ+ t ! long p]iod is mu* m probable ?an ! %ort "o4 ,we d n n[ ent] into ?is "q1 or into ! /ill m difficult matt] ( ! rotation ( ,m]cury2 x suffices to say t :i*ev] p]iod be adopt$ = ei!r ( ^! planets is really n mat]ial to our pres5t argum5t4 ,9 bo? cases x has nev] be5 d\bt$ t ! direction ( ! rotation ( ! planets is ! same z ! direction 9 :i* ,jupit] & ,m>s & ! e>? rotate1 ^! be+ also ! same z ! direction ( ! sol> rotation4 ,z to ! rotations ( ,uranus & ,neptune ab\t _! respective axes1 ! telescope c %[ u no?+4 ,! remot5ess ( bo? ^! planets is su* t we are unable to disc]n objects on _! discs ) ! def9it5ess t w\ld be requir$ if we desir$ to wat* _! rotations4 ,we h also no in=mation z to ! rotation ( ! sev]al a/]oids4 ,no "o1 ,i ?9k1 w d\bt t ea* ( ^! small planets1 equally ) ! l>ge planets1 does rotate ab\t its axis2 b x is impossible = u to say s f actual k4 ,b und\bt$ly ! five old planets1 ,m]cury1 ,v5us1 ,m>s1 ,jupit]1 & ,saturn1 z well z ! e>?1 all rotate 9 ! same direction z ! sun4 ,ea* planet might rotate twice z fa/1 or half z fa/1 z x does at pres5t4 ,!y might all rotate 9 ! opposite direction f t 9 :i* !y d n[1 or "s ( !m might g 9 "o direction1 & "s 9 ! o!r1 ) e v>iety 9 _! diurnal p]iods1 :ile ! prim>y condition ( ,kepl]'s ,laws w\ld h /ill be5 compli$ )4 ,we may also note t ! direction 9 :i* ! rotation takes place seems q immat]ial s f> z ! welf>e ( ! inhabitants on ^! planets is conc]n$4 ,! fact t ! planets & ! sun h ?is ?ird concord dem&s special att5tion4 ,! *ance t ! e>? %\ld rotate 9 ! same direction z ! sun is1 ( c\rse1 express$ by "o-half4 ,x is easy to %[1 t out ( sixty-f\r possible arrangem5ts ( ! directions ( rotation ( ! five planets & ! e>?1 !re w\ld be only "o 9 :i* all ! movem5ts co9cid$ ) ! direction ( ! rotation ( ! sun4 ,if1 !re=e1 x _h be5 by *ance t ! direction ( ^! motions 0 det]m9$1 !n ,nature w\ld h tak5 a c\rse ( :i* ! probability 0 only "o sixty-f\r?4 ,no d\bt ?is figure is by no means s l>ge z ^? :i* express$ ! probabilities ( ! o!r planet>y concords2 x is1 h[ev]1 q suffici5t to conv9ce u t ! direction ( ! rotation ( ! planets on _! axes has n be5 det]m9$ m]ely by ! op]ation ( *ance4 ,we are to see if !re is any physical ag5t by :i* ! planets h be5 =c$ to turn r\nd 9 ! same direction4 ,& "h comes 9 "o ( ^? subtle po9ts :i* ! metaphysical g5ius ( ,kant sugge/$4 ,let u take any two planets--say1 = in/ance1 ! e>? & ,jupit]--& let u endeav\r to see :at ! nature ( ! ag5t mu/ h be5 :i* has op]at$ on ^! planets s z to make !m bo? rotate 9 ! same direction4 ,kant urg$ t !re mu/ h be5 "s mat]ial ag5t work+ on ! mat]ials 9 ,jupit]1 & "s mat]ial ag5t work+ on ^? ( ! e>?1 & t to produce ! l effect 9 ea* planet !re mu/ h be5 at "o "t a mat]ial connection exi/+ betwe5 t body :i* is n[ ,jupit] & t body :i* is n[ ! e>?4 ,9 l mann] ,kant saw ?is mat]ial connection exi/+ betwe5 ! o!r planets & ! sun1 & ?us he 0 l$ to see t ! :ole mat]ial ( our sol> sy/em mu/ once h =m$ a m or less cont9u\s object4 ,! argum5t is a delicate "o1 b x seems c]ta9ly true t 9 ! pres5t arrangem5t ( ! orbits x is impossible = u to conceive h[1 ) int]vals ( empty space betwe5 ! tracks ( ! planets1 a common influ5ce c h be5 ex]t$ s z to give !m all rotations 9 ! same direction4 ,! nebul> !ory at once supplies ! explanation ( ! unanimity 9 ! rotation ( ! planets1 j z x suppli$ ! explanation ( ! unanimity 9 ! directions ( _! revolutions4 ,to expla9 ! rotation ( a planet on its axis1 let u imag9e t "o portion ( ! contract+ nebula has acquir$ exceptional d5sity4 ,9 virtue ( its sup]ior attraction x absorbs m & m mat]ial f ! adjac5t p>ts ( ! nebula1 & ?is w ultimately be consolidat$ into ! planet1 ?\gh 9 its initial /ages ?is contract+ matt] w rema9 "p ( ! nebula4 ,we h %[n t ! law :i* decrees t ! mom5t ( mom5tum mu/ rema9 con/ant w require t1 aft] a c]ta9 advance 9 ! contraction1 all ! p>ts ( ! nebula %all rotate 9 ! same direction4 ,?us we f9d t ! sun1 or r ! p>ts ( ! nebula t are to =m ! sun1 & ! p>ts t are to =m ! planets are all turn+ r\nd toge!r4 ,illu/ration3 ,fig4 #ea4--;,,an ,,elongat$ ,,irregul> ,,nebula 7n4g4c4 #fiib2 9 ,cygnus74 7,dr4 ,w4 ,e4 ,wilson1 ,f4,r4,s47 7,f ! ,a/ronomical & ,physical ,rese>*es at ,d>amona ,obs]vatory47 ,at ?is po9t we may consid] a geometrical pr9ciple :i*1 ?\gh really q simple1 is n always easily und]/ood4 ,x has inde$ pres5t$ consid]able difficulty to _m p4 ,suppose t an ord9>y c>d is laid on a flat bo>d1 & t1 ) a bradawl1 a hole is made ?r\gh ! c>d into ! bo>d4 ,! hole may be at ! c5tre1 or at "o ( ! corn]s1 or a little way 9 f "o ( ! edges1 or 9 any o!r position :atev] on ! c>d4 ,n[ suppose t a po/age /amp is /uck ^u ! c>d any:]e1 & t ! c>d is !n mov$ ar\nd ! bradawl4 ,h[ are we to describe ! motion ( t po/age /amp8 ,x w\ld c]ta9ly be revolv+ ar\nd ! bradawl2 b ?is motion we may consid] z compos$ ( two o!rs4 ,at any in/ant we may accurately repres5t ! movem5t ( ! po/age /amp by consid]+ t its c5tre 0 mov+ 9 a direction p]p5dicul> to ! l9e jo9+ t c5tre to ! hole made by ! bradawl1 & t x also _h a rotation ar\nd its c5tre1 ! p]iod ( t rotation be+ j ! same z ! "t ! c>d w\ld take to g r\nd ! bradawl4 ,?us we see t ! movem5t ( ! po/age /amp conta9s at any mom5t a movem5t ( translation & a movem5t ( rotation4 ,we may illu/rate ! case we h suppos$ by ! movem5t ( ! moon ar\nd ! e>?4 ,if ! c5tre ( ! e>? be consid]$ to be at ! c5tre ( rotation ! moon may be consid]$ to be 9 ! position ( ! po/age /amp4 ,z our satellite revolves1 ! same side ( ! moon is cont9ually turn$ t[>ds ! e>?1 b ?is is due to ! fact t ! moon1 at ea* mom5t1 really possesses two movem5ts1 namely1 a movem5t ( translation ( its c5tre1 9 a direction p]p5dicul> to ! l9e f ! moon's c5tre to ! e>?'s c5tre1 c\pl$ ) a sl[ rotation ( ! moon r\nd its axis4 ,! contract+ nebula we may lik5 to our piece ( c>dbo>d1 ! /amp w repres5t ! spot 9 :i* ! nebul\s mat]ial has contract$ to =m ! planet1 & ! position ( ! bradawl is ! c5tre ( ! sun4 ,z we h se5 by our illu/ration1 ! nebul\s planet is end[$ ) a c]ta9 movem5t ( rotation1 ! p]iod ( its rotation on its axis be+ equal to t ( its revolution ar\nd ! c5tre2 & x is important also to notice t bo? ^! movem5ts take place 9 ! same direction4 ,?us we see f ! nebul> !ory h[ ! primval nebula1 9 ! c\rse ( its contraction1 orig9at$ a planet1 & h[ t planet 0 also end[$ ) a movem5t ( rotation2 its p]iod ( rotation be+ orig9ally equal to ! p]iod ( rotation ( ! :ole nebula4 ,?is expla9s h[ ! planet1 or r ! mat]ials :i* are to =m ! future planet1 d]iv$ f ! nebula _! movem5t ( rotation1 :i* mu/ h be5 extremely sl[ 9 ! beg9n+4 ,z ! contraction cont9u$1 ! mat]ials ( ! gradually gr[+ globe drew !mselves toge!r1 & t5d$ to become sep>ate f ! surr\nd+ nebula4 ,at l5g? ! "t arriv$ :5 ! planet became suffici5tly isolat$ f ! re/ ( ! nebula to p]mit ! cons]vation ( mom5t ( mom5tum to be appli$ to x individually4 ,?us1 ?\gh ! rotation 0 at fir/ excessively sl[1 yet1 z ! contraction proce$$1 & z ! p>ts ( ! =m+ planet drew !mselves clos] toge!r1 9 consequ5ce ( _! mutual attractions1 x became necess>y t ! spe$ ) :i* ^! p>ts accompli%$ _! revolutions %\ld be accel]at$4 ,at la/1 :5 ! planet _h become consolidat$1 & :5 consequ5tly ! mutual di/ances ( ! sev]al p>ticles con/itut+ ! planet _h be5 r$uc$ to b a fraction ( :at ^? di/ances 7 orig9ally1 ! spe$ ( ! planet's rotation _h become enorm\sly increas$4 ,9 ?is mann] we le>n h[1 f ! v sl[ rotation :i* ! nebul\s mat]ial _h at fir/1 a solid planet may be made to rotate on its axis z rapidly z ! planets 9 ! sol> sy/em d to-day4 ,we ?us f9d t ! ?ird concord1 namely1 ! agreem5t 9 ! directions ( ! planets' rotations1 is a fur!r /rong corroboration ( ! nebul> !ory4 ,! unanimity ( all ^! v>i\s movem5ts is ! dom9ant *>act]i/ic ( ! sol> sy/em4 ,b ?is ?ird concord1 d]iv$ f ! rotation ( ! planets1 may be yet fur!r /r5g!n$4 ,! movem5ts ( ! satellites1 :i* accompany s _m ( ! planets1 mu/ also f9d _! explanation f ! primval nebula4 ,! circum/ances ( ! satellites are1 h[ev]1 diff]5t 9 ! diff]5t cases4 ,z reg>ds ! moon1 ! !ory ( its evolution is n[ well kn[n1 ma9ly by ! rese>*es ( ,pr(essor ,george ,d>w94 ,9 ! moon !re appe> to h be5 causes at "w ( a some:at special k9d4 ,we mu/ j ref] to :at is well kn[n ) reg>d to ! hi/ory ( ! moon4 ,"h1 aga91 we obs]ve ! importance ( ! pr9ciples ( ! cons]vation ( mom5t ( mom5tum4 ,z ! moon raises tides on ! ocean surr\nd+ ! e>?1 & z ^? tides fl[ ar\nd ! globe1 !y cause friction1 & t friction involves1 z we h s (t5 po9t$ out1 ! loss ( en]gy to ! sy/em4 ,?us1 ! en]gy ( ! e>?-moon sy/em mu/ be decl9+1 :ile ! mom5t ( mom5tum rema9s con/ant4 ,n[ !re are only two s\rces f :i* ! en]gy c be d]iv$4 ,"o ( ^? s\rces is t due to ! rotation ( ! e>? on its axis4 ,! o!r is due to ! moon1 & consi/s ( two p>ts1 namely1 ! en]gy aris+ f ! velocity ( ! moon 9 its orbit1 & ! en]gy due to ! di/ance by :i* ! e>? is sep>at$ f ! moon4 ,z ! moon's velocity dep5ds ^u its di/ance1 we _c view ^! two portions z indep5d5t4 ,!y are connect$ toge!r1 & we associate !m into "o4 ,s t we say ! total en]gy ( ! e>?-moon sy/em consi/s p>tly ( t due to ! rotation ( ! e>? on its axis1 & p>tly ( t due to ! revolution ( ! moon ar\nd ! e>?4 ,x might also seem t we ought to add to ?is ! en]gy due to ! rotation ( ! moon ar\nd its own axis2 b ?is is too inconsid]able to ne$ att5tion4 ,9 ! fir/ place1 ! moon is s small t ev5 if x rotat$ z rapidly z ! e>? ! en]gy due to ! rotation w\ld n be important4 ,see+1 h[ev]1 t ! moon has = ! rotation on its axis a p]iod ( betwe5 tw5ty-sev5 & tw5ty-eight days1 its velocity ( rotation is s small t1 = ?is reason also1 ! en]gy ( rotation w\ld be inconsid]able4 ,we are1 !re=e1 amply ju/ifi$ 9 omitt+ f our pres5t consid]ation ! en]gy due to ! rotation ( ! moon on its axis4 ,! en]gy ( ! e>?-moon sy/em is on ! decl9e3 ! lo/ en]gy might conceivably be drawn f ! rotation ( ! e>?1 or x might be drawn f ! revolution ( ! moon1 or x might be drawn f bo? ,if x 7 drawn f ! revolution ( ! moon1 t w\ld imply t ! moon w\ld lose "s ( its spe$ or "s ( its di/ance1 or 9 any case t ! moon w\ld get ne>] to ! e>? & revolve m sl[ly1 ! spe$ ( ! e>? be+ on ?is supposition unalt]$4 ,9 ?is case1 ! mom5t ( mom5tum ( ! e>? w\ld rema9 ! same z be=e1 :ile ! mom5t ( mom5tum ( ! moon w\ld be less5$2 ! total mom5t ( mom5tum w\ld !re=e h decreas$1 b ?is we h se5 to be impossible4 ,x !re=e foll[s t ! en]gy )drawn f ! e>?-moon sy/em is n to be obta9$ at ! exp5se ( ! revolution ( ! moon4 ,! en]gy mu/ !re=e be obta9$ at ! exp5se ( ! rotation ( ! e>? on its axis4 ,b if ?is be ! case1 ! spe$ ) :i* ! e>? rotates mu/ be dim9i%$2 t is to say1 ! l5g? ( ! day mu/ be increas$4 ,& if ! spe$ ( ! e>?'s rotation be r$uc$1 t means t ! am\nt ( mom5t ( mom5tum contribut$ by ! e>? is less5$4 ,b ! total quantity ( mom5t ( mom5tum mu/ be su/a9$1 & ?is c only be done by mak+ ! moon g fur!r away & describe a l>g] orbit4 ,we ?us see t 9 consequ5ce ( ! tides ! l5g? ( ! day mu/ be increas+1 & ! moon mu/ be gradually retreat+4 ,?us we f9d t at e>li] p]iods ! moon's di/ance f ! e>? mu/ h be5 less ?an x is at pres5t1 & ! fur!r we look back ?r\gh remote p]iods ! less d we f9d ! di/ance betwe5 ! e>? & ! moon4 ,?us we see t !re mu/ h be5 a "t :5 ! moon or ! mat]ials ( ! moon 7 9 actual contact ) ! mat]ials ( ! e>?4 ,9 fact1 x seems q possible t ! moon may h be5 a portion ( ! e>?1 brok5 (f at "s v e>ly p]iod1 :ile ! e>? 0 /ill 9 a liquid /ate1 if inde$ x _h cond5s$ to ev5 t ext5t4 ,?us ! revolution ( ! moon r\nd ! e>? is h>dly to be us$ z an argum5t 9 fav\r ( ! nebul> hypo!sis4 ,! moon is inde$ a consequ5ce ( ! e>?'s rotation4 ,! satellites ( ,m>s (f] conditions ( a v diff]5t k9d1 ?\gh "h1 aga91 tidal influ5ces h be5 s important1 t x is p]haps que/ions relat+ to tides t are illu/rat$ by ^! satellites r ?an ! nebul> !ory4 ,a rem>kable circum/ance may be not$ ) reg>d to ! movem5ts ( ! satellites ( ,m>s4 ,! inn] satellite has a p]iod ( ab\t sev5 & a half h\rs1 :i* is n a ?ird ( ! p]iod t ! planet itself takes to g r\nd on its axis4 ,?is leads to a some:at curi\s consequ5ce4 ,! tides rais$ on ,m>s by ?is inn] satellite w\ld c]ta9ly t5d r to accel]ate ! rotation ( ! planet ?an to ret>d x2 = ^! tides mu/ c\rse r\nd ! planet 9 ! direction ( its rotation1 b ) a spe$ 9 excess ( t rotation4 ,any tidal friction1 s f> z ?is satellite is conc]n$1 w t5d to augm5t ! velocity ( ! planet's rotation1 j z 9 ! opposite case1 :]e ! moon raises tides on ! e>?1 x is ! lagg+ ( ! tides beh9d ! movem5t due to ! rotation t acts z a brake1 & t5ds to *eck t spe$4 ,if1 !re=e4 ,m>s is accel]at$ by ?is satellite1 x w d m ?an its orig9al %>e ( ! mom5t ( mom5tum ( ! ,m>tian sy/em2 x is !re=e imp]ative t ! satellite %all d less4 ,accord+ly1 we f9d t ?is satellite mu/ g 9 t[>ds ! planet4 ,no d\bt ?is effect is mu* complicat$ by ! influ5ce ( ! o!r satellite ( ! same planet1 b ! illu/ration may suffice to %[ t if ! satellites ( ! e>? & ,m>s d n convey to u mu* direct evid5ce ) reg>d to ! nebul> !ory1 ?is is l>gely because ! effect ( ! tides has be5 a prepond]at+ influ5ce4 ,! ,m>tian sy/em z we n[ see x has acquir$ its *>act]i/ic features by tidal influ5ce1 s t ! m simple influ5ces :i* w\ld imm$iately illu/rate ! nebul> !ory h become hidd54 ,z to ! satellites ( ,jupit] & ,saturn1 ! circum/ances are aga9 q diff]5t f ^? t we f9d 9 ! e>? & 9 ,m>s4 ,!re is little m to be said ) reg>d to !m ?an t ev]y?+ t !y pres5t to u is consi/5t ) ! indications ( ! nebul> !ory4 ,! evolution 9 ea* case has be5 a reproduction 9 m9iature ( ! evolution ( ! sol> sy/em4 ,b ! satellites ( ,uranus & ,neptune pres5t1 x mu/ be admitt$1 ! greate/ /umbl+ block to ! acceptance ( ! nebul> !ory4 ,bo? z to ! directions 9 :i* !y move & z to ! planes 9 :i* _! orbits lie1 x mu/ be admitt$ t ! satellites ( ,uranus are di/9ctly at v>iance ) :at ! nebul> !ory w\ld sugge/4 ,! consid]ation ( ?is subject w be f\nd 9 ! next *apt]4 ---------------------------------------- -------------------------------- ,,*apt] ,,xvii4 ,,objections ,,to ,,! ,,nebul> ,,!ory4 ,!re are ,difficulties 9 ! ,nebul> ,!ory--,! ,g5]al ,con=mity ( ! ,movem5ts--,details ( ! ,uranian ,movem5ts--,! ,anomaly 9 ! ,satellite ( ,neptune--,:]e ! ,difficulty ,lies--,! ,fundam5tal ,pr9ciple :i* ,dynamics ,(f]s = our ,guidance--,! ,imm5se ,contra/ betwe5 ! ,nebula 9 its ,orig9al ,=m & its ,f9al ,=m--,en]gy t c\ld be ,obta9$ by a re>rangem5t ( our ,sy/em--,probable ,nature ( ! ,pres5t ,*ange 9 ! ,plane ( ! ,orbits ( ! ,satellites ( ,uranus--,! ,simil> ,explanation 9 ! ,case ( ,neptune4 ,,no "o w d5y t !re are po9ts 9 connection ) ! nebul> !ory :i* pres5t difficulties :i* to "s seem important4 ,we %all endeav\r to e/imate ! significance ( ^! difficulties 9 ?is *apt]4 ,!y are c]ta9 anomal\s ph5om5a pres5t$ by ! planets ,uranus & ,neptune4 ,! satellites :i* att5d ^u ! planets exhibit a g5]al con=mity ) ^? movem5ts ( ! planets !mselves on :i* we h dwelt 9 ,*apt]s ,,xiv41 ,,xv41 ,,xvi4 ,! planes 9 :i* ! orbits ( ! satellites are conta9$ are usually n mu* incl9$ to ! plane ( ! ecliptic1 & ! directions 9 :i* ! satellites revolve also agree ) ! g5]al direction ( ! planet>y movem5t4 ,we f9d ^! conditions 9 ! "o satellite ( ! e>?1 9 ! two satellites ( ,m>s1 9 ! five satellites ( ,jupit]1 9 ! eight or n9e satellites ( ,saturn2 b1 :5 we come to ,uranus & ,neptune1 ! two out]mo/ planets1 we obs]ve a /rik+ b mo/ in/ructive violation ( ! laws :i* we h f\nd s consi/5tly prevail+ 9 ! o!r p>ts ( ! sol> sy/em4 ,let me fir/ m5tion ! special circum/ances ( ,uranus4 ,x is n[ kn[n t ?is planet has f\r satellites4 ,( ^!1 ,titania & ,ob]on 7 bo? discov]$ by ,sir ,william ,h]s*el on ,janu>y #aa?1 #aghg4 ,! two rema9+ satellites1 nam$ ,ariel & ,umbriel1 7 n discov]$ = m ?an half a c5tury lat] by ,mr4 ,lassell1 on ,octob] #bd?1 #ahea4 ,x is1 h[ev]1 j possible t !y 7 previ\sly se5 by ,sir ,william ,h]s*el4 ,! inn]mo/ ( ! f\r satellites1 ,ariel1 accompli%es a revolution 9 a day & a half1 ,umbriel goes r\nd 9 f\r days & ?ree h\rs1 ,titania 9 eight days & sev5te5 h\rs1 & ,ob]on 9 ?irte5 days & elev5 h\rs4 ,we h already m5tion$ h[ ! inve/igations ( ,newcomb %[ t ^! f\r satellites ( ,uranus revolve 9 ! same direction & 9 ! same plane2 b ?is plane1 in/ead ( ly+ 9 or ne> ! ecliptic1 is v ne>ly p]p5dicul> !reto1 ! actual angle be+ eighty-?ree degrees4 ,?is is "o ( ! features 9 :i* ! satellites ( ,uranus are 9 />tl+ disob$i5ce to ! laws :i* h be5 s rigidly obs]v$ 9 mo/ o!r p>ts ( ! sy/em4 ,b !re is also a second anomaly4 ,! direction 9 :i* ! satellites move1 :5 project$ on ! plane ( ! ecliptic1 is f\nd to be opposite to ! univ]sal direction 9 :i* all ! o!r movem5ts 9 ! sol> sy/em are p]=m$4 ,( c\rse ! fact t ! plane ( ! orbits ( ! satellites lies s ne>ly at "r angles to ! plane ( ! ecliptic detracts some:at f ! significance ( ?is circum/ance4 ,if ! two planes 7 absolutely at "r angles1 !re w\ld be1 ( c\rse1 no projection at all1 &1 9 ! actual circum/ances1 ! mom5t ( mom5tum1 :5 project$1 loses n9ete5-tw5tie?s ( its am\nt4 ,x foll[s t 9 ! actual position ( ! plane ! abnormal direction 9 :i* ! satellites are mov+ is n v mat]ial4 ,x mu/ be admitt$ t1 9 ! position ( ! plane ( _! orbits & ! direction ( _! movem5ts1 ! satellites ( ,uranus are 9 contra/ to :at a ha/y consid]ation ( ! nebul> !ory might h l$ u to expect4 ,if ! orbits ( ^? satellites _h all la9 close to ! plane ( ! ecliptic1 & if ! direction 9 :i* ! satellites revolv$ _h also conspir$ ) t ( ! revolution ( ,uranus r\nd ! sun1 & ) all ! o!r hundr$s ( movem5ts :i* are 9 ! same direction1 !re c be no d\bt t we %\ld 9 ?is place h be5 appeal+ to ! satellites ( ,uranus z confirmatory evid5ce ( ! tru? ( ! nebul> !ory4 ,! fact t !y move 9 a mann] s totally at v>iance ) :at might h be5 expect$ _c !re=e be ov]look$4 ,neptune1 ! out]mo/ planet ( our sy/em1 pres5ts u also ) difficulties ( an analog\s "*4 ,s f> z ! orbit ( ,neptune itself is conc]n$1 x agrees entirely ) ! g5]al planet>y conv5tion2 ! incl9ation ( t orbit to ! plane ( ! ecliptic is no m ?an six degrees1 & ! direction 9 :i* ! out]mo/ planet revolves r\nd ! fronti] ( our sy/em is n diff]5t f ! directions 9 :i* all ! o!r planets revolve4 ,we "k no?+ ab\t ! axis ( rotation ( ,neptune except t x may be reasonably presum$ to be 9 ! same plane z ! movem5t ( its satellite4 ,on ,octob] #aj?1 #ahdf1 ,lassell1 ) ! help ( 8 great telescope1 suspect$ ! exi/5ce ( a satellite to ,neptune1 & he ann\nc$ x def9itely on ,july #g?1 #ahdg4 ,we are indebt$ to ,newcomb = a c>eful inve/igation ( ! orbit ( ?is satellite4 ,x moves 9 a track :i* is practically circul>1 & x requires ab\t five days & tw5ty-"o h\rs to accompli% ea* revolution4 ,its incl9ation to ! ecliptic is n s anomal\s z 9 ! case ( ,uranus1 ! incl9ation be+ 9 ?is case n m ?an ?irty-five degrees4 ,?is is n mu* great] ?an ! incl9ations ( ! orbits ( "s ( ! a/]oids1 & x might h pass$ )\t mu* comm5t _h x n be5 = ! circum/ance t ! direction ( motion ( ! satellite 9 ?is track is antagoni/ic to all ! o!r movem5ts 9 ! sol> sy/em4 ,?is is inde$ a m />tl+ fact 9 "s respects ?an ! movem5ts ( ! satellites ( ,uranus1 =1 z we po9t$ out1 ! plane ( ! orbits ( ! satellites ( ,uranus is s ne>ly p]p5dicul> to ! plane ( ! ecliptic t ! direction ( ! movem5t c\ld n be held to be ( mu* significance4 ,! satellite ( ,neptune1 hav+ an orbital incl9ation b>ely m ?an a ?ird ( a "r angle1 exhibits a retrograde movem5t :i* is 9 "s respects ! mo/ anomal\s feature 9 ! sol> sy/em4 ,^! circum/ances connect$ ) ! satellites ( ,uranus & ,neptune h be5 sometimes br\ght =w>d z argum5ts aga9/ ! nebul> !ory4 ,:at ,laplace w\ld h said to !m we c only conjecture1 =1 at ! "t he br\ght out 8 !ory1 ,neptune 0 entirely unkn[n1 & none ( ! satellites ( ,uranus _h be5 obs]v$4 ,b x has sometimes be5 urg$ t ! movem5ts ( ^! two sy/ems are inconsi/5t ) ! pr9ciples ( ! nebul> !ory1 & t1 !re=e1 ! nebul> !ory mu/ be ab&on$4 ,i h no desire to m9imise ! difficulties1 b ,i ?9k ! consid]ations to :i* ,i n[ invite att5tion may help to less5 !m ev5 if !y d n altoge!r remove !m4 ,i tru/1 at lea/1 we may be able to %[ t ev5 ^? anomal\s movem5ts are n incompatible ) ! acceptance ( ! acc\nt ( ! orig9 ( our sol> sy/em giv5 by ! nebul> !ory4 ,! primval nebula may be reg>d$ z *aotic 9 its e>lie/ /ages2 p]haps x 0 l ! nebul\s wisps 9 ,fig4 #ea4 ,x 0 *aotic 9 ! arrangem5t ( ! mat]ial ( :i* x is =m$1 & 9 ! movem5ts ( t mat]ial4 ,be=e a disorganis$ nebula c become evolv$ into a nebula ) any def9ite =m l t 9 ,fig4 #eb1 or into any?+ resembl+ a sol> sy/em1 an imm5se p]iod ( "t mu/ elapse1 & dur+ t "t ! op]ation ( ! laws ( dynamics gradually impresses c]ta9 well-m>k$ features on ! nebula1 & disposes x to assume an ord]ly =m4 ,we h expla9$ t no matt] h[ ! nebula orig9at$1 or no matt] :at may h be5 ! irregul>ities 9 its ext5t or di/ribution1 & no matt] h[ div]se may h be5 ! agitations ( its v>i\s p>ts1 ! pr9ciples ( dynamics assure u t ea* su* nebula mu/1 = all "t1 /& 9 "s special relation to a c]ta9 p>ticul> plane4 ,! mom5t ( mom5tum :i* ! nebula has ) respect to ?is plane1 exce$s ! mom5t ( mom5tum t x has ) respect to any o!r plane4 ,we h po9t$ out h[1 not)/&+ ! vicissitudes & trans=mations to :i*1 9 ! c\rse ( illimitable ages1 ! nebula mu/ submit1 its mom5t ( mom5tum relatively to ?is plane w rema9 absolutely unalt]$4 ,we h %[n h[ ! en]gy ( ! nebula becomes gradually exhau/$4 ,! collisions betwe5 v>i\s p>ticles1 ! frictions t w necess>ily arise1 & ! actions :i* we may suffici5tly describe by say+ t !y are ( a tidal "*1 w all result 9 ! trans=mation ( en]gy into heat4 ,?is heat is radiat$ away & lo/1 & !re is a correspond+ decl9e 9 ! en]gy ( ! sy/em4 ,to pres]ve its mom5t ( mom5tum unalt]$ 9 ! c\rse ( ages1 not)/&+ ! cont9u\s r$uction ( en]gy1 ! mat]ials ( ! nebula w ev] f9d !mselves m & m approximat+ to ! plane1 & w ev] f9d !mselves m & m compell$ to revolve 9 ! same direction4 ,if ! orig9al size ( ! nebula be comp>$ ) ! area ( ! ,atlantic ,ocean1 ! cond5s$ =m :i* ! nebula may ultimately assume may be no l>g] ?an a coral isl&4 ,if ! nett mom5t ( mom5tum1 diffus$ ov] ! space z l>ge z ! ocean1 has /ill to be pres]v$ 9 ! space z l>ge z ! isl&1 we ne$ n be surpris$ t ! sp9 ( ! sy/em 9 its cond5s$ =m is its dom9at+ *>act]i/ic4 ,9 ! evolution ( our sol> sy/em f ! primval nebula1 ?is op]ation ( r$uc+ ! movem5ts to ! same plane & ( requir+ t all ! movem5ts %all take place 9 ! same direction1 hav+ _h play = unmeasur$ ages1 has 9 ! ma9 accompli%$ its end4 ,all ! important bodies ( ! sy/em d g r\nd 9 ! same direction2 t mu*1 at lea/1 has be5 atta9$4 ,all ( !m also g r\nd 9 planes :i* are ne>ly co9cid5t1 b1 z we h already not$1 !y are n yet absolutely co9cid5t4 ,! greate/ planets h1 h[ev]1 v ne>ly become reconcil$1 s f> z ! planes ( _! orbits are conc]n$1 to ! condition :i* dynamics imposes4 ,! same is true ( ! rotation ( ! sun on its axis4 ,t axis is incl9$ at an angle ( eighty-?ree degrees to ! plane ( ! ecliptic1 s t ! sun's equator w\ld h to be %ift$ only ?r\gh an angle no great] ?an sev5 degrees1 if x 7 to be plac$ 9 ! plane 9 :i* x %\ld be situat$1 if ! condition ( ! smalle/ quantity ( en]gy = a giv5 am\nt ( mom5t ( mom5tum 0 to be realis$4 ,we f9d a great] discrepancy 9 ! plane ( ! e>?'s equator4 ,?is is incl9$ by ab\t tw5ty-?ree degrees to ! plane ( ! ecliptic4 ,"h !re is "s en]gy :i* might yet be exp5d$ )\t a dim9ution ( ! am\nt ( mom5t ( mom5tum 9 ! sy/em2 = if ! e>?'s axis 7 to be made p]p5dicul> to ! plane ( ! ecliptic1 !n ! velocity ( rotation ( ! e>? ab\t its axis might und]go a correspond+ abatem5t1 & yet keep up ! requisite mom5t ( mom5tum4 ,we ?us see t ev5 ) ! old] planets ! conditions :i* w\ld be en=c$1 if ! mom5t ( mom5tum 0 to be su/a9$ ) ! lea/ quantity ( en]gy1 are n absolutely compli$ )2 :i* simply means t !re has n yet be5 "t en\gh = our sy/em to arrive at ! p]fect /ate1 to :i* x mu/ be approximat+4 ,if we h f\nd t 9 ! rotations ( ! e>? & ( ! sun1 & 9 ! revolutions ( ! planets r\nd ! sun1 ! conditions ultimately aim$ at h n yet be5 rea*$1 :y %\ld we feel surpris$ t 9 ! out] planets ( our sy/em1 ,uranus & ,neptune1 ! conditions :i* evolution t5ds to produce h n yet be5 fully atta9$8 ,t ! op]ation ( ! cons]vation ( mom5t ( mom5tum is 9 progress 9 ! int]nal economy ( ! ,uranian sy/em1 we h already _h occasion to expla9 9 ,*apt] ,,xi4 ,! fact :i* ,newcomb demon/rat$1 t ! f\r satellites revolve 9 ! same plane1 c only be acc\nt$ = by ! supposition t 9 t sy/em ! cons]vation ( mom5t ( mom5tum1 ) decl9+ en]gy1 has gradually impos$ ?is condition on ! sy/em belong+ to ,uranus4 ,) ref]5ce to ! position ( ! plane ( ! satellites1 9 ! case ( ,uranus & ,neptune1 we w\ld say1 t ?\gh at pres5t _! arrangem5t appe>s anomal\s1 x w probably n always rema9 s4 ,! fact t ! satellites ( ,uranus are 9 a plane ne>ly p]p5dicul> to ! plane ( ! ecliptic really implies t !re is a c]ta9 am\nt ( en]gy /ill disposable 9 our sy/em1 if by readju/m5t ( ! plane ( ! ,uranian satellites ! necess>y mom5t ( mom5tum 9 ! sy/em is /ill pres]v$4 ,illu/ration3 ,fig4 #eb4--,,two-,,bran*$ ,,spiral 7n4g4c4 #gdgi2 9 ,pegasus74 7,lick ,obs]vatory47 ,! laws ( dynamics tell u t ! orbits ( planets mu/ be gradually1 if ) excessive sl[ness1 t5d+ /ill fur!r to ! same plane4 ,9 ?is process en]gy c be exp5d$ by ! sy/em1 :ile ! mom5t ( mom5tum is unabat$4 ,we c at lea/ sugge/ :at seems to be at ?is mom5t 9 progress 9 ! sy/em belong+ to ,uranus4 ,x w readily be admitt$ t !re may be a difficulty 9 see+ h[ ! movem5t ( a planet1 :i* is go+ 9 ! wrong direction1 c\ld be /opp$ & turn$ into ! "r direction4 ,b we ne$ n suppose t s viol5t a *ange z ?is w\ld imply is to be expect$ 9 our sy/em4 ,we are q accu/om$ to f9d ! planes ( ! orbits ( all planets 9 gradual movem5t4 ,! plane conta9+ ! orbits ( ! f\r satellites ( ,uranus is at ?is mom5t probably mov+ gradually upw>ds4 ,x w 9 due c\rse become actually at "r angles to ! ecliptic1 & we may !n reasonably assume t x w advance fur!r 9 ! same direction4 ,at ! mom5t ! "r angle is pass$1 ?is cont9u\s movem5t w h ! effect ( *ang+ ! directions ( ! satellites' movem5t f retrograde to direct4 ,! pres5t anomaly w !n t5d to become evanesc5t1 =1 z ! exhau/ion ( ! en]gy cont9ues1 ! planes ( ! satellites ( ,uranus w gradually come into con=mity ) ! plane ( ! ecliptic4 ,we make no d\bt t !re may be a simil> explanation ( ! movem5ts ( ! satellite ( ,neptune4 ,! incl9ation ( ! plane ( ! orbit ( ! satellite to ! ecliptic is probably n[ increas+4 ,x w ultimately come to be at "r angles !reto1 & !n ! next advance ( ! plane w conv]t1 by a cont9u\s action1 ! retrograde motion ( ! satellite1 at pres5t s disconc]t+1 into a direct motion4 ,! *ange ( ! plane w /ill cont9ue until x1 too1 may ultimately coalesce ) ! ecliptic4 ,! fact appe>s to be1 t ?\gh an enorm\s quantity ( en]gy mu/ h be5 lo/ by radiation f our sy/em dur+ ! illimitable ages ?r\gh :i* ! evolution has be5 runn+ its c\rse1 ! disposable en]gy is n yet q exhau/$4 ,!re are c]ta9 adju/m5ts 9 our sy/em :i* may /ill be made & :i* w all[ ( yet fur!r radiation ( en]gy1 :ile /ill pres]v+ suffici5t to keep up ! necess>y mom5t ( mom5tum4 ,x seems obvi\s t ! sy/em is t5d+ t[>ds a condition 9 :i* ! planes ( all ! orbits %all be co9cid5t1 & 9 :i* all ! directions %all be absolutely unanim\s4 ,if we 7 at once to alt] ! sy/em by mov+ all ! orbits into ! plane ( ! ecliptic1 b mak+ no *ange 9 ! dim5sions ( ^? orbits1 or ! velocities conc]n$2 if we 7 also to adju/ ! rotations ( ! e>?1 z well z ( ! o!r planets1 s t all ! axes ( rotation %\ld be p]p5dicul> to ! plane ( ! ecliptic2 if we 7 to turn ! plane ( ! satellites ( ,uranus ?r\gh t angle ( #ig1 :i* w\ld suffice at ! same "t to br+ x into co9cid5ce ) ! ecliptic1 & lay ! movem5ts ( ! satellites 9 ! "r direction2 if we 7 also to turn ! orbit ( ! satellite ( ,neptune ?r\gh #ade1 ?us br++ t orbit to co9cide ) ! plane ( ! ecliptic1 9 su* a mann] t ! direction ( ! movem5t ( ! satellite ( ,neptune conspir$ ) all ! o!r movem5ts ( ! sy/em1 !n ?is re>rangem5t ( ! sy/em w\ld increase ! mom5t ( mom5tum1 :ile ! quantity ( en]gy 0 n alt]$4 ,b ?is is ! same ?+ z say+ t "s en]gy yet rema9s to be dispos$ (1 :ile ! sy/em /ill pres]ves ! requisite mom5t ( mom5tum4 ,! conclusion we come to may be ?us express$3 ! movem5ts ( ! satellites ( ,uranus & ,neptune d n disprove ! nebul> hypo!sis4 ,!y r illu/rate ! fact t ! great evolution :i* has wr\ght ! sol> sy/em into =m has n yet f9i%$ its "w2 x is /ill 9 progress4 ,! "w is v ne>ly done1 & :5 t "w %all h be5 complet$1 ! satellites ( ,uranus & ,neptune w no long] be dissociat$ f ! g5]al concord4 ---------------------------------------- -------------------------------- ,,*apt] ,,xviii4 ,,! ,,beg9n+ ,,( ,,! ,,nebula4 ,nebula n ( ,inf9ite ,duration--#h1cjj ,coal-,units 0 ! ,total ,en]gy ( ! ,sy/em--#dfj ,miles a ,second--,sol> ,nebula f a ,collision--,:at we ,"k z to ! ,collid+ ,bodies--,probability ( ,cele/ial ,collisions--,multitudes ( ,d>k ,objects--,new ,/> 9 ,p]seus--,*>act]i/ics ( ,new ,/>s--,inc&esc5t ,hydrog5--,! ,ruby 9 ! ,spectrum--,photographs ( ! ,spectrum--,r>ity ( a ,collision on a ,scale ,adequate to a ,sol> ,sy/em4 ,,:atev] may h be5 ! antiquity ( ! actual elem5ts t =m$ ! primval nebula f :i* ! sol> sy/em has be5 evolv$1 ! nebula itself has c]ta9ly n be5 ( inf9ite duration4 ,! "q !n arises z to :at has be5 ! orig9 ( ! nebula z su*1 or r by :at ag5cy ! mat]ial f :i* ! nebula 0 =m$ und]w5t s radical a trans=mation f its previ\s condition z to be *ang$ into t gl[+ object :i* we h consid]$ s frequ5tly 9 ?is book4 ,we h to expla9 h[1 by ! op]ation ( natural causes1 a d>k body c be trans=m$ into a gl[+ nebula4 ,let u fir/ e/imate :at ! quantity ( en]gy 9 t sy/em is4 ,! sun has be5 p\r+ =? heat = inimitable ages1 & w d\btless cont9ue to p\r =? heat = millions ( ye>s to come4 ,b ! de/9y :i* awaits ! sun1 ?\gh x may be protract$1 yet _c be av]t$4 ,! sun w g on p\r+ =? its heat & gradually %r9k+4 ,! "t w come at la/ :5 ! radius ( ! sun w h appreciably decreas$1 & :5 once x has assum$ a d5sity correspond+ to a solid /ate its hi/ory z a radiant globe w be approa*+ its close4 ,a p]iod ( insignificant ext5t1 a c5tury or less1 w !n suffice = t solid globe to cool d[n s z to be no long] an effici5t s\rce ( light & heat4 ,we %all assume t :5 ! sun has ultimately become solid & cold1 & :5 x is no long] ! life & light ( our sy/em1 x w h atta9$ a mean d5sity ( #ba4e1 :i* we h *os5 because t is ! d5sity ( plat9um1 ! heavie/ sub/ance kn[n4 ,9 all probability ! sol> d5sity w nev] become s great z ?is1 b to include ! mo/ extreme case 9 our argum5t ,i am mak+ ! assumption 9 ! =m /at$4 ,we are n[ to e/imate :at w h be5 ! total en]gy t ! sun has radiat$ f ! mom5t :5 z an indef9itely great nebula x fir/ began to radiate at all1 d[n to t mom5t 9 ! future :51 hav+ %runk to ! d5sity ( plat9um1 & hav+ p>t$ ) all its heat1 ! sol> radiation is at an end4 ,9 ! beg9n+ ( ! evolution>y hi/ory ! sun 0 a nebula1 :i* we h suppos$ to ext5d 9 e direction to an indef9itely great di/ance4 ,! sy/em has result$ f ! contraction ( t nebula1 & ! en]gy lib]at$ 9 t contraction has suppli$ ! sun's radiation4 ,we calculate 7see ,app5dix7 ! en]gy t w\ld be giv5 out 9 ! contraction ( a nebula ^: mat]ials 7 orig9ally at inf9ity1 & :i* ultimately coalesc$ to =m a cold1 solid globe ( ! d5sity ( plat9um1 & z heavy z ! sun4 ,!re is no object 9 attempt+ to express ?is quantity ( en]gy 9 foot-p\nds--! figures w\ld convey no di/9ct impression--we %all employ ! coal-unit expla9$ 9 ,*apt] ,,vi4 ,we imag9e a globe ( coal ! weight ( ! sun2 !n1 if t globe ( coal 7 adequately suppli$ ) oxyg51 x w\ld1 on combu/ion1 give out a c]ta9 am\nt ( heat1 :i* is a conv5i5t unit = our measurem5ts4 ,x is demon/rat$ t ! quantity ( en]gy giv5 out by ! contraction ( ! nebula f inf9ity1 to ?is globe ( ! d5sity ( plat9um1 w\ld be ab\t equal to ! quantity ( en]gy :i* w\ld be produc$ by ! combu/ion ( #h1cjj globes ( coal z heavy z ! sun1 an adequate contribution ( oxyg5 be+ suppos$ to be suppli$4 ,?is expresses ! orig9al end[m5t ( en]gy 9 ! sol> sy/em1 or r a major limit to t end[m5t2 x %[s t ! sol> sy/em c nev] h develop$ m en]gy by contraction ?an t :i* c\ld be produc$ by ! combu/ion ( #h1cjj globes ( coal z heavy z ! sun4 ,we may m5tion t ( ?is great end[m5t ( en]gy an am\nt :i* is r less ?an half 7#c1djj7 has be5 already exp5d$1 s t r m ?an half ( ! sun's c>e] z a radiant globe may yet h to be run4 ,we c also express ! total en]gy ( ! sol> sy/em 9 a diff]5t mann]4 ,we %all consid] :at mu/ be ! velocity ( ! sun1 s t ! en]gy t x w possess1 9 virtue ( t velocity1 %all be equal to ! en]gy :i* c\ld be produc$ by ! combu/ion ( #h1cjj globes ( coal ( ! same weight4 ,?is calculation is v mu* simplifi$ by mak+ use ( a pr9ciple :i* we h already /at$ & appli$ 9 ,*apt] ,v4 ,we h %[n t if a piece ( coal be animat$ ) a velocity ( five miles a second1 ! en]gy x possesses 9 virtue ( t motion is equal to ! en]gy produc$ by ! coal 9 ! act ( combu/ion4 ,if a body 7 mov+ at ! rate (1 let u say1 #ajj miles a second--its spe$ be+ !n tw5ty times z great z ! p>ticul> spe$ j m5tion$--its en]gy1 :i* dep5ds on ! squ>e ( ! velocity1 w\ld be #djj times z mu* z w\ld be produc$ by ! burn+ ( a piece ( coal equal to x 9 weight4 ,we c easily calculate t if ! sun 7 mov+ at a spe$ ( #dfj miles a second1 x w\ld possess1 9 virtue ( its motion1 z mu* en]gy z w\ld be g5]at$ by ! contraction ( ! primval nebula f inf9ity d[n to a globe ( ! d5sity ( plat9um4 ,x is ?us easy to =m a supposition z to h[ ! nebula con/itut+ our sol> sy/em may h come into be+2 mo/ probably x orig9at$ 9 ?is way4 ,let u suppose t two masses1 ei!r d>k or bright1 ei!r hot or ( ! temp]ature ( space1 or ! temp]ature ( froz5 air1 7 mov+ ) spe$s ( #dfj miles a second4 ,no d\bt ! velocities we are "h po/ulat+ are v high velocities1 b !y are n unprec$5t$ly high4 ,we "k ( />s :i* at ?is pres5t mom5t move q z fa/1 s t !re is no?+ unreasonable 9 our supposition s f> z ! velocities are conc]n$4 ,let u suppose t ea* ( ^! bodies _h a mass :i* is half t ( our pres5t sol> sy/em4 ,if ^! two bodies da%$ into collision1 :5 mov+ f opposite directions1 ! effect ( ! bl[ w\ld be to trans=m ! en]gy into heat4 ,t heat w\ld be s great t x w\ld be suffici5t n alone to r5d] ^! globes r$-hot & :ite-hot1 b ev5 to fuse !m--nay1 fur!r1 to drive !m into vap\r1 ev5 to a vap\r :i* might exp& to an enorm\sly great di/ance4 ,9 o!r words1 x is q conceivable t a collision ( two su* masses z we h "h suppos$ might be adequate to ! =mation ( a nebula su* z t "o :i* 9 ! lapse ( indef9ite ages has %ap$ itself into ! sol> sy/em4 ,be=e ! collision1 :i* result$ 9 ! =mation ( ! nebula1 ea* ( ^! bodies1 or r _! c5tres ( gravity1 w\ld be mov+ 9 :at may be reg>d$ = ! mom5t z /raight l9es1 & a plane ?r\gh ^? two /raight l9es w be a plane :i* = ev] aft]w>ds w /& 9 important relation to ! sy/em4 ,x w be1 9 fact1 t pr9cipal plane ( :i* we h s (t5 spok54 ,z ^? two bodies met !y w\ld possess a c]ta9 mom5t ( mom5tum1 & ?is mom5t ( mom5tum w\ld rema9 = ev] unalt]$1 no matt] :at may be ! future vicissitudes ( ! sy/em4 ,= ! sake ( simplicity 9 describ+ :at has occurr$1 we h spok5 z if ! two bodies 7 ( equal mass1 &1 mov+ ) equal velocities f opposite po9ts ( ! heav5s1 da%$ into collision4 ,b :at actually happ5s _c h be5 q s symmetrical4 ,!re is "o feature 9 ! sol> sy/em :i* absolutely proves t ! collision _c h tak5 place precisely 9 ! way we h laid d[n4 ,if x _h happ5$ t two equal masses _h be5 hurl$ into collision ) equal velocities f precisely opposite directions1 !n !re c\ld h be5 no resultant mom5t ( mom5tum4 ,f ! pr9ciple ( ! cons]vation ( mom5t ( mom5tum1 we c see t1 if abs5t 9 ! beg9n+1 x c\ld nev] orig9ate lat]4 ,z1 h[ev]1 we h a l>ge mom5t ( mom5tum 9 ! movem5ts ( ! planets & ! sun1 x is c]ta9 t ! collision _c h tak5 place 9 a mann] q s simple4 ,illu/ration3 ,fig4 #ec4--;,,clu/] ,,) ,,/>s ,,( #ag,,? ,,magnitude 7n4g4c4 #fgje2 9 ,ant9\s74 7,photograph$ by ,dr4 ,isaac ,rob]ts1 ,f4,r4,s47 ,! probabilities ( ! case %[ t x is almo/ inf9itely unlikely t two bodies ( equal dim5sions1 & mov+ ) equal velocities 9 opposite directions1 %\ld come squ>ely into collision4 ,x w\ld be mu* m likely t ! bodies %\ld be n ( ! same size1 n mov+ ) ! same velocity1 & %\ld collide p>tially r ?an squ>ely4 ,! collision may h be51 9 fact1 little m ?an a graze4 ,! probabilities ( ! case are su* z to %[ t :at actually occurr$ 0 a collision betwe5 two unequal masses1 :i* 7 mov+ 9 directions incl9$ to ea* o!r & ) diff]5t velocities4 ,x is easy to %[ t1 grant$ suffici5tly great velocities1 an impact :i* fell f> %ort ( direct collision might /ill produce en\gh heat to trans=m ! :ole sol> sy/em into vap\r4 ,! circum/ances :i* w\ld naturally accompany s transc5d5t an incid5t w also g f> to acc\nt = a difficulty :i* has be5 (t5 felt ) reg>d to ! evolution ( ! sy/em f a nebula4 ,7 su* a collision to take place we %\ld c]ta9ly n expect t ! result+ nebul\s mass1 ! product ( a %ock ( su* /up5d\s viol5ce1 w\ld be a homog5e\s or symmetrical object4 ,portions ( ! collid+ body w\ld become m highly heat$ ?an o!rs2 portions ( ! bodies w\ld n be s completely trans=m$ into vap\r z w\ld o!r p>ts4 ,!re w\ld ?us be diff]5ces 9 ! nebula at ! diff]5t p>ts ( its mass4 ,?is non-homog5eity w\ld be connect$ ) ! =mation & gr[? ( planets 9 ! diff]5t p>ts ( ! nebula4 ,!re is ano!r circum/ance connect$ ) ! movem5t ( ! sun :i* %\ld "h be m5tion$4 ,x is well kn[n t ! sun has a velocity :i* c>ries x on ?r\gh space at ! rate ( half a million miles a day4 ,9 ?is movem5t ! :ole sol> sy/em1 ( c\rse1 p>ticipates4 ,?is movem5t ( translation ( our sy/em mu/ also be a result ( ! movem5ts ( ! two orig9al collid+ masses4 ,^! two masses imp>t$ to ! sy/em1 :i* result$ f _! union1 bo? ! l9eal velocity ) :i* x advances ?r\gh space1 & also t mom5t ( mom5tum :i* is ( su* va/ importance 9 ! !ory4 ,a consid]ation ( ! probabilities ( ! case make x q c]ta9 t ! cele/ial bodies we see are z no?+ comp>$ ) ! d>k bodies we d n see4 ,! />s we see are mov+1 & ! natural assumption is t ! d>k objects ) :i* ! heav5s teem are also 9 motion4 ,we %all1 "u ^! conditions1 n feel any insup]able difficulty 9 ! supposition t collisions betwe5 diff]5t bodies 9 ! heav5s may h tak5 place f "t to "t4 ,we rememb] t ^! bodies are mov+ 9 all directions1 & at extremely high velocities4 ,we are q will+ to grant ! excessive improbability t any two bodies p>ticul>ly specifi$ %\ld come into collision4 ,)9 view ( our telescopes we h1 h[ev]1 a hundr$ millions ( />s1 & if we multiply t figure ev5 by millions1 x w /ill1 we may well suppose1 n be too l>ge to express ! numb] ( bodies :i*1 ?\gh conta9$ )9 ! region ( space rang$ ov] by our telescopes1 are /ill totally invisible4 ,9 ^! circum/ances1 we may admit t occasional collisions are n impossible4 ,please note ! /r5g? :i* ! argum5t d]ives f ! enorm\s increase 9 our e/imate ( ! numb] ( bodies1 :5 we include ! d>k objects z well z ! />s4 ,if we 7 ask$ :e!r x w\ld ev] be possible = two bright />s to come into collision1 we might well hesitate ab\t ! answ]4 ,we "k1 ( c\rse1 t ! />s h prop] motions2 we "k1 too1 t ! />s1 9 ?is respect unlike ! planets1 h no def9ite directions ( movem5t "u ! control ( a supreme co-ord9at+ attraction4 ,"s />s move to ! "r1 & "s to ! left1 "s "o way & "s ano!r2 b ev5 /ill1 not)/&+ _! great numb]1 ! ext5t ( space is su* t ! />s keep widely ap>t1 & ?us collisions c h>dly be expect$ to take place1 unless p]haps 9 a clu/] su* z t %[n 9 ,fig4 #ec4 ,we h no reason to ?9k t a collision betwe5 two actual bright />s 0 ! orig9 ( ! primval nebula ( our sy/em4 ,b :5 we reflect t ! />s1 prop]ly s call$1 are b ! visible memb]s ( an enorm\sly great] ho/ ( objects1 !n ! possibilities ( occasional collision betwe5 a pair ( ^! incomp>ably m abundant d>k bodies seems to m]it our close att5tion4 ,we are n by any means claim+ t su* collisions occur frequ5tly4 ,b :at we d say is1 t if1 z we believe1 ^! bodies are to be reckon$ 9 _m millions ( millions1 !n x does sometimes happ5 t two ( !m1 mov+ ab\t 9 space1 w approa* toge!r suffici5tly to give rise to a collision4 ,x 0 f "s su* collision t we believe ! nebula took its rise f :i* ! sol> sy/em orig9at$4 ,we h ! be/ reason = kn[+ t cele/ial collisions d sometimes occur4 ,x w be 9 ! recollection ( ! read]s ( ?is *apt] t 9 ,febru>y1 #aija1 ! a/ronomical _w 0 />tl$ by ! ann\ncem5t ( ! outbreak ( a new /> 9 ,p]seus4 ,a photograph ( t "p ( ! heav5s _h be5 tak5 a few days be=e4 ,!re 7 ! ord9>y />s1 su* z exi/$ f "t immemorial1 & su* z h be5 repres5t$ on ! num]\s maps 9 :i* ! />s are fai?fully set d[n4 ,b1 on ,febru>y #bbnd1 ,dr4 ,&]son1 already fam\s by simil> discov]ies1 notic$ t ! con/ellation ( ,p]seus conta9$ a /> :i* he _h n se5 be=e4 ,in/antly ! a/ronomical _w 0 appris$ by telegraph t a new /> _h appe>$ 9 ,p]seus1 & =?) mo/ dilig5t att5tion 0 paid to its obs]vation4 ,photographs !n obta9$ %[ ! />s t _h be5 se5 !re be=e1 ) ! addition ( ! new /> t _h sudd5ly come into view4 ,= a few nights aft] its discov]y ! object increas$ 9 lu/re1 until x atta9$ a brightness z great z t ( ,capella or ,vega4 ,b 9 ?is /ate x did n long rema94 ,?is brilliant object began to wane4 ,pres5tly x c\ld n be class$ z a /> ( ! fir/ magnitude1 nor yet ( ! second1 & !n x ran d[n until a little bel[ ! ?ird1 & ev5 bel[ ! f\r?4 ,9 ! subsequ5t decl9e ( ! /> !re 7 sev]al curi\s oscillations4 ,on "o night ! /> might be se51 ! next night x w\ld be h>dly disc]n$1 :ile ! night aft] x _h aga9 ris5 consid]ably4 ,b1 not)/&+ su* tempor>y rallies1 ! brightness1 on ! :ole1 decl9$1 until at la/ ! /> dw9dl$ to ! dim5sions ( a small po9t ( light1 sc>cely di/+ui%able ) ! nak$ eye4 ,! decl9e 0 app>5tly n s rapid z ! increase1 b nev]!less f ! fir/ mom5t ( its appe>ance to ! la/ 0 n long] ?an a few weeks4 ,?is new /> 9 ,p]seus e/abli%$1 9 "o s5se1 a record4 ,= ! /> 0 bright] ?an any new /> :i* _h be5 notic$ s9ce ! days ( accurate a/ronomical obs]vations4 ,n inde$ = ?ree c5turies _h a /> ( su* lu/re sprung into exi/5ce4 ,b a tempor>y />1 su* z ?is 01 has be5 by no means an infrequ5t occurr5ce4 ,_m su* h be5 record$4 ,^? :o h be5 acqua9t$ ) a/ronomical matt]s = ?irty ye>s w recollect f\r or five su* />s4 ,9 ea* ( !m ! g5]al "* 0 some:at ! same4 ,!re 0 a sudd5 outbreak1 & !n a gradual decl9e4 ,! que/ions h sometimes aris5 z to :e!r ! outbreak ( su* an object is really ! tempor>y exaltation ( a /> :i* 0 previ\sly visible1 or :e!r x ought n to be reg>d$ z ! creation ( a totally new />4 ,9 "s cases x does seem possible t a new /> may h be5 p>tly1 at all ev5ts1 due to a l>ge increase ( brightness ( "s /> :i* _h be5 kn[n be=e4 ,9 ! case ( ,nova ,p]sei1 h[ev]1 we h ! be/ au?ority t ?is is n ! case4 ,pr(essor ,pick]+1 ! di/+ui%$ a/ronom] ( ,h>v>d ,college ,obs]vatory1 happ5$ to photograph ! region 9 :i* ,nova ,p]sei appe>$ a few days be=e ! outbreak took place4 ,he tells u t !re is n ! lea/ indication on 8 photograph ( ! pres5ce ( a /> 9 t region4 ,illu/ration3 ,fig4 #ed4--,,spectrum ,,( ,,nova ,,p]sei 7#aija74 7,photograph$ ) ! #dj 94 ,y]kes ,telescope by ,mr4 ,f]d9& ,ell]man47 ,! spectrum ( ,nova ,p]sei1 9 an in/rum5t ( suffici5t p[]1 appe>$ a truly magnific5t object4 ,l o!r /ell> spectra1 x display$ ! long l9e ( light m>k$ ) ! hues ( ! ra9b[1 b x 0 unlike ! spectra ( ord9>y />s 9 respect ( ! enorm\s enhancem5ts ( ! brightness at v>i\s p>ts ( ?is spectrum4 ,= in/ance1 at "o end ( ! long col\r$ b& a brilliant ruby l9e gl[$ ) a lu/re t w\ld at once attract att5tion1 & demon/rat$ t ! object "u view mu/ be some?+ totally diff]5t f ord9>y />s4 ,?is sup]b feature is "o ( ! l9es ( hydrog54 ,! pres5ce ( t l9e %[$ t m ! s\rce f :i* ! light came !re mu/ h be5 a rem>kable outbreak ( inc&esc5t hydrog5 gas4 ,at v>i\s po9ts along ! spectrum !re 7 o!r beautiful bright l9es :i*1 9 ea* case1 mu/ h be5 due to gl[+ gas4 ,"h we h ! evid5ce ( ! spectrum tell+ u 9 unmi/akable language t !re 7 features 9 ?is /> :olly unlike ! features f\nd 9 any ord9>y />4 ,x is impossible to dissociate ^! facts f ! hi/ory ( ! />4 ,mu* ( :at we h said ) reg>d to ! spectrum ( ,nova ,p]sei might be repeat$ ) reg>d to ! spectrum ( ! o!r tempor>y />s :i*1 f "t to "t1 h bur/ =?4 ,9 ea* case ! spectrum *>act]i/ic ( an ord9>y /> is pres5t1 b sup]add$ to x are bright l9es :i* indicate t "s great convulsion has tak5 place1 a convulsion by :i* va/ volumes ( gas h be5 r5d]$ inc&esc5t4 ,9 ,fig4 #ed we %[ ! spectrum ( ,nova ,p]sei on five dates1 f ,febru>y #bg? to ,m>* #bh?1 #aija4 ,^! photographs 7 tak5 by ,mr4 ,f]d9& ,ell]man ) ! great telescope ( ! ,y]kes ,obs]vatory4 ,!y %[ 9 ! cle>e/ mann] ! bright l9es indicat+ ! inc&esc5t gases4 ,we h po9t$ out ! high probability t among ! millions & millions ( bodies 9 ! univ]se x may n[ & !n happ5 t a collision takes place4 ,h we n also expla9$ h[ ! heat g5]at$ 9 virtue ( su* a collision might be suffici5t1 &1 inde$1 mu* m ?an suffici5t1 to raise ! masses ( ! two collid+ bodies to a /ate ( vivid inc&esc5ce8 ,a collision af=ds ! simple/ explanation ( ! sudd5 outbreak ( ! />1 & also acc\nts = ! rem>kable spectrum :i* ! /> exhibits4 ---------------------------------------- -------------------------------- ,,*apt] ,,xix4 ,,conclud+ ,,*apt]4 ,compreh5siv5ess ( ! ,nebul> ,!ory--,illu/ration--,huxley & ! ,orig9 ( ,species--,rudim5t>y ,organs--,! ,apt]yx--,its ,evanesc5t ,w+s--,! ,skeleton--,an ,hi/orical ,explanation--,application ( ! ,same ,me?od to ! ,nebul> ,!ory--,! ,int]nal ,heat ( ! ,e>?--,! ,lady ,psy*e4 ,,x is n difficult to %[ t ! nebul> !ory occupies a unique position among o!r speculations ( ! human intellect4 ,x is s compreh5sive t almo/ e conceivable topic w be> "s relation to x4 ,p]haps ,i may v5ture to give a r curi\s illu/ration ( ?is fact1 :i* 0 told me _m ye>s ago by "o :o att5d$ a c\rse ( lectures by an em95t ,pr(essor 9 ! m$ical faculty at1 let u say1 ,vi5na4 ,! subject ( ! c\rse 0 ! no d\bt highly important1 b possibly n g5]ally int]e/+1 subject ( 8inflammation40 ,i ?9k ,i am "r 9 say+ t ! c\rse _h to la/ = six mon?s1 because ! subject 0 to be treat$ ) *>act]i/ic bread? & pr(undity4 ,at all ev5ts1 ,i di/9ctly rememb] t ! le>n$ ,pr(essor comm5c$ 8 long s]ies ( pr(essional disc\rses ) an acc\nt ( ! nebul> !ory1 & f t />t+ po9t he gradually evolv$ ! sequ5ce ( ev5ts :i* ultimately culm9at$ 9--inflammation6 ,x may be rememb]$ t 9 ! ye> #ahhj1 ,pr(essor ,huxley deliv]$ at ! ,royal ,in/itution a fam\s lecture :i* he t]m$ 8,! ,com+ ( ,age ( ! ,orig9 ( ,species40 ,among ! _m rem>kable & =cible illu/rations :i* ?is lecture conta9$1 ,i recall "o :i* br\ght be=e ! audi5ce1 9 ! mo/ conv9c+ mann]1 ! tru? ( ! great ,d>w9ian ,!ory ( ,evolution4 ,huxley po9t$ out h[ ! discov]ies 9 ,biology1 dur+ ! tw5ty-"o ye>s :i* imm$iately succe$$ ! publication ( ! 8,orig9 ( ,species10 _h be5 s num]\s & s important1 & _h a be>+ s rem>kable on ! great evolution>y !ory1 t ev5 if ! ,d>w9ian ,!ory _h n be5 =m$ to expla9 ! facts ( ,nature1 z !y 7 kn[n at ! "t :5 ,d>w9 publi%$ 8 immortal book1 ! same !ory w\ld h _h to be =m$1 7 x only to expla9 ! additional facts :i* _h come to light s9ce ! great !ory itself _h be5 fir/ giv5 to ! _w4 ,i believe we may use simil> language ) reg>d to ! nebul> !ory & its great f\nd]s1 ,kant1 ,laplace1 & ,h]s*el4 ,if ! facts :i* 7 kn[n to ^! philosoph]s l$ !m to adopt 9 "o =m or ano!r t view ( ! ,orig9 ( ! ,univ]se :i* ! nebul> !ory sugge/s1 h[ /&s ! !ory n[ 9 ! light ( ! additional facts t h be5 s9ce disclos$8 ,if we m]ely took ! discov]ies :i* h be5 made s9ce ! la/ ( ! ?ree great philosoph]s pass$ away1 x might well be ma9ta9$ t a nebul> !ory w\ld be dem&$ to acc\nt = ! facts br\ght to light1 9 ! int]val4 ,! argum5t on :i* ! nebul> !ory ( ! sol> sy/em is f\nd$ has o!r p>allels ) t wond]ful doctr9e ( ,natural ,selection by :i* ,d>w9 reveal$ ! hi/ory ( life on our globe4 ,x n unfrequ5tly happ5s t an animal has 9 its organisation "s rudim5ts ( a /ructure :i* is obvi\sly ( no use to ! animal 9 8 pres5t mode ( life1 & w\ld be un9telligible if we suppos$ ! animal to h be5 creat$ z he is4 ,a curi\s in/ance ( a rudim5t>y /ructure is furni%$ 9 ! apt]yx1 ! fam\s w+less bird :i* /ill lives 9 ,new ,zeal&4 ,! arrival ( civilisation 9 ,new ,zeal& seems likely to be accompani$ ) fatal results1 s f> z ! un=tunate apt]yx is conc]n$4 ,weasels & o!r fi]ce enemies h be5 introduc$1 ) :i* ?is qua9t bird ( antiquity is unable to cope4 ,! apt]yx is def5celess aga9/ su* foes4 ,nature _h n end[$ x ) weapons :]e) to fight1 = x _h1 app>5tly1 no s]i\s adv]s>ies until ^! importations appe>$ 9 its isl& home4 ,unlike ! o/ri*1 ! apt]yx has nei!r /r5g? to fight 8 enemies1 nor spe$ to run away f !m1 ?\gh1 l ! o/ri*1 x has no w+s = flight2 inde$1 ! apt]yx has no w+s at all4 ,z its "n signifies ! apt]yx is ! w+less bird4 ,liv+ specim5s are /ill to be se5 9 ! ,zoological ,g>d5s4 ,! special po9t to notice is t1 ?\gh he has no w+s :atev]1 /ill !re are small rudim5t>y w+-bones :i* c be easily se54 ,y ne$ n be afraid to put y\r h& on ! apt]yx1 & feel ! puny little remnants ( w+s 7,fig4 #ee74 ,if1 hav+ se5 ! bird 9 ! ,zoological ,g>d5s1 y g to ! ,natural ,hi/ory ,museum1 y w !re f9d a skeleton ( ! apt]yx 7,fig4 #ef74 ,look ne> ! ribs 9 ! photograph1 & !re y w see ^? poor little w+-bones--w+-bones :]e !re nev] 0 a w+4 ,f our pres5t po9t ( view ^! w+s are1 h[ev]1 m int]e/+ & in/ructive ?an ! mo/ p]fect w+s ( an eagle or a c>ri]-pigeon4 ,^? w+s 9 ! apt]yx may be incapable ( flight1 b !y are full ( in/ruction to ! lov] ( ,nature4 ,z x is c]ta9 t !y are absolutely ( no use :atev] to ! bird1 we may well ask1 :y are !y !re8 ,!y are n !re to give assi/ance to ! bird 9 8 /ruggle = life2 !y _c help him to escape f 8 enemies or to procure 8 food2 !y _c help him to t5d & nurture ! "y "o :i* is hat*$ f ! egg2 !y c help him 9 no way4 ,! explanation ( ^? ineffectual w+s is hi/orical4 ,^? bones are pres5t 9 ! apt]yx simply because t bird has come d[n by a long l9e ( desc5t f birds :i* 7 end[$ ) g5u9e w+s1 ) w+s :i* enabl$ !m to fly l rooks or p>tridges4 ,illu/ration3 ,fig4 #ee4--,,! ,,apt]yx3 ,a ,,w+less ,,bird ,,( ,,new ,,zeal&4 ,illu/ration3 ,fig4 #ef4--,,skeleton ,,( ,,! ,,apt]yx1 ,,%[+ ,,rudim5t>y ,,w+s4 ,b if ?is be ! explanation1 h[ has x come to pass t ! w+s h dw9dl$ to useless little bones8 ,we _c ( c\rse feel c]ta9 ( ! reason1 b x seems possible to make surmises4 ,9 e>ly times w+$ birds flew ov] ! sea into ,new ,zeal&1 & f\nd x a c\ntry ( abundance1 z _m o!r immigrants h done 9 lat] times4 ,x may h be5 t ! food 9 ,new ,zeal& 0 s pl5tiful t ! wants ( ! birds c\ld be readily suppli$1 )\t ! necessity = rang+ ov] l>ge tracts4 ,x may h be5 t ! newly arriv$ birds f\nd t !y _h few or no enemies 9 ,new ,zeal&1 f :i* flight w\ld be necess>y z a means ( escape4 ,x may possibly h be5 bo? causes toge!r1 & d\btless !re mu/ h be5 o!r causes z well4 ,! fact is1 h[ev]1 c]ta91 t 9 ! c\rse ( long g5]ations ?is bird gradually lo/ ! p[] ( flight4 ,natural selection decrees t an organ :i* has ceas$ to s]ve a useful purpose %all det]iorate 9 ! c\rse ( g5]ations4 ,if ! w+s _h become ne$less 9 ! se>* = food1 unnecess>y = escape f enemies1 & useless = protection ( its "y1 !y w\ld c]ta9ly t5d t[>ds disappe>ance4 ,! organism f9ds x uneconomical to ma9ta9 ! nutrition ( a /ructure :i* dis*>ges no useful end4 ,! w+s1 9 su* circum/ances1 w\ld be an encumbrance r ?an an aid1 & s we may readily conjecture t1 9 accordance ) ?is well-kn[n pr9ciple1 ! w+s gradually decl9$1 until !y ceas$ to be useful organs1 s t n[ m]ely a few rudim5t>y bones rema9 to %[ t ! bird's ance/ors _h once be5 z o!r birds4 ,:atev] may h be5 ! cause1 x seems c]ta9 t 9 ! c\rse ( ?\s&s ( ye>s1 or x may be 9 scores ( ?\s&s ( ye>s1 ^! birds lo/ ! p[] ( flight2 ?us !y gradually ceas$ to h w+s1 & ^! little bones are all t n[ rema9 to r5d] x almo/ c]ta9 t1 if we c\ld le>n :at ?is bird's ance/ry has be51 we %\ld f9d t x 0 desc5d$ f a bird :i* _h useful w+s & vigor\s flight4 ,:5ev] we f9d an organ :i* is obvi\sly rudim5t>y1 or ( no use to its possessor 9 its pres5t =m1 ,d>w9 has taught u to look = an hi/orical explanation4 ,let u see if we _c apply ?is pr9ciple to ! illu/ration ( ! nebul> !ory4 ,illu/ration3 ,,spirals ,,9 ,,o!r ,,dep>tm5ts ,,( ,,nature4 ,fig4 #eg4--;,,=am9if]4 ,fig4 #eh4--,,nautilus4 ,we lik5 ! int]nal heat ( ! e>? to ! rudim5t>y w+-bones ( ! apt]yx4 ,9 ea* case we f9d a survival devoid ( mu* significance1 unless 9 reg>d to its hi/orical int]pretation4 ,b t hi/orical significance c h>dly be ov]-e/imat$4 ,unimportant z ! w+-bones may be1 !y admit ( explanation only on ! supposition t ! apt]yx 0 desc5d$ f a w+$ ance/or4 ,unimportant z ! int]nal heat1 /ill l+]+ 9 our globe1 may seem1 x admits ( explanation only on ! supposition t ! e>? has _h ! orig9 :i* ! nebul> !ory sugge/s4 ,t ! e>?'s beg9n+ has be5 sub/antially 9 accordance ) ! great ,nebul> ,!ory is1 ,i believe1 n[ v g5]ally admitt$4 ,b ! only au?ority ,i %all cite 9 illu/ration ( ?is f9al /atem5t is ! ,lady ,psy*e1 :o comm5ces h] exquisite address to h] 8pati5t range ( pupils0 ) ! words3-- 8,?is _w 0 once a fluid haze ( light1 ,till t[>d ! c5tre set ! />ry tides1 ,& eddi$ into suns1 t :eel+1 ca/ ,! planets20 ---------------------------------------- -------------------------------- ,,app5dices4 ------- ,i4--,,on ,,! ,,heat ,,giv5 ,,out ,,9 ,,! ,,contraction ,,( ,,! ,,nebula4 #a4 ,,fundam5tal ,,!orems ,,9 ,,! ,,attraction ,,( ,,gravitation4 ,! fir/ !orem to be prov$ is z foll[s3-- ,! attraction ( a ?9 homog5e\s sph]ical %ell on any po9t 9 its int]ior vani%es4 ,illu/ration3 ,fig4 #ei4 ,take any po9t ,p )9 ! sph]e4 ,let ?is be ! v]tex ( a cone produc$ bo? ways1 b ) a v small v]tical angle1 s t ! small areas ,s & ,s1 9 :i* ! two p>ts ( ! cone cut ! sph]e1 may be reg>d$ z planes4 ,draw ! tang5t planes at ,s & ,s4 ,let ! plane ( ! pap] pass ?r\gh ,p & be p]p5dicul> to bo? ^! tang5t planes4 ,let ,o ,p ,o be "o ( ! g5]ators ( ! cone1 & let fall ,p ,q p]p5dicul> to ! tang5t plane at ,o1 & ,p ,q p]p5dicul> to ! tang5t plane at ,o4 ,! volume ( ! cone ) ! v]tex at ,p & ! base ,s is ,p ,q ,s1 & ! o!r "p ( ! cone has ! volume ,p ,q ,s4 ,z ! v]tical angles ( ! cones are small1 _! volumes w1 9 ! limit1 be 9 ! ratio ( ,o ,p#c to ,o ,p#c1 & accord+ly ,p ,q ,s ,p ,q ,s ,p ,o#c ,o ,p#c4 ,b f ! figure ,p ,q ,p ,q ,p ,o ,p ,o1 & h5ce ,s ,o ,p#b ,s ,o ,p#b4 ,z ! %ell is uni=m1 ! masses ( ! p>ts cut out by ! cones are respectively proportional to ,s & ,s4 ,h5ce we see t ! attractions ( ,s & ,s on ,p w neutralise4 ,! same mu/ be true = e su* cone ?r\gh ,p1 & accord+ly ! total attraction ( ! %ell on a p>ticle inside is z]o4 ,! second fundam5tal !orem is z foll[s3-- ,a ?9 sph]ical homog5e\s %ell produces ! same attraction at an ext]nal po9t z if its entire mass 7 conc5trat$ at ! c5tre ( ! sph]e4 ,?is is ano!r fam\s !orem due to ,newton4 ,he gives a beautiful geometrical pro( 9 ,section ,,xii4 ( ! fir/ book ( ! 8,pr9cipia40 ,we %all "h take x = grant$1 & we %all consequ5tly assume t-- ,! attraction by ! law ( gravitation ( a homog5e\s sph]e on an ext]nal po9t is ! same z if ! entire mass ( ! sph]e 7 conc5trat$ at its c5tre4 #b4 ,,on ,,! ,,en]gy ,,betwe5 ,,two ,,attract+ ,,masses4 ,let m & m be two attract+ bodies suppos$ to be small 9 comp>ison ) _! di/ance x4 ,let ! =ce betwe5 !m be m m x#b :5 is ! =ce betwe5 two unit masses at unit di/ance4 ,x is requir$ to f9d ! en]gy necess>y to sep>ate !m to inf9ity1 x be+ suppos$ t !y />t f an initial di/ance a4 ,! en]gy requir$ is obta9$ by integrat+ betwe5 ! limits inf9ity & a1 & is consequ5tly m m a4 #c4 ,,on ,,! ,,en]gy ,,giv5 ,,out ,,9 ,,! ,,contraction ,,( ,,! ,,nebula4 ,we assume t ! nebula is contract+ symmetrically1 s t at any mom5t x is a homog5e\s sph]e4 ,we %all consid] ! %ell :i* lies betwe5 ! two sph]es ( radii1 r dr & r respectively4 ,let ,m be ! mass ( ! nebula conta9$ )9 ! sph]e ( radius r1 & let d,m be ! mass ( ! %ell j def9$4 ,!n x foll[s f #a t ! cond5sation ( ! %ell w h be5 effect$ by ! attraction ( ! mass ,m solely4 ,! ext]ior p>ts ( ! nebula c h _h no effect1 = ! out] "p has always be5 9 symmetrical sph]ical %ells ext]ior to d,m1 & ! attraction ( ^! is z]o4 ,we see f #b t ! contraction ( d,m f inf9ity1 until x =ms a %ell ) radius r1 repres5ts a quantity ( en]gy1 7 ,md,m7_/r 2 = x is obvi\s t ! en]gy involv$ 9 ! contraction ( ! :ole %ell is ! sum ( ! en]gies correspond+ to its sev]al p>ts4 ,if ,m be ! total mass & a ! radius ( ! nebula always suppos$ homog5e\s ,m ,m 7r#c_/;a#c71 & !re=e d,m #c ,m 7r#b_/;a#c7 dr4 ,h5ce ! "w done 9 ! contraction is 7_/r7 ,m 7r#c_/;a#c7 #c ,m 7r#b_/;a#c7 dr 7#c _/a#f7 ,m#b r#d dr4 ,integrat+1 !re=e1 ! total "w ( contraction is 7 ,m#b_/;a7 ,at ! pres5t mom5t a mass ( #a lb4 at ! surface ( ! sun w\ld weigh #bg lbs4 if te/$ by a spr+ balance4 ,h5ce ,m_/a#b #bg4 ,) ?is sub/itution we f9d ! expression = ! foot-p\nds ( "w correspond+ to ! contraction ( ! nebula f inf9ity to a sph]e ( radius a to be1 #bg a ,m #af a ,m v ne>ly4 ,h5ce we h ! foll[+ fundam5tal !orem due to ,helmholtz1 :i* is ! basis ( ! !ory ( sun heat4 ,if ! sun he reg>d$ z a homog5e\s sph]e ( mass ,m p\nds & radius a feet1 !n ! foot-p\nds ( en]gy r5d]$ available = sun heat by ! contraction ( ! sol> mat]ial f1 an inf9ite di/ance is #af a ,m4 #d4 ,,evaluation ,,( ,,! ,,sun ,,heat ,,giv5 ,,out ,,9 ,,contraction4 ,! numb] ( foot-p\nds ( "w giv5 out 9 ! contraction f inf9ity is #af a ,m4 ,z #ggb foot-p\nds are equal to "o unit ( heat1 i4e4 to ! quantity ( heat necess>y to raise #a lb4 ( wat] #a ,fahr5heit1 we see t #ggb ,m is ! "w requir$ to raise a mass ( wat] equal to ! mass ( ! sun ?r\gh #a ,fahr5heit4 ,h5ce ! numb] ( globes ( wat]1 ea* equal to ! sun 9 mass1 :i* w\ld be rais$ #a ,fahr5heit by ! total heat aris+ f ! contraction1 is 7#af a7_/#ggb1 b a1 ! radius ( ! sun 9 feet1 is #b1bhj1jjj1jjj1 & h5ce we h ! foll[+ !orem3-- ,! en]gy lib]at$ 9 ! contraction ( ! sun f inf9ity to its pres5t dim5sions w\ld1 if turn$ into heat1 suffice to raise #dg1jjj1jjj globes ( wat]1 ea* hav+ ! same mass z ! sun1 ?r\gh #a ,fahr4 ,x is f\nd by exp]im5t t #a lb4 ( good coal may develop #ad1jjj units ( heat1 & is !re=e equival5t to #ad1jjj #ggb foot-p\nds ( "w4 ,a mass ( coal equal to ! sun w\ld !re=e 7grant$ oxyg5 en\gh7 be equival5t to #ad1jjj #ggb ,m foot-p\nds ( "w4 ,b we h 7#af a ,m7 #af #b1bhj1jjj1jjj -------------- --------------- #c1djj4 #ad1jjj #ggb ,m #ad1jjj #ggb ,h5ce we see t ,! en]gy lib]at$ 9 ! contraction ( ! sun f inf9ity to its pres5t dim5sions1 is z great z c\ld be produc$ by ! combu/ion ( #c1djj globes ( coal1 ea* z heavy z ! sun4 ,we may speak ( #c1djj 9 ?is case z ! coal equival5t4 #e4 ,,on ,,! ,,fur!r ,,contraction ,,( ,,! ,,sun ,,& ,,! ,,heat ,,t ,,may ,,?us ,,be ,,giv5 ,,out4 ,let u suppose ! sun contracts to ! radius r1 & !n1 z already prov$1 #c1 ! en]gy x gives out is 7 ,m#b7_/r1 b we h ,m_/a#b #bg1 :5ce on contraction to ! radius r ! total en]gy giv5 out f ! comm5cem5t is #af ,m 7a#b_/r7 ,! av]age d5sity ( ! sun at pres5t is #a4d4 ,let u suppose x cond5ses until x has a d5sity 4 r#c a#c #a4d 1 :5ce ! en]gy becomes #ad a ,m 2 b ! coal equival5t ( #af a ,m has be5 f\nd 9 #d to be #c1djj1 & h5ce ! coal equival5t 9 ?is case is #c1jjj 4 ,if we take to be ! d5sity ( plat9um 7#ba4e71 we get a coal equival5t #h1cjj4 ,?is1 !re=e1 seems to repres5t a major limit to ! quantity ( heat :i* c be obta9$ f ! cond5sation ( ! nebula f inf9ity into a sun ( ! utmo/ d5sity4 #f4 ,,on ,,! ,,pres5t ,,emission ,,( ,,sun ,,heat4 ,accord+ to ,s*e9]1 8,/rahlung und ,temp]atur d] ,sonne1 ,leipzig1 #ahii10 ! value ( ! sol> con/ant1 i4e4 ! numb] ( cubic c5timetres ( wat] :i* w\ld be rais$ #a ,c5tigrade by ! quantity ( sun heat :i*1 if !re 7 no atmosph]ic absorption1 w\ld fall p]p5dicul>ly on a squ>e c5timetre1 at ! e>?'s mean di/ance f ! sun1 is betwe5 #c4e & #d4j4 ,if we take ! mean value1 we h 7translat$ into ,briti% units71 ! foll[+ /atem5t3-- ,if at a po9t 9 space1 di/ant f ! sun by ! e>?'s mean di/ance1 "o squ>e foot 0 expos$ p]p5dicul>ly to ! sol> rays1 !n ! sun heat t w\ld fall ^u x 9 "o m9ute w\ld raise "o p\nd ( wat] #ad ,fahr4 ,?is %[s t ! sol> en]gy emitt$ daily am\nts to #gjj1jjj1jjj1jjj #d a#b foot-p\nds4 #g4 ,,on ,,! ,,daily ,,contraction ,,( ,,! ,,sun ,,necess>y ,,to ,,supply ,,! ,,pres5t ,,exp5diture ,,( ,,heat4 ,we h se5 t at ! radius r ! en]gy is #af ,m 7a#b_/r74 ,h5ce = a *ange dr x is -#af ,m 7a#b_/r#b7 dr4 ,at its pres5t size1 accord+ly1 ! en]gy giv5 out by a %r9kage dr is #af ,m dr4 ,"o cubic foot ( ! sun av]ages #hg p\nds1 s t ,m #d_/c a#c #hg #af ,m dr #dfd #d a#c dr4 ,we h to equate ?is to ! expression 9 ! la/ article1 & we get dr #gjj1jjj1jjj1jjj_/7dfd a7 4#fe4 ,?is is ! %r9kage ( ! sun's radius express$ 9 feet4 ,h5ce ! daily r$uction ( ! sun's diamet] is #af in*es4 ,"o coal equival5t possesses en]gy repres5t$ by ,m #ad1jjj #ggb4 ,h5ce we c calculate t "o coal equival5t w\ld supply ! sol> radiation at its pres5t rate = ab\t #b1hjj ye>s4 ,,ii4--,,! ,,cons]vation ,,( ,,mom5t ,,( ,,mom5tum4 ,we give "h an elem5t>y inve/igation ( ! fundam5tal dynamical pr9ciple :i* has be5 ( su* importance ?r\gh\t ?is volume4 #h4 ,,case ,,:]e ,,!re ,,are ,,no ,,=ces4 ,newton's fir/ law ( motion tells u t a p>ticle 9 motion if unact$ ^u by =ce1 w move cont9u\sly 9 a /raight l9e )\t *ange ( velocity4 ,let ,a#j1 ,fig4 #fj1 be ! position ( ! p>ticle at any mom5t4 ,let ,a#a be its position aft] ! "t t2 ,a#b be ! position at ! "t #bt2 ,a#c be ! position at ! "t #ct1 & s on4 ,!n ! fir/ law ( motion tells u t ! di/ances ,a#j ,a#a1 ,a#a ,a#b1 ,a#b ,a#c1 ,a#c ,a#d1 mu/ =m p>ts ( ! same /raight l9e & mu/ be all equal4 ,if l9es ,o ,a#j1 ,o ,a#a1 ,o ,a#b1 etc41 be drawn f any fix$ po9t #j1 !n ! areas ( ! triangles ,o ,a#j ,a#a1 ,o ,a#a ,a#b1 ,o ,a#b ,a#c1 #j ,a#c ,a#d1 w be all equal4 ,= ea* area is "o-half ! product ( ! base ( ! triangle into ! p]p5dicul> ,o ,t f ,o on ,a#j ,a#a1 &1 z ! bases ( all ! triangles are equal1 x foll[s t _! areas are equal4 ,?us we le>n t a p>ticle mov+ )\t ! action ( =ce w describe ar\nd any fix$ po9t ,o equal areas 9 equal times4 ,illu/ration3 ,fig4 #fj4--;,,fir/ ,,law ,,( ,,motion ,,exemplifies ,,con/ant ,,mom5t ,,( ,,mom5tum4 ,! product ( ! mass ( ! p>ticle & its velocity is t]m$ ! mom5tum4 ,if ! mom5tum be multipli$ by ,o ,t ! product is t]m$ ! mom5t ( mom5tum ar\nd ,o4 ,we h 9 ?is case ! simple/ example ( ! important pr9ciple kn[n z ! cons]vation ( mom5t ( mom5tum4 ,! mom5t ( mom5tum ( a sy/em ( p>ticles mov+ 9 a plane is def9$ to be ! excess ( ! sum ( ! mom5ts ( mom5tum ( ^? p>ticles :i* t5d r\nd ,o 9 "o direction1 ov] ! sum ( ! mom5ts ( mom5tum ( ^? p>ticles :i* t5d r\nd ,o 9 ! opposite direction4 ,if we deem ^? mom5ts 9 "o direction r\nd ,o z positive1 & ^? 9 ! o!r direction z negative1 !n we may say t ! mom5t ( mom5tum ( a sy/em ( p>ticles mov+ 9 a plane is ! algebraical sum ( ! sev]al mom5ts ( mom5tum ( ea* ( ! p>ticles4 #i4 ,a ,,geometrical ,,proposition4 ,! foll[+ !orem 9 elem5t>y geometry w be requir$3-- ,illu/ration3 ,fig4 #fa4--;,a ,,useful ,,geometrical ,,proposition4 ,let ,a ,b & ,a ,c be adjac5t sides ( a p>allelogram1 ,fig4 #fa1 ( :i* ,a ,d is ! diagonal1 & let ,o be any po9t 9 its plane4 ,!n ! area ,o ,a ,c is ! diff]5ce ( ! areas ,o ,a ,d & ,o ,a ,b4 ,draw ,d ,q & ,c ,p p>allel to ,o ,a4 ,!n ,o ,a ,d ,o ,a ,q1 :5ce ,o ,a ,d - ,o ,a ,b ,o ,b ,q ,o ,a ,p ,o ,a ,c4 #aj4 ,,relation ,,betwe5 ,,! ,,*ange ,,( ,,mom5t ,,( ,,mom5tum ,,& ,,! ,,=ce ,,act+ ,,on ,,! ,,p>ticle4 ,illu/ration3 ,fig4 #fb4--;,,accel]ation ,,( ,,mom5t ,,( ,,mom5tum ,,equals ,,mom5t ,,( ,,=ce4 ,let ,a#a & ,a#b1 ,fig4 #fb1 be two adjac5t po9ts on ! pa? ( ! p>ticle1 & let ,a#a ,q & ,a#b ,r be ! tang5ts at ^? po9ts4 ,let ,s ,q repres5t ! velocity ( ! p>ticle at ,a#a1 & ,,sr ! velocity ( ! p>ticle at ,a#b4 ,!n ,q ,r repres5ts bo? 9 magnitude & direction ! *ange 9 velocity due to ! =ce ,f1 :i* we suppose con/ant bo? 9 magnitude & direction1 :ile ! p>ticle moves f ,a#a to ,a#b 9 ! small "t t2 we h also ,q ,r ,f t m4 ,complete ! p>allelogram ,s ,q ,r ,u1 & let fall ,o ,p#a1 ,o ,p#b1 ,o ,t p]p5dicul>s f ,o on ,s ,q1 ,s ,r1 ,s ,u respectively4 ,s9ce ,s ,q is ! velocity ( ! p>ticle :5 at ,a#a ! mom5t ( mom5tum is m ,o ,p#a ,s ,q2 :5 ! p>ticle is at ,a#b ! mom5t ( mom5tum is m ,o ,p#b ,s ,r4 ,:5ce ! diff]5ce ( ! mom5ts ( mom5tum at ,a#a & ,a#b is m 7,o ,p#b ,s ,r - ,o ,p#a ,s ,q7 #b m 7,o ,s ,r - ,o ,s ,q7 #b m ,o ,s ,u m ,o ,t ,s ,u m ,o ,t4 ,q ,r ,f t ,o ,t4 ,b 9 ! limit ,s co9cides ) ,a#a & ,a#b1 & we see t ! ga9 9 mom5t ( mom5tum is t times ! mom5t ( ! =ce ar\nd ,o4 ,h5ce we d$uce ! foll[+ fundam5tal !orem1 9 :i*1 by ! expression accel]ation ( mom5t ( mom5tum1 we mean ! rate at :i* ! mom5t ( mom5tum increases3-- ,if a p>ticle "u ! action ( =ce describes a plane orbit1 !n ! accel]ation ( ! mom5t ( mom5tum ar\nd any po9t 9 ! plane is equal to ! mom5t ( ! =ce ar\nd ! po9t4 ,if ! =ce is con/antly direct$ to a fix$ po9t1 !n ! mom5t ( ! =ce ab\t ?is po9t is always z]o4 ,h5ce ! accel]ation ( ! mom5t ( mom5tum ar\nd ?is po9t is z]o1 & ! mom5t ( mom5tum is con/ant4 ,?us we h ,kepl]'s law ( ! description ( equal areas 9 equal times1 & we le>n t ! velocity is inv]sely proportional to ! p]p5dicul> on ! tang5t4 #aa4 ,,if ,,two ,,or ,,m ,,=ces ,,act ,,on ,a ,,po9t1 ,,!n ,,! ,,accel]ation ,,( ,,! ,,mom5t ,,( ,,mom5tum1 ,,due ,,to ,,! ,,resultant ,,( ,,^! ,,=ces1 ,,is ,,equal ,,to ,,! ,,algebraic ,,sum ,,( ,,! ,,mom5ts ,,( ,,mom5tum ,,due ,,to ,,! ,,action ,,( ,,! ,,sev]al ,,compon5ts4 ,let ,a ,d1 ,fig4 #fa1 be a =ce1 & ,a ,c & ,a ,b its two compon5ts4 ,!n1 s9ce ,o ,a ,d ,o ,a ,b ,o ,a ,c1 we see t ! mom5t ( ,a ,d ar\nd ,o is equal to ! sum ( ! mom5ts ( its compon5ts4 ,h5ce we easily inf] t if a =ce be resolv$ into sev]al compon5ts ! mom5t ( t =ce ar\nd a po9t is equal to ! algebraical sum ( ! mom5ts ( its sev]al compon5ts4 ,! accel]ation ( ! mom5t ( mom5tum ar\nd ,o1 due to ! resultant ( a numb] ( =ces1 is equal to ! mom5t ( t resultant ar\nd ,o4 ,b1 z we h j %[n1 ?is is equal to ! sum ( ! mom5ts ( ! sep>ate =ces1 & h5ce ! !orem is prov$4 #ab4 ,,if ,,any ,,numb] ,,( ,,p>ticles ,,be ,,mov+ ,,9 ,a ,,plane1 ,,& ,,if ,,!y ,,are ,,n ,,subject$ ,,to ,,any ,,=ces ,,save ,,^? ,,:i* ,,arise ,,f ,,_! ,,mutual ,,actions1 ,,!n ,,! ,,algebraic ,,sum ,,( ,,_! ,,mom5ts ,,( ,,mom5tum ,,r\nd ,,any ,,po9t ,,is ,,con/ant4 ,?is important !orem is d$uc$ f ! fact /at$ 9 ! ?ird law ( motion1 t action & reaction are equal & opposite4 ,let u take any two p>ticles2 !n1 ! accel]ation ( ! mom5t ( mom5tum ( "o ( !m1 ,a1 by ! action ( ! o!r1 ,b1 w be ! mom5t ( ! =ce betwe5 !m4 ,! accel]ation ( ! mom5t ( mom5tum ( ,b by ! action ( ,a w be ! same mom5t1 b ) an opposite sign4 ,h5ce ! total accel]ation ( ! mom5t ( mom5tum ( ! sy/em by ! mutual action ( ,a & ,b is z]o4 ,9 l mann] we dispose ( e o!r pair ( actions1 & ?us1 z ! total accel]ation ( ! mom5t ( mom5tum is z]o1 x foll[s t ! mom5t ( mom5tum ( ! sy/em itself mu/ be con/ant4 ,?is fundam5tal pr9ciple is also kn[n z ! doctr9e ( ! cons]vation ( areas4 ,x may be /at$ 9 ! foll[+ mann]3-- ,if a sy/em ( p>ticles are mov+ 9 a plane "u ! influ5ce ( _! mutual actions only1 ! algebraic sum ( ! areas swept out ar\nd a po9t1 ea* multipli$ by ! mass ( ! p>ticle1 is directly proportional to ! "t4 #ac4 ,,if ,a ,,p>ticle ,,( ,,mass m1 ,,is ,,mov+ ,,9 ,,space ,,"u ,,! ,,action ,,( ,,any ,,=ce ,f1 ,,!n ,,! ,,projection ,,( ,,t ,,p>ticle ,,on ,,any ,,fix$ ,,plane ,,w ,,move ,,z ,,if ,,x ,,7 ,a ,,p>ticle ,,( ,,mass m ,,act$ ,,^u ,,by ,,t ,,compon5t ,,( ,f ,,:i* ,,is ,,p>allel ,,to ,,! ,,plane4 ,?is is evid5t f ! consid]ation t ! accel]ation ( ! p>ticle p>allel to ! plane mu/ be proportional to ?is compon5t ( ,f4 ,let u n[ suppose a sy/em ( p>ticles mov+ 9 space "u _! mutual actions4 ,! projections ( ^! p>ticles on a plane w move z if !y 7 ! p>ticles !mselves subject$ to ! action ( =ces :i* are ! projections ( ! actual =ces on ! same plane1 & z ! reactions betwe5 any two p>ticles are equal & opposite1 ! projections ( ^? reactions on ! plane are equal & opposite4 ,h5ce ! pro( already giv5 ( ! con/ancy ( ! mom5ts ( mom5tum ( a plane sy/em1 w apply equally to prove ! con/ancy ( ! mom5ts ( mom5tum ( ! projections ( ! p>ticles on ! plane4 ,h5ce we h ! foll[+ important !orem3-- ,let a sy/em ( p>ticles be mov+ 9 space "u ! action ( =ces int]nal to ! sy/em only4 ,let any plane be tak51 & any po9t 9 t plane1 & let ! mom5tum ( ea* p>ticle be project$ into ! plane1 !n ! algebraic sum ( ! mom5ts ( ^! projections ar\nd ! po9t is con/ant4 #ad4 ,,on ,,! ,,pr9cipal ,,plane ,,( ,a ,,sy/em4 ,let u suppose a sy/em ( p>ticles mov+ "u ! influ5ce ( _! mutual actions4 ,let ,o be any po9t1 & draw any plane ,l ?r\gh ,o4 ,!n ! mom5t ( mom5tum ( ! sy/em ar\nd ! po9t ,o & project$ into ! plane ,l is con/ant4 ,let u call x ,s4 ,if ano!r plane1 ,l1 _h be5 drawn ?r\gh ,o1 ! simil> mom5t ) reg>d to ,l is ,s4 ,?us = ea* plane ?r\gh ,o !re w be a correspond+ value ( ,s4 ,we h n[ to %[ t "o plane c be drawn ?r\gh ,o1 su* t ! value ( ,s is great] ?an x is = any o!r plane4 ,?is is ! pr9cipal plane ( ! sy/em4 ,if v be ! velocity ( a p>ticle1 !n 9 a small "t t x moves ov] ! di/ance v t4 ,if p be ! p]p5dicul> f ,o on ! tang5t to ! motion1 !n ! area ( ! triangle swept r\nd ,o 9 ! "t t is p v t1 & we see t ! mom5tum is proportional to ! mass ( ! p>ticle multipli$ into ! area swept ov] 9 ! "t t4 ,! quantity ,s w1 !re=e1 be proportional to ! sum ( ! projections ( ! areas 9 ,l1 swept ov] 9 ! "t t1 ea* increas$ 9 ! proportion ( ! mass ( ! p>ticle4 ,x is easily se5 t ! projection ( an area 9 "o plane on ano!r is obta9$ by multiply+ ! orig9al area by ! cos9e ( ! angle betwe5 ! two planes4 ,= if ! area be divid$ into ?9 /rips by l9es p>allel to ! l9e ( int]section ( ! planes1 !n 9 ! projection ( ^! /rips ! l5g?s are un*ang$1 :ile ! bread?s are alt]$ by be+ multipli$ by ! cos9e ( ! angle betwe5 ! two planes4 ,if1 !re=e1 we m>k (f on ! normal to a plane ,l a l5g? h proportional to any area 9 t plane1 !n ! projection ( ?is area on any o!r plane ,l may be measur$ by ! projection ( h on ! normal to ,l4 ,illu/ration3 ,fig4 #fc4--,,mom5t ,,( ,,mom5tum ,,unalt]$ ,,by ,,collision4 ,to det]m9e ! mom5t ( mom5tum resolv$ 9 any plane we !re=e proce$ z foll[s3 ,draw a plane ?r\gh ,o1 & ! tang5t to ! pa? ( "o ( ! p>ticles1 & m>k (f on ! normal drawn ?r\gh ,o to ?is plane a l5g? l proportional to ! mom5t ( mom5tum4 ,repeat ! same process = ea* ( ! o!r p>ticles ) l5g?s l1 l1 etc41 on _! sev]al normals4 ,suppose t l1 l1 l repres5t =ces act+ at ,o1 & det]m9e _! resultant ,r4 ,!n ,r1 resolv$ along any o!r direction1 w give ! compon5t ( mom5t ( mom5tum 9 ! plane to :i* t direction is normal4 ,9 any plane :i* passes ?r\gh ,r ! compon5t ( mom5t ( mom5tum is z]o4 ,! plane p]p5dicul> to ,r conta9s ! maximum projection ( mom5t ( mom5tum4 ,?is is ! pr9cipal plane ( ! sy/em :i* we h se5 to be ( su* importance 9 connection ) ! nebul> !ory4 #ae4 ,,collisions4 ,! cons]vation ( mom5t ( mom5tum rema9s true 9 a sy/em1 ev5 ?\gh !re may h be5 actual collisions betwe5 ! sev]al p>ts4 ,?is is includ$ 9 ! pro( already giv51 = collisions are among ! mutual actions ref]r$ to4 ,x may1 h[ev]1 be in/ructive to give a direct pro( ( a p>ticul> case4 ,let two p>ticles collide :5 meet+ 9 ! directions ,a ,p & ,b ,p 7,fig4 #fc7 respectively4 ,:e!r ! p>ticles be ela/ic or inela/ic is q immat]ial1 = 9 bo? cases ! action & reaction mu/ be equal & opposite1 & take place along "s l9e ,p ,q4 ,! action on ! p>ticle mov+ along ,a ,p w give to x an accel]ation ( mom5t ( mom5tum :i* is equal to ! mom5t ( ! action ar\nd ,o4 ,! accel]ation ( ! mom5t ( mom5tum com+ along ,b ,p w be equal & opposite4 ,?us ! total accel]ation ( ! mom5t ( mom5tum is z]o4 ,h5ce ! collision has no effect on ! total mom5t ( mom5tum4 #af4 ,,friction ,,& ,,tides4 ,we h %[n t su* actions z collisions _c affect ! mom5t ( mom5tum ( ! sy/em1 nei!r c x be affect$ by friction ( "o body on ano!r4 ,"h1 z 9 ! =m] case1 ! actions & reactions are equal & opposite1 & consequ5tly ! accel]ations ( mom5t ( mom5tum are z]o4 ,nor is x possible = any tidal action to affect ! total mom5t ( mom5tum ( ! sy/em4 ,e su* action mu/ be compos$ ( ! effects ( "o p>ticle 9 ! sy/em on ano!r1 & z ?is mu/ inv>iably produce an equal & opposite reaction ! total mom5t ( mom5tum is unalt]$4 ---------------------------------------- -------------------------------- ,,index4 ,accel]ation ( mom5t ( mom5tum1 #cgg ,aldeb>an1 #bg1 #bh ,&]son1 ,dr41 #cef ,&rom$a1 ,great ,nebula 91 #dc1 #bjd ,ant9\s1 ,clu/] ( />s 91 #cec ,apt]yx1 ,rudim5t>y w+-bones (1 #cfd1 #cff ----1 ,skeleton (1 #cfd1 #cff ----1 ,!1 #cfc1 #cfe ,arcturus1 ,spectrum (1 #he ,argon1 #bfe ,argus & surr\nd+ />s1 #ajc ,ariel1 #cch ,bor+1 ,! great1 #abc ,brooks' comet1 #hi ,buns5 burn]1 ,!1 #bhc ,butt]fly & ! oak-tree1 ,!1 #ae ,calcium1 #bgd ,capella1 ,spectrum (1 #fa-fd ,c>bon1 #bhj ,c]es1 #caa ,*ange ( mom5t ( mom5tum1 #cge ,clu/]1 ,nebul\s region r\nd a1 #cc ,clu/]s ( />s1 #ec-fj1 #bjc ---- ---- ( #ag? magnitude1 #cec ,coal-unit1 #aaj ,collisions1 #bai1 #chj ----1 ,cause ( =mation ( nebul1 #cef ,comets1 #cg ,comet1 ,brooks'1 #hi ---- ( #ahhb1 #aai ----1 ,spectrum (1 #bij ,common1 ,dr4 ,a4 ,a41 #dd ,concord1 ,! fir/1 #bid-cjg ----1 ,! second1 #cjh-cbc ----1 ,! ?ird1 #cbd-ccf ,conglom]ates1 #aei ,cons]vation ( mom5t ( mom5tum1 #cgd ,corona ( ! sun1 #aag ,crab nebula1 ,!1 #ai1 #dd ,crossley ,reflector1 ,!1 #de1 #df1 #dh1 #di1 #ej1 #fg1 #aii ,cygnus1 ,nebula 91 #cbi ,d>k bodies 9 univ]se1 #cee ,d>w91 ,pr(essor ,g4 ,h41 #aec1 #bed1 #ccb ,d>w9ian !ory1 #aj1 #bfh1 #cfb ,dew>1 ,pr(essor1 #add1 #bgb ,diurnal motion1 ,!1 #ba ,dumb-bell nebula1 #dc1 #dd1 #de1 #df1 #ej1 #gd1 #aie ,du/ f ,krakatoa1 #ahe ,e>?1 ,heat 9 int]ior (1 #acd1 #cfg ----1 ----1 ,cause (1 #aec ----1 ,hi/ory (1 #abb-aeg1 #bea ----1 ,rigidity (1 #afb ,e>?-moon sy/em1 #bec1 #ccb ,e>?quakes1 #aeh-aij ---- 9 ,engl&1 #age ----1 ,r\tes (1 #aga ,emission ( sun heat1 #cgc ,en]gy betwe5 two attract+ masses1 #cgj ---- giv5 out 9 contraction ( nebula1 #cgj ---- ( a sy/em1 #baf1 #bce ,equival5t ( heat1 #hh ,eros1 #cab ,evaluation ( sun heat giv5 out 9 contraction1 #cga ,ev]ett1 ,pr(essor1 #adi ,fire-mi/1 ,!1 #bfh 8,fla%0 spectrum1 #gj ,foot-p\nd1 #ia ,=am9if]a1 #cfg ,friction & tides1 #cha ,gas 9 r>efaction1 #aah ,h & ,k l9es1 #gj1 #bgf ,heat1 ,cause (1 #aec ----1 ,equival5t (1 #hh ---- giv5 out 9 contraction ( nebula1 #cfi ---- 9 int]ior ( ! e>?1 #acd1 #cfg ----1 ,unit (1 #hj1 #hi ,helium1 #bgg ,helmholtz1 #hf1 #if1 #ajj ,h]cules1 ,/>-clu/] 91 #eb1 #ec1 #ef1 #eg1 #ei ,h]s*el1 ,sir ,william1 #d1 #aa1 #gb1 #gc1 #gd ,hugg9s1 ,sir ,w41 #fj1 #fa1 #fc1 #fe ,huxley1 ,pr(essor1 & ,d>w9ian !ory1 #cfb ,huyss51 ,capta91 #abg ,hydrog5 9 spectrum ( ,nova ,p]sei1 #ceh 8,inflammation0 & nebul> !ory1 #cfa ,j\le's equival5t ( heat1 #hh ,jupit]1 #bc1 #be1 #bf1 #bi1 #bjh1 #bcg1 #caj1 #cbg ,k & ,h l9es1 #gj1 #bgf ,kant1 ,immanuel1 #d1 #e1 #gb1 #gc1 #gd1 #cbg ,keel]1 ,pr(essor1 #de-dh1 #fg1 #gc1 #aii1 #bjj1 #bjb1 #bde ,kelv91 ,"l1 #aec1 #afb ,krakatoa1 #agf-ahi ,langley1 ,pr(essor1 #gh ,laplace1 #d1 #gb1 #gc1 #gd1 #bjf ,lassell1 ,mr41 #cch1 #cdj ,lick ,obs]vatory1 #da1 #dc1 #dd1 #de ,locky]1 ,sir ,norman1 #bgg ,lyra1 ,r+ nebula 91 #bdi ,m>s1 #be1 #bf1 #bg1 #bh1 #bi1 #caa1 #cda1 #cdi ----1 ,satellites (1 #cda ,mcanique ,cle/e1 #e1 #h ,m]cury1 #bc1 #be1 #bf1 #bi1 #bjh ,meteors1 #cg ,milky ,way1 #bje1 #bjf1 #bad1 #bbj ,milne1 ,pr(essor1 #afe ,mom5t ( mom5tum1 #bbb1 #bbf1 #bdj1 #ceb ---- ----1 ,accel]ation (1 #cgg ---- ----1 ,*ange (1 #cge ---- ----1 ,cons]vation (1 #cgd ,mom5tum1 ,mom5t (1 #bbb1 #bbj1 #bdj1 #ceb ,monoc]os1 ,nebul\s region r\nd a clu/] 91 #cc ,moon1 ,orig9 (1 #bed ----1 ,surface (1 #bee ,nautilus1 ,!1 #cfg ,nebula1 ,contraction (1 ,heat giv5 out 91 #cfi ----1 ----1 ,en]gy giv5 out 91 #cgj ---- 9 ,orion1 ,! great1 #dj1 #da1 #db1 #dd1 #df1 #ej1 #gd1 #aie1 #bdb ---- ----1 ----1 ,spectrum (1 #fc1 #fd1 #fe ----1 ,! great spiral1 #aib1 #aic ,nebul1 #dj1 #da1 #dc1 #de1 #dg1 #ej1 #eg1 #eh1 #ff1 #fg1 #ga1 #gc1 #aje1 #abj1 #aeg1 #aia-bjf1 #bdb1 #bdg1 #bdi1 #bef1 #beg1 #beh1 #bei1 #bif1 #cbi1 #cde1 #cdh-cfj ----1 ,developm5t (1 #bdb ----1 ,discov]y (1 #aa ----1 ,numb] (1 #fg1 #bjj ,nebul> anecdote1 #cfb ---- ,!ory1 ,!1 #b1 #c1 #gb1 #gd1 #aeg1 #bje1 #bff1 #bib1 #cjg1 #cbc1 #cbh1 #cca1 #ccg-cdg1 #cfb1 #cfh ,nebulosity1 ,fa9t diffus$1 9 ,p]seus1 #ag ,neptune1 #cg ----1 ,satellites (1 #ccj1 #cdj ,newcomb1 ,pr(essor1 #bch ,norway1 ,conglom]ates 91 #aei ,nova ,p]sei1 #ceh ---- ----1 ,spectrum (1 #ceh1 #cei1 #cfj ,oak-tree & ! butt]fly1 ,!1 #ae ,ob]on1 #cch ,orbits ( ! planets1 #bjh ,orion1 #bb ,orion1 ,great nebula 91 #dj1 #da1 #db1 #dd1 #df1 #ej1 #gd1 #aie1 #bdb ----1 ,spectrum (1 #fc1 #fd1 #fe ,pegasus1 ,nebula 91 #dg1 #cde ,p]seus1 ,a fa9t diffus$ nebulosity 91 #ag ----1 ,new /> 91 #cef ,photosph]e1 ,!1 #fi ,pick]+1 ,pr(essor1 #ceh 8,plane1 ,pr9cipal10 ,!1 #bbe1 #ceb1 #cgi ,planet>y sy/em1 ,!1 #cg1 #bjh ,planets1 #bb1 #bf1 #bh ----1 ,movem5t (1 #ce1 #caa ----1 ,orbits (1 #bjh1 #bih ----1 ,rotation (1 on _! axes1 #cbe ,plat9um1 #bfc ,pleiades1 #bb ----1 ,nebulae 91 #ga ,potassium1 #bgb 8,plane1 ,pr9cipal0 ,!1 #bbe1 #ceb1 #cgi ,probabilities1 ,!ory (1 #cje ,radiation ( sun's heat1 #hb ,ramsay1 ,pr(essor1 #bgh ,ray nebul1 #bja1 #baa ,rigidity ( ! e>?1 #afb ,r+ nebula 9 ,lyra1 ,!1 #bdi ,rob]ts1 ,dr4 ,isaac1 #aih ,rosse1 ,"l1 #eg1 #aif-bja ,r[l&1 ,pr(4 ,h5ry1 #bgc ,sagitt>ius1 ,nebula 91 #aje ,satellites1 #cg1 #bji ,saturn1 #be1 #bf1 #bi1 #bbj1 #bcc ----1 ,dwell] 91 & ! ,sirian1 #ad ----1 ,r+ (1 #baj1 #bbj1 #bca1 #bcb1 #bcc1 #bcd ,s*e9]1 ,pr(essor1 #bjb1 #bjd ,seismomet]1 ,!1 #afe ,sirian1 ,!1 & ! dwell] 9 ,saturn1 #ad ,sirius1 #bae1 #baf ,smi?s1 ,! p>able ( !1 #cjc ,sol> sy/em1 #cf1 #bjg ----1 ,en]gy (1 #cej ----1 ,evolution (1 #bj1 #bdf-bfj1 #cdi ----1 ,orig9 (1 #cea ,sol> sy/em1 ,scale (1 #bi1 #cj1 #ca ,spectra1 ,cont9u\s1 #fh1 #bjc ----1 ,discont9u\s1 #fh ,spectroscope1 ,!1 #fj1 #bga ,spiral =m 9 ,nature1 #bef1 #beg ,spiral nebula1 ,! great1 #aib1 #aic1 #bdg ,spiral nebul1 #aia-bjf1 #baa1 #bab1 #bac1 #bbj1 #bdc1 #bdg1 #bef1 #beg1 #beh1 #bei1 #bif1 #cde ,/>-clu/]s1 #ec-fj ,/>1 ,spectrum (1 #fd ,/>s di/+ui%$ f planets1 #bh1 #bi ,/oney1 ,dr4 ,g4 ,john/one1 #bgi ,sun comp>$ ) ! planets1 #bf1 #bi ----1 ,corona (1 #aag ----1 ,contraction (1 #ii1 #cgc ----1 ,d5sity (1 #ajb1 #aae ----1 ,heat (1 #ge-id1 #ie-aaa1 #cga1 #cgb1 #cgc ----1 ,hi/ory (1 #aab-aba1 #bea ----1 ,nebul\s "p (1 #aba ----1 ,spectrum (1 #fa1 #fb1 #fi1 #gj1 #he1 #bgc ----1 ,surface (1 #bgh ----1 ,velocity (1 #ced ----1 ,weight (1 #aja ,sun heat1 giv5 out 9 contraction1 ,evaluation (1 #cga1 #cgb ----1 ,pres5t emission (1 #cgc ,sunsets1 ,! ,krakatoa1 #ahi ,sy/me du ,monde1 #h ,!rmomet] = te/+ ! heat ( ! e>?'s int]ior1 #abi ,?omson1 ,pr(4 ,j4 ,j41 #caf ,tides & friction1 #cha ,titania1 #cch ,umbriel1 #cch ,unit ( heat1 #hj1 #hi ,uranus1 #cg1 #bch1 #bci ----1 ,satellites (1 #bch1 #cch ,v5us1 #bc1 #be1 #bf1 #bi1 #bjh1 #cbe ,volcanoes1 #aeh-aij ,voltaire1 ,fable (1 #ad ,waves caus$ by ,krakatoa e>? quake1 #agi1 #ahb1 #ahc ---------------------------------------- ---------- ,,pr9t$ ,,by ,,cassell ,,company1 ,,limit$1 ,,la ,,belle ,,sauvage1 ,,london1 ,e4,c4 #bj4eji ---------------------------------------- -------------------------------- ,transcrib]'s ,notes3 ,! rais$ dot 771 us$ to indicate multiplication1 0 confus$ ) ! decimal po9t 9 sev]al numb]s4 ,! rais$ dot has be5 *ang$ to ! decimal po9t 9 numb]s & ! rais$ dot us$ only = multiplication4 ,9 places :]e 80 0 us$ = multiplication1 x 0 left z ! au?or wrote x4 ,miss+ or obscur$ punctuation 0 sil5tly correct$4 ,typographical errors 7 sil5tly correct$4 ,inconsi/5t spell+ & hyph5ation 7 made consi/5t only :5 a pr$om9ant =m 0 f\nd 9 ?is book4 ,sup]scripts are us$ to indicate numb]s rais$ to a p[]4 ,9 ?is pla9 text docum5t1 !y are repres5t$ by *>act]s l ?is3 8,p#c0 or 8#ajah01 i4e4 ,p cub$ or #aj to ! #ah? p[]4 ,v>iables 9 =mul sometimes use subscripts1 :i* look l ?is3 8,a#j04 ,?is w\ld be read 8,a sub #j04 ,text t 0 9 italics is enclos$ by und]scores 7italics74