,illu/ration ,,/>-,,l& ,,be+ ,,talks ,,) ,,"y ,,p ,,ab\t ,,! ,,wond]s ,,( ,,! ,,heav5s ,,by ,,sir ,,rob]t ,,/awell ,,ball1 ,f4,r4,s4 ,,l[ndean ,,pr(essor ,,( ,,a/ronomy ,,9 ,,! ,,univ]sity ,,( ,,cambridge ,,au?or ,,( 8,,! ,,/ory ,,( ,,! ,,heav5s10 ,,etc4 ,illu/rat$ ,,new ,,& ,,revis$ ,,edition ,,bo/on1 ,u4,s4,a41 ,,& ,,london ,,g9n ,,company1 ,,publi%]s ,! ,a!num ,press #ahii ,,ent]$ ,,at ,,/ation]s' ,,hall ,,copyright1 #ahii1 ,,by ,,cassell ,,company1 ,,limit$ ,,all ,,rights ,,res]v$ ,to ,,^? ,,"y ,,fri5ds ,,:o ,,h ,,att5d$ ,,my ,,*ri/mas ,,lectures ,,?is ,,little ,,book ,,is ,,d$icat$ ,,preface ,,to ,,fir/ ,,edition4 ,x has long be5 ! cu/om at ! ,royal ,in/itution ( ,great ,brita9 to provide ea* ,*ri/ma/ide a c\rse ( ,lectures specially address$ to a juv5ile audi5ce4 ,on two occasions1 namely1 9 #ahha & 9 #ahhg1 ! ,manag]s entru/$ ?is honorable duty to me4 ,! second c\rse 0 9 ! ma9 a repetition ( ! fir/2 & on my notes & recollections ( bo? ! pres5t little volume has be5 f\nd$4 ,i am indebt$ to my fri5ds ,rev4 ,,maxwell ,,close1 ,mr4 ,,ar?ur ,,rambaut1 & ,dr4 ,,john ,,todhunt] = _! k9dness 9 read+ ! pro(s4 ,,rob]t ,s4 ,,ball4 ,,obs]vatory1 ,,co4 ,,dubl91 ,oct4 #bb1 #ahhi4 ,,cont5ts4 ,,lecture ,i4 ,,! ,,sun4 ,,page ,! ,heat & ,brightness ( ! ,sun--,fur!r ,b5efits t we receive f ! ,sun--,! ,di/ance ( ! ,sun--,h[ ,a/ronom]s measure ! ,di/ances ( ! ,heav5ly ,bodies--,! ,app>5t ,smallness ( ,di/ant ,objects--,! ,%ape & ,size ( ! ,sun-- ,! ,spots on ! ,sun--,appe>ances se5 dur+ a ,total ,eclipse ( ! ,sun--,night & ,day--,! ,daily ,rotation ( ! ,e>?-- ,! ,annual ,motion ( ! ,e>? r\nd ! ,sun--,! ,*anges ( ! ,seasons--,sun%9e at ! ,nor? ,pole #a ,,lecture ,,ii4 ,,! ,,moon4 ,! ,phases ( our ,att5dant ! ,moon--,! ,size ( ! ,moon--,h[ ,eclipses are produc$--,effect ( ! ,moon's ,di/ance on its ,appe>ance--,a ,talk ab\t ,telescopes--,h[ ! ,telescope aids u 9 ,view+ ! ,moon--,telescopic ,views ( ! ,lun> ,sc5]y--,on ! ,orig9 ( ! ,lun> ,crat]s--,! ,movem5ts ( ! ,moon--,on ! ,possibility ( ,life 9 ! ,moon #gd ,,lecture ,,iii4 ,,! ,,inn] ,,planets4 ,m]cury1 ,v5us1 & ,m>s--,h[ to make a ,draw+ ( our ,sy/em-- ,! ,planet ,m]cury--,! ,planet ,v5us--,! ,transit ( ,v5us-- ,v5us z a ,_w--,! ,planet ,m>s & 8 ,movem5ts--,! ,ellipse--,! ,discov]ies made by ,ty*o & ,kepl]--,! ,discov]ies made by ,newton--,! ,geography ( ,m>s--,! ,satellites ( ,m>s--,h[ ! ,telescope aids 9 ,view+ ,fa9t ,objects--,! ,a/]oids1 or ,small ,planets #acd ,,lecture ,,iv4 ,,! ,,giant ,,planets4 ,jupit]1 ,saturn1 ,uranus1 ,neptune--,jupit]--,! ,satellites ( ,jupit]--,saturn--,! ,nature ( ! ,r+s--,william ,h]s*el-- ,! ,discov]y ( ,uranus--,! ,satellites ( ,uranus--,! ,discov]y ( ,neptune #bab ,,lecture ,v4 ,,comets ,,& ,,%oot+ ,,/>s4 ,! ,movem5ts ( a ,comet--,encke's ,comet--,! ,great ,comet ( ,halley--,h[ ! ,telegraph is us$ = ,comets--,! ,p>abola-- ,! ,mat]ials ( a ,comet--,meteors--,:at becomes ( ! ,%oot+ ,/>s--,gr& ,meteors--,! ,great ,novemb] ,%[]s--,o!r ,great ,%[]s--,meteorites #bee ,,lecture ,,vi4 ,,/>s4 ,we try to make a ,map--,! ,/>s are ,suns--,! ,numb]s ( ! ,/>s--,! ,clu/]s ( ,/>s--,! ,rank ( ! ,e>? z a ,globe 9 ,space--,! ,di/ances ( ! ,/>s--,! ,brightness & ,color ( ,/>s--,d\ble ,/>s--,h[ we f9d :at ! ,/>s are made (--,! ,nebul--,:at ! ,nebul are made (--,photograph+ ! ,nebul--,conclusion #cah ,,conclud+ ,,*apt]4 ,,h[ ,,to ,,"n ,,! ,,/>s4 #cha ,,/>-,,l&4 ,,lecture ,i4 ,,! ,,sun4 ,! ,heat & ,brightness ( ! ,sun--,fur!r ,b5efits t we receive f ! ,sun--,! ,di/ance ( ! ,sun--,h[ ,a/ronom]s measure ! ,di/ances ( ! ,heav5ly ,bodies--,! ,app>5t ,smallness ( ,di/ant ,objects--,! ,%ape & ,size ( ! ,sun--,! ,spots on ! ,sun--,appe>ances se5 dur+ a ,total ,eclipse ( ! ,sun--,night & ,day--,! ,daily ,rotation ( ! ,e>?--,! ,annual ,motion ( ! ,e>? r\nd ! ,sun--,! ,*anges ( ! ,seasons--,sun%9e at ! ,nor? ,pole4 ,,! ,,heat ,,& ,,brightness ,,( ,,! ,,sun4 ,we c all feel t ! sun is v hot1 & we "k t x is v big & a long way (f4 ,let u fir/ talk ab\t ! heat f ! sun4 ,on a cold day x is pleasant to g into a room ) a good fire1 & ev]ybody kn[s t ! ne>] we g to ! fire1 ! m /rongly we feel ! heat4 ,! boy :o is at ! f> end ( ! room may be %iv]+ ) cold1 :ile ^? close to ! fire are z hot z !y f9d to be pleasant4 ,if we c\ld draw mu* ne>] to ! sun ?an we actually are1 we %\ld f9d ! heat greatly increas$4 ,inde$1 if we w5t close en\gh1 ! temp]ature w\ld rise s mu* t we c\ld n endure x2 we %\ld be roa/$4 ,on ! o!r h&1 we %\ld c]ta9ly be froz5 to dea? if we 7 transport$ mu* fur!r away f ! sun ?an we are n[4 ,we are able to live com=tably1 because our bodies are j arrang$ to suit ! w>m? :i* ! sun s5ds to t di/ance f x at :i* ! e>? is actually plac$4 ,suppose y 7 able to endure any degree ( heat1 & t y _h "s way ( sett+ out on a voyage to ! sun4 ,take ) y a wax c&le1 a lead5 bullet1 a p5ny1 a pok]1 & a fl9t4 ,soon aft] y h />t$ y f9d ! w>m? f ! sun increas+1 & ! c&le beg9s to get s(t & melt away4 ,/ill1 on y g1 & y notice t ! lead5 bullet gets hott] & hott]1 until x becomes too hot to t\*1 until at la/ ! lead has melt$1 z ! wax _h previ\sly done4 ,h[ev]1 y are /ill a v long way f ! sun1 & y h ! p5ny1 ! pok]1 & ! fl9t rema9+4 ,z y approa* clos] to ! lum9>y ! heat is ev] increas+1 & at la/ y notice t ! p5ny is beg9n+ to get r$-hot2 g /ill ne>]1 & x melts away1 & foll[s ! example ( ! bullet & ! c&le4 ,if y /ill press onw>ds1 y f9d t ! iron pok]1 :i* 0 r$-hot :5 ! p5ny melt$1 beg9s to get bright] & bright]1 till at la/ x is brilliantly :ite1 & becomes s dazzl+ t y c h>dly be> to look at x2 !n melt+ comm5ces1 & ! pok] is *ang$ into liquid l ! p5ny1 ! lead1 & ! wax4 ,yet a little ne>] y may c>ry ! fl9t1 :i* is n[ gl[+ ) ! same f]vor :i* fus$ ! pok]1 b ev5 ! fl9t itself w h to yield at la/ & become1 n m]ely a liquid l wat]1 b a vapor l /eam4 ,y w ask1 h[ d we le>n all ?is8 ,z nobody c\ld ev] make su* a j\rney1 h[ c we feel c]ta9 t ! sun is s excessively hot8 ,i "k t :at ,i say is true = v>i\s reasons1 b ,i w only m5tion "o1 :i* is d]iv$ f an exp]im5t ) ! burn+-glass1 t mo/ boys h (t5 tri$4 ,illu/ration3 ,,fig4 #a4--;,h[ to use ! ,burn+-glass4 ,illu/ration3 ,,fig4 #b4--,! ,noonday ,gun4 ,we may use "o ( ^? l>ge l5ses t are int5d$ = magnify+ photographs4 ,b almo/ any k9d ( l5s w d1 except x be too flat1 z ^? 9 spectacles g5]ally are4 ,on a f9e sunny day 9 summ]1 y turn ! burn+-glass to ! sun1 & by hold+ a piece ( pap] at ! prop] di/ance a bright spot w be obta9$ 7,fig4 #a74 ,at t spot !re is int5se heat1 by :i* a mat* c be light$1 gunp[d] explod$1 or ! pap] itself k9dl$4 ,! broad l5s collects toge!r ! rays f ! sun t fall ^u x1 & conc5trates !m 9 "o spot1 :i* consequ5tly becomes hot & bright4 ,if we m]ely us$ a flat piece ( glass ! sunbeams w\ld g /raight ?r\gh2 !y w\ld n be ga!r$ toge!r1 & !y w\ld n be /rong en\gh to burn ! pap]4 ,! l5s1 y see1 is n flat2 its faces are curv$1 & !y ?us acquire ! p[] ( b5d+ 9 rays ( light or heat1 s z to unite _! effect on t "o po9t :i* we call ! focus4 ,:5 a great numb] ( rays are ?us collect$ on ! same spot1 ea* ( !m contributes a little w>m?4 ,illu/ration3 ,,fig4 #c4--;,a ,tell-tale = ! ,sun4 ,"s +5i\s p]son has turn$ ?is pr9ciple to an odd use1 by arrang+ a burn+-glass ov] a cannon 9 su* a way t j :5 noon arriv$ ! spot ( light %\ld rea* ! t\*-hole ( ! cannon & fire x (f4 ,?us ! sun itself is made to ann\nce ! middle ( ! day 7,fig4 #b74 ,ano!r application ( ! burn+-glass is to obta9 a record ( ! numb] ( h\rs ( sun%9e 9 ea* day4 ,y w und]/& ! app>atus f ,fig4 #c2 ! l5s is "h replac$ by a glass globe1 :i* acts z a burn+-glass4 ,z ! sun moves ov] ! sky ! bright spot ( light also moves1 & !re=e burns its track on a %eet ( pap] m>k$ ) l9es correspond+ to ! h\rs4 ,:5 ! sun is hidd5 by cl\ds ! burn+ ceases1 s by pres]v+ ea* day ! piece ( pap]1 we h an un]r+ tell-tale1 :i* %[s u dur+ :at h\rs ! sun 0 %9+ brightly1 & ! h\rs dur+ :i* he 0 hidd54 ,y see1 ! burn+-glass is n m]ely a toy1 x c be made useful 9 help+ u to le>n some?+ ab\t ! wea!r4 ,ano!r exp]im5t ) ! burn+-glass w also tea* u some?+4 ,take a c&le1 & f its flame y c get a bright po9t at ! focus4 ,x may fall ^u y\r h&1 b y c h>dly feel x1 & y w readily believe t ! focus is n ne>ly s hot z ! c&le4 ,ev5 :5 a burn+-glass is held 9 front ( a bright fire !re is comp>atively little heat 9 ! focus4 ,by us+ a l5s to cond5se ! beams f an electric lamp1 ,pr(essor ,tyndall has %[n h[ to light a piece ( pap]1 & to produce _m o!r effects4 ,b1 nev]!less1 ! focus is n ne>ly s hot z ! arc betwe5 ! two gl[+ c>bons4 ,y might move y\r f+] ?r\gh ! focus )\t mu* inconv5i5ce1 b ,i w\ld n recomm5d y to tru/ y\r f+] betwe5 ! poles ( ! electric light itself4 ,! temp]ature obta9$ at ! focus ( a burn+-glass seems ?us to be always less ?an t prevail+ at ! s\rce ( heat itself4 ,?is pr9ciple w be equally true :5 we turn a burn+-glass to ! sun1 & h5ce we "k t ! sun mu/ be hott] ?an any heat :i* c be obta9$ by ! bigge/ burn+-glass on ! brighte/ ( summ] days4 ,b burn+-glasses a y>d wide h be5 made1 & a/oni%+ heat effects h be5 produc$4 ,/eel has ?us be5 melt$ by ! sunbeams1 & s h o!r sub/ances :i* ev5 our greate/ furnaces _c fuse4 ,!re=e ! sun mu/ h a high] temp]ature ?an t ( molt5 /eel2 high]1 inde$1 ?an any temp]ature we c produce on ! e>?4 ,i h tri$ to prove to y t ! sun is v hot2 b x w\ld be well to see :at argum5ts might be us$ on ! o!r side4 ,inde$1 x is by consid]+ objections t we (t5 le>n4 ,s ,i %all tell y ( a difficulty t 0 once rais$ :5 ,i 0 endeavor+ to expla9 ! heat ( ! sun to an intellig5t man4 8,i am sure10 said my fri5d1 8t y mu/ be q wrong4 ,y said t ! ne>] y got to ! sun ! hott] x w\ld be2 b ,i "k ?is to be a mi/ake4 ,:5 t\ri/s g to ,switz]l&1 !y sometimes climb v high m\nta9s4 ,b ! top ( a m\nta91 ( c\rse1 is ne>] ! sun ?an bel[2 & s1 if ! sun 7 really hot1 ! climb] %\ld h f\nd x mu* w>m] on ! top ( ! m\nta9 ?an at its base4 ,b e "o kn[s t !re is abundant ice & sn[ on l(ty ,alp9e summits1 :ile d[n bel[ 9 ! valleys !re may be at ! same "t excessively w>m wea!r4 ,does x n !re=e seem t ! ne>] we g to ! sun ! cold] x is1 & ! fur!r we are f ! sun ! w>m] x is80 ,b my fri5d 0 q wrong 9 8 argum5t4 ,! coldness ( ! m\nta9 tops dep5ds ^u some?+ :i* he _h n tak5 into acc\nt4 ,!re is some?+ else besides ! sun :i* helps to make u s w>m & com=table4 ,?is o!r ess5tial ?+ is m or less defici5t at great heights4 ,y "k t we live by brea?+ air1 & we f9d air :]ev] we g1 ov] l& & sea1 all r\nd ! e>?4 ,^? :o asc5d 9 balloons are borne upw>ds by ! air1 & ?us we c %[ t air ext5ds = miles & miles ov] our heads1 ?\gh x becomes light] & ?9n] ! l(ti] ! elevation4 ,we n only utilize ! air = brea?+1 b x is also ( indisp5sable s]vice to u 9 ano!r way4 ,x acts z a blanket to keep ! e>? w>m2 inde$1 we ought r to describe ! air z a pile ( blankets "o ov] ! o!r4 ,^! air blankets enable ! e>? to pres]ve ! heat receiv$ f ! sunbeams by prev5t+ x f escap+ back aga9 into space4 ,?us w>m? is ma9ta9$1 & our globe is r5d]$ habitable4 ,y see !n1 t = our com=t we require n only ! sun to give u ! heat1 b also ! set ( blankets to keep x :5 we h got x4 ,if we ?rew (f ! blankets we %\ld be uncom=table1 ?\gh ! sun 7 z bright z be=e4 ,a man :o goes to ! top ( a m\nta9 at mid-day does approa* ! sun to "s ext5t1 &1 s f> z ?is goes1 he ought no d\bt to feel w>m]1 b ! ga9 is f> too small to be ?\ght (4 ,ev5 at ! top ( ,mont ,blanc ! increase 9 heat due to ! approa* to ! sun w\ld be only "o t5-million? "p ( ! :ole4 ,?is w\ld be utt]ly inappreciable2 ev5 a !rmomet] w\ld n be delicate en\gh to %[ x4 ,on ! o!r h&1 by asc5d+ to ! top ( ! m\nta91 ! climb] has got above ! l[] regions ( ! air2 he has n1 x is true1 rea*$ ev5 halfway to ! upp] surface--t is /ill v f> ov] 8 head--b ! high] lay]s ( ! atmosph]e are s v ?9 t !y =m mo/ indiff]5t blankets4 ,! ,alp9e climb] on ! top ( ! m\nta9 has ?us ?r[n (f ! be/ portion ( 8 blankets1 & receives a *ill2 :ile ! ga9 ( heat aris+ f 8 clos] approa* to ! sun is imp]ceptible4 ,p]haps y w n[ be able to und]/& :y et]nal sn[ re/s on ! summits ( ! great m\nta9s4 ,!y are *ill$ because !y h n s _m air blankets z ! snug valleys b5ea?4 ,! brightness ( ! sun is among ! mo/ wond]ful ?+s 9 nature1 & !re are ?ree po9ts t ,i ask y to rememb]1 & !n inde$ y w agree ) ,milton1 t ! sun is 8) surpass+ glory cr[n$40 ,fir/ ?9k ( ! beauty & brilliancy ( a lovely day 9 ,june4 ,!n rememb] t all ?is flood ( light comes f a s+le lamp at a mo/ trem5d\s di/ance2 & ?irdly1 recollect t ! sun is n l a bull's-eye lant]n1 conc5trat+ all 8 light specially = our b5efit1 b t he diffuses x equally ar\nd1 & t we d n get on ?is e>? ! two-?\s&-million? "p ( :at he gives out s pl5te\sly6 ,:5 we ?9k ( ! brightness ( day1 ( ! di/ance f :i* ! light has come1 ?\gh ,nature has n adju/$ any va/ l5ses to direct ! light specially 9 our direction1 we beg9 to compreh5d ! sun's true magnific5ce4 ,,fur!r ,,b5efits ,,t ,,we ,,receive ,,f ,,! ,,sun4 ,i want to %[ y h[ great %\ld be ! ext5t ( our gratitude to ! sun4 ,( c\rse1 on a bright summ]'s day1 :5 we are revell+ 9 ! g5ial w>m? & enjoy+ ! gladness ( sun%9e1 x ne$s no words to conv9ce u ( ! utility & ( ! b5efic5ce ( sunbeams4 ,s we w n take midsumm]4 ,let u take midw9t]4 ,take ?is v ,*ri/mas season :5 ! days are %ort & *e]less1 ! nights are long & d>k & cold4 ,we might be tempt$ to ?9k t ! sun _h well-nigh =gott5 u4 ,x is true he only seems to pay u v occasional visits1 & betwe5 fogs & cl\ds we 9 ,engl& see b little ( him2 b1 visible or invisible1 ! sun incessantly t5ds u1 & provides = our welf>e 9 ways t p]haps we d n always rememb]4 ,let me give an illu/ration ( :at ,i mean4 ,y w g back ?is dull & cold aft]noon to ! happy home :]e y\r ,*ri/mas holidays are be+ enjoy$4 ,x w be q d>k ere y get !re1 = ! sun 9 ^! w9try days sets s v e>ly4 ,y w ga!r ar\nd a *e]ful fire4 ,! curta9s w be drawn1 ! lamps w be light$1 & ! disagreeable wea!r outside w be =gott5 9 ! pleasant w>m? & light )94 ,five o'clock has arriv$1 ! pretty wick] table has be5 plac$ ne> mamma's *air2 on x are ! cups & sauc]s & ! fancy teapot4 ,"u ! table is a little %elf1 ) "s tempt+ cakes & a t5d] muff94 ,two or ?ree welcome fri5ds h jo9$ ! little gr\p1 & a delightful half-h\r is sure to foll[4 ,b y may say1 8,:at h tea & muff9s1 lamps & fireplaces to d ) ! sun8 ,are !y n all m]e artificial devices1 z f> remov$ z possible f ! sunbeams or ! natural beauties :i* sunbeams create80 ,well1 n s f>1 p]haps1 z y may ?9k4 ,let u see4 ,poke up ! fire1 & :ile x is ?r[+ =? t delici\s w>m?1 & *>m+ b flick]+ light1 we w try to discov] :]e t light & heat h come f4 ,no d\bt !y h come f ! coal1 b !n1 :5ce came ! coal8 ,x came f ! m9e1 :]e brave colli]s hew$ x out deep "u ! gr\nd1 & !n x 0 hoi/$ to ! surface by /eam eng9es4 ,our inquiry mu/ n /op "h1 = ano!r "q imm$iately arises1 z to h[ ?is wond]ful fuel came into ! e>?8 ,:5 we exam9e coal c>efully1 by us+ ! microscope to see its /ructure1 we f9d t x is n l a /one2 x is compos$ ( trees & o!r plants1 ! leaves & /ems ( :i* c be sometimes recogniz$4 ,inde$1 ! fossil trunks & roots ( ! great trees are occasionally conspicu\s 9 ! coal-pit4 ,x is q pla9 t ^! are only ! rema9s ( a vegetation :i* 0 =m]ly gr[+ & fl\ri%+1 & on fur!r inquiry we le>n t coal mu/ h be5 produc$ 9 ! foll[+ mann]3-- ,once ^u a "t a great =e/ fl\ri%$4 ,! sun %one d[n on ?is =e/1 & x 0 wat]$ by g5ial %[]s1 :ile insects & o!r creatures sport$ 9 its %ades4 ,x is true t ! trees & plants 7 n l ^? we n[ see ab\t u4 ,!y 7 m l f]ns & m>e's-tails & gigantic club-mosses4 ,9 ! fulness ( "t !y di$1 & fell1 & decay$1 & o!rs sprang up to meet ! l end4 ,?us x happ5$ t1 9 c\rse ( ages1 ! rema9s ( leaves1 & fruits1 & trunks accumulat$ ov] ! soil4 ,! =e/ 0 situat$ ne> ! sea%ore1 & !n a rem>kable *ange took place--! l& began sl[ly to s9k4 ,y ne$ n ?9k t ?is is impossible4 ,l& has (t5 be5 kn[n to *ange its level gradually4 ,9 fact1 a s9k+ process is sl[ly go+ on n[ 9 _m places on ! e>?1 :ile ! l& is ris+ 9 o!r localities4 ,z ! =e/ gradually sank l[] & l[]1 ! sea-wat] began to inundate x1 & all ! trees p]i%$ until1 at la/1 deep wat] subm]g$ ! surface :i* _h once be5 cov]$ by a f9e =e/4 ,at ! bottom ( ?is sea lay ! decay+ vegetation4 ,t :i* 0 ! de/ruction ( ! gr[+ =e/1 prov$ to be ! means ( pres]v+ its rema9s1 =1 !n z n[1 ! riv]s fl[$ into ! sea1 & ! wat]s ( ! riv]s1 especially 9 times ( flood1 c>ri$ d[n ) !m clay or mud1 held 9 susp5sion4 ,^u ! floor ( ! ocean ?is mat]ial 0 sl[ly deposit$2 & ?us a coat+ ( mud ov]lay ! rema9s ( ! =e/4 ,9 ! c\rse ( ages1 ^! lay]s grew ?ick & heavy1 & h>d5$ into a great flat rock1 :ile ! trunks & leaves und]nea? 7 squeez$ toge!r by ! weight1 & pack$ into a solid mass :i* became black1 & 9 ! c\rse ( "t 0 trans=m$ into coal4 ,aft] ages & ages _h pass$ by1 ! b$ ( ! sea ceas$ to s9k1 & began sl[ly to rise4 ,! wat] ov] ! newly made lay]s ( /one became %all[]1 & at la/ ! floor 0 rais$ until x em]g$ f ! sea4 ,b1 ( c\rse1 x w\ld n be ! orig9al gr\nd :i* =m$ ! surface ( ! newly uncov]$ l&4 ,! %eets ( consolidat$ clay lay on ! top2 ov] ! fre% surface life gradually spread1 until man himself came to dwell !re1 :ile f> b5ea? 8 feet ! rema9s ( ! anci5t vegetation 7 buri$4 ,:5 we n[ dig d[n ?r\gh ! rocks we come ^u ! portions ( trees & o!r plants :i* ! lapse ( "t1 & ! influ5ce ( pressure1 h turn$ f leaves & wood into our famili> coal4 ,t anci5t =e/ grew because sunbeams ab\nd$ 9 ^? e>ly times1 & n\ri%$ a luxuriant vegetation4 ,! heat & ! light !n exp5d$ s lib]ally by ! sun 7 seiz$ by ! leaves ( fl\ri%+ plants1 & 7 /or$ away 9 _! /ems & foliage4 ,?us x is t ! anci5t sunbeams h be5 pres]v$ 9 our coal-b$s = unc\nt$ ?\s&s ( ye>s4 ,:5 we put a lump ( coal on our fire ?is ev5+1 & :5 x s5ds =? a grateful w>m? & *e]ful light1 x b reproduces = our b5efit "s ( t /ore ( pres]v$ sunbeams ( :i* our e>? holds s l>ge a treasure4 ,?us1 ! sun has contribut$ v mat]ially to our com=t1 = x has provid$ ! fire to keep u w>m4 ,! orb ( day has1 h[ev]1 m9i/]$ fur!r to our tea p>ty1 = has x n produc$ ! tea itself8 ,! tea grew a long way (f1 mo/ likely 9 ,*9a1 :]e ! plant 0 matur$ by ! w>m? ( ! sunbeams4 ,f ,*9a ! tea-*e/s 7 br\ght by a sail+ vessel to ,london2 ! %ip p]=m$ ?is long voyage by ! use ( sails1 bl[n by :at we call w9d1 :i* is m]ely ! passage ( great volumes ( air z !y hurry f "o "p ( ! e>? to ano!r4 ,we may ask :at makes ! air move1 = x w n ru% ab\t 9 ?is way unless !re be consid]able =ce to drive x4 ,"h aga9 we p]ceive ! influ5ce ( ! sun4 ,tracts ( l& are w>m$ by ! g5ial sunbeams4 ,! air receives ! heat f ! l&1 & ! w>m air is buoyant & asc5ds1 :ile cool] air cont9ually fl[s 9 to supply its place4 ,to d ?is x has1 ( c\rse1 to ru% across ! c\ntry1 & ?us w9d is caus$4 ,all ! air curr5ts on our e>? are consequ5tly due to ! sun4 ,y see1 !re=e1 h[ greatly we are indebt$ to our brilliant lum9>y = ! enjoym5t ( our tea-table4 ,n only has ! sun giv5 u ! coal & ! tea1 b x has actually provid$ ! means by :i* ! tea 0 c>ri$ all ! way f ,*9a to our own %ores4 ,we c also trace ! connection betwe5 ! hot wat] & ! sun4 ,( c\rse1 ! wat] has come imm$iately f ! kettle1 & t has be5 tak5 f ! fire1 & ! fire 0 produc$ by sunbeams4 ,?us we le>n t x is ! w>m? ( ! sun t has made ! wat] boil4 ,if y visit ! wat]-works y w see great res]voirs4 ,9 "s cases !y h be5 fill$ by a riv]1 sometimes ! wat] is pump$ f a deep well 9 ! gr\nd1 sometimes x is ! surface-wat] caught on a m\nta9 side4 ,:atev] be ! imm$iate s\rce ( our wat] supply1 ! real orig9 is to be s\ght1 n 9 ! e>? b5ea?1 b 9 ! heav5s above4 ,all ! wat] we use day by day has come f ! cl\ds4 ,x is ! cl\ds :i* s5t d[n ! ra91 or sometimes ! sn[1 or ! hail1 & x is ?is wat] f ! cl\ds :i* fills our riv]s4 ,x is ?is wat] also :i* s9ks deep into ! e>? & supplies our wells1 s t f :atev] app>5t s\rce ! wat] seems to h come1 x is inde$ ! cl\ds :i* h be5 ! real b5efactors4 ,! wat] 9 y\r teacup to-night 01 a little :ile ago1 9 a cl\d1 float+ f> ov]head 9 ! sky4 ,we may look a little fur!r & f9d :5ce ! cl\ds h come4 ,x is c]ta9 t cl\ds are m]ely a =m ( /eam or vapor ( wat]1 & z !y are s cont9ually s5d+ d[n ra9 on ! e>?1 !re mu/ be "s means by :i* _! supply w be repl5i%$4 ,"h aga9 our excell5t fri5d ! sun is to be f\nd ev] help+ u secretly1 if n help+ u op5ly4 ,he p\rs d[n 8 ri* & w>m beams on ! great oceans1 & ! heat turns "s ( ! wat] into vapor1 :i*1 be+ light] ?an ! air1 asc5ds upw>ds = miles4 ,!re ! vapor (t5 passes into ! =m ( cl\ds1 & ! w9ds waft ^! cl\ds to refre% ! ?ir/y l&s ( ! e>?4 ,?us1 y see1 x is ! sun :i* procures = u wat] f ! great oceans :i* cov] s mu* ( our globe1 & s5ds x on by ! w9ds to supply our wat]-works1 & fill our teapots4 ,notice ano!r little k9dl9ess ( our great b5efactor4 ,! wat] ( ! oceans is q salt4 ,b we c\ld n make tea ) salt wat]1 s ! sun1 :5 lift+ ! vapor f ! sea1 mo/ ?\ghtfully leaves all ! salt beh9d1 & ?us provides u ) ! pure/ ( sweet wat]4 ,t nice muff9 0 bak$ by ! sun1 toa/$ by ! sun1 & made f :eat gr[n by ! sun4 ,if ! :eat 0 gr\nd 9 a w9d-mill1 !n ! sun rais$ ! w9d :i* turn$ ! mill4 ,p]haps ! fl\r-mill 0 driv5 by /eam1 9 :i* case ! sun1 long ago1 provid$ ! coal = ! boil]4 ,! mill] might h liv$ on a riv] & us$ a wat]-mill1 b if he did1 !n "h aga9 ! sun actually did ! "w4 ,! sun rais$ ! wat] to ! cl\ds1 & aft] x _h fall5 9 ra91 & 0 on its way back to ! sea1 its desc5t 0 utiliz$ to turn ! wat]-:eel4 ,! wat] d]ives its p[] to turn ! mill f ! fact t x is runn+ d[nhill1 b x c\ld n run d[n unless x _h fir/ be5 rais$ up2 & ?us x is inde$ ! sun :i* drives ! wat]-:eel4 ,nor c ! bak] disp5se ) ! sun's aid ev5 if he reject$ w9d-mills1 or /eam-mills1 or wat]-mills1 & det]m9$ to gr9d ! corn himself ) a pe/le & mort>4 ,"h1 at lea/1 x might be ?\ght t x is a man's s9ews & muscles t are do+ ! "w1 & s no d\bt !y are4 ,b y are mi/ak5 if y ?9k ! sun has n r5d]$ indisp5sable aid4 ,! sun has j z surely provid$ ! p[] :i* moves ! bak]'s arms z x has rais$ ! w9d :i* turn$ ! w9d-mill4 ,! =ce ex]t$ 9 gr9d+ ) ! pe/le has be5 d]iv$ f ! food t ! man has eat52 t food 0 gr[n by ! sun1 & ! man receiv$ f ! food ! en]gy x _h d]iv$ f ! sun's heat4 ,s t1 look at x any way y please1 ev5 = ! gr9d+ ( ! :eat to make ! muff9 = y\r tea p>ty1 y are :olly indebt$ to ! sun4 ,x is ! sun :i* has blea*$ ! tableclo? to t sn[y :it5ess4 ,! sun has giv5 ^? bright colors :i* look s pretty 9 ! girls' dresses4 ,) h[ mu* significance c we say & feel t light is pleasant to ! eye1 & :at pretti] "n ?an ,little ,sunbeam c we h = ! d>l+ *ild :o makes our home s bright8 ,,! ,,di/ance ,,( ,,! ,,sun4 ,! sun is a v long way (f4 ,x is n easy = y to imag9e a di/ance s great1 b if y want to le>n a/ronomy y mu/ make ! attempt4 ,?is is ! fir/ measurem5t t we %all h to make on our way to t f>-(f c\ntry call$ ,/>-,l&2 b long z we %all f9d x to be1 we %all aft]w>ds h to consid] di/ances v mu* long]4 ,:5 y are out 9 ! /reet1 or tak+ a walk 9 ! c\ntry1 y c see at once t ?is man is ne>1 or t h\se is f>1 or t m\nta9 is _m miles away4 ,?is is because y h o!r objects betwe5 to help y to judge ( ! di/ances ( ^! diff]5t objects4 ,y w see1 = example1 t !re are _m h\ses or f>my>ds1 & y w notice h$ges divid+ diff]5t fields betwe5 y & ! m\nta94 ,y also see t !re are woods & p>ks1 & p]haps /ret*es ( moorl& ext5d+ up ! slopes4 ,y h an impression t ! f>my>ds & fields are ( consid]able size1 & t ! woods or moors are wide & ext5sive2 & putt+ ^! ?+s toge!r1 y realize t ! m\nta9 mu/ be miles away4 ,b :5 we look at ! sun we h no aids conv5i5tly plac$ to help u 9 judg+ 8 di/ance4 ,!re are no int]v5+ objects1 & m]ely gaz+ at ! sun helps u b little 9 obta9+ any accurate k4 ,we mu/ g to ! a/ronom] & ask him to tell u h[ f> he has f\nd ! sun to be1 & !n we mu/ also beg f him "s explanation ( ! me?od he has us$ 9 mak+ 8 measurem5ts4 ,x has be5 f\nd t ! sun is1 on ! av]age1 ab\t n9ety-?ree millions ( miles f ! e>?2 b sometimes x is a little fur!r & sometimes x is a little ne>]4 ,let u fir/ try to c\nt #ic1jjj1jjj4 ,! easie/ way w be to get ! clock to d ?is = u2 & "h is a sum t ,i w\ld sugge/ = y to "w out4 ,h[ long w ! clock h to tick be=e x has made z _m ticks z !re are miles betwe5 ! e>? & ! sun8 ,e m9ute ! clock1 ( c\rse1 makes #fj ticks1 & 9 #bd h\rs ! total numb] w rea* #hf1djj4 ,by divid+ ?is into #ic1jjj1jjj y w f9d t m ?an #ajgf days1 or ne>ly ?ree ye>s1 w be requir$ = ! clock to p]=m ! task4 ,we may consid] ! subject 9 ano!r way1 & f9d h[ long an express tra9 w\ld take to g all ! way f ! e>? to ! sun4 ,we %all suppose ! spe$ ( ! tra9 to be #dj miles an h\r2 & if ! tra9 ran = a :ole day & a :ole night )\t /opp+1 x w\ld !n accompli% #ifj miles4 ,9 a ye> ! di/ance travell$ w\ld rea* #cej1djj miles1 & by divid+ ?is into #ic1jjj1jjj we arrive at ! conclusion t a tra9 w\ld h to travel at a pace ( #dj miles an h\r1 n alone = days & = weeks & = ye>s1 b ev5 = c5turies4 ,inde$1 n until #bfe ye>s _h elaps$ w\ld ! mighty j\rney h be5 end$4 ,ev5 ?\gh ,k+ ,*>les ,i4 _h be5 pres5t :5 ! tra9 began to move1 ! de/9ation w\ld n yet h be5 rea*$4 ,no "o :o />t$ 9 ! tra9 c\ld expect to rea* ! end ( ! trip4 ,t w\ld n occur till ! "t ( 8 great-great-gr&*ildr54 ,,h[ ,,a/ronom]s ,,measure ,,! ,,di/ances ,,( ,,! ,,heav5ly ,,bodies4 ,i %all s (t5 h to speak ( ! di/ances ( ! cele/ial bodies t ,i may once = all expla9 h[ x is t we h be5 able to discov] :at ^! di/ances are4 ,?is w\ld be a v puzzl+ matt] if we 7 to try & describe x fully1 b ! pr9ciple ( ! me?od is n at all difficult4 ,d y "k :y y h be5 provid$ ) two eyes8 ,x is und\bt$ t "o ( ! reasons is to aid y 9 e/imat+ di/ances4 ,y see ?is boy 7,fig4 #d7 judges ( ! di/ance ( 8 f+] by ! incl9ation ( 8 two eyes :5 direct$ at x4 ,9 a simil> way we judge ( ! di/ance ( a heav5ly body by mak+ obs]vations on x f two diff]5t /ations4 ,illu/ration3 ,,fig4 #d4--,two ,eyes are bett] ?an ,"o4 ,illu/ration3 ,,fig4 #e4--;,h[ we measur$ ! ,height ( ! ,ball4 ,i %all illu/rate our me?od ( measur+ ! actual di/ance ( a body 9 ! heav5s by %[+ y h[ we c f9d ! height ( t l>ge india-rubb] ball :i* is hang+ f ! ceil+4 ,( c\rse1 ,i d n int5d to h a measur+ tape f ! ball itself1 because ,i want to solve ! problem on ! same pr9ciple z t by :i* we measure ! di/ance ( ! sun or ( any o!r cele/ial body :i* we _c rea*4 ,i w ask ! aid ( a boy & a girl1 :o w please /& "o at ea* end ( ! lecture table4 ,! app>atus we %all want is v simple2 x consi/s ( two c>ds & a pair ( scissors4 ,! boy w k9dly %ape 8 c>d to su* an angle t :5 he holds x to 8 eye "o side ( ! angle %all po9t /raight at ! little girl1 & ! o!r side %all po9t /raight at ! ball1 j z y see 9 ! picture 7,fig4 #e74 ,! girl w also please d ! same ) h] c>d1 s t along "o side %e j sees ! little boy's face1 :ile ! o!r side po9ts up to ! ball4 ,x w be necess>y to cut ^! angles prop]ly4 ,if ! angle be too big1 !n :5 "o side po9ts to ! boy's face1 ! o!r w be direct$ above ! ball4 ,if ! angle on ! c>d be too small1 !n "o side w be direct$ bel[ ! ball1 :ile ! o!r is po9t$ to ! boy4 ,! :ole accuracy ( our little obs]vations dep5ds ^u cutt+ ! c>d angles prop]ly4 ,:5 !y h be5 truly %ap$ x w be easy to f9d ! di/ance ( ! ball4 ,we fir/ take a foot rule & measure ! l5g? ( our table f "o ( our "y fri5ds to ! o!r4 ,t l5g? is twelve feet1 & to discov] ! di/ance ( ! ball we mu/ make a draw+4 ,we get a %eet ( pap]1 & fir/ rule a l9e twelve in*es long4 ,t w repres5t ! l5g? ( ! table1 x be+ und]/ood t ea* in* ( ! draw+ is to correspond to a foot ( ! actual table4 ,let ! end :]e ! girl /ood be m>k$ ,b1 & t ( ! boy1 ,a1 & n[ br+ ! c>ds & place !m on ! l9e j z %[n 9 ! figure4 ,! c>d ! girl has %ap$ is to be put s t ! corn] ( x lies at ,b1 & "o edge along ,b ,a4 ,!n ! boy's c>d is to be s put t its corn] is at ,a & "o edge along ,a ,b4 ,next ) a p5cil we rule l9es on ! o!r edges ( ! c>ds1 tak+ c>e t !y are kept all ! "t 9 _! prop] positions4 ,^! two l9es c>ri$ on w meet at ,c2 & ?is mu/ be ! position ( ! ball on ! scale ( our little sket*4 ,x only n[ rema9s to take ! foot rule & measure on ! draw+ ! l5g? f ,a to ,c4 ,i f9d x to be tw5ty in*es1 & ,i h s arrang$ x t ! di/ance f ,b to ,c is ! same4 ,illu/ration3 ,,fig4 #f4--,?is is :at we want$ ! ,c>ds =4 ,i d n int5d to tr\ble y mu* ) ,euclid 9 ^! lectures1 b z _m ( my "y fri5ds h le>n$ ! six? book1 ,i w j ref] to ! well-kn[n proposition1 :i* tells u t ! l5g?s ( ! correspond+ sides ( two simil> triangles are proportional4 ,we h "h two simil> triangles4 ,!re is ! big "o ) ! boy at "o corn]1 ! girl at ! o!r1 & ! ball ov]head4 ,"h is ! small triangle :i* we h j drawn4 ,^! triangles are simil> because !y h got ! same angles1 & x 0 to insure t !y %\ld h ! same angles t we 7 s c>eful 9 %ap+ ! c>ds4 ,z ^! two triangles are simil>1 _! sides mu/ be proportional4 ,we h agre$ t ! l9e ,a ,b1 :i* is twelve in*es long1 is to repres5t ! l5g? ( ! table betwe5 ! little boy & girl4 ,h5ce ! di/ance1 ,a ,c1 mu/1 on ! same scale1 be ! int]val betwe5 ! ball & ! boy at ! end4 ,?is is tw5ty in*es on ! draw+1 & !re=e ! actual di/ance f ! end ( ! table to ! ball is tw5ty feet4 ,h5ce y see t )\t go+ up to ! ball or hav+ a /r+ f x1 or 9 any o!r way mak+ direct communication ) x1 we h be5 able to asc]ta9 h[ f> up 9 ! air ! ball is actually hung4 ,?is simple illu/ration expla9s ! pr9ciple ( ! me?od by :i* a/ronom]s are able to le>n ! di/ances ( ! diff]5t cele/ial bodies f ! e>?4 ,y mu/ ?9k ( ! sun1 ! moon1 & ! />s z globes support$ 9 "s mann] ov] our heads1 & we seek to discov] _! di/ances f measurem5ts ( angles made at ! ends ( a base-l9e4 ,illu/ration3 ,,fig4 #g4--,?is w\ld be our ,base-l9e :5 f9d+ ! ,sun's ,di/ance4 ,( c\rse1 a/ronom]s mu/ *oose two /ations :i* are f> m widely sep>at$ ?an are ^? 9 our little exp]im5t4 ,9 fact1 ! great] ! int]val betwe5 ! two /ations1 ! bett]4 ,a/ronom]s require a mu* long] di/ance ?an f "o side ( ?is room to ! o!r1 or f "o side ( ,london to ! o!r side4 ,if x 7 m]ely a balloon at :i* we 7 look+1 !n1 :5 "o obs]v] at "o side ( ,london & ano!r at ! opposite side %ap$ _! c>ds c>efully1 we %\ld be able to tell ! height ( ! balloon v easily4 ,b z ! sun is s mu* fur!r (f ?an any balloon c\ld ev] be1 we mu/ sep>ate ! obs]v]s mu* m widely4 ,ev5 ! bread? ( ,engl& w\ld n be en\gh1 s we h to make !m sep>ate m & m until !y are z widely divid$ z x is possible = any two p on ?is e>? to be4 ,"o a/ronom] takes up 8 position at ,a 7,fig4 #g71 & ! o!r at ! opposite side at ,b1 s t !y c bo? see ! sun4 ,!y are oblig$ to use a mu* m accurate way ( measur+ ! angles ?an by cutt+ out c>ds ) pairs ( scissors2 & z ! a/ronom] at ,a is n able to see 8 fri5d at ,b1 x becomes no easy matt] to measure ! angles accurately4 ,h[ev]1 we %all n n[ tr\ble ourselves ab\t su* difficulties4 ,x may suffice = ! pres5t to "k t ! angles are measur$ by delicate & v accurate in/rum5ts us$ by a/ronom]s4 ,!y w n1 inde$1 make a little sket* su* z suffic$ = our purpose4 ,!y make a calculation :i* is a mu* m accurate way ( effect+ true measurem5t4 ,! a/ronom]s "k ! size ( ! e>?1 & ?us !y "k h[ _m ?\s&s ( miles lie betwe5 ! two /ations :]e ! obs]vations are made4 ,?is di/ance means 9 _! calculation j :at ! l5g? ( ! table did 9 our sket*4 ,f ea* end ( ! l9e !y set (f an angle j z we did1 & ! a/ronom] mu/ use ! pr9ciple ( simil> triangles :i* he f9ds 9 ,euclid1 j we _h to d4 ,at la/1 :5 !y h calculat$ ! sides ( _! triangle1 !y obta9 ! di/ance ( ! sun4 ,,! ,,app>5t ,,smallness ,,( ,,di/ant ,,objects4 ,illu/ration3 ,,fig4 #h4--,! ne>] y are1 ! bigg] ! ,globe looks4 ,illu/ration3 ,,fig4 #i4--,! ,globe is s f> (f t x lies beyond ! ,picture4 ,! dott$ l9es %[ h[ small x seems4 ,i ought "h to expla9 a pr9ciple :i* ^? :o are le>n+ ab\t ! />s mu/ always be> 9 m9d4 ,! pr9ciple ass]ts t ! fur!r a body is1 ! small] x looks4 ,p]haps ?is w be und]/ood f ! adjo9+ little sket* 7,fig4 #h74 ,x repres5ts a great globe1 on :i* oceans & cont95ts are %[n1 & y see a little boy & a little girl are look+ at ! globe4 ,! girl /&s q close to x1 & ,i h drawn two dott$ l9es f h] eye1 "o to ! top ( ! globe1 & ! o!r to ! "u surface4 ,if %e wants to exam9e ! entire side ( ! globe :i* is visible to h]1 %e mu/ fir/ look along ! upp] dott$ l9e1 & !n %e mu/ turn h] glance d[nw>ds until %e comes to ! l[] l9e1 & hav+ to turn h] eyes ?us up & d[n %e w ?9k ! globe is v big1 & %e w be q "r4 ,! boy is1 z y see1 on ! o!r side ( ! globe1 b ,i h put him mu* fur!r (f ?an ! girl4 ,i h also drawn two dott$ l9es f 8 eye to ! globe1 & x is pla9 t he w n h to turn 8 head mu* up & d[n to see ! :ole globe4 ,he c take x all 9 at a glance1 & to him1 !re=e1 ! globe w appe> to be comp>atively small1 because he is suffici5tly f> f x4 ,! m di/ant he is1 ! small] x w appe>4 ,y c easily imag9e t1 if ! globe 7 f> en\gh1 ! two l9es t w\ld include ! :ole w\ld be l ^? %[n 7,fig4 #i71 9 :i* ! globe is s di/ant t x _c be se5 9 ! picture4 ,! app>5t size ( ! globe1 :i* is really measur$ by ! angle betwe5 ^! two l9es1 w\ld always be small] & small] accord+ z ! di/ance 0 great]4 ,n[ y c und]/& :y an object seems small] ! fur!r away x is2 inde$1 :5 suffici5tly f>1 ! object ceases to be visible at all4 ,i c\ld give _m illu/rations ( ! dim9ution ( size by di/ance1 & s1 d\btless1 c\ld y4 ,e boy kn[s t 8 kite looks small] & small] ! great] ! l5g? ( /r+ t he lets out4 ,i h se5 9 ! ,we/ ( ,irel& a bird t seem$ l a little speck high up ne> ! cl\ds1 b f its flight & o!r circum/ances ,i knew t ! speck 0 n a little bird4 ,x 01 inde$1 a great eagle1 :i* 0 dw>f$ by ! elevation to :i* x _h so>$4 ,x is 9 a/ronomy t we h ! be/ illu/rations ( ?is pr9ciple4 ,enorm\s objects seem to be small because !y are s v f> (f4 ,y mu/ !re=e always rememb] t al?\gh an object may appe> to be small1 ?is appe>ance may be only a delusion4 ,x may be t ! object is v big1 b v di/ant4 ,9 a/ronomy1 ?is is almo/ always ! case1 !re is s mu* room above u1 ar\nd u1 on all sides 9 space4 ,look up at ! ceil+4 ,x c]ta9ly does n b\nd space1 = !re is ano!r side to x2 & !n !re is ! ro( ( ! h\se4 ,b ! ro( is n a b\nd>y1 =1 ( c\rse1 !re is ! air above x1 & !n1 high] up /ill1 !re are ! cl\ds1 & s we c c>ry our imag9ation on & on ?r\gh & beyond ! air up to :]e ! />s are1 & /ill on & on4 ,& z !re is unlimit$ room1 ! cele/ial bodies take advantage ( x1 & are1 g5]ally speak+1 at di/ances s gigantic t1 no matt] h[ small !y may appe>1 _! smallness is m]ely deceptive4 ,let u try to illu/rate 9 ano!r way ! exce$+ remot5ess ( ! sun4 ,s please imag9e t y 7 on ! sun1 & t y took a view ( our e>? f t di/ance4 ,to f9d out :at we mu/ expect to see1 let u ?9k ( a balloon voyage4 ,if y 7 to g up 9 a balloon1 y w\ld at fir/ see only ! h\ses1 or objects imm$iately ab\t y1 b z y rose ! view w\ld become wid] & wid]4 ,y w\ld see t ,london 0 surr\nd$ by ! c\ntry1 & !n1 z y /ill so>$ up & up1 ! sea w\ld become visible1 & y w\ld be able to trace out ! coa/s1 ea/ & we/ & s\?4 ,if1 9 "s way1 y c\ld so> high] ?an any balloon c\ld c>ry y1 ! :ole ( ! ,briti% ,isl&s w\ld pres5tly lie spread l a map b5ea?4 ,/ill on & on1 & !n ! cont95t ( ,europe w\ld be gradually op5$ out1 until ! great oceans1 & ev5 o!r cont95ts1 w\ld at la/ be caught sight (1 & !n y w\ld p]ceive t our :ole e>? 0 inde$ a globe4 ,! high] y w5t1 ! less di/9ctly w\ld y be able to see ! details on ! surface4 ,at la/ ! outl9es ( ! cont95ts & oceans w\ld fade1 & y w\ld beg9 to lose any p]ception ( ! %ape ( ! e>? itself4 ,long ere y _h rea*$ ! di/ance ( ! sun1 ! e>? w\ld look m]ely z ! planet ,v5us n[ does to u4 ,x is in/ructive to consid] h[ small our e>? w\ld seem if x 7 possible to view x f ! sun4 ,?9k ( t v famili> little globe1 a lawn-t5nis ball1 :i* is two & ?ree-qu>t] in*es 9 diamet]4 ,b suppose a t5nis ball 7 at ! opposite side ( ! /reet1 or /ill fur!r away2 suppose1 = example1 t x 7 half a mile away1 :at c\ld y expect to see ( x8 ,& yet ! e>?1 z se5 f ! sun1 w\ld appe> to be no l>g] ?an a t5nis ball w\ld look :5 view$ f a di/ance ( half a mile4 ,,! ,,%ape ,,& ,,size ,,( ,,! ,,sun4 ,we h spok5 ( ! heat ( ! sun1 h[ hot he is2 ( ! di/ance ( ! sun1 h[ f> he is2 & n[ we mu/ say a little ab\t ! size ( ! sun2 & also ab\t 8 %ape4 ,x is pla9 t ! sun is r\nd1 t x has ! %ape ( a ball4 ,we are sure ( ?is because1 ?\gh a plate is circul>1 yet1 if x 7 plac$ s t we only saw x edgeways f a di/ance1 x w\ld n appe> to be r\nd4 ,! sun is always rotat+1 & z x always seems to be a circle1 we are !re=e c]ta9 t ! true %ape ( ! sun mu/ be globul>1 & n m]ely circul> l a flat plate4 ,9 ! middle ( ! day1 :5 ! sun is high 9 ! heav5s1 x is impossible = u to =m a notion ( ! size ( ! sun4 ,p w =m v diff]5t e/imates z to 8 app>5t bigness4 ,"s w say he looks z l>ge z a d9n] plate1 b su* /atem5ts are mean+less1 unless we say :]e ! plate is to be held4 ,if x be ne> ! eye1 ( c\rse ! plate may hide ! sun1 &1 = t matt]1 ev]y?+ else also4 ,if ! plate 7 ab\t a hundr$ feet away1 !n x w\ld (t5 hide ! sun4 ,if ! plate 7 m ?an a hundr$ feet di/ant1 !n x c\ld n hide ! sun entirely1 & ! fur!r ! plate1 ! small] x w\ld seem4 ,no means ( e/imat+ ! sun's size are available :5 8 orb /&s high 9 ! heav5s4 ,b :5 he is ris+ or sett+1 we see t he passes beh9d trees or m\nta9s1 s t !re are int]v5+ objects ) :i* we c comp>e him2 !n we h actual pro( t ! sun mu/ be a v l>ge body inde$4 ,illu/ration3 ,,fig4 #aj4--;,a ,sunset view$ f ,m>seilles 7,m>cus ,codde74 ,i give "h a picture1 by ,m>cus ,codde1 tak5 f a ,fr5* j\rnal1 l',a/ronomie1 :i* gives a *>m+ illu/ration ( a sunset at ,m>seilles 7,fig4 #aj74 ,if y wi% to see t ! sun is bigg] ?an a m\nta91 y may g to ! top ( ,notre ,dame de la ,g>de1 b y mu/ *oose ei!r ! #aj? ( ,febru>y or ! #ca/ ( ,octob] = y\r visit1 because x is only on ! ev5+s ( ^? days t ! sun sets 9 ! "r position4 ,on bo? ^! ev5+s ! sun s9ks directly beh9d ,m\nt ,c>ig\ 9 ! ,pyr5ees2 ?is m\nta9 is a long way f ,m>seilles--no less1 inde$1 ?an "o hundr$ & fifty-eight miles4 ,b ! m\nta9 is s l(ty1 t :5 ! sky is cle>1 ! summit c be di/9ctly se5 ^u ! sun z a backgr\nd1 9 ! way %[n 9 ! picture4 ,?is mu/ be a v pretty sight1 & x tea*es u an important lesson4 ,! sun is fur!r away ?an ! m\nta91 & yet y see ! sun on bo? sides ( ! m\nta91 & above x4 ,"h1 !n1 we le>n )\t any calculations1 t ! sun mu/ be bigg] ?an ! upp] "p ( a great m\nta9 9 ! ,pyr5ees4 ,:5 we calculate ! size ( ! sun f ! measurem5ts made by a/ronom]s1 we discov] t x is mu* bigg] ?an ,m\nt ,c>ig\2 we see t ev5 ! entire range ( ! ,pyr5ees1 ! :ole ( ,europe1 & ev5 our :ole globe1 are insignificant by comp>ison4 ,illu/ration3 ,,fig4 #aa4--;,h[ we comp>e ! ,e>? & ! ,sun4 ,!re is a football on ! table1 %[n 9 ,fig4 #aa4 ,we %all suppose x to repres5t ! sun2 we %all n[ *oose some?+ else to repres5t ! e>?4 ,we mu/1 h[ev]1 exhibit ! proportions accurately4 ,a t5nis ball w n d2 x is f> too l>ge4 ,! fact is1 ! wid? ( ! e>? is less ?an ! "o-hundr$? "p ( ! wid? ( ! sun4 ,! t5nis ball is1 h[ev]1 only a qu>t] ! wid? ( ! football1 s we mu/ *oose some?+ a good deal small]4 ,i try ) a m>ble1 ev5 ) ! smalle/ m>ble ,i c f9d1 b :5 ,i measure x1 ,i f9d t "o hundr$ su* m>bles1 plac$ side by side1 w\ld be f> long] ?an ! wid? ( ! football2 ,i mu/ !re=e look = some?+ /ill small]4 ,a gra9 ( small-siz$ %ot w give ! "r size = ! model ( our e>?4 ,ab\t "o hundr$ ( ^! gra9s plac$ side by side w ext5d to a l5g? equal to ! wid? ( ! football4 ,n[ y w be able to =m "s conception ( h[ enorm\s ! sun really is4 ,?9k ( ?is e>?1 h[ big we f9d x :5 we beg9 to travel4 ,:at a trem5d\s voyage we h to take to get to ,new ,zeal&1 & ev5 !n we h only got halfway r\nd ! globe4 ,!n ?9k t ! sun is 9 ! same proportion bigg] ?an ! e>? z t football is bigg] ?an t gra9 ( %ot4 ,if a million ( su* gra9s ( %ot 7 melt$ & ca/ into "o globe1 x w\ld n be s l>ge z t football4 ,if a million globes1 z l>ge z our e>?1 c\ld be unit$ toge!r1 no d\bt a va/ globe w\ld be produc$1 b x w\ld n be s l>ge z ! sun4 ,?9k ( a s+le h\se1 ) ?ree or f\r p liv+ 9 x1 & !n ?9k ( ?is mighty ,london1 ) its millions ( inhabitants4 ,! h\se w repres5t our e>?1 :ile great ,london repres5ts ! sun6 ,,! ,,spots ,,on ,,! ,,sun4 ,i h %[n y t ! sun is int5sely hot1 & a v long way (f1 & enorm\sly big4 ,& n[ we h to describe ! appe>ance ( ! surface ( ! sun :5 we exam9e x closely4 ,illu/ration3 ,,fig4 #ab4--,look+ at ! ,sun4 ,if y get a piece ( v d>k glass1 or if y smoke a piece ( glass ov] a c&le1 !n y c look directly at ! sun ) com=t4 ,a nic] plan is to prick a p9hole 9 a c>d1 ?r\gh :i* y c look at ! sun )\t any inconv5i5ce4 ,g5]ally speak+1 a view ( ! sun 9 ?is way w %[ y only a uni=mly bright surface4 ,to /udy ! face ( our great lum9>y c>efully1 y mu/ use ! aid :i* ! telescope gives to ! a/ronom]4 ,a v good way ( do+ ?is is %[n 9 ,fig4 #ab4 ,a small telescope1 fix$ on a /&1 is po9t$ to ! sun1 &1 ! eyepiece be+ drawn out some:at fur!r ?an :5 direct obs]vations are be+ made1 ! sun draws its own picture on a scre54 ,?is may be exam9$ )\t any inconv5i5ce1 or )\t ! necessity = any protection to ! eye1 & a numb] ( "y a/ronom]s c all view ! sun at ! same mom5t4 ,on su* a picture y w g5]ally see ! brilliant surface m>k$ ) d>k spots1 :i* are sometimes z num]\s z 9 ! case repres5t$ 9 ,fig4 #ac4 ,^! spots pres5t v diff]5t appe>ances accord+ to circum/ances4 ,"o su* spot :5 se5 ) a v p[]ful telescope %[$ ! wond]ful /ructure :i* is repres5t$ 9 ,fig4 #ad4 ,illu/ration3 ,,fig4 #ac4--,?is is :at ! ,sun sometimes looks l4 ,! visible surface ( ! sun is entirely =m$ ( int5sely heat$ vapors4 ,we might almo/ say t ! spots are holes1 by :i* we c look ?r\gh ! brilliant surface to ! int]ior & d>k] p>ts4 ,sometimes ! spots close up1 & fre% ones w op5 else:]e4 ,n[ & !n ! :ole surface is mottl$ ov] 9 a rem>kable way4 ,i give "h a picture :i* 0 tak5 f ,mr4 ,nasmy?'s beautiful draw+1 9 :i* he %[s h[ ! sun sometimes assumes ! appe>ance :i* has be5 lik5$ to will[ leaves 7,fig4 #ae74 ,?is appe>ance 0 v noticeable 9 ! great spot ( ,septemb]1 #ahih4 ,illu/ration3 ,,fig4 #ad4--;,a ,sun-spot 7aft] ,janss574 ,illu/ration3 ,,fig4 #ae4--,nasmy?'s ,draw+ ( ! ,will[-leav$ ,/ructure ( ! ,sun4 ,illu/ration3 ,,fig4 #af4--,spot ne>+ ! ,sun's ,edge4 ,! spots (t5 la/ long en\gh to demon/rate a rem>kable fact4 ,we mu/ rememb] t ! sun is a great globe1 & t x is pois$ freely 9 space4 ,!re is no?+ to hold x up1 & !re is no?+ to prev5t x f turn+ r\nd4 ,t x does turn r\nd1 we c prove by c>eful obs]vation ( ! spots4 ,i c be/ illu/rate :at ,i want by ,fig4 #ag1 :i* %[s six imag9>y pictures4 ,! fir/ repres5ts ! sun on ! #a/ day ( ! mon?2 ! next %[s x five days lat]1 on ! #f?2 ano!r view is five days lat] /ill1 on ! #aa?2 & s on until ! la/ picture1 :i* corresponds to ! #bf?4 ,y see1 on ! fir/ day !re is a spot ne> ! left edge2 by ! #f?1 ?is spot is ne> ! middle2 by ! #aa?1 x is ne> ! "r edge2 !n y d n see x at all on ! #af?1 or on ! #ba/2 b on ! #bf? x is back 9 ! same place f :i* x />t$4 ,we f9d o!r spots to h a simil> hi/ory4 ,!y appe> to move across ! face1 & !n to return 9 a little less ?an f\r weeks to ! same place :]e !y 7 orig9ally notic$4 ,^! appe>ances c be illu/rat$ v simply by cutt+ a small hole ?r\gh ! r9d ( an orange d[n to ! :ite int]ior sk91 :i* may be d>k5$ ) ink4 ,put a knitt+ ne$le ?r\gh ! axis ( ! orange1 & !n turn x sl[ly r\nd4 ,! spot w be f\nd to g ?r\gh ! *anges t we h se54 ,we />t ) ! spot ne> ! left1 x moves across ! face1 & !n passes to invisibility by mov+ beh9d ! globe until x reappe>s aga91 aft] hav+ mov$ r\nd ! back4 ,z ! same may be obs]v$ ) e spot :i* la/s long en\gh1 we le>n t ! *anges 9 ! places mu/ be produc$ by ! turn+ r\nd ( ! sun4 ,"h y see is ! way 9 :i* an a/ronomical discov]y is made4 ,we fir/ obs]ve ! fact t ! spots d always appe> to move4 ,!n we try to acc\nt = ?is1 & we f9d a v simple explanation1 by suppos+ t ! :ole sun1 spots & all1 turns /eadily r\nd & r\nd4 ,x c also be prov$ 9 a v conclusive mann] t no o!r explanation is possible4 ,?is rotation ( ! sun is always go+ on uni=mly1 & "s curi\s consequ5ces foll[ f x4 ,! view ( ! sun :i* is turn$ t[>ds u to-day is q diff]5t f t :i* 0 t[>ds u a =tnight ago1 or f t :i* we %all see 9 a =tnight h5ce4 ,!re is no actual or visible axis ab\t :i* ! sun rotates4 ,9 ?is ! sun is l ! e>? & o!r cele/ial bodies4 ,illu/ration3 ,,fig4 #ag4--;,h[ ! ,sun turns r\nd4 ,,appe>ances ,,se5 ,,dur+ ,a ,,total ,,eclipse ,,( ,,! ,,sun4 ,= a great deal ( our k ab\t ! sun we are indebt$ to ! moon4 ,x w sometimes happ5 t ! moon comes 9 betwe5 u & ! sun1 & produces an eclipse4 ,at fir/ y might ?9k t an eclipse w\ld only h ! effect ( prev5t+ u f see+ any?+ ( ! sun1 b x really reveals mo/ beautiful & int]e/+ objects1 ( ^: exi/5ce we %\ld o!rwise be ignorant4 ,! great lum9>y has curi\s app5dages :i* are q hidd5 "u ord9>y circum/ances4 ,9 ! full gl>e ( day ! dazzl+ spl5dor ( ! sun oblit]ates & r5d]s invisible ^! app5dages1 :i* only %9e ) comp>atively feeble light4 ,x =tunately happ5s t ! moon is j l>ge en\gh to int]cept ! :ole ( ! direct light f ! sun1 or r1 ,i %\ld say1 f ! c5tral p>ts ( ! sun4 ,surr\nd+ t c5tral & m famili> "p f :i* ! brilliancy is *iefly d]iv$ is a rem>kable fr+e ( delicate & beautiful objects :i* are self-lum9\s no d\bt1 b ) a light s feeble t :5 pres5t$ to u amid ! full blaze ( sunlight !y are invisible4 ,:51 h[ev]1 ! moon s k9dly /ops all ! /rong] beams1 !n ^! fa9t objects spr+ into visibility1 & we h ! exquisite spectacle ( a total eclipse4 ,! objects t ,i desire to m5tion p>ticul>ly are ! corona & ! prom95ces4 ,illu/ration3 ,,fig4 #ah4--,total ,eclipse ( ! ,sun1 ,may #f1 #ahhc 7drawn by ,tr\velot74 ,a pretty picture ( ! total eclipse ( ! sun :i* occurr$ on ,may #f1 #ahhc1 is "h %[n 7,fig4 #ah74 ,x is tak5 f a draw+ made by ,m4 ,tr\velot1 :o 0 s5t out ) a ,fr5* obs]v+ p>ty4 ,!y w5t a v long way to see an eclipse1 b :at !y saw recomp5s$ !m = all _! tr\ble4 ,! track along :i* ! ph5om5on c\ld be be/ se5 lay 9 ! ,pacific ,ocean1 & a place _h to be select$ :i* 0 s situat$ t ! sun %\ld be high 9 ! heav5s at ! important mom5t1 & also t ! duration :ile ! total eclipse la/$ %\ld be z long z possible4 ,!y accord+ly w5t to ,c>ol9e ,isl&1 & all ?is j\rney to ! o!r side ( ! e>? 0 tak5 to witness a ph5om5on t only la/$ five m9utes & tw5ty-?ree seconds4 ,%ort ?\gh ^! preci\s m9utes 71 !y 7 long en\gh to enable good "w to be done4 ,c>eful prep>ations _h be5 made s t n a mom5t %\ld be ?r[n away4 ,ea* memb] ( ! p>ty _h 8 special duty allott$ to him1 & ?is _h be5 rehe>s$ s c>efully be=eh& t :5 ! long-expect$ mom5t ( 8totality0 arriv$ !re 0 nei!r ha/e nor confusion2 e "o c>efully w5t ?r\gh 8 "p ( ! programme4 ,m4 ,tr\velot1 = in/ance1 occupi$ himself = two m9utes & a few seconds 9 mak+ ! sket* t we n[ %[4 ,no d\bt an accompli%$ a/ronomical arti/ l ,m4 ,tr\velot w\ld gladly h tak5 long] "t = 8 sket* ( s unique a sight1 b brevity 0 imp]ative4 ,he _h already _h exp]i5ce ( simil> eclipses1 s t he 0 prep>$ at once to note :at ought to be not$1 & ! picture we h %[n is ! result4 ,?is 0 complet$ )9 less ?an half ( ! duration ( totality1 & ! arti/ _h /ill ?ree m9utes left to devote to ano!r & q diff]5t "p ( ! "w1 :i* does n conc]n u at pres5t4 ,illu/ration3 ,,fig4 #ai4--,! ,corona ( ! ,sun1 #ahhb 7by ,s*u/]74 ,i want y p>ticul>ly to look at ^! long bran*es or projections :i* we see surr\nd+ ! sun :5 totally eclips$4 ,!y %9e ) a pe>ly light1 &1 9 fact1 x is /at$ t ev5 dur+ ! gloomie/ portion ( ! "t !re 0 /ill z mu* illum9ation z on a bright moonlight night4 ,all t light came f ?is glori\s halo r\nd ! sun :i* a/ronom]s call ! 8corona40 ,we d n "u ord9>y circum/ances obta9 ev5 ! slighte/ glimpse ( ?is object4 ,ev5 dur+ a p>tial eclipse ( ! sun x is n visible1 b directly ! moon q cov]s ! sun1 s z to cut (f all ! direct light1 !n ! corona spr+s into visibility4 ,x is always !re1 no d\bt1 ?\gh we _c see x4 ,"o ( ! mo/ int]e/+ photographs ( ! eclips$ sun :i* has ev] be5 tak5 0 t by ,pr(essor ,s*u/] 9 #ahhb 7,fig4 #ai74 ,! corona is well %[n1 & also a comet4 ,! o!r app5dages to ! sun :i* c be se5 dur+ an eclipse are ! objects :i* we call 8prom95ces40 ,!y are ( a ruddy color1 & seem to be great flames1 :i* leap upw>ds f ! gl[+ surface ( ! sun bel[4 ,?\gh ! exi/5ce ( ! prom95ces 0 fir/ discov]$ by _! pres5ce dur+ eclipses1 x =tunately happ5s t we are no long] :olly dep5d5t on eclipses = ! purpose ( mak+ our obs]vations ( ^! rem>kable objects4 ,x is true t we may look at ! sun ) ev5 ! bigge/ & mo/ p[]ful telescope 9 ! _w1 & /ill n be able to p]ceive any?+ ( ! prom95ces4 ,we require ! aid ( a special appliance call$ ! spectroscope to r5d] !m visible4 ,b ,i am n n[ go+ to describe ?is +5i\s contrivance4 ,i am only go+ to speak ( ! results :i* h be5 obta9$ by its means4 ,we %all "h aga9 avail ourselves ( ! exp]i5ce ( ,m4 ,tr\velot = a picture ( two ( ^! wond]ful app5dages4 ,illu/ration3 ,,fig4 #bj4--,sol> ,prom95ces 7drawn by ,tr\velot74 ,! view 7,fig4 #bj7 %[s ! ord9>y aspect ( ! sun div]sifi$ ) gr\ps ( d>k spots4 ,! fr+e ar\nd ! m>g9 ( ! globe is ( "s ruddy mat]ial1 =m+ ! base ( ! flames :i* rise f ! gl[+ surface4 ,no d\bt ^! flames are also (t5 pres5t on ! face ( ! sun1 b we _c see !m aga9/ ! brilliant backgr\nd4 ,!y are only p]ceptible :5 %[n aga9/ ! sky beh9d4 ,at two po9ts ( ?is ruddy fr+e1 :i* happ5 curi\sly en\gh to be ne>ly opposite to ea* o!r1 two colossal flames h bur/ =?4 ,!y ext5d to a va/ di/ance1 :i* is q "o-?ird ( ! wid? ( ! sun4 ,! vigor ( ^! outbreaks may be e/imat$ by ! rem>kable *anges :i* are incessantly go+ on4 ,^! great flames may inde$ be said to flick]2 only1 consid]+ _! size1 we mu/ all[ !m a little m "t ?an is dem&$ = ! movem5ts ( flames ( ord9>y dim5sions4 ,! great flame on ! left 0 obvi\sly decl9+ 9 brilliancy :5 fir/ se54 ,9 a qu>t] ( an h\r x _h brok5 up into fragm5ts1 "s ( :i* 7 /ill to be se5 float+ 9 ! sun's atmosph]e4 ,9 t5 m9utes m ! light ( ?is flame _h almo/ entirely vani%$4 ,surely ^! are *anges ( extraord9>y rapidity :5 we rememb] ! size ( ?is prom95ce4 ,x 0 ne>ly #cjj1jjj miles 9 height--t is to say1 ab\t ?irty-sev5 times ! wid? ( our e>?4 ,great z are ^! prom95ces1 o!rs h be5 record$ :i* are ev5 l>g]4 ,"o ( !m has be5 se5 to ru% up ) a spe$ ( #bjj1jjj miles an h\r--t is1 ) m ?an two hundr$ times ! pace ( ! swifte/ ( rifle-bullets4 ,,night ,,& ,,day4 ,! sun is bright1 & ! e>? is d>k4 ,! sun gives light & heat1 & ! e>? receives light & heat4 ,we %\ld be 9 utt] d>kness 7 x n = ! sun2 at lea/1 all ! light we %\ld h1 beyond our trivial artificial light1 w\ld come f ! feeble tw9kle ( ! />s4 ,! moon w\ld be no use1 = ! brightness ( ! moon is m]ely ! reflection ( ! sunbeams4 ,7 ! sun's light completely ext+ui%$ we c\ld nev] aga9 see ! moon1 & we %\ld also miss f ! sky a few o!r bodies1 :i* we call planets1 su* z ,jupit] & ,v5us1 ,m>s & ,saturn4 ,b ! />s w\ld be ! same z be=e1 = !y d n dep5d ^u ! sun = _! light4 ,we %all1 inde$1 aft]w>ds see t ea* /> is itself a sun4 ,picture to y\rself ! e>? z receiv+ a /ream ( sunbeams4 ,^! beams fall on "o half ( our globe1 & give to x ! brilliance ( day4 ,! o!r half ( ! e>? ( c\rse receives no sunlight4 ,x is 9 ! %ad[1 & consequ5tly ! d>kness ( night !re prevails4 ,! b\nd>y betwe5 light & d>kness is n q %>ply def9$1 = ! pleasant twilight s(t5s x a little1 s t we pass gradually f day to night4 ,look+ at ! progress ( ! sun 9 ! c\rse ( ! day1 we see t he rises f> away 9 ! ea/1 !n he gradually moves across ! heav5s pa/ ! s\?1 & 9 ! ev5+ decl9es to ! we/1 sets1 & disappe>s4 ,all ?r\gh ! night ! sun is gradually mov+ r\nd ! opposite side ( ! e>?1 illum9at+ ,new ,zeal& & ,japan & o!r remote c\ntries1 & !n gradually work+ r\nd to ! ea/1 :]e he />ts afre% to give u a new day "h4 ,our ance/ors _m ages ago did n "k t ! e>? 0 r\nd4 ,!y ?\ght x 0 a great flat pla91 & t x ext5d$ endlessly 9 e direction4 ,!y 71 h[ev]1 mu* puzzl$ ab\t ! sun4 ,!y c\ld see f ! coa/s ( ,france & ,spa9 or ,brita9 t ! sun gradually disappe>$ 9 ! ocean2 !y ?\ght t x actually took a plunge into ! sea4 ,?is w\ld c]ta9ly qu5* ! gl[+ sun2 & "s ( ! anci5ts us$ to ?9k !y he>d ! dreadful hiss+ noise :5 ! great r$-hot body dropp$ into ! ,atlantic4 ,b !re 0 "h a difficulty4 ,if ! sun 7 to be *ill$ d[n e ev5+ by dropp+ into ! wat] hundr$s ( miles away to ! we/1 h[ did x happ5 t e>ly ! next morn+ he came up z fre% & z hot z ev]1 hundr$s ( miles away to ! ea/8 ,= ?is1 inde$1 x seem$ h>d to acc\nt4 ,"s said t we _h an entirely new sun e day4 ,! gods />t$ ! sun f> (f 9 ! ea/1 & aft] hav+ run its c\rse x p]i%$ 9 ! we/4 ,all ! night ! gods 7 busy prep>+ a new sun to be us$ on ! succe$+ day4 ,b ?is 0 ?\ght to be su* a wa/e ( good suns t a m economical !ory 0 aft]w>ds propos$4 ,! anci5ts believ$ t ! cont95ts ( ! e>?1 s f> z !y knew !m1 7 surr\nd$ by a limitless ocean4 ,at ! nor?1 !re 7 high m\nta9s & ice & sn[1 :i* !y ?\ght prev5t$ access to ?is ocean f civiliz$ regions4 ,vulcan 0 ! presid+ deity :o navigat$ ^? wa/es ( wat]s1 & to him 0 intru/$ ! responsible duty ( sav+ ! sun f ext9ction4 ,he _h a great boat ready1 s t :5 ! sun 0 j dropp+ into ! ocean at sunset he caught x1 & dur+ all ! night he paddl$ ) 8 glori\s c>go r\nd by ! nor?4 ,! gl[ ( ! sun dur+ ! voyage c\ld ev5 be sometimes trac$ 9 summ] ov] ! great highl&s to ! nor?4 ,?is1 at all ev5ts1 0 _! way ( acc\nt+ = ! long midsumm] twilight4 ,aft] a t$i\s night's voyage ,vulcan got r\nd to ! ea/ 9 good "t = sunrise4 ,!n he %ot ! sun up ) su* t]rific =ce t x w\ld g across ! :ole sky1 & !n ! indu/ri\s deity paddl$ back ) all 8 might by ! way he _h come1 s z to be ready to cat* ! sun 9 ! ev5+ & ?us repeat 8 nev]-end+ task4 ,,! ,,daily ,,rotation ,,( ,,! ,,e>?4 ,vulcan & 8 boat seem$ a pretty way ( acc\nt+ = ! sun's app>5t motion4 ,! *ief drawback 0 t x 0 all "w & no play = poor ,vulcan4 ,!re 7 also a few o!r difficulties4 ,capta9s ( %ips told u t !y _h sail$ out on ! great sea1 & t s f> f f9d+ t ! ocean ext5d$ on & on 9 "o flat pla9 =ev]1 ! wat] seem$ to b5d r\nd1 s t1 9 fact1 aft] sail+ f> en\gh 9 ! same direction1 !y f\nd t !y w\ld be br\ght back aga9 to ! place f :i* !y />t$4 ,!y also knew a little ab\t ! nor?4 ,!y told u t !re c\ld be no su* ocean z t :i* ,vulcan 9 ?is fable 0 suppos$ to navigate4 ,x also appe>$ t %ips _h be5 voyag+ all ov] ! globe night & day 9 e direction1 & t no capta9 _h ev] se5 ! sun com+ d[n to ! sea1 & /ill less _h he ev] met ) ,vulcan 9 ! c\rse ( 8 incessant voyages4 ,?us x 0 discov]$ t ! e>? c\ld n be a nev]-end+ flat1 b t x mu/ be a globe1 pois$ freely 9 space )\t any atta*m5t to hold x up4 ,x 0 ?\ght t ! *ange f day to night might be acc\nt$ = by suppos+ t ! sun actually w5t r\nd ! e>? ?r\gh ! space und]nea? our feet4 ,?is is1 inde$1 :at x seems to d4 ,b !re 0 a great difficulty ab\t ?is explanation1 :i* began to be p]ceiv$ :5 ! size & di/ance ( ! sun 7 consid]$4 ,x requir$ ! sun to possess an al>m+ activity4 ,he w\ld actually h to ru% r\nd a circle "o hundr$ & eighty million miles 9 diamet] & complete ?is a/oni%+ voyage once e day4 ,illu/ration3 ,,fig4 #ba4--;,h[ we illu/rate ! ,*anges betwe5 ,day & ,night4 ,a little reflection w %[ t a v mu* simpl] explanation 0 available4 ,x 0 %[n t ! sun ne$ n revolve r\nd ! e>? once e day1 b t ev]y?+ w\ld be expla9$ if ! e>? itself turn$ r\nd 9 su* a way z to produce ! *anges f day to night4 ,we may illu/rate ! case by ?is figure 7,fig4 #ba74 ,! small globe is ! e>?1 :i* ,i c turn by ! h&le4 ,! lamp w repres5t ! sun1 &1 z at pres5t %[n1 ! side ( ! e>?1 on :i* ,engl& lies1 is t[>ds ! lamp & 9 full day4 ,on ! opposite side ( ! globe are o!r c\ntries su* z ,new ,zeal&1 & !re x is d>k4 ,y see t by simply turn+ ! h&le ,i c move ,engl& gradually r\nd s t x passes into ! d>k side1 & !n night falls ov] ! c\ntry4 ,at ! same "t ,new ,zeal& is turn$ r\nd to enjoy ! smiles ( day4 ,?is is a v simple me?od ( acc\nt+ = ! succession ( day & night1 & x is also ! true me?od4 ,we h already se5 t ! sun turns r\nd1 & n[ we f9d t ! e>? also turns1 b ! little body1 ! e>?1 goes mu* ! fa/]1 = x makes tw5ty-five turns :ile ! sun goes r\nd once4 ,our e>? is at ?is mom5t sp9n+ r\nd at a spe$ s great t ,london moves _m hundr$s ( miles e h\r4 ,a t[n ne> ! equator w\ld gallop r\nd at a pace ( m ?an a ?\s& miles an h\r--quick]1 9 fact1 ?an a rifle-bullet4 ,don't y ?9k t we ought to p]ceive t we are be+ :irl$ ab\t 9 ?is t]rific fa%ion8 ,we "k t :5 we are fly+ along 9 a railway tra91 we feel ! jolt+ & we he> ! noise1 & we feel ! bla/ ( air if we put our heads out ( w9d[1 & we see ! trees z !y appe> to ru% pa/4 ,all ^! ?+s tell u t we are 9 rapid motion4 ,b suppose ^! s5sations 7 abs5t4 ,imag9e a l9e s p]fectly laid t no jolts are p]ceptible1 & t no racket is he>d2 draw d[n ! bl9ds s t no?+ c be se51 h[ !n are we to "k t we are mov+8 ,inde$1 y\r gr&fa!rs us$ to be able to enjoy su* a tranquil locomotion4 ,i rememb] see+ 9 my *ildhood ! fly-boats1 z !y 7 call$1 on ! ,royal ,canal1 :]e9 pass5g]s 7 convey$ f ,dubl9 to ! ,we/ ( ,irel&1 be=e ! railway 0 made4 ,! fly-boat 0 a sort ( ,noah's ark 9 appe>ance1 drawn by a horse cant]+ along ! t[+-pa?4 ,9 ! cab9 ( su* a vessel1 :]e !re 0 n ! slighte/ motion ( roll+ or pit*+--no?+ b noiseless glid+ along ! canal--no "o w\ld be consci\s ( motion1 s long z he did n look ?r\gh ! cab9 w9d[s4 ,no "o 0 ev] seasick 9 a fly-boat2 x 0 ! p]fection ( travell+ = ^? :o lov$ ease & quiet4 ,! motion ( ! e>? r\nd its axis is1 s f>1 l t ( ! fly-boat4 ,x is s absolutely smoo? t we d n feel any?+1 & we only become consci\s ( x by look+ at outside objects4 ,^! are ! sun1 or ! moon1 or ! />s4 ,we see ^! bodies app>5tly go+ ?r\gh _! unv>y+ ris+ & sett+1 j z1 9 look+ out f ! fly-boat1 ! pass5g]s 9 t qua9t old conveyance c\ld see ! h\ses & trees z !y pass$4 ,see+ is believ+2 & ,i %\ld l "h1 9 ?is v !atre1 to %[ y t we are actually turn+ r\nd2 & ?is ,i am enabl$ to d by ! k9dness ( my di/+ui%$ fri5d1 ,pr(essor ,dew>4 ,illu/ration3 ,,fig4 #bb4--;,a ,p5dulum4 ,i am tempt$ to wi% t ,i _h ,aladd9's lamp = ! mom5t1 = ,i w\ld rub x1 & :5 ! great g5ie appe>$1 ,i w\ld bid him take ! ,royal ,in/itution1 & all ( u "h1 to a place :i* ev]ybody has he>d (1 & nobody has se5--,i mean ! ,nor? ,pole4 ,x w\ld be s easy to describe ! exp]im5t ,i am ab\t to %[ y1 !re4 ,x is n s easy "h4 ,b x w be suffici5tly accurate = our purpose to suppose t we actually h made ! voyage1 & t ?is is ! ,pole at ! c5tre ( ! lecture-table4 ,! direction ( ! axis r\nd :i* ! e>? is turn+ is a l9e po9t+ up /raight to ! ceil+4 ,?is lecture-table & all ! re/ ( ! !atre is go+ r\nd4 ,9 ab\t six h\rs x w h mov$ a qu>t] ( ! way1 & 9 tw5ty-f\r h\rs x w h gone completely r\nd4 ,t is1 at lea/1 :at w\ld happ5 if we 7 actually at ! ,pole4 ,z we are n !re1 = ! ,pole is _m miles away f ! ,royal ,in/itution1 ,i mu/ slightly modify ?is /atem5t1 & say t ! table "h takes m ?an tw5ty-f\r h\rs to g r\nd4 ,& n[ ,i want "s way ( prov+ t su* is actually ! case4 ,!re is no use 9 our m]ely look+ at x1 because we ourselves1 & ?is :ole build+1 & ! :ole ( ,london1 are all turn+ toge!r4 ,:at we want is some?+ :i* does n p>take ( ! motion4 ,"h is a heavy lead5 ball 7,fig4 #bb74 ,x is fa/5$ to ! ro( by a f9e /eel wire1 & y see x sw+s to & fro ) a delib]ate & graceful motion4 ,i want x to oscillate v /eadily1 s ,i draw x to "o side & tie x by a piece ( ?read to a support1 & !n ,i burn ! ?read1 & ! great ball beg9s to sw+ to & fro4 ,x w\ld cont9ue to d s = an h\r1 or inde$ = sev]al h\rs1 & x is a peculi>ity ( ?is motion t ! vibration always rema9s 9 ! same direction 9 space4 ,ev5 ! rotation ( ! e>? w n affect ! plane ( ?is great p5dulum1 s f> at lea/ z our exp]im5t is conc]n$4 ,"h1 !n1 we h a me?od ( te/+ my ass]tion ab\t ! turn+ r\nd ( ?is !atre4 ,i m>k a l9e on ! table1 directly und]nea? ! motion ( ! ball to & fro4 ,if we c\ld wait = an h\r or s1 we %\ld see t ! motion ( ! ball seem$ to h alt]$ to a direction incl9$ to its orig9al position1 b x is really ! table t has mov$1 = ! direction ( ! motion ( ! ball is unalt]$4 ,we _c1 h[ev]1 wait s long1 !re=e ,i %[ y ! +5i\s me?od :i* ,pr(essor ,dew> has devis$4 ,by a beam f ! electric light1 he has succe$$ 9 s magnify+ ! effect t ev5 9 a s+le m9ute x is q obvi\s t ! :ole ( ?is room is di/9ctly turn+ r\nd1 ) respect to ! oscillations ( ! p5dulum4 ,?is celebrat$ exp]im5t proves by actual inspection t ! e>? mu/ be rotat+4 ,by measur+ ! motion we might ev5 calculate ! l5g? ( ! day1 ?\gh ,i d n say x w\ld be an accurate me?od ( do+ s4 ,! prop] way ( f9d+ h[ long ! e>? takes to turn r\nd is by obs]v+ ! />s4 ,fix on any /> y please1 & note x 9 a c]ta9 position to-night2 if y !n obs]ve ! mom5t :5 ! /> is 9 ! same place to-morr[1 ! int]val ( "t t has elaps$ is ! true duration ( "o complete rotation4 ,:5 accurately measur$ its l5g? is f\nd to be #bc h\rs #ef m9utes #d seconds1 or ab\t f\r m9utes %ort] ?an ! ord9>y day1 measur$ f "o noon to ! next4 ,,annual ,,motion ,,( ,,! ,,e>? ,,r\nd ,,! ,,sun4 ,illu/ration3 ,,fig4 #bc4--,! ,*anges ( ! ,sun ) ! ,seasons4 ,i h z yet only be5 speak+ ( ! daily movem5ts by :i* ! sun appe>s to g across ! heav5s betwe5 morn+ & ev5+4 ,we next consid] ! annual movem5ts :i* give rise to ! *anges ( ! seasons4 ,x is n[ ,*ri/ma/ide1 :5 ! days are %ort & d>k1 :ile six mon?s ago ! days 7 long & glori\s 9 ! w>m? & brightness ( summ]4 ,a simil> recurr5ce ( ! seasons takes place e ye>1 & ?us we le>n t "s great *anges alt] ! relation betwe5 ! e>? & ! sun ye> aft] ye>4 ,we mu/ try & expla9 ?is4 ,:y is x t we enjoy w>m? at "o season1 & suff] f fro/ & sn[ at ano!r8 ,note fir/ a great diff]5ce betwe5 ! sun 9 summ] & ! sun 9 w9t]4 ,i w ask y to look out at noon any day :5 ! cl\ds are abs5t1 & y w !n f9d ! sun at ! highe/ po9t x rea*es dur+ ! day4 ,all ! morn+ ! sun has be5 gradually climb+ f ! ea/2 all ! aft]noon x w be gradually s9k+ d[n to ! we/4 ,let u make ! same obs]vation at diff]5t p>ts ( ! ye>4 ,suppose we take ! %orte/ day 9 ,decemb]4 ,y w look out ab\t twelve o'clock f "s situation :i* af=ds a view t[>ds ! s\?1 & !re1 z %[n 9 ! adjo9+ sket* 7,fig4 #bc71 is ! midw9t] sun4 ,b n[ ! spr+ approa*es1 & ! days beg9 to l5g!n4 ,if y wat* ! sun y w see x pass high] & high] e noon until ,midsumm] ,day is rea*$1 & !n ! sun at noon is f\nd q high up 9 ! sky4 ,z autumn draws ne>1 ! sun at noon creeps d[nw>ds aga9 until1 :5 ! next %orte/ day has come r\nd1 we f9d t x passes j :]e x did at ! previ\s midw9t]4 ,) unceas+ regul>ity ye> aft] ye> ! sun goes ?r\gh ^! *anges4 ,:5 he is high at noon we h days bo? long & w>m2 :5 he is l[ at noon we h days bo? %ort & cold4 ,vulcan ) 8 gold5 boat 0 naturally expect$ to give an explanation ( ?is4 ,z ! summ] drew on1 ea* day ,vulcan %ot out ! sun ) a /rong] impulse1 s t x %\ld asc5d high] & high]4 ,8 greate/ ef=t 0 made on ,midsumm] ,day1 :51 aft] r[+ b a little way r\nd f ! nor? t[>ds ! ea/1 he drove (f ! sun ) a t]rific ef=t4 ,! sun so>$ al(t to ! utmo/ height x c\ld rea*1 & 9 ! meantime ,vulcan return$ to ! we/ to be ready to cat* ! sun z x desc5d$4 ,on ! o!r h&1 9 midw9t]1 he came r\nd mu* fur!r ?r\gh ! ea/ to ! s\?1 & !n %ot up ! sun ) 8 feeble/ ef=t1 & _h to paddle z h>d z ev] he c\ld s z to complete 8 long return voyage dur+ ! brief day4 ,illu/ration3 ,,fig4 #bd4--;,h[ ! ,/>s are to be se5 9 broad ,daylight4 ,x is evid5t t !re are two q di/9ct k9ds ( motion ( ! sun4 ,!re is fir/ ! daily ris+ & sett+1 = :i* we h acc\nt$ by %[+ t x is m]ely an appe>ance produc$ by ! fact t ! e>? is turn+ r\nd4 ,b n[ we h be5 consid]+ q a diff]5t motion by :i* ! sun seems to creep up & d[n 9 ! heav5s1 & ?is takes a :ole ye> to g ?r\gh its *anges4 ,!re is /ill ano!r po9t :i* we mu/ consid] be=e we c und]/& all ^! puzzl+ movem5ts ( ! sun4 ,we %all ask ! />s to help u by _! famili> con/ellations4 ,y "k1 p]haps1 ! ,great ,be>1 or ! ,pl\gh z x is (t5 call$1 & ,orion4 ,!re are also ,aries ! ,ram1 ,taurus ! ,bull1 & o!r fancifully nam$ sy/ems4 ,^! con/ellations h be5 kn[n = c\ntless ages1 & = our pres5t purposes we may ?9k ( !m z p]man5t gr\ps 9 ! heav5s1 :i* d n alt] ei!r _! own %apes or _! positions relatively to ea* o!r4 ,^! gr\ps ( />s ext5d all ar\nd ! sky4 ,!y are n only ov] our heads & on all sides d[n to ! horizon1 b if we c\ld dig a deep hole ?r\gh ! e>?1 com+ out some:]e ne> ,new ,zeal&1 & if we !n look$ ?r\gh1 we %\ld see t !re 0 ano!r vault ( />s b5ea? u4 ,we /& on our comp>atively little e>? 9 :at seems ! c5tre ( ?is great univ]se ( />s all ar\nd4 ,x is true we d n (t5 see ! />s 9 broad daylight1 b !y are !re nev]!less4 ,! blaze ( sunlight makes !m invisible4 ,a good telescope w always %[ ! />s1 & ev5 )\t a telescope !y c sometimes be se5 9 daylight 9 r an odd way4 ,if y c obta9 a glimpse ( ! blue sky on a f9e day f ! bottom ( a coal pit1 />s are (t5 visible4 ,! top ( ! %aft is1 h[ev]1 g5]ally ob/ruct$ by ! ma*9]y = hoi/+ up ! coal1 b ! />s may be se5 occasionally ?r\gh ! tall *imney atta*$ to a manufactory :5 an opportune disuse ( ! *imney p]mits ( ! obs]vation be+ made 7,fig4 #bd74 ,! fact is t ! long tube has ! effect ( completely scre5+ f ! eye ! direct light ( ! sun4 ,! eye ?us becomes m s5sitive1 & ! feeble light f ! />s c make its impression1 & produce vision4 ,f all ^! v>i\s l9es ( reason+ we see t !re c be no d\bt ( ! cont9u\s pres5ce ( />s above & ar\nd u1 & bel[ u1 on e side1 & at all times4 ,illu/ration3 ,,fig4 #be4--,! ,sun seems to revolve ar\nd ! ,e>?4 ,if y look out at ,*ri/mas "t1 t[>ds ! s\?1 y w see ! ,belt ( ,orion & ! ,dog ,/> 9 a spl5did portion ( ! heav5s4 ,^! />s y w see e w9t] 9 ! same place4 ,b y may look 9 va9 = !m 9 summ]4 ,no d\bt y c see />s 9 ! summ] ev5+s1 b !y w be totally diff]5t f ^? t adorn$ ! skies 9 w9t]4 ,ea* season has its own con/ellations4 ,?is simple fact 0 kn[n to ! anci5ts1 & we %all f9d its explanation full ( mean+4 ,let u select f\r well-kn[n con/ellations :i* w be/ answ] our purpose4 ,!y lie 9 a circle r\nd ! heav5s4 ,!y are ,orion1 ,virgo1 ,scorpio1 & ,pisces4 ,i am suppos+ t y are look+ out at midnight t[>ds ! s\?4 ,9 ,decemb] y w see ,orion2 9 ,m>*1 ,virgo2 9 ,june1 ,scorpio2 & 9 ,septemb]1 ,pisces2 & !n next ,decemb] y w be look+ at ,orion aga94 ,see :at ?is proves4 ,at midnight1 ( c\rse1 ! sun is at ! o!r side ( ! e>?1 s t if ,i am look+ at ,orion 9 midw9t] ! sun mu/ be beh9d my back4 ,look at our little picture 7,fig4 #be74 ,! e>? is 9 ! middle1 & ! sun mu/ be on ! opposite side to ,orion4 ,t is1 ! sun mu/ be some:]e ab\t ! position ,i h m>k$ at ,a4 ,9 ,m>* we see ,virgo 9 ! s\? at midnight1 :51 ( c\rse1 ! sun is at ! o!r side ( ! e>?2 s t ! sun mu/ be some:]e at ,b4 ,9 ,june ,scorpio is se51 s t ! sun mu/ be at ! o!r side1 at ,c4 ,t is to say1 9 midsumm] ! sun is 9 t "p ( ! sky :]e ,orion is situat$4 ,if1 !re=e1 on a bright ,june day we c\ld see ! />s1 we %\ld f9d ,orion 9 ! s\?4 ,b1 ( c\rse1 ! light ( ! sun makes ,orion invisible4 ,we c1 h[ev]1 see ! />s by our telescopes1 & on r>e occasions an eclipse ( ! sun w occur1 by :i* he is tempor>ily ext+ui%$1 & !n we c see ! />s )\t ! help ( a telescope1 ev5 ?\gh x is daytime4 ,illu/ration3 ,,fig4 #bf4--,! ,e>?1 h[ev]1 really revolves ar\nd ! ,sun4 ,?us x w\ld seem z if ! sun 7 fir/ at ,a & !n at ,b1 ,c1 & ,d1 & !n began to g r\nd aga94 ,i say x w\ld seem z if ! sun _h ^! movem5ts1 & ! anci5ts ?\ght !re 0 no d\bt ab\t ! matt]4 ,ev5 aft] x 0 pla9 t ! e>? turn$ r\nd on its axis s z to give ! *anges ( day & night1 x 0 /ill ?\ght necess>y to suppose t ! sun w5t r\nd ! e>? once 9 ! ye>1 9 ord] to expla9 h[ ! *anges 9 ! />s dur+ ! diff]5t seasons 7 produc$4 ,"h is ano!r case 9 :i* we mu/ be c>eful to di/+ui% betwe5 :at appe>s to be true & :at is actually ! case4 ,ev]y?+ t we und\bt$ly see w\ld be j z well expla9$ by suppos+ t ! sun rema9$ at re/1 & t ! e>? revolv$ ar\nd x1 z 9 ,fig4 #bf4 ,if1 = in/ance1 ! e>? 7 at ,a 9 midw9t]1 !n ! sun is on ! opposite side to ,orion1 & ( c\rse at midnight we %all be able to see ,orion4 ,s 9 spr+ ! e>? is at ,b1 & we see ,virgo1 & simil>ly 9 summ] we h ,scorpio1 & 9 autumn ,pisces4 ,?us all t is actually visible c\ld be fully acc\nt$ = by reg>d+ ! sun z fix$ 9 ! c5tre1 & ! e>? z travell+ r\nd x f ,a to ,b1 to ,c & to ,d respectively1 & complet+ ! j\rney 9 a twelvemon?4 ,:i* idea are we to adopt8 ,%all we say t ! e>? goes r\nd ! sun1 or ! sun goes r\nd ! e>?8 ,i rememb] an old college /ory1 :i* ,i _c help giv+ y at ?is place4 ,x may s]ve to light5 :at ,i fe> y mu/ o!rwise h ?\ght r a t$i\s "p ( our subject4 ,!re 7 ?ree /ud5ts br\ght up = exam9ation 9 a/ronomy1 & !y %[$ a lam5table ignorance ( ! subject1 b ! exam9]1 be+ a k9d-he>t$ man1 wi%$1 if possible1 to pass !m2 & s he propos$ to ! ?ree y\?s ! v simple/ "q t he c\ld ?9k (4 ,accord+ly1 address+ ! fir/ /ud5t1 he said3 8,n[ tell me1 does ! e>? g r\nd ! sun1 or ! sun g r\nd ! e>?80 8,x is--! e>?--goes r\nd ! sun40 8,:at d y say80 he inquir$1 turn+ r sudd5ly on ! next1 :o gasp$ out3 8,oh1 sir--( c\rse--x is ! sun goes r\nd ! e>?40 8,:at d y say80 he %\t$ at ! ?ird unhappy victim4 8,oh1 sir1 x is--sometimes "o way1 sir1 & sometimes ! o!r60 ,b :i* is x8 ,well1 we mu/ rememb] t ! e>? is comp>atively a v little body & ! sun a v big "o1 s x is n at all surpris+ to le>n t ! e>? goes r\nd ! sun1 :i* rema9s1 practically speak+1 at re/ 9 ! c5tre4 ,?us our great e>? & all x conta9s are cont9ually b\nd 9 :at is v ne>ly a circul> c\rse r\nd ! great lum9>y4 ,y w f9d x in/ructive to "w out ?is little sum4 ,h[ fa/ is ! e>? mov+1 or h[ f> d we g 9 a second8 ,we are ab\t #ic1jjj1jjj miles f ! sun1 & ! great circle t we g r\nd has a diamet] twice z great z ?is--t is1 ab\t #ahf1jjj1jjj miles4 ,! circumf]5ce ( a circle is ne>ly ?ree & "o-sev5? times its diamet]1 & accord+ly ! :ole l5g? ( ! voyage 9 ! ye> is ab\t #ehe1jjj1jjj miles4 ,?is has to be accompli%$ 9 #cfe days1 s t ! daily run mu/ be ab\t #a1fjj1jjj miles4 ,we divide ?is by #bd1 to f9d ! di/ance j\rney$ ea* h\r1 :i* we f9d to be ab\t #fg1jjj miles2 & we mu/ divide ?is aga9 by #fj to f9d ! l5g? cov]$ 9 a m9ute1 & by #fj aga9 = ! progress made ea* second4 ,x is truly />tl+ to f9d t1 night & day1 ?is great e>? has to travel m ?an eighte5 miles e second 9 ord] to get r\nd its mighty pa? 9 ! allott$ "t4 ,i began ?is lecture ab\t =ty m9utes ago1 & ,i ?9k f :at ,i h said y w be able to calculate a result t w1 ,i d>e say1 a/oni% y4 ,9 ^! =ty m9utes we h mov$ ab\t #de1jjj miles4 ,no d\bt my lecture comm5c$ 9 ?is hall1 & 9 y\r pres5ce2 b c ,i truly say ,i began x "h8 ,well1 no2 ,i began x n "h1 b at a place #de1jjj miles away2 b we h all be5 travell+ toge!r1 & ! j\rney has be5 s v smoo? & free f all jolts1 t we nev] ?\ght any?+ ab\t ! motion4 ,i am sure _m ( ^? to :om ,i am n[ speak+ h read acc\nts ( voyages 9 ! ,arctic regions4 ,y h be5 told ( ! suff]+s ( ! crews dur+ ! long w9t]s1 amid ! ice & sn[2 & y h he>d h[1 dur+ t dismal p]iod1 !re is total d>kness1 = ! sun nev] rises = weeks & mon?s toge!r4 ,on ! o!r h&1 ^! nor!rn regions (t5 pres5t a m *e]ful picture4 ,dur+ midsumm]1 ! long d>kness ( w9t] is aton$ = by p]petual sun%9e4 ,at midnight !re is /ill ! full brilliance ( day1 & ! sun1 ?\gh l[1 no d\bt1 has n pass$ bel[ ! horizon4 ,ev5 9 ! nor!rly p>ts ( ,europe we c see ! midnight sun4 ,"l ,duff]91 9 8 delightful n>rative ( a cruise1 entitl$ 8,lett]s f ,high ,latitudes10 gives an int]e/+ illu/ration ( ! p]plexities aris+ f endless daylight4 ,x appe>s t ev]y?+ w5t on happily until ! fatal mom5t :5 ! ya*t cross$ ! ,arctic circle4 ,!n x 0 t dire tribulation arose among ! p\ltry4 ,a f9e cock 0 ! cause ( ! tr\ble4 ,kn[+ 8 duty1 he always lik$ to be p>ticul> ab\t p]=m+ ! important task ( cr[+ at sunrise4 ,?is he c\ld d regul>ly1 s long z ! ya*t rema9$ 9 reasonable latitudes1 :]e ! sun behav$ prop]ly4 ,b :5 !y cross$ ! ,arctic circle1 ! cock 0 confront$ ) a :olly new exp]i5ce4 ,! sun nev] set 9 ! ev5+1 & consequ5tly nev] _h to rise 9 ! morn+4 ,:at 0 ! di/ract$ bird to d8 ,he did ev]y?+4 ,he bur/ into occasional fits ( t]rific cr[+ at all sorts ( h\rs1 !n he gave up cr[+ altoge!r1 b f9d+ t did n m5d matt]s1 he took to cr[+ incessantly4 ,exhau/ion 0 succe$$ by delirium1 & r ?an live any long] 9 a univ]se :]e ! sun 0 capable ( pranks s he>tless1 ! indignant f[l flung himself f ! vessel & p]i%$ 9 ! ,arctic ,ocean4 ,,! ,,*anges ,,( ,,! ,,seasons4 ,illu/ration3 ,,fig4 #bg4--,! ,*anges ( ! ,seasons4 ,9 ! adjo9+ figure1 ,i %[ a little sket* 7,fig4 #bg71 by :i* ,i try to expla9 ! *anges ( ! seasons4 ,x exhibits f\r positions ( ! e>?1 "o on ea* side ( ! sun4 ,! left4 ,a1 repres5ts ! e>? :5 summ] gladd5s ! nor!rn hemisph]e2 :ile ! "r1 ,c1 %[s w9t] 9 ! same region4 ,y w see ! two c5tral l9es :i* repres5t ! axis ab\t :i* ! e>? rotates4 ,( c\rse1 ! e>? has no visible axis4 ,! l9e :i* runs ?r\gh ! globe f ! ,nor? to ! ,s\? ,pole is imag9>y4 ,x rema9s fix$ 9 ! e>?1 = we c prove 9 our obs]vatories t ! ,pole does n %ift its position to any consid]able ext5t 9 ! e>? itself4 ,9 fact1 if we c\ld rea* ! ,nor? ,pole & drive a peg into ! gr\nd ye> aft] ye> to m>k ! exact spot1 we %\ld f9d t ! position ( ! ,pole 0 s5sibly ! same4 ,does x n seem /range t we %\ld be able to "k s mu* ab\t ! ,pole1 ?\gh we h nev] be5 able to get !re2 h nev]1 9 fact1 be5 able to get )9 less ?an #djj miles ( x8 ,i ?9k y w be able to und]/& ! po9t q easily4 ,! latitude ( a place1 z y "k f y\r geography1 is ! numb] ( degrees1 & p>ts ( a degree1 betwe5 t place & ! equator4 ,9 our obs]vatories1 we c det]m9e ?is s accurately t ! diff]5ce betwe5 ! latitude ( "o side ( a room & ( ! o!r side ( ! same room is q p]ceptible4 ,z we f9d t ! latitudes ( our obs]vatories rema9 s5sibly un*ang$ f ye> to ye>1 we are c]ta9 t ! ,pole mu/ rema9 9 ! same place4 ,inde$1 if ! ,pole 7 to alt] its position by ! di/ance ( a /one's ?r[1 ! c>eful wat*]s 9 _m obs]vatories w\ld spe$ily detect ! occurr5ce4 ,& n[ ,i mu/ direct y\r att5tion to some?+ app>5tly q diff]5t4 ,:5 ! battle ( ,wat]loo 0 f\ght1 ! great victory 0 won ) ! aid ( ! old-fa%ion$ musket1 a smoo?-bore gun :i* 0 load$ at ! muzzle ) a good *>ge ( p[d]1 & !n a r\nd bullet 0 ramm$ d[n4 8,br[n ,bess10 z ! musket 0 call$1 0 a mo/ effici5t weapon at close qu>t]s1 & inde$ at any di/ance :5 ! bullet hit2 b !re 0 ! difficulty4 ,! r\nd bullets1 ru%+ up ! tube & out into ! air 9 a some:at vague mann]1 _h a habit ( roam+ ab\t1 :i* 0 q incompatible ) ! accurate %oot+ ( our mod]n rifles4 ,"o great improvem5t 9 small arms consi/$ 9 giv+ to ! bullet a rapid rotation ab\t an axis :i* is 9 ! l9e ( fire4 ,?is is :at ! rifle accompli%es4 ,! grooves 9 ! b>rel ( ! rifle twi/ r\nd1 & ?\gh !y only give half a complete turn 9 ! l5g? ( ! b>rel1 yet ! spe$ ( ! bullet is s great t :5 x flies (f x is actually sp9n+ ) ! trem5d\s velocity ( ab\t "o hundr$ & fifty revolutions a second4 ,ev5 ) ! old-fa%ion$ r\nd bullet1 ! rifl+ ( ! b>rel effect$ great improvem5t 9 ! accuracy ( ! %oot+4 ,! introduction ( ! elongat$ bullets 0 ano!r great improvem5t1 :ile ! adaptation ( bree*-load+ enabl$ a bullet to be us$ r l>g] ?an t :i* c\ld h be5 =c$ d[n ! b>rel1 & ?us x 0 insur$ t ! grooves %\ld bite into ! bullet z x hurries pa/ & imp>t ! necess>y sp94 ,a body rapidly rotat+ ab\t an axis has a t5d5cy to pres]ve ! direction ( t axis1 & p[]fully resi/s any attempt to *ange x4 ,our e>? is sp9n+ 9 ?is fa%ion4 ,x is true t ! rotation is1 9 "o s5se1 a sl[ "o1 = x requires almo/ an entire day = ea* rotation4 ,b :5 we rememb] ! dim5sions ( our e>?1 we %all modify ?is notion4 ,we h already /at$ t any place on ! equator has to travel m ?an "o ?\s& miles ea* h\r 9 ord] to accompli% ! j\rney )9 ! requir$ "t4 ,s f>1 !re=e1 ! e>? moves l a rifle-bullet1 & ! direction ( its axis rema9s con/ant4 ,9 ! c\rse ( ! great voyage betwe5 summ] & w9t]1 ! e>? travels f "o side ( ! sun to ! opposite side1 & 9 do+ s x /ill cont9ues to sp9 ab\t an axis p>allel to ! orig9al direction4 ,see ! consequ5ces :i* foll[4 ,! sun illum9ates half ! e>?1 & 9 ! left position 9 ,fig4 #bg1 repres5t+ summ]1 ! ,nor? ,pole is turn$ ov] t[>ds ! sun1 & lies 9 ! bright half ( ! e>?4 ,!re is cont9ual day at ! ,nor? ,pole1 & night is unkn[n !re at ?is "t ( ye>1 because ! turn+ ( ! e>? ab\t its axis w n br+ ! ,pole nor ! regions ne> ! ,pole into ! d>k hemisph]e4 ,?us x is t ! ,arctic regions enjoy p]petual day at ?is season4 ,look n[ at ! position ( ,engl& :5 ! nor!rn hemisph]e is tilt$ t[>ds ! sun1 & is consequ5tly enjoy+ ! full spl5dor ( midsumm]4 ,z ! e>? turns r\nd1 ,engl& w gradually cross ! b\nd>y betwe5 light & %ade1 & w ent] ^u ! d>k5$ hemisph]e4 ,!n !re w be night 9 ,engl&1 b y w see f ! figure t ! day is mu* long] ?an ! night1 & h5ce x is t we enjoy ! f9e long days 9 summ]4 ,we next look at a diff]5t sc5e six mon?s lat]4 ,! e>? has rea*$ ! o!r side ( ! sun1 b ! axis has rema9$ p>allel to itself1 consequ5tly ! ,nor? ,pole is n[ incl9$ entirely away f ! sun4 ,! e>? cont9ues to turn r\nd z be=e1 b its movem5ts d n br+ ! ,nor? ,pole or ! surr\nd+ ,arctic regions out ( ! d>k hemisph]e1 & consequ5tly ! night mu/ be unbrok5 9 ^! dismal circum/ances4 ,! long cont9u\s day :i* =ms ! ,pol> midsumm] is de>ly pur*as$ by ! gloom & cold ( a w9t] 9 :i* !re is no sun = _m weeks 9 succession4 ,obs]ve also ! *ang$ circum/ances ( ,engl&4 ,9 ! c\rse ( ea* tw5ty-f\r h\rs x lies mu* long] 9 ! d>k half ( ! e>? ?an 9 ! bright1 & consequ5tly !re is only a %ort day succe$$ by a long night4 ,,sun%9e ,,at ,,! ,,nor? ,,pole4 ,x is a privilege ( a/ronom]s to be able to pr$ict ev5ts t w happ5 9 ?\s&s ( ye>s to come1 & to describe ?+s accurately ?\gh !y nev] saw !m1 & ?\gh nobody else has ev] se5 !m ei!r4 ,no "o has ev] yet got to ! ,nor? ,pole1 b :5ev] !y d1 we are able to tell !m mu* ( :at !y w see !re4 ,we may leave x to ,jules ,v]ne to describe h[ ! j\rney is to be made1 & h[ ! p>ty are to be kept alive at ! ,nor? ,pole4 ,i %all give a picture ( ! *anges ( ! seasons1 & ( ! appe>ance 9 ! />s1 z se5 f !nce4 ,we %all1 !re=e1 prep>e to make obs]vations f t v p>ticul> spot on ?is e>?--! ,nor? ,pole4 ,i suppose t et]nal ice & sn[ abide !re4 ,i don't ?9k x w\ld be a pleasant resid5ce4 ,h[ev]1 we %all arrange to arrive on ,midsumm] ,day1 prep>$ to make a ye>'s soj\rn4 ,! fir/ "q to be settl$ is ! erection ( ! hut4 ,9 a cold c\ntry x is important to give ! "r aspect1 & we are 9 ! habit ( say+ t a s\!rly aspect is ! be/ & w>me/1 :ile ! nor? & ! ea/ are sugge/ive only ( *ills & discom=t4 ,b :at is a s\!rly aspect at ! ,nor? ,pole1 or1 r1 :at is n a s\!rly aspect8 ,:atev] way we look f ! ,nor? ,pole we are fac+ due s\?4 ,!re is no su* ?+ z ea/ or we/2 e way is ! s\?w>d way4 ,?is is truly an odd "p ( ! e>?4 ,! only o!r locality at all resembl+ x w\ld be ! ,s\? ,pole1 f :i* all directions w\ld be nor?4 ,! sun w\ld be mov+ all ?r\gh ! day 9 a fa%ion utt]ly unlike its behavior 9 our latitudes4 ,!re w\ld1 ( c\rse1 be no su* ?+ z ris+ & sett+4 ,! sun w\ld1 inde$1 at fir/ seem nei!r to g any ne>] to ! horizon nor to rise any high] above x1 b w\ld simply g r\nd & r\nd ! sky4 ,!n x w\ld gradually get l[] & l[]1 mov+ r\nd day aft] day 9 a sort ( spiral1 until at la/ x w\ld get d[n s l[ t x w\ld j graze ! horizon1 "r r\nd :i* x w\ld circulate till half ! sun 0 bel[1 & !n until ! :ole disk _h disappe>$4 ,ev5 ?\gh ! sun _h n[ vani%$1 a twilight gl[ w\ld = "s "t be cont9u\s4 ,x w\ld seem to come f a s\rce mov+ r\nd & r\nd bel[ ! horizon1 !n gradually ! light w\ld become fa9t] & fa9t] until at la/ ! w9t] ( utt] & cont9u\s blackness _h set 94 ,! fir/ indications ( ! return ( spr+ w\ld be detect$ by a feeble gl[ ne> ! horizon1 :i* w\ld seem to move r\nd & r\nd day aft] day4 ,!n ?is gl[ w\ld pass into a cont9u\s dawn1 gradually increas+ until ! sun's edge crept into visibility1 & ! great globe w\ld at la/ beg9 to climb ! heav5s by its cont9ual spiral until midsumm] 0 rea*$1 :5 ! *ange w\ld g on aga9 z be=e4 ,our fir/ excursion to ! c\ntry ( ,/>-l& has n[ be5 tak51 & we h naturally comm5c$ by /udy+ t sun to :i* we owe s mu*4 ,b we %all h to le>n t ?\gh our sun is ( su* vital importance to u1 yet1 9 magnific5ce & size1 he has _m rivals among ! ho/ ( />s4 ,,lecture ,,ii4 ,,! ,,moon4 ,! ,phases ( our ,att5dant1 ! ,moon--,! ,size ( ! ,moon--,h[ ,eclipses are produc$--,effect ( ! ,moon's ,di/ance on its ,appe>ance--,a ,talk ab\t ,telescopes--,h[ ! ,telescope aids u 9 ,view+ ! ,moon--,telescopic ,views ( ! ,lun> ,sc5]y--,on ! ,orig9 ( ! ,lun> ,crat]s--,! ,movem5ts ( ! ,moon--,on ! ,possibility ( ,life 9 ! ,moon4 ,,! ,,phases ,,( ,,our ,,att5dant1 ,,! ,,moon4 ,! fir/ day ( ! week is relat$ to ! greate/ body 9 ! heav5s--! sun--& accord+ly we call t day ,sun-day4 ,! second day ( ! week is simil>ly call$ aft] ! next mo/ important cele/ial body--! moon--& ?\gh we d n actually say ,moon-day1 we d say ,monday1 :i* is v ne>ly ! same4 ,9 ,fr5*1 too1 we h lune = moon1 & ,lundi signifies our ,monday4 ,! o!r days ( ! week also h names d]iv$ f ! heav5s1 b ( ^! we %all speak h]eaft]4 ,we are n[ go+ to talk ab\t ! moon4 ,we c divide ! objects 9 ?is room into two classes4 ,!re are ! bright faces 9 front ( me1 & !re are ! bright electric lights above4 ,! electric lights give light1 & ! faces receive x4 ,i c see bo? lights & faces2 b ,i see ! electric lamps by ! light :i* !y !mselves give4 ,i see ! faces by ! illum9ation :i* !y h receiv$ f ! electric lights4 ,?is is a v simple di/9ction1 b x is a v important "o 9 ,/>-l&4 ,among all ^! bodies :i* glitt] 9 ! heav5s !re are "s :i* %9e by _! own light1 l ! lamps4 ,!re are o!rs only brilliant by reflect$ light1 l ! faces4 ,x seems impossible = u to confuse ! brightness ( a pleasant face ) ! beam f a pretty lamp1 b x is (t5 n v easy to di/+ui% 9 ! heav5s betwe5 a body :i* %9es by its own light & a body :i* m]ely %9es by "s o!r light reflect$ f x4 ,i ?9k _m p w\ld make great mi/akes if ask$ to po9t out :i* objects on ! sky 7 really self-lum9\s & :i* objects 7 m]ely light$ up by o!r bodies4 ,a/ronom]s !mselves h be5 sometimes deceiv$ 9 ?is way4 ,! easie/ example we c give ( bodies s contra/$ is f\nd 9 ! case ( ! sun & ! moon4 ,( c\rse1 z we h already se51 ! sun is ! spl5did s\rce ( light :i* x scatt]s all ar\nd4 ,"s ( t light falls on our e>? to give u ! glories ( ! day2 "s ( ! sunbeams fall on ! moon1 & ?\gh ! moon has itself no m light ?an e>? or /ones1 yet :5 expos$ to a torr5t ( sunbeams1 %e enjoys a day z we d4 ,"o side ( h] is brilliantly light$2 & ?is x is :i* r5d]s our satellite visible4 ,h5ce we expla9 ! m>k$ contra/ betwe5 ! sun & ! moon4 ,! :ole ( ! sun is always bright2 :ile half ( ! moon is always 9 d>kness4 ,:5 ! bright side ( ! moon is turn$ directly t[>ds u1 !n1 no d\bt1 we see a complete circle1 & we say ! moon is full4 ,on o!r occasions a portion only ( ! bright surface is direct$ to u1 & ?us are produc$ ! beautiful cresc5ts & semicircles & o!r phases ( ! moon4 ,illu/ration3 ,,fig4 #bh4--,to %[ t ! ,moon is light$ by ,sunbeams4 ,a simple app>atus 7illu/rat$ 9 ,fig4 #bh7 w expla9 _! v>i\s appe>ances4 ,! l>ge india-rubb] ball !re %[n repres5ts ! moon1 :i* ,i %all illum9ate by a beam f ! electric light4 ,! side ( ! ball turn$ t[>ds ! light is gl[+ brilliantly1 & f ! "r side ( ! room y see ne>ly ! :ole ( ! bright side4 ,to y ! moon is ne>ly full4 ,f ! c5tre ( ! room y see ! moon l a semicircle1 & f ! left x appe>s a ?9 cresc5t ( light4 ,i alt] ! position ( ! ball ) respect to ! lamp1 & n[ y see ! phases are q *ang$4 ,to ^? on my left our mimic moon is n[ full2 to ^? on my "r ! moon is almo/ new1 or is visible ) only a sl5d] cresc5t4 ,f ! c5tre ( ! room ! qu>t] is visible z be=e4 ,we c also %[ ! same s]ies ( *anges by a little contrivance ( ,figs4 #bi & #cj4 ,?us e phase ( ! moon 7,fig4 #ca71 f ! ?9ne/ beautiful cresc5t ( light t y c j see l[ 9 ! we/ aft] sunset up to ! spl5dor ( ! full moon1 c be completely acc\nt$ = by ! diff]5t aspects ( a globe1 ( :i* "o-half is brilliantly illum9at$4 ,illu/ration3 ,,fig4 #bi4 ,,fig4 #cj4 ,! ,phases ( ! ,moon4 ,we c n[ expla9 a beautiful ph5om5on t y w see :5 ! moon is /ill q "y4 ,we fancifully describe ! old moon z ly+ 9 ! new moon's arms :5 we obs]ve ! fa9tly illum9at$ portion ( ! re/ ( t circle1 ( :i* a "p is ! brilliant cresc5t4 ,?is c only be expla9$ by %[+ h[ "s light has fall5 on ! %ad[$ side2 = no?+ :i* is n itself a s\rce ( light c ev] become visible unless illum9at$ by light f "s o!r body4 ,illu/ration3 ,,fig4 #ca4--,! ,*anges 9 ! ,moon4 ,let u suppose t !re is a man on ! moon :o is look+ at ! e>?4 ,to him ! e>? w appe> 9 ! same way z ! moon appe>s to u1 only v mu* l>g]4 ,at ! "t ( new moon ! bright side ( ! e>? w be turn$ directly t[>ds him1 s t ! man 9 ! moon w see an e>? ne>ly full1 & consequ5tly p\r+ =? a l>ge flood ( light4 ,?9k ( ! brighte/ ( all ! bright moonlight nights y h ev] se5 on e>?1 & !n ?9k ( a light :i* w\ld be produc$ if y _h ?irte5 moons1 all z big & z bright z our full moon1 %9+ toge!r4 ,h[ spl5did ! night w\ld !n be6 ,y w\ld be able to read a book q easily6 ,well1 t is ! sort ( illum9ation :i* ! lun> man w enjoy "u ^! circum/ances2 all ! features ( 8 c\ntry w be brightly light$ up by ! full e>?4 ,( c\rse1 ?is e>?-light$ side ( ! moon _c be comp>$ 9 brilliancy ) ! sun-light$ side1 b ! brightness w /ill be p]ceptible1 s t :5 f ! e>? we look at ! moon1 we see ?is gl[ di/ribut$ all ov] ! d>k portion2 t is1 we obs]ve ! feebly light$ globe clasp$ 9 ! brilliant arms ( ! cresc5t4 ,at a lat] phase ! d>k "p ( ! moon entirely ceases to be visible1 & ?is = a d\ble reason3 fir/ly1 ! bright side ( ! e>? is !n n s fully turn$ to ! moon1 & !re=e ! illum9ation x receives f e>?-%9e is n s great2 &1 secondly1 ! increas+ size ( ! sun-light$ "p ( ! moon has su* an augm5t$ gl[ t ! fa9t] light is ov]p[]$ by contra/4 ,y mu/ rememb] t m light does n always increase ! numb] ( ?+s t c be se54 ,x has sometimes ! opposite effect4 ,h we n already m5tion$ h[ ! brightness ( day makes ! />s invisible8 ,! moon h]self1 se5 9 full daylight1 seems no bright] ?an a small p>ticle ( :ite cl\d4 ,,! ,,size ,,( ,,! ,,moon4 ,x is n easy to answ] ! "q :i* ,i am sometimes ask$1 8,is ! moon v big80 ,i w\ld meet t "q by ano!r1 8,is a cat a big animal80 ,! fact is1 !re is no su* ?+ z absolute bigness or smallness4 ,! cat is no d\bt a small animal :5 comp>$ ) ! tig]1 b ,i ?9k a m\se w\ld probably tell y t ! cat 0 q a big animal--r too big1 inde$1 9 ! m\se's op9ion4 ,& ! tig] himself is small comp>$ ) an elephant1 :ile ! m\se is l>ge z comp>$ ) a fly4 ,:5 we talk ( ! bigness or ! smallness ( a body1 we mu/ always consid] :at we are go+ to comp>e x )4 ,x is natural 9 speak+ ( ! moon to comp>e x ) our own globe1 & !n we c say t ! moon is a small body4 ,! relative sizes ( ! e>? & ! moon may be illu/rat$ by objects ( v mu* small] dim5sions4 ,bo? a t5nis ball & a football are no d\bt famili> objects to ev]ybody4 ,if ! e>? be repres5t$ by ! football1 !n ! moon w\ld be ab\t z l>ge z ! lawn-t5nis ball4 ,b ?is proportion is n q accurate1 s ,i w sugge/ to y an in/ructive way ( mak+ a bett] pair ( models ( ! e>? & ! moon4 ,9 fact1 exp]im5ts some:at simil> to ^? ,i describe h be5 actually go+ on 9 e kit*5 9 ! l& dur+ ?is fe/ive season4 ,= h n globes & balls ( all sorts & sizes be5 made ( plum-pudd+1 & x w only require a little c>e on ! "p ( ! cook to make a pair ( lusci\s sph]es t %all fairly set =? ! sizes ( ! e>? & ! moon4 ,!re is fir/ to be a nice little r\nd plum-pudd+1 ?ree in*es 9 diamet]4 ,x is j a little bigg] ?an a cricket ball4 ,x %\ld1 h[ev]1 only make its appe>ance at a ba*elor's table4 ,7 x set d[n be=e a he>ty circle on ,*ri/mas ,day1 dire disappo9tm5t w\ld result4 ,"o boy ( s\nd con/itution c\ld eat x all4 ,p]haps x w\ld weigh ab\t ?ree-qu>t]s ( a p\nd4 ,?is little globe is to repres5t ! moon4 ,illu/ration3 ,,fig4 #cb4--,relative ,sizes ( ! ,e>? & ,moon4 ,ano!r plum-pudd+ is to be con/ruct$ :i* %all repres5t ! e>? 7,fig4 #cb74 ,we mu/1 h[ev]1 beg ! cook to obs]ve ! proportions4 ,! wid? ( ! e>?1 or ! diamet]1 to use ! prop] ^w1 is ab\t f\r times ! diamet] ( ! moon4 ,h5ce1 z ! small plum-pudd+ 0 ?ree in*es across1 ! l>ge "o mu/ h a diamet] ( twelve in*es4 ,?is w be a family pudd+ ( truly satisfactory dim5sions2 p]haps ! cook w be a little surpris$ to f9d ! al>m+ quantity ( mat]ials t w be requir$ to complete a sph]e ( plum-pudd+ a foot 9 diamet]4 ,^! models hav+ be5 duly made1 & boil$1 & plac$ on ! table1 we are n[ to propose ! foll[+ problem3-- 8,if "o s*oolboy c\ld eat ! small plum-pudd+1 h[ _m boys w\ld be requir$ to dispose ( ! l>ge "o80 ,! ha/y p]son1 :o does n reflect1 w at once da% out ! answ]1 8,f\r60 ,he w say1 8,x is q pla9 t1 s9ce "o ( ! pudd+s has f\r times ! diamet] ( ! o!r1 x mu/ be f\r times z big2 & !re=e1 z "o boy is able to eat ! small pudd+1 f\r boys w be adequate = ! l>ge "o40 ,b ! ha/y p]son w1 z usual1 be q wrong4 ,8 argum5t w\ld be s\nd if x 7 m]ely two pieces ( sug>-/ick t he 0 comp>+2 no d\bt !re is only f\r times z mu* mat]ial 9 a piece twelve in*es long z !re is 9 a piece ?ree in*es long4 ,b ! plum-pudd+s h bread? & dep?1 :i* are 9 ! same proportions z ! l5g?1 & ! consequ5ce is t ! l>ge plum-pudd+ is f> m ?an f\r times z big z ! small "o4 ,no f\r boys1 h[ev] admirable _! capacities1 w\ld be equal to ! task ( consum+ x4 ,nor ev5 if f\r m boys 7 call$ 9 to help w\ld ! di% be cle>$4 ,tw5ty boys1 =ty boys1 fifty boys w\ld n be en\gh4 ,x w\ld take sixty-f\r boys to demoli% ! magnific5t plum-pudd+ "o foot 9 diamet]4 ,if ! cook w try ! exp]im5t1 %e w f9d t by tak+ ! mat]ials suffici5t = sixty-f\r small plum-pudd+s all ( ! same size1 & mix+ !m toge!r1 %e w1 no d\bt1 make a l>ge plum-pudd+1 b its diamet] w only be f\r times t ( ! small pudd+s4 ,z a matt] ( fact1 ! moon is #bafj miles 9 diamet]1 & ! e>? is #giah miles4 ,^! numb]s are s ne>ly #bjjj & #hjjj respectively1 t = simplicity ,i h spok5 ( ! e>? z hav+ a diamet] f\r times z great z ! moon4 ,if we want to be v accurate1 we ought to det]m9e ! ratio ( ! two quantities f ! figures j giv54 ,our illu/ration ( ! plum-pudd+s mu/1 !re=e1 be a little modifi$4 ,! e>? is n q s mu* z sixty-f\r times z big z ! moon2 b ?is figure is suffici5tly accurate = our pres5t purpose4 ,ano!r int]e/+ "q may be propos$1 namely3 ,h[ mu* l& is !re on ! moon8 ,we might /ate ! answ] 9 acres or 9 squ>e miles2 b x w1 p]haps1 be m in/ructive to make a comp>ison betwe5 ! moon & ! e>?4 ,"h also ,i %all use an illu/ration2 & we %all aga9 consid] two globes :i* are respectively ?ree in*es & twelve in*es 9 diamet]4 ,! globes ,i use ?is "t are holl[ balls ( india-rubb]4 ,^! w repres5t ! e>? & ! moon ) suffici5t accuracy1 & ! relative surfaces ( ^! two globes is :at ,i want to f9d4 ,!re are diff]5t ways 9 :i* ! comp>ison might be made4 ,i might1 = in/ance1 pa9t ! two globes & see ! quantity ( pa9t t ea* requires4 ,if ,i did ?is1 ,i %\ld f9d t ! great globe took j sixte5 times z mu* pa9t z ! small "o4 ,we c adopt a simpl] plan4 ,! india-rubb] 9 "o ( ^! balls has ! same ?ickness z 9 ! o!r1 z !y are ea* holl[1 s t ! quantity :i* is requir$ = ea* ball may be tak5 to repres5t its surface4 ,by simply weigh+ ! two balls1 ,i p]ceive t ! l>ge "o is sixte5 times z heavy z ! small "o4 ,y notice "h ! diff]5ce betwe5 ! comp>ative weights ( two holl[ balls & two solid ones ( ! same mat]ial4 ,_h ^! globes be5 ( solid india-rubb]1 ! l>ge "o w\ld h weigh$ sixty-f\r times z mu* z ! small "o1 j z 9 ! case ( ! plum-pudd+s2 b be+ holl[1 ! ratio ( _! weights is only ! squ>e ( ! ratio ( _! diamet]s--t is to say1 f\r times f\r1 or sixte54 ,we are ?us taught t if ! moon 7 exactly "o-f\r? ( ! diamet] ( ! e>?1 its surface w\ld be "o-sixte5? "p ( t ( ! e>?4 ,x w\ld1 no d\bt1 h made our subject a little easi] & simpl] if ! moon _h be5 creat$ some:at small] ?an x is4 ,z1 h[ev]1 ! univ]se has n be5 solely con/ruct$ = ! purpose ( ^! talks ab\t ,/>-l&1 we mu/ take ?+s z we f9d !m4 ,?is proportion is n f\r2 x is m ne>ly #c1 & ! relative surfaces ( ! two bodies is ! squ>e ( #aa_/c1 or ab\t #ac4 ,9 o!r words1 ! entire ext5t ( ! surface ( our globe is ab\t ?irte5 & a half times t ( ! moon4 ,! face ( ! full moon1 be+ half ! entire ext5t ( ! surface1 is1 !re=e1 ab\t "o-tw5ty-sev5? "p ( ! e>?'s surface--cont95ts1 oceans1 seas1 & isl&s all tak5 toge!r4 ,! ,briti% ,empire & ! ,russian ,empire are ea* ( !m z l>ge z ! face ( ! full moon4 ,,h[ ,,eclipses ,,are ,,produc$4 ,! moon is ! att5dant1 or ! satellite ( ! e>?1 m9i/]+ to ! wants ( ! e>? by mitigat+ ! d>kness ( our nights4 ,! e>? goes ar\nd ! sun 9 its annual j\rney ( #cfe days4 ,! moon revolves ar\nd ! e>? once e tw5ty-sev5 days4 ,! motion ( ! moon is ?us a v complicat$ "o1 = x is1 9 fact1 mov+ r\nd a body :i* is itself 9 con/ant motion 7,fig4 #cc74 ,y w see by y\r almanacs e ye> t c]ta9 eclipses are to take place2 & aft] :at we h said ab\t ! sun & ! moon1 x w be easy to und]/& h[ eclipses arise4 ,!re are two diff]5t k9ds4 ,y w sometimes see an eclipse ( ! moon1 & sometimes ^? eclipses ( ! sun ( :i* we h spok5 9 ! la/ ,lecture4 ,y may be surpris$ to f9d ) :at accuracy ! eclipses c be pr$ict$4 ,we c tell n only ^? t w occur ?is ye> & next ye>1 b we c\ld also =etell ! eclipses t w appe> 9 a hundr$ or a ?\s& ye>s to come2 or we c1 ) equal ease1 calculate backw>ds1 s z to f9d ! circum/ances ( eclipses t happ5$ ?\s&s ( ye>s ago4 ,?is %[s h[ well we h le>n$ ! way ! moon moves4 ,illu/ration3 ,,fig4 #cc4--,to %[ h[ ! ,e>? goes r\nd ! ,sun & ! ,moon r\nd ! ,e>?4 ,illu/ration3 ,,fig4 #cd4--;,a ,total ,eclipse to ! ,girl & a ,p>tial ,eclipse to ! ,boy4 ,illu/ration3 ,p>tial4 ,annul>4 ,,fig4 #ce4--;,diff]5t ,k9ds ( ,sol> ,eclipse4 ,an eclipse ( ! sun is ! simpl] occurr5ce1 s we %all describe x fir/4 ,x happ5s :5 ! moon comes betwe5 ! e>? & ! sun4 ,look at our little a/ronom]s %[n 9 ,fig4 #cd4 ,a boy & a girl are bo? gaz+ at ! sun1 :5 ! moon comes betwe54 ,to ! boy ! moon appe>s to take a great bite out ( ! sun1 s t x looks l ! left-h& picture 9 ,fig4 #ce4 7,i h drawn a l9e f ! end ( ! telescope 9 ,fig4 #cd1 :i* %[s h[ mu* ( ! sun is cut (f47 ,?is w\ld be call$ a p>tial eclipse ( ! sun4 ,! almanac w sometimes describe ! eclipses z visible 9 ,london1 or visible at ,gre5wi*2 b t ne$ n be tak5 s lit]ally z 0 suppos$ by a ,k5s+ton g5tleman1 :o1 on notic+ t ! almanac said an eclipse 0 to be visible 9 ,london1 call$ a cab & drove into ! city to look = x4 ,8 almanac _h n m5tion$ t x w\ld be visible f 8 own h\se4 ,y may usually take = grant$ t :5 an eclipse is said to be visible f ,london or ,gre5wi*1 x w be m or less visible all ov] ,engl&4 ,mo/ ( ^! eclipses are only p>tial1 & ?\gh !y are int]e/+ to wat* !y d n tea* u mu*4 ,by f> ! mo/ wond]ful k9d ( eclipse is t 9 :i* ! :ole ( ! bright "p ( ! sun is blott$ out4 ,!n1 inde$1 we d see wond]s4 ,b su* eclipses are r>e1 & ev5 :5 !y d occur !y only la/ a v few m9utes4 ,! sights t are display$ are s int]e/+ t a/ronom]s (t5 travel ?\s&s ( miles to rea* a suitable locality = mak+ obs]vations4 ,! girl 9 ,fig4 #cd is plac$ 9 ! be/ possible position = see+ ! eclipse4 ,!re y f9d h] "r 9 ! l9e ( ! sun & moon2 & ,i ?9k y w agree t %e _c see any "p ( ! sun1 = ! moon is altoge!r 9 ! way4 ,i h drawn two dott$ l9es1 "o at ea* side4 ,all t %e c see beyond ! moon mu/ lie outside ^! dott$ l9es1 & %e w be 9 ! d>k z long z ! moon /ays 9 ! way4 ,:5 ! eclipse is complete1 comp>ative d>kness /eals ov] ! l&4 ,! birds are deceiv$1 & fly home to ! trees to roo/4 ,! owls & ! bats1 ?9k+ _! "t has arriv$1 v5ture =? on _! nocturnal bus9ess4 ,ev5 fl[]s close _! petals1 only to op5 a few m9utes lat] :5 ! sun aga9 bur/s =?4 ,o!r fl[]s t give =? _! fragrance at night are also sweetly p]ceptible s long z ! sun rema9s obscur$4 ,an unruly c[1 accu/om$ to break into a mead[ at night1 0 f\nd !re aft] an eclipse 0 ov]2 :ile ,i le>n f ! same au?ority t a man ru%$ ov] 9 great excitem5t to see :at 8 *ick5s 7 do+1 b came back mu* disappo9t$ on f9d+ !m peck+ away z if no?+ _h happ5$4 ,x w sometimes happ5 t ! moon is s plac$ t ! edge ( ! sun c be se5 all r\nd x4 ,a case ( ! k9d is %[n 9 ! "r-h& picture ( ,fig4 #ce4 ,x is call$ an annul>1 or r+-%ap$ eclipse4 ,! eclipses ( :i* we h be5 speak+ are1 ( c\rse1 only to be se5 dur+ ! day :5 ! sun mu/ be up4 ,! lun> eclipses1 :i* are visible at night1 are due to ! int]position ( ! e>? betwe5 ! sun & ! moon4 ,! sun is at night-"t "u our feet at ! o!r side ( ! e>?1 & ! e>? ?r[s a long %ad[ upw>ds4 ,if ! moon ent] into ?is %ad[1 x is pla9 t ! sunlight is p>tly or :olly cut (f1 & s9ce ! moon %9es by no light ( h] own1 b only by light borr[$ f ! sun1 x foll[s t :5 %e is buri$ 9 ! %ad[ all ! direct light is int]cept$1 & %e mu/ lose h] brilliancy4 ,?us we obta9 :at is call$ a lun> eclipse4 ,x is total if ! moon be entirely 9 ! %ad[4 ,! eclipse is p>tial if ! moon be only p>tly 9 ! %ad[4 ,! lun> eclipse is visible to ev]ybody on ! d>k hemisph]e ( ! e>? if ! cl\ds w keep out ( ! way1 s t usually a great _m m p c see a lun> eclipse ?an a sol> eclipse1 :i* is only visible f a limit$ "p ( ! e>?4 ,x ?us happ5s t ! lun> eclipse is ! m famili> spectacle ( ! two4 ,:5 ! moon is entirely 9 ! %ad[1 "o might naturally ?9k t x w\ld become totally invisible4 ,?is is n always ! case4 ,x is a curi\s fact t 9 ! dep? ( a total eclipse ! moon is (t5 /ill visible1 = %e gl[s ) a copp]-color$ light1 :i* is bright en\gh to r5d] "s ( ! *ief m>ks on h] surface di/9ctly disc]nible4 ,,effect ,,( ,,! ,,moon',s ,,di/ance ,,on ,,its ,,appe>ance4 ,we are n[ ab\t to take a good look at ! moon & exam9e ! diff]5t objects :i* are m>k$ ^u x4 ,!re is a peculi> int]e/ atta*$ to ?is p>ticul> orb1 because x is mu* ! ne>e/ ( all ! heav5ly bodies to our globe1 & !re=e ! "o t we c see ! be/4 ,e o!r object--sun1 />1 or planet--is hundr$s1 or p]haps ?\s&s1 ( times z f> (f z ! moon4 ,x is "r t we %\ld desire to le>n all we c ab\t ! bodies 9 space4 ,we "k t ! e>? is a great ball1 & we see t !re are _m o!r su* bodies4 ,"s ( !m are mu* l>g]1 & "s ( !m are small] ?an ! globe on :i* we dwell2 "s ( !m are d>k bodies l ! e>?1 & among !m ! moon is "o4 ,is x n reasonable t we %\ld make special ef=ts to f9d out all we c ab\t ?is int]e/+ neighbor8 ,?\gh ! moon is s close to u relatively to o!r objects 9 space1 yet :5 we express its di/ance 9 ! ord9>y me?ods ( measurem5t x is a v long way (f--ab\t #bdj1jjj miles--a l5g? ne>ly z great z t ( all ! railways 9 ! _w put toge!r4 ,an express tra9 :i* runs =ty miles an h\r w\ld travel #bdj miles 9 six h\rs1 & ! :ole di/ance to ! moon w\ld be accompli%$ 9 #fjjj h\rs1 s t travell+ by night & day incessantly y w\ld accompli% ! j\rney 9 #bej days4 ,to take ano!r illu/ration1 if y wrapp$ a ?read t5 times r\nd ! equator ( ! e>?1 x w\ld be long en\gh to /ret* f ! e>? to ! moon4 ,or suppose a cannon c\ld be made suffici5tly /rong to be fir$ ) a report l\d en\gh to be audible #bdj1jjj miles away4 ,! s\nd w\ld only be he>d at t di/ance a =tnight aft] ! dis*>ge _h tak5 place4 ,! moon is too f> = u to exam9e ! p>ticul> features on its surface by ! unaid$ eye4 ,suppose t !re 0 a mighty city l ,london on ! moon1 ) great build+s & teem+ millions ( p1 & y w5t out on a f9e night to take a look at our neighbor4 ,:at d y ?9k y w\ld be able to see ( ! great lun> metropolis8 ,w\ld y be able to see its /reets full ( omnibuses1 or ev5 its great build+s8 ,w\ld y see ,/4 ,paul's & ,we/m9/]--! great p>ks & ! riv]8 ,( all ^! ?+s y\r unaid$ eye w\ld %[ y almo/ no?+4 ,i c give y a little illu/ration4 ,suppose t y made a t9y model ( ,london2 imag9e ?is little /ructure all complete1 s t ! /reets1 ! build+s1 ! bridges1 ! railways1 ! p>ks1 & ! ,?ames 7 plac$ 9 _! true proportions2 suppose t ! m9iature city 0 s small t x c\ld /& on a p5ny po/age /amp1 surely ev]y?+ w\ld look v insignificant1 ev5 if y _h ! model 9 y\r h& & look$ at x ) ! aid ( a magnify+ glass4 ,b suppose x 7 put on ! o!r side ( ! table or on ! o!r side ( ! room1 or ! o!r side ( ! /reet4 ,ev5 ,/4 ,paul's ,ca!dral itself w\ld h ceas$ to be di/+ui%able2 b yet ! di/ance is n ne>ly great en\gh4 ,y w\ld h to put ! little model a qu>t] ( a mile away be=e x w\ld be 9 ! "r position to illu/rate ! appe>ance ( a lun> ,london to ! unaid$ eye4 ,a ,,talk ,,ab\t ,,telescopes4 ,! a/ronom] w n be cont5t$ ) a m]e nak$-eye inspection ( a _w s int]e/+ z ! moon4 ,he w get a telescope to help 8 vision4 ,! ^w 8telescope0 means a contrivance = look+ at objects :i* are a long way (f4 ,we h expla9$ t ! fur!r an object is1 ! small] x appe>s to be4 ,! telescope enables u to l>gely ov]come ?is inconv5i5ce4 ,x has ! effect ( mak+ a di/ant object look l>g]4 ,!re are great diff]5ces 9 ! =ms ( telescopes2 & "s in/rum5ts are l>ge & "s small1 accord+ to ! purposes = :i* !y are requir$4 ,p]haps ! mo/ useful practical application ( ! telescope is by ! (fic] on duty on bo>d a %ip4 ,he is g5]ally provid$ ) a pair ( ^! in/rum5ts b\nd toge!r to =m ! 8b9ocul>40 ,y are all acqua9t$ ) ?is useful contrivance1 or at all ev5ts ) ! op]a-glass1 t is us$ = purposes ) :i* l&sm5 are m famili>4 ,! %ip's telescope1 or ! b9ocul>1 or ! op]a-glass1 is feeble 9 p[] :5 comp>$ ) ! great in/rum5ts ( ! ,obs]vatory4 ,! (fic] on ! %ip w g5]ally be satisfi$ ) a telescope :i* %all %[ ! objects ) :i* he is conc]n$ at ab\t "o-?ird ( _! actual di/ance4 ,?us1 suppose 8 att5tion is direct$ to a great /eam] ?ree miles away1 he wi%es to see h] m cle>ly1 & accord+ly he takes a view ?r\gh 8 b9ocul>4 ,imm$iately ! vessel is s trans=m$ t x seems to be only "o mile away4 ,! app>5t dim5sions ( ! object are increas$ ?reefold4 ,! hull is ?ree times z long1 ! ma/s & ! funnel are ?ree times z high1 ! sailors are ?ree times z tall2 v>i\s objects on ! %ip too small to be se5 at ?ree miles w\ld be visible f "o mile1 & to t app>5t di/ance ! %ip has n[ be5 br\ght4 ,if ! sailor desires to r$uce ! app>5t di/ance ( objects1 h[ mu* m ke5ly does ! a/ronom] feel ! same want8 ,at be/1 ! sailor only has to scan a range ( a few miles ) 8 glass1 b :at are a few miles to ! a/ronom]8 ,x is true t he c c\nt ! di/ance ( ! moon by ?\s&s ( miles1 a good _m ?\s&s1 no d\bt1 b = all o!r objects he mu/ use millions1 :ile = mo/ bodies 9 space1 millions ( millions ( miles are ! figures we are con/ra9$ to employ4 ,ne$ x be said t ! a/ronom] mu/ resort to e device he c to make ! body appe> clos]4 ,he does n despise ! mode/ b9ocul>4 ,x is (t5 a useful in/rum5t 9 ! ,obs]vatory4 ,x gives mo/ beautiful pictures ( ! cele/ial sc5]y1 & y w\ld be amaz$ to f9d h[ _m ?\s&s ( />s y c see ) its help :i* y\r unaid$ eye w\ld n %[ y at all4 ,! b9ocul> w also greatly improve ! appe>ance ( ! moon1 b /ill its p[]s fall f> %ort ( :at we require = ! /udy ( lun> l&scapes4 ,ev5 ?\gh we c r$uce ! moon's app>5t di/ance to "o-?ird its actual am\nt1 yet /ill t ?ird is a v consid]able di/ance4 ,"o-?ird ( #bdj1jjj is #hj1jjj1 s t we c see ! moon no bett] ) a b9ocul> ?an we %\ld see x 7 x #hj1jjj miles away1 & 7 we view+ x ) ! unaid$ eye4 ,illu/ration3 ,,fig4 #cf4--,! ,dome at ,duns9k ,obs]vatory4 ,illu/ration3 ,,fig4 #cg4--,! ,equatorial at ,duns9k ,obs]vatory4 ,i am n go+ to ent] "h ^u any detail$ acc\nt ( ! telescope1 because ,i %all say a little m on ! subject 9 a lat] lecture2 at pres5t ,i only describe t =m ( in/rum5t :i* is mo/ conv5i5t = /udy+ ! moon4 ,i take z an illu/ration ! ,s\? ,equatorial at ,duns9k ,obs]vatory1 :i* belongs to ,tr9ity ,college1 ,dubl94 ,?is telescope has a build+ to itself1 :i* /&s on ! lawn 9 front ( ! h\se4 ,! site is op5 & elevat$1 s z to comm& an ext5sive prospect ( ! heav5s4 ,y w see 9 ,fig4 #cf a picture ( ! /ructure4 ,x is circul> 9 =m & is ent]$ by ! little por*4 ,! mo/ peculi> feature ( an edifice int5d$ to conta9 ?is k9d ( telescope is its ro(1 or ,dome1 z we call x4 ,x is ( a hemisph]ical %ape ) a project+ rim at ! bottom4 ,b no "o w\ld g to ! tr\ble & exp5se ( mak+ a r\nd dome l t ov] ! ,obs]vatory if x 7 n necess>y = a p>ticul> purpose4 ,! dome is v unlike ord9>y ro(s1 n only 9 appe>ance1 b also because x c turn r\nd4 ,9 ! next figure y w see a section ?r\gh ! build+1 & ! :eels are expos$ by :i* ! dome is c>ri$4 ,^! :eels run easily on rails1 s t :5 ! att5dant pulls ! rope :i* y see 9 8 h&s1 he turns r\nd a l>ge pulley1 & t op]ates a little cog:eel :i* works into a rack1 & ?us makes ! dome revolve4 ,! ro( is built ( timb]1 cov]$ ) copp]2 x weighs m ?an six tons1 b ! ma*9]y is s nicely adju/$1 t a *ild f\r ye>s old c easily set ! :ole 9 motion4 ,! object ( all ?is ma*9]y is se5 :5 we le>n t !re is only "o op5+ 9 ! dome4 ,x is cov]$ by ! %utt] %[n ov] ! doorway 9 ,fig4 #cf4 ,:5 op5$ to ! top1 x gives a long & wide ap]ture1 ?r\gh :i* ! a/ronom] c look out at ! heav5s4 ,( c\rse ! dome has to be turn$ until ! op5+ has be5 br\ght to face ! requir$ aspect4 ,! big telescope c ?us be direct$ to any object above ! horizon4 ,y see a g5tleman us+ ! telescope 7,fig4 #cg71 & ?is %[s t ! great in/rum5t is ne>ly ?ree times z long z ! a/ronom] himself6 ,no d\bt ! telescope seems to be compos$ ( a good _m diff]5t p>ts1 b ! ess5tial portions ( ! in/rum5t are comp>atively few & simple4 ,at ! upp] end is ! object glass1 :i* consi/s ( two l5ses1 "o ( fl9t glass & ! o!r ( cr[n glass4 ,bo? ( ^! mu/ be ( exceptional purity1 & ! %ape to be giv5 to ! l5ses is a matt] ( ! utmo/ importance4 ,x is 9 ! mak+ ( ?is pair ( glasses t ! skill ( ! optician has to be specially put =?4 ,s valuable inde$ is an object glass :i* fulfils all ! requirem5ts1 t x is by f> ! mo/ co/ly "p ( ! in/rum5t4 ,!re are no glasses 9 ! int]ior ( ! tube until y come to ! end :]e ! obs]v] is look+ 94 ,?is is clos$ by an eyepiece consi/+ ( a l5s1 or a pair ( l5ses4 ,!re are usually _m diff]5t eyepieces = a telescope1 & !y conta9 l5ses ( v>i$ p[]s1 to be us$ accord+ to ! /ate ( ! atmosph]e1 or to ! p>ticul> k9ds ( obs]vation 9 progress4 ,if y po9t a big telescope to ! sky1 & see !re9 ! sun or ! moon or any ( ! />s1 y w spe$ily f9d t ! objects pass away out ( view4 ,rememb] our e>? is con/antly turn+ r\nd1 & be>s1 ( c\rse1 ! ,obs]vatory ) x1 s t ?\gh ! telescope be rightly po9t$ to ! heav5s at "o mom5t1 by ! next x w h be5 turn$ aside4 ,to y :o are us+ ! telescope1 ! appe>ance produc$ is z if ! heav5ly bodies 7 !mselves mov+4 ,we c c\nt]act ?is inconv5i5ce4 ,! telescope is support$ on a p$e/al1 :i* is built on masonry1 t goes d[n ?r\gh ! floor to its f\ndation on ! solid rock b5ea?4 ,9 ! iron cas+ at ! top ( ! p$e/al y w see a little w9d[1 & inside is clockwork driv5 by a heavy weight4 ,?is clockwork turns ! :ole telescope r\nd 9 ! opposite direction to t 9 :i* ! e>? is mov+4 ,! consequ5ce is t ! telescope rema9s con/antly po9t$ to ! same "p ( ! heav5s4 ,illu/ration3 ,,fig4 #ch4--,! ,y]kes ,telescope1 ,univ]sity ( ,*icago4 ,?is in/rum5t is no d\bt a l>ge "o1 b ( late ye>s _m mu* great] h be5 built4 ,! mo/ p[]ful telescope t has ev] be5 erect$ is ! great ,y]kes in/rum5t belong+ to ! ,univ]sity ( ,*icago1 ( :i* a picture is %[n 9 ,fig4 #ch4 ,! object glass is #dj in*es across4 ,,h[ ,,! ,,telescope ,,aids ,,u ,,9 ,,view+ ,,! ,,moon4 ,^? :o are 9 *>ge ( an obs]vatory are (t5 visit$ by p]sons :o1 com+ to see ! wond]s ( ! heav5s1 & f9d+ in/rum5ts ( su* great proportions1 n unnaturally expect ! views !y are to obta9 ( ! cele/ial bodies %all be ( correspond+ magnific5ce4 ,s !y are1 no d\bt1 b !n x frequ5tly happ5s t ! pictures :i* ev5 ! greate/ telescope c display w fall f> %ort ( ! ideal pictures :i* ! visitors h conjur$ up 9 _! own imag9ations1 s t !y are (t5 sadly disappo9t$4 ,especially is ?is true ) reg>d to ! moon4 ,i h se5 p :o1 :5 !y _h a view ( ! moon ?r\gh a great telescope1 7 surpris$ n to f9d va/ ranges ( m\nta9s :i* look$ to !m z big z ! ,alps1 or mighty des]ts1 ov] :i* ! eye c\ld roam = ?\s&s ( miles4 ,!y h sometimes expect$ to behold /up5d\s volcanoes t n only 71 b t look$ to be z big z ,vesuvius4 ,o!rs seem to h ?\ght !y ought to see ! moon ) su* cle>ness t ! fields 7 to be q visible1 & "s w\ld n h be5 mu* a/oni%$ if !y _h obs]v$ h\ses & f>my>ds1 &1 p]haps1 ev5 cocks & h5s4 ,!re are diff]5t ways ( e/imat+ ! app>5t dim5sions ( an object1 b ! size ! moon appe>s to me to h 9 a great telescope may be illu/rat$ by tak+ an orange 9 y\r h& & look+ at ! innum]able little m>ks & spots on its surface4 ,! am\nt ( detail t ! eye w %[ on ! orange is ab\t equal to ! am\nt ( detail t a good telescope w %[ on ! moon4 ,a des]t on ! moon1 :i* really is a hundr$ miles across1 w !n correspond to a m>k ab\t an eigh? ( an in* 9 diamet] on ! orange4 ,"s ( y may ask :at is ga9$ by ! use ( a telescope1 = ! moon looks to u z l>ge z a plate ) ! unaid$ eye1 & n[ we he> x only looks z big z an orange 9 ! telescope4 ,b :]e is ! plate ) :i* y comp>e y\r moon suppos$ to be held8 ,x is surely n 9 y\r h&4 ,x is imag9$ to be up 9 ! sky1 a v long way (f4 ,?\gh an orange is mu* small] ?an a plate1 yet y w be able to see _m m details 9 ! orange by tak+ x 9 y\r h& ?an y c\ld see on a plate :i* 0 at ! o!r side ( ! /reet4 ,illu/ration3 ,,fig4 #ci4--,! ,advantage ( us+ a ,telescope4 ,i sometimes f9d t p w n believe h[ mu* ! telescope t !y are us+ is magnify+ ! moon until !y use bo? eyes toge!r1 ( :i* "o is appli$ to ! telescope1 :ile ! o!r is direct$ to ! moon4 ,x w !n be se51 ev5 ) a v small in/rum5t1 t ! telescopic moon is z big z ! l>g] ( ! two cresc5ts 9 ! adjo9+ figure 7,fig4 #ci71 :ile ! nak$-eye moon is l ! small]4 ,! greate/ telescopes are capable ( r$uc+ ! app>5t di/ance ( an object to ab\t "o-?\s&? "p ( its actual am\nt4 ,if1 !re=e1 a body 7 a ?\s& miles away1 x w\ld1 :5 view$ by "o ( ^! mighty in/rum5ts1 be se5 z l>ge z our unaid$ vision w\ld %[ x1 7 ! body only a s+le mile di/ant4 ,no d\bt ?is is a l>ge accession to our p[]1 b x (t5 falls f> %ort ( :at ! a/ronom] w\ld desire4 ,! di/ances ( ! />s are all s great t ev5 :5 divid$ by "o ?\s&1 !y are /ill enorm\s4 ,if y h a numb] express$ by #ajj1jjj1jjj1jjj1jjj1 !n divid+ x by a ?\s& m]ely means tak+ (f ?ree ( ! ciph]s1 & !re is /ill a l>ge numb] left4 ,we are1 h[ev]1 at pres5t conc]n$ ) ! moon1 &1 z its di/ance is ab\t #bdj1jjj miles1 ! effect ( ! be/ telescope is to r$uce ?is di/ance app>5tly to #bdj miles4 ,"h1 !n1 we f9d a limit to :at ! be/ ( all telescopes c d4 ,x c nev] %[ u ! moon bett] ?an1 h>dly inde$ s well z1 we c\ld see x ) our unaid$ eye 7 x only #bdj miles ov] our heads4 ,we _c expect ! mo/ p[]ful in/rum5ts to reveal any object on ! moon unless t object 7 big en\gh to be se5 by ! unaid$ eye :5 #bdj miles away4 ,:at c\ld we expect to see at a di/ance ( #bdj miles8 ,"h is a little exp]im5t :i* ,i made to /udy ?is po9t4 ,i m>k$ a r\nd black dot on a %eet ( :ite pap]4 ,! dot 0 a qu>t] ( an in* 9 diamet]1 & !n ,i fa/5$ ?is on a door 9 ! g>d51 & walk$ backw>ds until ! dot ceas$ to be visible4 ,i f\nd ?is di/ance to be ab\t ?irty-six y>ds4 ,i tri$ a little boy ( eight ye>s old1 & x appe>$ t ! dot became invisible to him ab\t ! same "t z x did to me4 8,:at has ?is to d ) ! moon80 y w say4 ,well1 we %all soon see4 ,9 ?irty-six y>ds !re are #eahd qu>t]s ( an in*1 & z x is unnecess>y to be v p>ticul> ab\t ! figures1 we may say1 9 r\nd numb]s1 t ! di/ance :5 we ceas$ to be able to di/+ui% ! dot 0 ab\t five ?\s& times z great z ! wid? ( ! dot itself4 ,y ne$ n1 !re=e1 expect to see any?+ on ! moon or on any?+ else :i* is n at lea/ z wide z ! five-?\s&? "p ( ! di/ance f :i* we are view+ x4 ,! great telescope practically places ! moon at a di/ance ( #bdj miles1 & ! five-?\s&? "p ( t is ab\t eighty y>ds2 consequ5tly a r\nd object on ! moon ab\t eighty y>ds 9 diamet] w\ld be j glimps$ z ! m]e/ dot 9 ! mo/ p[]ful telescope4 ,to attract att5tion1 a lun> object %\ld be mu* l>g] ?an ?is4 ,if ,/4 ,paul's ,ca!dral /ood on a lun> pla91 x w\ld be visible 9 our great telescopes4 ,x is true t we c\ld n see any details4 ,we %\ld n be able to di/+ui% betwe5 a ,ca!dral & a ,t[n-hall4 ,!re w\ld j be some?+ visible1 s t ! arti/ :o 0 mak+ a sket* ( t "p w\ld put d[n a m>k ) 8 p5cil to %[ t some?+ 0 !re4 ,?is w %[ u t we ne$ n expect to see objects on ! moon1 ev5 ) ! mightie/ ( telescopes1 unless !y are ( great size4 ,,telescopic ,,views ,,( ,,lun> ,,sc5]y4 ,i h already w>n$ y n to expect too mu*1 ev5 ) ! bigge/ ( telescopes2 & j z a caution1 ,i may1 p]haps1 tell y a /ory ,i once he>d ( an a/ronom] :o _h a great telescope4 ,x 0 a v fam\s in/rum5t1 & p (t5 came to ! ,obs]vatory at night to enjoy a look at ! heav5s4 ,sometimes ^! visitors 7 grave philosoph]s1 b frequ5tly !y 7 n v accompli%$ m5 ( sci5ce4 ,"o ev5+ su* a visitor came to ! ,obs]vatory1 & s5t 9 8 "n & an introduction to ! a/ronom]1 ) a reque/ t he might ent] ! temple ( my/]y4 ,! a/ronom] c\rte\sly welcom$ ! /rang]1 & ask$ him :at he specially desir$ to see4 8,oh60 said ! visitor1 8,i h specially come to see ! moon--t is ! object ,i am p>ticul>ly int]e/$ ab\t40 8,b10 said ! a/ronom]1 8my de> sir1 ,i w\ld %[ y ! moon ) pleasure1 if y 7 "h at ! prop] "t2 b :at br+s y "h n[8 ,look up2 ! ev5+ is f9e4 ,!re are ! />s %9+ brightly1 b :]e is ! moon8 ,y see x is n up at pres5t4 ,9 fact1 x won't rise till ab\t half-pa/ two to-morr[ morn+1 & x is only n9e o'clock n[4 ,come back aga9 9 five or six h\rs1 & y %all obs]ve ! moon ) ! great telescope40 ,b ! visitor evid5tly ?\ght ! a/ronom] 0 m]ely try+ to get rid ( him by a pretext4 ,& he 0 equal to ! occasion--he 0 n go+ to be put (f 9 t way4 8,( c\rse1 ! moon is n up10 he repli$2 8any "o c see t1 & t is ! reason :y ,i h come1 = if ! moon _h be5 up1 ,i c\ld h se5 x )\t y\r telescope at all60 ,al?\gh no explor] c ev] rea* our satellite1 yet x is h>dly an exagg]ation to say t 9 "s respects we "k ! geography ( ! moon a good deal bett] ?an we "k ! geography ( ! e>?4 ,?9k ( ! cont95t ( ,africa4 ,9 t great c\ntry !re are mighty tracts1 !re are va/ lakes & ranges ( m\nta9s1 ( :i* we "k b little4 ,we c\ld make a bett] map ( ,africa1 s f> at lea/ z its broad outl9es are conc]n$1 if x 7 fa/5$ up on our side ( ! moon ?an we actually possess at ?is mom5t4 ,!re is no spot on ! ne>] side ( ! moon z l>ge z an ord9>y p>i% 9 ?is c\ntry :i* has n be5 survey$4 ,!re are maps & *>ts ( ! moon %[+ e "p ( x1 :i* is z big z a good-siz$ field4 ,inde$1 z !re are no lun> cl\ds1 ! features ( its surface are nev] obscur$ :5ev] our own atmosph]e w p]mit u to make our obs]vation4 ,arti/s h frequ5tly sket*$ ! lun> features1 & !re is pl5ty ( mat]ial = !m to "w on4 ,we h also _h photographs tak5 ( ! moon1 b !re is a special difficulty to be enc\nt]$ 9 tak+ photographs ( cele/ial bodies :i* photograph]s ( famili> objects on ?is e>? d n exp]i5ce4 ,= a photograph to be successful1 ev]ybody kn[s t ! fir/ requisite is = ! sitt] to /ay quiet :ile ! plate is be+ expos$4 ,?is is1 unhappily1 j :at ! moon _c d4 ,we endeavor to obviate ! difficulty by mov+ ! telescope r\nd s z to foll[ ! moon 9 its progress4 ,?is c be done ) consid]able accuracy1 b1 un=tunately1 !re is ano!r difficulty :i* lies entirely beyond our control4 ,z ! rays ( light f ! moon p]=m _! j\rney ?r\gh hundr$s ( miles ( un/eady air1 ! rays are b5t hi!r & ?i!r1 s t ! picture is m affect$ by ! atmosph]e ?an 9 ! case ( a photograph]'s portrait tak5 9 ! /udio4 ,if we are m]ely view+ ! moon ?r\gh ! telescope1 ! quiv]+ effect on ! rays ( ?is long atmosph]ic voyage1 ?\gh r inconv5i5t1 does n prev5t u f see+ ! object1 & we c readily detect ! true %ape ( ea* feature 9 spite ( incessant fluctuations4 ,:51 h[ev]1 ^! rays fall n on ! eye1 b on ! photographic plate1 !y produce by _! motion a picture :i* _c be mu* magnifi$ )\t becom+ v confus$ & want+ 9 %>pness4 ,nev]!less1 = ! g5]al outl9es ( our satellite's appe>ance & = ! portraiture ( its spl5did features we h d]iv$ ! greate/ assi/ance f photography4 ,illu/ration3 ,,fig4 #dj4--,! ,full ,moon4 ,! adjo9+ picture 7,fig4 #dj7 gives a fair idea ( :at ! full moon looks l :5 view$ ?r\gh a small telescope4 ,i d n1 h[ev]1 say t ! lun> objects c !n be obs]v$ "u favorable conditions2 = :5 ! moon is full is ! v wor/ "t = mak+ obs]vations ( our satellite4 ,9 fact1 at ?is phase y c h>dly see any?+ except slight diff]5ces betwe5 ! colors ( diff]5t p>ts4 ,! be/ "t = obs]v+ ! moon is at ! fir/ qu>t]2 b ev5 !n y c only obs]ve satisfactorily ^? objects :i* happ5 to lie along ! bord] betwe5 light & %ade4 ,to /udy ! moon prop]ly y mu/1 !re=e1 wat* x dur+ sev]al diff]5t phases1 f ! "t :5 x pres5ts a ?9 & delicate cresc5t 7j aft] new moon7 until x has aga9 wan$ to a ?9 & delicate cresc5t 7j be=e ! next new moon74 ,we want ! relief giv5 by %ad[s to br+ out ! full beauty ( lun> sc5]y4 ,on ! map y w fir/ notice ! l>ge d>k-color$ pat*es :i* are s conspicu\s on ! moon's face4 ,!y are1 app>5tly1 ! empty bas9s :i* great seas once fill$4 ,b if wat] 0 ev] !re x has at all ev5ts n[ q disappe>$4 ,^! d>k p>ts are1 no d\bt1 a good deal smoo!r ?an ! re/ ( ! surface2 b we c see _m little irregul>ities :i* tell u t we are n look+ at oceans4 ,! *ief features ,i want y to obs]ve are ! curi\s r+s :i* y see 9 ! figure2 !re is a v well-m>k$ "o a little bel[ ! c5tre1 & 9 ! upp] "p _m r+s--l>ge & small--are cr[d$ toge!r4 ,we call !m lun> crat]s4 ,y w see :at !y are l f ! model1 ( :i* a picture is %[n 9 ,fig4 #db4 ,b to realize f ?is picture ! prop] scale ( ! object1 y %\ld imag9e x to be "s miles 9 wid?4 ,! cliffs :i* rise all r\nd to =m ! wall1 z well z ! m\nta9 :i* adorns ! c5tre1 are q z high z any ( ! m\nta9s 9 ,great ,brita94 ,illu/ration3 ,,fig4 #da4--,view on ! ,moon4 7,by ,lwy & ,puiseux1 ,p>is ,obs]vatory47 ,! l>ge c5tral crat] is ,hipp>*us & above x is ,albategnius4 ,illu/ration3 ,,fig4 #db4--,our ,model ( a ,lun> ,crat]4 ,y may desire to "k h[ we are able to measure ! heights ( m\nta9s on ! moon4 ,t is :at ,i am n[ go+ to %[ y2 & = ?is purpose we %all look at our imitation lun> crat]4 ,"h is ! great r+1 or circul> enclosure1 surr\nd$ by cliffs1 & "h is a %>p m\nta9 peak ris+ 9 ! c5tre4 ,i %all ask to h ! beam f ! electric lamp turn$ on our model4 ,y see h[ prettily x is light$ up4 ,i h plac$ ! lamp s t ! beams are slop+2 & ,i h done ?is ) ! express object ( mak+ ! %ad[s long4 ,9 fact1 z we look at a lun> crat]1 :i* lies on ! bord] betwe5 light & %ade1 ! sun illum9ates ! object "u ! same conditions z ^? %[n 9 ! figure4 ,i d>e say y h (t5 notic$ :at long %ad[s are ca/ at sunset4 ,simil> %ad[s are made to tea* ! a/ronom] ! altitudes ( ! lun> m\nta9s2 = he measures ! l5g? ( ! %ad[1 & !n by a little calculation he c f9d ! height ( ! object by :i* t %ad[ has be5 ca/4 ,i %all suppose t we want to measure ! height ( a flag/aff 7,fig4 #dc74 ,x is q possible to d ?is by m]ely measur+ ! l5g? ( ! %ad[ :i* t flag/aff ca/s at noon4 ,x w\ld n be correct to say t ! height ( ! flag/aff is ! l5g? ( its %ad[4 ,?is w1 inde$1 be ! case if y are =tunate en\gh to make y\r measurem5t at or ne> ,london on ei!r ! #f? ( ,april or ! #e? ( ,septemb]4 ,on all o!r days 9 ! ye> a little calculation mu/ be made1 :i* ,i ne$ n n[ m5tion1 b :i* ! a/ronom]1 ) ! aid ( 8 ,nautical ,almanac1 c d 9 a v few m9utes4 ,9 a simil> mann]1 by measur+ ! l5g?s ( ! %ad[s on ! moon1 & by f9d+ ! numb] ( miles 9 ! %ad[1 we are able to calculate ! altitudes ( ! lun> m\nta9s & ( ! ranges ( cliffs by :i* ! wall$ pla9s are surr\nd$4 ,illu/ration3 ,,fig4 #dc4--;,h[ we f\nd ! ,height ( ! ,flag/aff4 ,,on ,,! ,,orig9 ,,( ,,! ,,lun> ,,crat]s4 ,we h n[ to (f] an explanation ( ! curi\s r+s :i* are ! mo/ *>act]i/ic features on ! moon4 ,to acc\nt = !m we mu/ look = a mom5t at "s objects on ! e>?4 ,y h all he>d ( volcanoes or burn+ m\nta9s1 su* z ,vesuvius or ,etna1 :i* occasionally break out into viol5t eruptions1 & s5d =? great %[]s ( a%es & torr5ts ( molt5 lava4 ,9 ! ,s&wi* ,isl&s !re is a celebrat$ volcano call$ ,kilauea4 ,x is l a va/ lake ( lava1 s hot t x is actually molt51 & gl[s ) heat l r$-hot iron4 ,! adv5tur\s t\ri/ :o visits ?is crat] c climb to ! br9k ( a l(ty range ( cliffs :i* surr\nd x1 & gaze d[n ^u ! f]vid sea b5ea?4 ,suppose t by "s great *ange ! int]nal heat :i* keeps ?is mighty bas9 gl[+ 7 to decl9e & g out1 ! sea ( lava w\ld cease to be liquid1 & w\ld ultimately gr[ h>d & cold1 & we %\ld !n h an imm5se flat pla91 surr\nd$ by a range ( cliffs4 ,else:]e 9 ! ,s&wi* ,isl&s examples ( ext9ct crat]s may be f\nd at ! pres5t day4 ,^? :o h /udi$ ^! int]e/+ localities po9t out h[ su* t]re/rial crat]s expla9 ! r+$ pla9s 9 ! moon4 ,x seems c]ta9 t 9 anci5t days great volcanoes ab\nd$ on our satellite1 & ! r+s 7 (t5 mu* l>g] ?an ^? on ! ,s&wi* ,isl&s1 "s ( !m be+ "o hundr$ miles or m 9 diamet]4 ,! volcanoes mu/ long ago h be5 rag+ on ! moon ) a fury altoge!r unkn[n 9 any active volcanoes :i* ?is e>? c n[ %[4 ,we c also surmise h[ ! l(ty m\nta9 peak1 :i* s (t5 rises 9 ! c5tre ( a lun> r+1 has be5 upheav$4 ,:5 ! fires _h almo/ subsid$1 & ! floor _h gr[n ne>ly cold1 "o la/ & expir+ ef=t is made by :i* ! congeal+ surface is bur/ ?r\gh at ! c5tre1 & mat]ials are %ot =? :i* rema9 z ! c5tral m\nta9 to ! pres5t day4 ,i mu/1 h[ev]1 impress ^u y t ev5 our greate/ telescopes nev] exhibit to u any volcanic eruptions at pres5t go+ on 9 ! moon2 9 fact1 x is mo/ d\btful if any *ange has be5 notic$ 9 ! features on its surface s9ce ! date ( ! inv5tion ( ! telescope4 ,! volcanoes sculptur$ ! cru/ ( ! moon into ! =m 9 :i* we see x1 & t =m our satellite has pres]v$ = ages1 ( :i* we _c e/imate ! duration4 ,all ! crat]s & all ! volcanoes 9 ! moon c only be describ$ z ext9ct4 ,x w\ld be int]e/+ = u to comp>e ! pres5t condition ( ! volcanoes 9 ! e>? ) t ( ! r+$ crat]s 9 ! moon4 ,! noisy volcanoes on our globe are ^? mo/ talk$ ab\t2 we (t5 he> ( ,vesuvius be+ 9 eruption1 & 9 ,augu/1 #ahhc1 !re 0 a t]rific eruption at ,krakatoa1 dur+ :i* a l>ge quantity ( du/ 0 %ot up into ! air1 to su* a height t x 0 borne "r r\nd ! e>?1 & produc$ beautiful sunsets & unwont$ sky hues 9 almo/ e c\ntry 9 ! _w4 ,! explosion at ,krakatoa made ! l\de/ noise t hi/ory has record$4 ,=tunately su* convulsions ( ! e>? d n (t5 happ51 =1 on t occasion1 ! sea ru%$ 9 on ! l&1 & ?\s&s ( lives 7 lo/4 ,!re are said to be "o hundr$ & fifty volcanoes on diff]5t p>ts ( ! e>?1 :i* are m or less active1 b !re are _m o!rs 9 :i* ! fire has gone out1 & :i* seem to be j z cold & j z ext9ct z any volcanoes 9 ! moon4 ,ev5 9 our own isl&s !re are abundant rema9s ( anci5t volcanoes4 ,masses ( lava are f\nd 9 _m places :]e n[ !re is no trace ( an active volcano4 ,p]haps !re is no m rem>kable sight 9 ! ,briti% ,isles ?an t l(ty rock :i* is cr[n$ by ,ed9burgh ,ca/le2 x is ! remnant ( a =m] volcano1 :ile ,ar?ur's ,seat1 close by1 is ano!r4 ,9 ! c5tre ( ,france is ! beautiful di/rict ( ,auv]gne1 9 :i* anci5t volcanoes ab\nd2 & ! lava /reams c be trac$ = miles across ! c\ntry4 ,^! volcanoes h be5 ext9ct = ?\s&s ( ye>s1 dur+ :i* "t ! lava has become l>gely cov]$ ) soil & vegetation1 & 9 "s places v9ey>ds are cultivat$ ^u x4 ,we are n[ able to contra/ ! e>? ) ! moon1 9 s f> z volcanoes are conc]n$4 ,on ! e>? we h "s t are active1 & a mu* great] numb] t are ext9ct4 ,on ! moon we f9d no active volcanoes1 = !re all are ext9ct4 ,i c expla9 h[ ?is diff]5ce has aris51 b fir/ let me %[ y a simple exp]im5t4 ,my assi/ant w k9dly br+ to me f t furnace two iron balls1 :i* we plac$ !re be=e ! comm5cem5t ( ?is lecture2 !re !y are1 y see1 bo? gl[+ ) a bright r$ heat1 = at pres5t !y are equally hot4 ,we w place !m on ^! /&s1 & all[ !m to gr[ cold4 ,"o ( ^! balls is a small cannon-ball1 f\r in*es 9 diamet]1 :ile ! o!r is only "o in*4 ,!y are 9 ! same proportion z ! e>? is to ! moon2 b look1 ev5 :ile ,i am speak+ ! balls h ceas$ to pres]ve ! same temp]ature1 = ! little "o has become almo/ black f loss ( its heat1 :ile ! l>ge "o /ill looks ne>ly z r$ z x did at ! beg9n+2 ?is simple exp]im5t w illu/rate ! pr9ciple t two heat$ bodies w cool at v diff]5t rates1 if _! sizes be diff]5t1 :ile ! o!r conditions are ! same4 ,! small body w always cool fa/] ?an ! l>ge "o4 ,!y ne$ n be globes = ?is exp]im5t2 if y put a pok] & a knitt+ ne$le into ! fire1 & leave bo? !re until !y are r$-hot1 & !n put !m out into ! f5d]1 y w spe$ily f9d t ?\gh !y 7 at ! same temp]ature :5 drawn f ! fire1 !y d n long rema9 s2 inde$1 ! knitt+ ne$le has become cold en\gh to h&le be=e ! pok] has ceas$ to gl[4 ,our exp]im5ts h be5 made )1 no d\bt1 small objects only1 b ! law ab\t :i* !y in=m u w rema9 true1 ev5 = ! greate/ objects4 ,our e>? at ! pres5t day %[s _m indications ( be+ mu* hott] )9 ?an x is on ! surface4 ,! volcanoes !mselves are m]e outbreaks ( inc&esc5t mat]ial f inside4 ,!n !re are hot spr+s ( wat] at ,ba?1 :i* gu% out f ! e>?4 ,!re are geys]s ( hot wat] 9 ,icel& & 9 ! ,yell[/one ,p>k 9 ,am]ica1 & 9 o!r places4 ,& !re are o!r indications also1 ) :i* e m9] is famili>4 ,:]ev] a deep pit is sunk into ! e>?1 ! rocks bel[ are always f\nd to be w>m] ?an ^? on ! surface1 & ! deep] ! pit ! great] is ! heat t is enc\nt]$4 ,?us1 f all ov] ! _w we obta9 pro(s ( ! pres5t exi/5ce ( int]nal heat4 ,great z is ! e>?1 we mu/ /ill apply ! simple common-s5se pr9ciples t we use 9 our ev]yday life "h4 ,let me give an illu/ration4 ,suppose t a s]vant came into ! room & plac$ a jug ( wat] on ! table1 & t an h\r aft]w>ds y w5t to ! jug ( wat] & f\nd x to be cold1 y w\ld n f t fact alone be able to inf] any?+ ) c]ta9ty1 z to :e!r ! wat] _h be5 w>m or cold :5 x 0 br\ght 94 ,x might h be5 p]fectly cold1 z x is at pres5t1 ?\gh on ! o!r h& ! wat] might h be5 w>m at fir/1 & h s9ce cool$ d[n to ! temp]ature ( ! room dur+ ! h\r4 ,suppose1 h[ev]1 t :5 y w5t to ! jug ( wat]1 :i* _h /ood on ! table = an h\r1 y f\nd x tepid1 no matt] h[ slightly its temp]ature might be above t ( ! room1 d y n see ! inf]5ce y w\ld be able to draw8 ,y w\ld argue 9 ?is way3 t wat] has /ill "s heat2 x mu/1 ( c\rse1 be gradually cool+1 & !re=e x 0 hott] a m9ute ago ?an x is n[2 x 0 hott] /ill two m9utes ago1 or t5 m9utes2 & mu/ h be5 v hot & p]haps boil+ :5 x 0 br\ght 9 an h\r ago4 ,i want y to apply exactly ! same reason+ to our e>?4 ,x is1 z ,i h %[n y1 /ill hot & w>m inside4 ,( c\rse1 t heat is gradually becom+ lo/2 s t ! e>? w f ye> to ye> gradually cool d[n1 ?\gh at an extremely sl[ rate4 ,b we mu/ look back into :at has happ5$ dur+ pa/ ages4 ,j z we inf]r$ t ! jug mu/ h conta9$ v hot wat] an h\r be=e f ! m]e fact t ! wat] 0 /ill w>m1 s we are entitl$ to inf]1 f ! fact t ! e>? /ill reta9s "s heat1 t x mu/ 9 ages gone by h be5 exce$+ly hot4 ,9 fact1 ! fur!r we look back1 ! hott] d we see ! e>? gr[+1 until at la/ we are con/ra9$ to ?9k ( a p]iod1 9 ! excessively remote pa/1 long ere life began to dawn on ?is e>?1 :5 ev5 ! surface ( ! e>? 0 hot4 ,back fur!r /ill we see ! e>? no long] cov]$ ) ! h>d1 ! d>k1 & ! cold surface we n[ f9d2 we are to ?9k ( x 9 ^! primitive times z a huge gl[+ mass1 9 :i* all ! sub/ances t n[ =m ! rocks 7 !n inc&esc5t1 & ev5 molt5 mat]ial4 ,!re is good reason = kn[+ t 9 ^? e>ly times ! moon also 0 molt5 ) heat2 & ?us our reason+ has l$ u to ?9k ( a p]iod :5 !re 7 two great r$-hot globes--"o ( :i* _h ab\t f\r times ! diamet] ( ! o!r--/>t+ on _! c>e] ( gradually cool+ d[n4 ,recall our little exp]im5t ) ! two cool+ globes ( iron2 imag9e ^! globes to pres]ve _! relative proportions1 b t "o ( !m 0 #hjjj miles & ! o!r #bjjj miles across4 ,ages w1 no d\bt1 elapse ere !y "p ) _! heat suffici5tly to all[ ! surfaces to cool & to consolidate4 ,we may1 h[ev]1 be sure t ! small globe w cool ! fa/]1 t its outside w become h>d soon] ?an w ! surface ( ! l>ge "o1 & long aft] ! small globe has become cold to ! c5tre1 ! l>ge "o may cont9ue to reta9 "s ( its primeval heat4 ,we c ?us readily und]/& :y all ! volcanoes on ! moon h ceas$--_! day is ov]4 ,x is ov] because ! moon1 be+ s small1 has gr[n s cold t x no long] su/a9s ! int]nal fires :i* are necess>y = volcanic outbreaks4 ,our e>?1 9 consequ5ce ( its mu* great] size1 has gr[n cold m sl[ly4 ,x has no d\bt lo/ ! high temp]ature on ! ext]ior1 & its volcanic en]gy has probably abat$ f :at x once 04 ,b !re is /ill suffici5t p[] 9 ! subt]ranean fires to awak5 u occasionally by a ,krakatoa1 or to supply ,vesuvius ) suffici5t mat]ials & vigor = its m frequ5t outbur/s4 ,! argum5t %[s u t ! "t w at la/ come :5 ?is e>? %all h p>t$ ) s l>ge a proportion ( its heat t x w be no long] able to provide volcanic ph5om5a1 & !n we %all pass into ! exhau/$ /age :i* ! moon atta9$ ages ago4 ,,! ,,movem5ts ,,( ,,! ,,moon4 ,?\gh ! moon is go+ r\nd & r\nd ! e>? incessantly1 yet x always manages to avoid af=d+ u a view ( :at is on ! o!r side4 ,our satellite always directs ! same face t[>ds ! e>?1 & we may reasonably conjecture t ! o!r side is cov]$1 l ! side we "k1 ) r+s & o!r traces ( =m] volcanoes4 ,9 ?is respect ! moon is q a peculi> object4 ,! o!r great cele/ial bodies1 su* z ! sun or ,jupit]1 turn r\nd on _! axes1 & %[ u n[ "o side & !n ! o!r1 ) complete imp>tiality4 ,! way 9 :i* ! moon revolves may be illu/rat$ by tak+ y\r wat* & *a91 & z y hold ! *a9 at ! c5tre mak+ ! wat* revolve 9 a circul> pa?4 ,at e po9t ( its pa? ! r+ ( ! wat* is1 ( c\rse1 po9t$ to ! c5tre :]e ! *a9 is held4 ,if y imag9e y\r eye plac$ at ! c5tre1 to repres5t ! e>?1 ! movem5ts ( ! wat* w\ld exemplify ! way ! moon turns r\nd x4 ,"o m po9t ,i mu/ expla9 ab\t ! moon be=e we close ?is lecture4 ,!re is no?+ m famili> ?an ! fact t a heavy body w fall to ! gr\nd4 ,inde$1 x h>dly matt]s :at ! mat]ial ( ! body may be1 = y see ,i h a small iron ball 9 "o h& & ,i hold a cork 9 ! o!r4 ,i drop !m at ! same mom5t1 & !y rea* ! gr\nd toge!r4 ,p]haps y w\ld h expect$ t ! cork w\ld h lagg$ beh9d ! iron4 ,i try ! exp]im5t aga9 & aga91 & y c see no diff]5ce 9 ! times ( _! fall+1 ?\gh ,i d n say ?is w\ld be true if !y 7 dropp$ f ! top ( ! ,monum5t4 ,9 g5]al we may say t bodies let drop w fall sixte5 feet 9 ! fir/ second4 ,ev5 a bit ( pap] & a p5ny piece w fall ?r\gh ! same height 9 ! same "t if y c get ov] ! difficulty ( ! resi/ance ( ! air4 ,?is is easily manag$4 ,cut a small piece ( tissue pap] :i* w lie flat on ! top ( ! p5ny1 & hold ! p5ny horizontal ) ! pap] upp]mo/4 ,?\gh !re is no?+ to fa/5 ! pap] to ! p5ny1 y w f9d t !y fall toge!r4 ,if we c\ld conduct ! exp]im5t ( dropp+ ! p5ny & ! bit ( pap] 9 a vacuum1 !n1 :e!r ! pap] 0 laid on ! p5ny or plac$ 9 any o!r way1 ! two objects w\ld rea* ! table at ! same mom5t if releas$ at ! same mom5t at equal heights4 ,:]ev] we g we f9d t bodies w always t5d to fall 9 t[>ds ! c5tre ( ! e>?2 ?us 9 ,new ,zeal&1 at ! opposite side ( our globe f :]e we are n[ /&+1 bodies w fall up t[>ds u1 & ?is law ( fall+ is obey$ at ! top ( a m\nta9 z x is d[n "h4 ,no matt] h[ high may be ! asc5t made 9 a balloon1 a body releas$ w fall t[>ds ! e>?'s c5tre4 ,( c\rse1 we c only asc5d "s five or six miles high1 ev5 9 ! mo/ buoyant ( balloons2 b we "k t ! attraction by :i* bodies are pull$ d[nw>ds t[>ds ! e>? ext5ds f> beyond ?is limit4 ,if we c\ld g t51 tw5ty1 or fifty miles up1 we %\ld /ill f9d t ! e>? tri$ to pull u d[n4 ,nor1 ev5 if y c\ld imag9e an asc5t made to ! height ( #ajjj miles1 w\ld gravitation h ceas$4 ,a cork or an iron ball1 or any o!r object dropp$ f ! height ( #ajjj miles1 w\ld assur$ly tumble d[n on ! gr\nd bel[4 ,suppose t by "s device we 7 able to so> al(t to a height ( #djjj miles4 ,i "n t elevation because we %\ld !n be z high above ! e>? z ! c5tre ( ! e>? is bel[ our feet4 ,we %\ld h d\bl$ our di/ance f ! c5tre ( ! e>?1 & ! int5sity ( ! gravitation w\ld h decreas$ to "o-qu>t] ( :at x is at ! surface4 ,a body :i* at ! e>?'s surface falls sixte5 feet 9 a second w\ld !re fall only f\r feet 9 a second1 & ! app>5t weight ( any body w\ld be s mu* r$uc$ t x w\ld seem to weigh only a qu>t] ( :at x weighs d[n "h4 ,?us1 ! high] & high] we g1 ! less & less does gravity become2 b x does n cease1 ev5 at a di/ance ( millions ( miles4 ,!re=e y might say t z gravity tries to pull ev]y?+ d[n1 :]ev] x may be1 :y does x n pull d[n ! moon8 ,?is is a difficulty :i* we mu/ c>efully consid]4 ,suppos+ t ! e>? & ! moon 7 simply held ap>t1 bo? be+ at re/1 & t !n ! moon 7 to be let g1 x w\ld no d\bt drop d[n directly on ! e>?4 ,! movem5t ( ! moon w\ld1 h[ev]1 be v diff]5t if1 in/ead ( be+ m]ely let fall1 x 0 ?r[n sideways4 ,! effect ( ! e>?'s pull ^u ! moon w\ld !n be %[n 9 keep+ ! moon revolv+ ar\nd u in/ead ( all[+ x to fly away altoge!r1 z x w\ld h done _h ! e>? n be5 !re to attract x4 ,illu/ration3 ,,fig4 #dd4--;,an ,illu/ration to expla9 ! ,movem5t ( ! ,moon ,we c expla9 ?is by an illu/ration4 ,on ! top ( a m\nta9 ,i h plac$ a big cannon 7,fig4 #dd74 ,we fire (f ! cannon1 & ! bullet flies away 9 a curv$ pa?1 ) a gradual desc5t until x falls to ! gr\nd4 ,i h made ! m\nta9 look hundr$s ( times l>g] ?an any m\nta9 c\ld possibly be2 & n[ ,i want y to imag9e a cannon f> /rong] & gunp[d] m pot5t ?an any p[d] or cannon t has ev] yet be5 manufactur$4 ,fire (f a bullet ) a /ill great] *>ge ?an ! la/ "t1 & n[ ! pa? is a mu* long] "o1 b /ill ! bullet curves d[n s z ultimately to fall on ! e>?4 ,b make n[ "o f9al %ot ) a *>ge suffici5tly p[]ful1 & away flies ! bullet1 foll[+ ?is "t ! curvature ( ! e>?1 = ! e>?'s attraction has ! effect ( b5d+ ! pa? ( ! bullet f a /raight l9e into ?is circul> =m4 ,by ! "t ! bullet has travell$ a qu>t] ( ! way r\nd1 x is no ne>] to ! e>? ?an x 0 at fir/1 nor has x p>t$ ) any ( its orig9al spe$4 ,?us1 not)/&+ its long j\rney1 ! bullet has practically j z mu* en]gy z :5 x fir/ left ! muzzle ( ! cannon4 ,away x w fly r\nd ano!r qu>t] ( ! e>?1 & /ill 9 ! same condition x w accompli% ! ?ird & ! f\r? qu>t]s1 ?us return+ to ! po9t f :i* x />t$4 ,if we h cle>$ ! cannon out ( ! way1 ! bullet w fly aga9 ov] ! m\nta9 top )\t hav+ lo/ any ( its spe$ by its voyage r\nd ! e>?4 ,!re=e x w be 9 a condition to />t aga91 & ?us to revolve ar\nd ! e>? p]man5tly4 ,if1 !n1 f ! top ( a m\nta9 #bdj1jjj miles high a great bullet #bjjj miles 9 diamet] _h once be5 project$ ) ! prop] velocity1 t bullet w\ld cont9ue =ev] to circle r\nd & r\nd ! e>?1 & ev5 ?\gh ! m\nta9 & ! cannon disappe>$1 ! motion w\ld be pres]v$ indef9itely4 ,?is illu/ration w1 at all ev5ts1 %[ h[ a cont9u\s revolution ( ! moon r\nd ! e>? c exi/1 not)/&+ t ! e>? is con/antly pull+ our satellite d[n t[>ds its surface4 ,,on ,,! ,,possibility ,,( ,,life ,,9 ,,! ,,moon4 ,a/ronom]s are (t5 ask$ :e!r any animals c be liv+ on ! moon4 ,no obs]vations we c make ) ! telescope c answ] t "q directly4 ,!re are great pla9s to be se5 on ! moon1 ( c\rse1 b ev5 if !re 7 elephants tramp+ ov] ^? pla9s1 our telescopes c\ld n %[ !m4 ,nor w our in/rum5ts pron\nce at once :e!r plants or trees fl\ri% on ! moon4 ,! mammo? trees ( ,cali=nia are s big t a tunnel has be5 cut ?r\gh ! trunk ( "o l>ge en\gh to give passage = a c>riage & pair4 ,ev5 if !re 7 trees z big z ?is on ! moon1 !y w\ld n be visible f ! mo/ fam\s obs]vatories4 ,let u ?9k :at we %\ld ourselves exp]i5ce if we c\ld 9 "s m>vell\s mann] be transf]r$ f ! e>? to its satellite1 & tri$ to explore t new & wond]ful c\ntry4 ,alas1 we %\ld f9d x utt]ly impossible to live !re = an h\r1 or ev5 = a m9ute6 ,troops ( difficulties w\ld imm$iately beset u4 ,! v fir/ w\ld be ! want ( air4 ,pond] = a mom5t on ! inv>iable pres5ce ( air ar\nd our own globe4 ,ev5 if y climb to ! top ( a high m\nta91 or if y take a l(ty voyage 9 a balloon1 y are all ! "t ba!d 9 air4 ,x is air :i* supports ! balloon1 j z a cork is buoy$ up by wat]4 ,9 all circum/ances1 we mu/ h air to brea!4 ,9 t air is oxyg5 gas1 & we mu/ h oxyg5 incessantly suppli$ to our lungs to re9vigorate our blood4 ,we require1 too1 t ?is oxyg5 %all be dilut$ ) a mu* l>g] am\nt ( nitrog5 gas1 = our lungs & sy/em ( circulation are adapt$ = abode 9 t p>ticul> mixture ( gases :i* we f9d "h4 ,! atmosph]e becomes m & m r>efi$ ! high] we asc5d1 & app>5tly t]m9ates altoge!r "s two or ?ree hundr$ miles ov] our heads4 ,beyond ! limits ( ! atmosph]e x seems z if empty space w\ld be met ) all ! way f ! e>? to ! moon4 ,we c\ld n procure a s+le brea? ( air1 & life w\ld be1 ( c\rse1 impossible4 ,ev5 at a height ( ?ree or f\r miles1 respiration becomes difficult1 & d\btless life c\ld n possibly be su/a9$ at a height ( t5 miles4 ,x is !re=e pla9 t = a voyage to ! moon we %\ld require an ample supply ( air1 or1 at lea/1 ( life-giv+ oxyg51 :i* 9 "s way or o!r 0 to be inhal$ dur+ ! progress ( ! j\rney4 ,:5 at l5g? #bdj1jjj miles _h be5 trav]s$1 & we 7 ab\t to l& on ! moon1 we w\ld fir/ ( all asc]ta9 :e!r x 0 surr\nd$ ) a coat+ ( air4 ,mo/ ( ! globes ?r\gh space are1 s f> z we c le>n1 cov]$ & w>m$ ) an envelop+ atmosph]e ( "s k9d2 b1 unhappily1 ! poor moon has be5 left entirely1 or almo/ entirely1 )\t any su* clo?+4 ,%e is q b>e ( atmosph]e at all comp>able 9 d5sity or 9 volume to t :i* surr\nds u1 ?\gh possibly we d n[ & !n p]ceive "s traces ( air1 or ( "s k9d ( gas1 9 small quantities 9 ! lun> valleys4 ,i am sure ea* intellig5t boy or girl w want to "k h[ we are able to tell all ?is4 ,we h nev] be5 at ! moon1 & h[ !n c we say t x is ne>ly de/itute ( air8 ,nor c our telescope answ] ?is "q imm$iately1 = y c\ld h>dly expect to see air1 ev5 if x 7 !re4 ,h[ !n are we able to make su* ass]tions8 ,!re are _m diff]5t ways 9 :i* we h le>n$ ! abs5ce ( air f ! moon4 ,i w tell y "o ( ! easie/ & ! mo/ c]ta9 ( ^! me?ods4 ,fir/ let me say t air is n p]fectly transp>5t4 ,no d\bt ,i c see y1 & y c see me1 ?\gh a good _m feet ( air may lie betwe5 u2 b :5 we deal ) di/ances mu* great]1 !re is a v simple way 9 :i* we c %[ t air is n q transp>5t4 ,9 ! ev5+1 :5 ! sun is sett+ & ! sky is cle>1 y c look at him )\t discom=t2 b 9 ! middle ( ! day y "k t x is impossible to look at ! sun )\t %ad+ y\r eyes ) smok$ glass or protect+ !m by "s simil> contrivance4 ,! reason is1 t :5 ! sun is ei!r sett+ or ris+ we look at x ?r\gh an imm5se ?ickness ( air1 :i* n be+ p]fectly transp>5t /ops "s ( ! light4 ,?us x is t ! sun 9 ^! circum/ances loses its dazzl+ brilliancy1 & we c view x )\t discom=t4 ,at ! seaside y c notice ! same effect 9 a diff]5t mann]4 ,g out on a f9e & cle> night1 :5 ! />s 9 _! ?\s&s are glitt]+ ov]head1 & !n look d[n gradually t[>ds ! horizon1 & y w f9d ! />s becom+ fa9t] & fa9t]4 ,inde$1 ev5 ! brighte/ /> _c be se5 :5 x is at ! horizon1 because an imm5se ?ickness ( ! atmosph]e is n transp>5t4 ,we c n[ /ate ! argum5t by :i* we may prove t !re is little or no air on our satellite4 ,! moon w frequ5tly pass betwe5 ! e>? & a />1 & :5 ! /> is a really bright "o ! obs]vations t c be made are ( great int]e/4 ,let me fir/ describe :at we actually see4 ,! /> is %9+ brightly until ! mom5t :5 ! moon eclipses x4 ,g5]ally speak+1 its disappe>ance is in/antane\s4 ,b ?is w\ld n be ! case if ! moon 7 encircl$ ) an atmosph]e4 ,if ! moon 7 coat$ ) air1 ! light f ! /> w\ld n be ext+ui%$ in/antly2 x w\ld gradually decl9e1 accord+ z x _h to pass ?r\gh m & m ( ! moon's atmosph]e4 ,?us y w\ld f9d t ! /> dw9dl$ d[n 9 brightness be=e ! solid body ( ! moon _h advanc$ f> en\gh to %ut x out4 ,! sudd5 ext9ction ( ! />s demon/rates ! airless /ate ( our satellite4 ,!re w\ld be ano!r insup]able difficulty 9 adopt+ ! moon z a resid5ce1 ev5 suppos+ t y c\ld get !re4 ,wat] is abs5t f its surface4 ,we h exam9$ e "p ( x1 & we f9d no evid5ces ( seas or ( oceans1 ( lakes or riv]s2 we nev] see any?+ l cl\ds or mi/s1 :i* are1 ( c\rse1 only wat] 9 ! vapor\s =m4 ,we are1 !re=e1 assur$ t1 s f> z wat] is conc]n$1 ! moon is an absolute des]t4 ,?is is1 p]haps1 ! mo/ /rik+ contra/ betwe5 ! aspect ( ! e>? & ! aspect ( ! moon4 ,7 an a/ronom] on ! moon to look at our e>? he w\ld f9d mo/ ( its surface conceal$ b5ea? cl\ds1 & ?r\gh ! op5+s 9 ^! cl\ds he w\ld see t by f> ! great] "p ( ?is globe 0 cov]$ by ! expanse ( ocean2 9 fact1 :5 ! lun> a/ronom] _h realiz$ ! preval5ce ( wat] ^u ?is e>?1 ei!r 9 ! =m ( ocean or cl\d1 ,i feel sure he w\ld come to ! conclusion t no?+ c\ld live "h except seals or o!r amphibi\s animals4 ,ow+ to ! abs5ce ( air & wat]1 ! moon w\ld be totally disqualifi$ = ! support ( life ( ^? types 9 :i* we "k x4 ,= air & wat] are necess>y to e animal1 f ! humble/ animalcule up to :ales or elephants4 ,air & wat] are necess>y = e =m ( vegetable life1 f ! li*5 :i* gr[s on a /one up to ! noble old oak ( ! =e/4 ,b ev5 suppos+ t we c\ld l& on ! moon1 be>+ ) u an ample supply ( oxyg5 to brea!1 & ( wat] to dr9k1 we %\ld f9d ourselves p]plex$ & emb>rass$1 to say ! v lea/ ( x1 by an extraord9>y diff]5ce t w\ld imm$iately attract our notice4 ,t famili> exp]i5ce ( gravity1 or ! weights ( ?+s1 :i* we h acquir$ 9 our resid5ce on a great globe l ! e>?1 w\ld seem ludicr\sly alt]$ :5 we began to walk ab\t on a little globe l ! moon4 ,we %\ld be a/oni%$ at ! trans=mation by :i* ! weight ( ev]y?+ 0 mu* less5$2 :5 y pull$ out y\r wat* y w\ld h>dly feel x at ! end ( ! *a92 x w\ld seem l a m]e %ell2 b yet ! wat* is all "r1 x is go+ z well z ev]4 ,no?+ has alt]$ ab\t x except its weight4 ,a big /one attracts y\r notice1 &1 to y\r amazem5t1 y f9d t x does n weigh s mu* z a piece ( wood ( ! same size w\ld weigh d[n "h4 ,a /one t y c\ld h>dly /ir on ! e>?1 y c c>ry ab\t on ! moon4 ,nor is ?is to be expla9$ by any peculi>ity 9 ! con/itution ( ! lun> /one4 ,mo/ probably x w be n v dissimil> to "s ( ! rocks on ! e>?4 ,! relative lightness ( a lun> /one is n due to its be+ =m$ ( "s v special mat]ial2 we mu/ seek = "s o!r explanation4 ,e object on ! moon w\ld be f\nd only "o-six? z heavy z ! same object on ! e>?4 ,a /urdy labor] at "o ( ! docks c c>ry "o sack ( corn on 8 back "h1 & he f9ds t ?is load is z mu* z is conv5i5t4 ,he w\ld1 h[ev]1 discov]1 7 he plac$ on ! moon1 t 8 load _h sudd5ly become light5$ to "o-six? "p 7,fig4 #de74 ,! labor] w\ld f9d t he c\ld c>ry six sacks ( corn on ! moon )\t mak+ a great] ef=t ?an ! support ( a s+le sack on ! e>? co/ him4 ,to expla9 h[ su* a *ange z ?is has occurr$1 look at ^! two pictures3 "o %[s ! labor] on a small body l ! moon1 ! o!r %[s him on a great globe l ! e>?4 ,:at ! labor] actually does feel is n q s simple a ?+ z he imag9es4 ,he imag9es t x is ! weight ( ! corn1 & ! corn alone1 :i* produces t pressure on 8 %\ld]s :i* he kn[s s well4 ,b t is n exactly ! mann] 9 :i* ! philosoph] w look at ! same "q4 ,:at ! labor] does actually feel is ! attraction betwe5 ! e>? b5ea? 8 feet & ! corn on 8 back4 ,x is ?is =ce :i* produces ! pressure on 8 %\ld]s4 ,its magnitude no d\bt dep5ds ^u ! quantity ( corn 9 ! sack1 b x also dep5ds on ! quantity ( matt] on ! e>? b5ea? 8 feet4 ,9 fact1 ! =ce betwe5 two attract+ bodies dep5ds ^u ! masses ( bo? ! attract+ bodies4 ,:5 ! labor] is transf]r$ to ! moon1 ( :i* ! mass is s mu* less ?an t ( ! e>?1 ! attraction is less !re ?an x is "h1 ev5 ?\gh ! corn is ! same 9 ! two cases4 ,illu/ration3 ,,fig4 #de4--,! ,less5$ ,gravitation on ! ,moon4 ,_m odd in/ances c\ld be giv5 ( ! extraord9>y consequ5ces ( life on a _w :]e all weights are r$uc$ to a six? "p4 ,"o occurr$ to me ! o!r day :5 ,i saw a po/man go+ 8 r\nds ) an amaz+ load ( ,*ri/mas pres5ts & p>cels4 ,i ?\ght1 h[ mu* happi] mu/ be ! lot ( a po/man on ! moon1 if su* function>ies are want$ !re6 ,all ! pres5ts ( toys or m sub/antial donations might be ! same z be=e1 ! only alt]ation w\ld be t !y w\ld n feel ne>ly s heavy4 ,a box :i* conta9s a p\nd ( *ocolate bonbons might /ill conta9 exactly ! same quantity ( sweetmeat on ! moon1 b ! ex]tion ( c>ry+ x w\ld be r$uc$ to "o-six?4 ,x w\ld only weigh z mu* z two or ?ree ounces d on ! e>?4 ,our /reets provide ano!r admirable illu/ration ( ! drawbacks ( our life "h z comp>$ ) ! facilities (f]$ by life on ! moon4 ,i feel q confid5t t no p]ambulators c be necess>y !re4 ,i _c inde$ say t !re are babies to be f\nd on ! moon1 b ( ?is ,i am c]ta91 t ev5 if ! lun> babies 7 z plump & z /urdy z ours1 !y mu/ /ill only weigh ab\t a six? z mu* z ours d4 ,a lun> nurse w\ld scorn to use a p]ambulator1 ev5 = a pair ( tw9s2 %e might take !m bo? out on h] arm = an air+1 & ev5 !n only be> "o-?ird ( ! load t h] t]re/rial si/] mu/ su/a9 if %e is c>ry+ b a s+le *ild4 ,! lightness ( bodies 9 ! moon w\ld entirely trans=m _m ( our mo/ famili> games4 ,9 cricket1 = in/ance1 ,i don't ?9k ! b[l+ w\ld be s mu* affect$1 b ! hits on ! moon w\ld be truly t]rific4 ,i believe an exceptionally good ?r[ ( ! cricket-ball "h is ab\t a hundr$ y>ds1 b ! same man1 us+ ! same ball & apply+ ! same =ce to x1 w\ld s5d ! ball six hundr$ y>ds on ! moon4 ,s1 too1 e hit w\ld 9 ! lun> game c>ry ! ball to six times ! di/ance x does "h4 ,football w\ld %[ a /rik+ developm5t 9 lun> play2 a good kick w\ld n only s5d ! ball ov] ! cross-b>1 b x w\ld g so>+ ov] ! h\ses1 & p]haps drop 9 ! next p>i%4 ,our own bodies w\ld1 ( c\rse1 p>ticipate 9 ! g5]al buoyancy1 s t1 :ile muscul> p[] rema9$ unabat$1 we %\ld be almo/ able to run & jump z if we _h on ! fam\s sev5-league boots4 ,i h se5 an a?lete 9 a circus jump ov] t5 horses plac$ side by side4 ,! same a?lete1 mak+ ! same ef=t1 w\ld jump ov] sixty horses on ! moon4 ,a run ) a pack ( lun> foxh\nds w\ld inde$ be a m>vell\s spectacle4 ,!re ne$ be no look+ r\nd by timid horsem5 to f9d op5 roads or easy gaps4 ,! five-b>r$ gate itself w\ld be utt]ly despis$ by a huntsman :o c\ld easily cle> a hay-rick4 ,x w\ld h>dly be wor? tak+ a s]i\s jump to cle> a canal unless !re 0 a road & a railway or s1 :i* c\ld be dispos$ ( at ! same "t4 ,to illu/rate ?is subject ( gravitation 9 ano!r way1 suppose t we 7 to be transf]r$ f ?is e>? to "s globe mu* great] ?an ! e>?--to a globe1 = in/ance1 z l>ge & massive z ! sun4 ,we c !n %[ t ! weight ( e object w\ld be increas$4 ,inde$1 ev]y?+ w\ld weigh ab\t tw5ty-sev5 times z mu* z we f9d x does "h4 ,to pull out y\r wat* w\ld be to hoi/ a weight ( ab\t five or six p\nds out ( y\r pocket4 ,inde$1 ,i d n see h[ y c\ld draw out y\r wat*1 = ev5 to raise y\r arm w\ld be impossible2 x w\ld feel heavi] by f> ?an if x 7 made ( solid lead4 ,x is1 p]haps1 conceivable t y might /& upright = a mom5t1 p>ticul>ly if y _h a wall to lean up aga9/2 b ( ?is ,i feel c]ta91 t if y once got d[n on ! gr\nd1 x w\ld be utt]ly out ( y\r p[] to rise aga94 ,^! illu/rations w at lea/ answ] "o purpose3 !y w %[ h[ difficult x is = u to =m any op9ion z to ! pres5ce or ! abs5ce ( life on ! o!r globes 9 space4 ,we are j adapt$ 9 e way = a resid5ce on ?is p>ticul> e>? ( a p>ticul> size & climate1 & ) atmosph]e ( a p>ticul> composition4 ,)9 c]ta9 sl5d] limits our vital p[]s c become accommodat$ to *ange1 b ! conditions ( o!r worlds seem to be s utt]ly diff]5t f ^? we f9d "h1 t x w\ld probably be q impossible = be+s con/itut$ z we are to rema9 alive = five m9utes on any o!r globe 9 space4 ,x is1 h[ev]1 q ano!r "q z to :e!r !re may n be inhabitants ( "s k9d on _m ( ! o!r spl5did globes4 ,we h ?r\gh ! wide ext5t ( space inconceivable myriads ( worlds1 pres5t+1 no d\bt1 e v>iety ( size & climate1 ( atmosph]e & soil4 ,x seems q prepo/]\s to imag9e t among all ^! globes ours alone %\ld be ! abode ( life4 ,! mo/ reasonable conclusion = u to come to is t ^! bodies may be end[$ ) life ( types :i* are j z appropriate to ! physical conditions ar\nd !m z is ! life1 bo? animal & vegetable1 on ?is globe to ! special circum/ances 9 :i* x is plac$4 ,,lecture ,,iii4 ,,! ,,inn] ,,planets4 ,m]cury1 ,v5us1 & ,m>s--,h[ to make a ,draw+ ( our ,sy/em--,! ,planet ,m]cury--,! ,planet ,v5us--,! ,transit ( ,v5us--,v5us z a ,_w--,! ,planet ,m>s & 8 ,movem5ts--,! ,ellipse--,! ,discov]ies made by ,ty*o & ,kepl]--,! ,discov]ies made by ,newton--,! ,geography ( ,m>s--,! ,satellites ( ,m>s--,h[ ! ,telescope aids 9 ,view+ ,fa9t ,objects--,! ,a/]oids1 or ,small ,planets4 ,,m]cury1 ,,v5us1 ,,& ,,m>s4 ,we c h>dly ?9k ( ei!r ! sun or ! moon z a _w 9 ! s5se 9 :i* our e>? is a _w1 b !re are "s bodies call$ planets :i* seem m l worlds1 & x is ab\t !m t we are n[ go+ to talk4 ,besides our ,e>? !re are sev5 planets ( consid]able size1 & a :ole ho/ ( insignificant little ones4 ,^! planets are l ours 9 a good _m respects4 ,"o ( !m1 ,v5us1 is ab\t ! same size z ?is e>?2 b ! two o!rs1 ,m]cury & ,m>s1 are v mu* small]4 ,!re are also "s planets v mu* l>g] ?an any ( ^!1 namely1 ,jupit]1 ,saturn1 ,uranus1 & ,neptune4 ,we %all 9 ?is lecture *iefly discuss ?ree bodies1 namely1 ,m]cury1 ,v5us1 & ,m>s1 :i*1 ) ! e>?1 =m ! gr\p ( 8inn]0 planets4 ,! planets are all memb]s ( ! great family dep5d5t on ! sun4 ,v5us & ! e>? may be consid]$ ! pair ( tw9s1 alike 9 size & weight4 ,m]cury & ,m>s are ! babies ( ! sy/em4 ,! big bro!rs are ,jupit] & ,saturn4 ,all ! planets revolve r\nd ! sun1 & d]ive _! light & _! heat f 8 beams4 ,we %\ld l to get a little clos] to "s ( our fell[-planets & le>n _! actual geography4 ,un=tunately1 ev5 "u ! mo/ favorable circum/ances1 !y are a v long way (f4 ,!y are _m millions ( miles di/ant1 & are always at lea/ a hundr$ times z f> z ! moon4 ,b f> z ! planets may be1 a/ronom]s h be5 famili> ) _! exi/5ce = ages pa/4 ,i c give y a curi\s pro( ( ?is4 ,y rememb] h[ we said ! fir/ & ! second days ( ! week 7 call$ aft] ! sun & ! moon1 ,sun-day & ,moon-day1 or ,monday1 respectively4 ,let u see ab\t ! o!r days4 ,tuesday is n q s obvi\s1 b translate x into ,fr5* & we h at once ,m>di2 ?is ^w means no?+ b ,m>s' day1 & our ,tuesday means exactly ! same4 ,w$nesday is also readily int]pret$ by ! ,fr5* ^w ,m]cr$i1 or ,m]cury's day1 :ile ,v5us corresponds to ,friday4 ,jupit]'s day is ,?ursday1 :ile ,saturn's day is naturally ,saturday4 ,! famili> names ( ! days ( ! week are ?us associat$ ) ! sev5 mov+ cele/ial bodies :i* h be5 kn[n = unc\nt$ ages4 ,,h[ ,,to ,,make ,a ,,draw+ ,,( ,,our ,,sy/em4 ,i want e "o :o reads ?is book to make a little draw+ ( ! sun & ! planets4 ,! app>atus t y w ne$ is a pair ( compasses2 any sort ( compasses t w c>ry a bit ( p5cil w d4 ,y mu/ also get a little scale t has in*es & p>ts ( in*es divid$ ^u x2 any c>p5t]'s rule w answ]4 ,! draw+ is int5d$ to give a notion ( ! true sizes & positions ( ! f9e family ( :i* ! e>? is "o memb]4 ,! figure ,i h giv5 7,fig4 #df7 is n on s l>ge a scale z t :i* ,i ask y to use1 & :i* ,i %all "h m5tion4 ,try & d ! "w neatly1 & !n p9 up y\r little draw+s :]e y w be able to see !m e day until y are q famili> ) ! notion ( :at we mean by our sol> sy/em4 ,illu/ration3 ,,fig4 #df4--,! ,orbits ( ! ,f\r ,inn] ,planets4 ,fir/ op5 ! compasses "o in*1 & !n describe a circle1 & m>k a dot on ?is z 8,,m]cury10 9 neat lett]s1 & also write on ! circle 8#hh days40 ,at ! c5tre y are to %[ ! 8,,sun40 ,?is circle gives ! track foll[$ by ,m]cury 9 its j\rney r\nd ! sun 9 ! p]iod ( #hh days4 ,next op5 y\r compasses to #a 941 :i* y mu/ d accurately by ! scale4 ,! circle drawn ) ?is radius %[s ! relative size ( ! pa? ( ,v5us1 & to indicate ! p]iodic "t1 y %\ld m>k x1 8#bbe days40 ,! next circle y h to draw is a v int]e/+ "o4 ,! compass is to be op5$ #b 94 ?is "t1 & ! pa? t x makes is to be m>k$ 8#cfe days40 ,?is %[s ! high road along :i* we ourselves j\rney e ye>1 along :i* we are1 inde$1 j\rney+ at ?is mom5t4 ,if y want$ to obta9 f y\r figure any notions ( ! true dim5sions ( ! sy/em1 ! pa? ( ! e>? w be ! mo/ conv5i5t means ( do+ s4 ,! e>? is #ic1jjj1jjj miles f ! sun1 & our draw+ %[s its orbit z a circle ( #b 94 radius4 ,x foll[s t ea* in* on our little scale w correspond to ab\t #cg1jjj1jjj miles4 ,z1 !re=e1 ! radius ( ! orbit ( ,m]cury has be5 tak5 to be "o in*1 x foll[s t ! di/ance ( ,m]cury f ! sun is ab\t #cg1jjj1jjj miles4 ,we h1 h[ev]1 /ill "o m circle to draw be=e we complete ?is little sket*4 ,! compass mu/ n[ op5 to f\r in*es1 & a circle :i* repres5ts ! orbit ( ,m>s is !n to be drawn4 ,we m>k on ?is 8#fhg days10 & ! inn] "p ( ! sol> sy/em is !n fully repres5t$4 ,y see1 ?is diagram %[s h[ our e>? is 9 e s5se a planet4 ,x happ5s t "o ( ! f\r planets revolves outside ! e>?'s pa?1 :ile !re are two inside4 ,by m>k+ ! days on ! circles :i* %[ ! p]iods ( ! planets1 y p]ceive t ! fur!r a planet is f ! sun1 ! long] is ! "t t x takes to g r\nd4 ,p]haps y w n be surpris$ at ?is1 = ! l5g? ( ! j\rney is1 ( c\rse1 great] 9 ! great] orbits2 b ?is consid]ation w n entirely expla9 ! augm5tation ( ! "t ( revolution4 ,! fur!r a planet is f ! sun1 ! m sl[ly does x actually move1 & !re=e1 = a d\ble reason1 ! l>g] orbit w take a long] "t4 ,f ,london to ,brighton is a mu* long] j\rney ?an f ,london to ,gre5wi*1 &1 !re=e1 ! j\rney by rail to ,brighton w1 ( c\rse1 be a long] "o ?an by rail to ,gre5wi*4 ,b suppose t y comp>$ ! railway j\rney to ,gre5wi* ) ! j\rney1 n by rail1 b by coa*1 to ,brighton1 "h ! comp>ative sl[ness ( ! coa* w\ld =m ano!r reason besides ! great] l5g? ( ! j\rney = mak+ ! ,brighton trip a mu* m t$i\s "o ?an t to ,gre5wi*4 ,m>s may be lik5$ to ! coa* :i* has to g all ! way to ,brighton1 :ile ,m]cury may be lik5$ to ! tra9 :i* flies along ov] ! v %ort j\rney to ,gre5wi*4 ,illu/ration3 ,,fig4 #dg4--;,comp>ative ,sizes ( ! ,planets4 ,we c easily %[ f our little sket* t ,m]cury mu/ be mov+ m quickly ?an ,m>s1 = ! radii ( ! two circles are respectively "o in* & f\r in*es1 & !re=e ! pa? ( ,m>s mu/ be f\r times z long z ! orbit ( ,m]cury4 ,if ,m>s mov$ z fa/ z ,m]cury1 he w\ld1 ( c\rse1 require only f\r times z _m days to complete 8 l>ge pa? z ,m]cury takes = 8 small pa?2 b f\r times #hh is #ceb1 &1 consequ5tly1 ,m>s ought to get r\nd 9 #ceb days if he mov$ z fa/ z ,m]cury does4 ,z a matt] ( fact1 ,m>s requires ne>ly twice t numb] ( days2 inde$1 no less ?an #fhg1 & h5ce we inf] t ! av]age spe$ ( ,m>s _c be mu* m ?an half t ( ,m]cury4 ,illu/ration3 ,,fig4 #dh4--,phases ( an ,inf]ior ,planet4 ,to appreciate duly ! position ( ! e>? ) reg>d to its bro!rs & si/]s 9 ! sun's family x w be necess>y to use y\r compasses 9 draw+ ano!r little sket*1 by :i* ! sizes ( ! f\r bodies !mselves %all be fairly repres5t$4 ,rememb] t ! la/ draw+ %[$ no?+ :atev] ab\t ! sizes ( ! bodies2 x m]ely exhibit$ ! dim5sions ( ! pa?s 9 :i* !y mov$4 ,z ,m]cury is ! smalle/ globe ( ! f\r1 we %all op5 ! compasses half an in* & describe a circle to repres5t x4 ,! e>? & ,v5us are s ne>ly ! same size 7?\gh ! e>? is a trifle ! l>g]7 t x is n necess>y to attempt to exhibit ! diff]5ce betwe5 !m1 s we %all repres5t bo? bodies by circles1 ea* #a in*es 9 radius4 ,m>s1 l ,m]cury1 is "o ( ! globes small] ?an ! e>?1 & ! circle t repres5ts x w h a radius ( ( an in*4 ,y %\ld draw ^! figures neatly1 & by a little %ad+ make !m look l globes4 ,x w\ld be bett] /ill if y 7 to make actual models1 tak+ c>e1 ( c\rse1 to give ea* ( !m ! exact size4 ,a comp>ative view ( ! pr9cipal planets is %[n 9 ,fig4 #dg4 ,,! ,,planet ,,m]cury4 ,quicksilv] is a bright & pretty metal1 &1 unlike e o!r metal1 x is a liquid "u ord9>y circum/ances4 ,if y spill quicksilv]1 x is a difficult task to ga!r ! liquid up aga94 ,x breaks into little drops1 & y _c easily lift !m ) y\r f+]s2 !y slip away & escape y\r grasp4 ,quicksilv] w run easily ?r\gh a hole s small t wat] w\ld h>dly pass1 & x is s heavy t an iron nail or a bun* ( keys w float ^u x4 ,n[1 ?is heavy1 bright1 nimble metal is kn[n by ano!r "n besides quicksilv]2 a *emi/ w\ld call x m]cury1 & ! a/ronom]s use exactly ! same ^w to d5ote a pretty1 bright1 nimble1 & heavy planet :i* seems to try to elude our vision4 ,?\gh ,m]cury is s h>d to see1 yet x 0 discov]$ s long ago1 t all record is lo/ ( :o ! discov]] 04 ,y mu/ take special pa9s if y want to see ! planet ,m]cury1 = dur+ ! great] "p ( ! ye> x is n to be se5 at all4 ,e n[ & !n a glimpse is to be _h1 b y mu/ be on ! al]t to look out j aft] sunset1 or y mu/ be up v e>ly 9 ! morn+ s z to see x j be=e sunrise4 ,m]cury is always f\nd to be 9 att5dance on ! sun1 s t y mu/ se>* = him ne> ! sun2 t is1 l[ d[n 9 ! we/ 9 ! ev5+s1 or l[ d[n 9 ! ea/ 9 ! morn+s4 ,to asc]ta9 ! prop] "t ( ! ye> at :i* to look = him y mu/ ref] to ! almanac4 ,we h se5 h[ ,m]cury revolves 9 a pa? inside t ( ,v5us1 & x is !re=e ne>] to ! sun4 ,inde$1 ,m]cury is s close to ! sun t x is g5]ally ov]p[]$ by 8 brilliance & _c be se5 at all4 ,l e o!r planet1 ,m]cury is light$ by ! sun's rays1 & %[s phases 9 ! telescope j z ! moon does 7,fig4 #dh74 ,9 ?is figure ! diff]5t app>5t sizes ( ! planet at diff]5t p>ts ( its pa? are %[n4 ,( c\rse ! ne>] ,m]cury is to ! e>? ! l>g] does x seem4 ,if we c only see ,m]cury s r>ely1 & if ev5 !n x is a v long way (f1 does x n seem /range t we c tell h[ heavy x is8 ,ev5 if we _h a pair ( scales big en\gh to hold a planet1 :at1 x may be ask$1 w\ld be ! use ( ! scales :5 ! body to be weigh$ 0 ab\t a hundr$ millions ( miles away8 ,( c\rse ! weigh+ ( a planet mu/ be conduct$ 9 "s mann] totally diff]5t f ! k9d ( weigh+ t we ord9>ily use4 ,a/ronom]s h1 h[ev]1 v>i\s me?ods = weigh+ ^! big globes1 ev5 ?\gh !y c nev] t\* !m4 ,we d n1 ( c\rse1 want to "k h[ _m p\nds1 or h[ _m millions ( tons !y conta92 !re is b little use 9 try+ to express ! weight 9 t way4 ,x gives no conception ( a planet's true importance4 ,"o _w mu/ be comp>$ ) ano!r _w1 & we !re=e e/imate ! weights ( ! o!r worlds by comp>+ !m ) t ( our own4 ,we accord+ly h to consid] ,m]cury plac$ beside ! e>?1 & to see :i* ( ! two bodies is ! bigg] & ! heavi]1 or :at is ! proportion betwe5 !m4 ,x s happ5s t ,m]cury1 view$ z a _w1 is a v small body4 ,x is a good deal less 9 size ?an our e>?1 & x is n ne>ly s massive4 ,to %[ y h[ we f\nd out ! mass ( ,m]cury ,i %all v5ture on a little /ory4 ,x w expla9 "o ( ! /range devices t a/ronom]s h to use :5 !y want to weigh a di/ant body 9 space4 ,!re 0 once1 & !re is /ill1 a little comet :i* flits ab\t ! sky2 we %all call x aft] ! "n ( its discov]]1 ,encke4 ,!re are sometimes spl5did comets :i* ev]ybody c see--we w talk ab\t ^! aft]w>ds--b ,encke is n su* a "o4 ,x is v fa9t & delicate1 b a/ronom]s are int]e/$ 9 x1 & !y always look out = x ) _! telescopes2 inde$1 !y c\ld n see ! poor little ?+ )\t !m4 ,encke goes = long j\rneys ?r\gh space--s f> t x becomes q invisible1 & rema9s out ( sight = two or ?ree ye>s4 ,all ?is "t x is te>+ along at a trem5d\s spe$4 ,if y 7 to take a ride on ! comet1 x w\ld :irl y along f> m swiftly ?an if y 7 sitt+ on a cannon-ball4 ,:5 ! comet has rea*$ ! end ( its j\rney1 !n x turns r\nd & returns by a diff]5t road1 until at la/ x comes ne> en\gh to %[ itself4 ,a/ronom]s give x all ! welcome !y c1 b x won't rema92 sometimes x w h>dly /ay long en\gh = u to obs]ve t x has come at all1 & sometimes x is s ?9 & worn aft] all its w&]+s t we are h>dly able to see x4 ,! comet nev] takes any re/2 ev5 dur+ its brief visit to u x is scamp]+ along all ! "t1 & !n aga9 x d>ts (f1 gradually to s9k into ! dep?s ( space1 :i!r ev5 our be/ telescopes _c foll[ x4 ,no m is !re to be se5 ( ,encke = ano!r ?ree ye>s1 :5 aga9 x w come back = a :ile4 ,encke is l ! cuckoo1 :i* only comes = a brief visit e spr+1 & ev5 !n is (t5 n he>d by _m :o de>ly love 8 welcome note2 b ,encke is a great] /rang] ?an ! cuckoo1 = ! comet nev] repeats 8 visit ( a few weeks m ?an once 9 ?ree ye>s2 & he is !n s %y t usually v few cat* a glimpse ( him4 ,an a/ronom] & a ma!matician 7 great fri5ds1 & !y us$ to help ea* o!r 9 _! "w4 ,! a/ronom] wat*$ ,encke's comet1 not$ exactly :]e x 01 on ea* night x 0 visible1 & !n told ! ma!matician all he _h se54 ,provid$ ) ?is in=mation ! ma!matician %>p5s 8 p5cil1 sits d[n at 8 desk1 & beg9s to "w long columns ( figures1 until at l5g? he discov]s h[ to make a "t table :i* %all set =? ! w&]+s ( ,encke4 ,he is able to v]ify ! accuracy ( 8 table 9 a v unmi/akable way by v5tur+ ^u prophecies4 ,! ma!matician pr$icts to ! a/ronom] ! v day & ! v h\r at :i* ! comet w reappe>4 ,he ev5 indicates ! v "p ( ! heav5s to :i* ! telescope mu/ be direct$1 9 ord] to greet ! w&]] on 8 return4 ,:5 ! "t comes ! a/ronom] f9ds t 8 fri5d has be5 a true prophet2 !re is ! comet on ! expect$ day1 & 9 ! expect$ con/ellation4 ,?is happ5s aga9 & aga91 s t ! ma!matician1 ) 8 p5cil & 8 figures1 m>ks /age by /age ! progress ( ,encke ?r\gh ! ye>s ( 8 invisible voyage4 ,at ea* mom5t he kn[s :]e ! comet is situat$1 ?\gh utt]ly unable to see x4 ,! jo9t labors ( ! two fri5ds hav+ ?us discov]$ law & ord] 9 ! movem5ts ( ! comet1 y may judge ( _! dismay :5 on "o occasion ,encke disappo9t$ !m4 ,he appe>$1 x is true1 b !n he 0 a little late1 & he 0 also n 9 ! spot :]e he 0 expect$4 ,!re 0 ne>ly be+ a s]i\s diff]5ce betwe5 ! two fri5ds4 ,! a/ronom] accus$ ! ma!matician ( hav+ made mi/akes 9 8 figures1 ! ma!matician retort$ t ! a/ronom] mu/ h made "s blund] 9 8 obs]vations4 ,a qu>rel 0 imm95t1 :5 f9ally x 0 sugge/$ to int]rogate ,encke himself1 & see :e!r he c\ld (f] any explanation4 ,! ma!matician employ$ peculi> me?ods t ,i c\ld n expla91 s ,i %all trans=m 8 processes into a dialogue betwe5 himself & ! (f5d+ comet4 8,y are late10 said he to ! comet4 8,y h n turn$ up at ! "t ,i expect$ y1 nor are y exactly 9 ! "r place2 nor1 inde$1 = t matt]1 are y n[ mov+ exactly z y ought to d4 ,9 fact1 y are entirely out ( ord]1 & :at explanation h y to give ( ?is irregul>ity80 ,y see ! que/ion] felt q confid5t t !re mu/ h be5 "s cause at "w t he did n "k (4 ,ma!maticians h "o great privilege2 !y are ! only p 9 ! _w :o nev] make any mi/akes4 ,if !y knew accurately all ! v>i\s influ5ces t 7 at "w on ! comet1 !y c\ld1 by work+ out ! figures1 h f\nd exactly :]e ! comet w\ld be plac$4 ,if ! comet 0 n !re1 x is inevitable t !re mu/ h be5 some?+ or o!r act+ ^u ! comet1 ( :i* ! ma!matician 0 9 ignorance4 ,! comet1 l e o!r transgressor1 imm$iately began to make excuses1 & to %uffle (f ! blame on somebody else4 8,i 010 said ,encke1 8go+ quietly on my r\nds z usual4 ,i 0 foll[+ out /age by /age ! track t y "k s well1 & ,i w\ld c]ta9ly h complet$ my j\rney & h arriv$ "h 9 good "t & 9 ! spot :]e y expect$ me _h ,i be5 let alone1 b un=tunately ,i 0 n let alone4 ,9 ! c\rse ( my long travels--b at a "t :5 y c\ld n h se5 me--,i _h ! mis=tune to come v close to a planet1 ( :i* ,i d>e say y h he>d--x is call$ ,m]cury4 ,i did n want to int]f]e ) ,m]cury2 ,i 0 only anxi\s to hurry pa/ & keep on my j\rney1 b he 0 m$dlesome1 & began to pull me ab\t1 & ,i _h a great deal ( tr\ble to get free f him1 b at la/ ,i did %ake him (f4 ,i kept my pace z well z ,i c\ld aft]w>ds1 b ,i c\ld n make up ! lo/ "t1 & consequ5tly ,i am "h a little late4 ,i "k ,i am n j :]e ,i ought to be1 nor am ,i n[ mov+ q z y expect me to d2 ! fact is1 ,i h n yet q recov]$ f ! bad treatm5t ,i h exp]i5c$40 ,! a/ronom] & ! ma!matician proce$$ to te/ ?is /ory4 ,!y f\nd out :at ,m]cury 0 do+2 !y knew :]e he 0 at ! "t1 & !y asc]ta9$ t :at ! comet _h said 0 true1 & t x _h come v close inde$ to ! planet4 ,! a/ronom] 0 q satisfi$1 & 0 propos+ to turn to "s o!r matt]1 :5 ! ma!matician said3-- 8,t>ry a mom5t1 my fri5d4 ,x is ! "p ( a wise man to extract special b5efit f mi%aps & disa/]s4 ,let u see :e!r ! tribulations ( poor ,encke _c be made to af=d "s v valuable in=mation4 ,we expect$ to f9d ,encke "h4 ,well1 he is n "h--he is !re1 a little way (f4 ,let u measure ! di/ance betwe5 ! place :]e ,encke is1 & ! place :]e he ought to h be540 ,?is ! a/ronom] did4 8,well10 he said1 8:at w ?is tell y8 ,x m]ely expresses ! am\nt ( del9qu5cy on ! "p ( ,encke40 8,no d\bt10 said ! ma!matician1 8t is s2 b we mu/ rememb] t ! del9qu5cy1 z y call x1 0 caus$ by ,m]cury4 ,! bigg] & ! heavi] ,m]cury 01 ! great] w\ld be 8 p[] ( do+ mis*ief1 ! m w\ld he h tr\bl$ poor ,encke1 & ! l>g] w\ld be ! d]angem5t ( ! comet 9 consequ5ce ( ! un=tunate incid5t4 ,we h measur$ h[ mu* ,encke has actually be5 l$ a/ray4 ,_h ,m]cury be5 heavi] ?an he is1 t di/ance w\ld h be5 l>g]2 & if ,m]cury _h be5 light] ?an he is1 y w\ld n1 ( c\rse1 h f\nd s l>ge an error 9 ! comet40 ,we may illu/rate :at is meant 9 ?is way4 ,a /eam] sails f ,liv]pool to ,new ,york1 & 9 favorable circum/ances ! voyage across ! ,atlantic %\ld be accompli%$ )9 a week4 ,b suppos+ t 9 ! middle ( ! ocean a /orm is enc\nt]$1 by :i* ! %ip is driv5 f h] c\rse4 ,%e w1 ( c\rse1 be delay$1 & h] voyage w be l5g!n$4 ,a trifl+ /orm1 p]haps1 %e w n m9d1 b a heavy /orm might delay h] six h\rs2 a /ill great] /orm might keep h] back half a day2 :ile cases are n infrequ5t 9 :i* ! delay has am\nt$ to "o day1 or two days1 or ev5 m4 ,! delay :i* ! %ip has exp]i5c$ may be tak5 z a measure ( ! vehem5ce ( ! /orm4 ,i am n suppos+ t h] ma*9]y has brok5 d[n2 ( c\rse1 t sometimes happ5s at sea1 z d calamities ( a f> m tragic nature4 ,i am m]ely suppos+ ! %ip to be expos$ to v heavy wea!r1 f :i* %e em]ges j z s\nd z %e 0 :5 ! /orm began4 ,9 su* cases z ?is we may reasonably measure ! int5sity ( ! /orm by ! numb] ( h\rs' delay to :i* ! pass5g]s 7 subject$4 8,! wea!r we _h 0 mu* worse ?an ! wea!r y _h10 "o travell] may say to ano!r4 8,our %ip 0 two days late1 :ile y escap$ ) a loss ( "o day40 ,:5 ! comet at la/ return$ to ! e>? aft] a cruise ( ?ree ye>s ?r\gh space1 ! numb] ( h\rs by :i* x 0 late express$ ! vehem5ce ( ! /orm x exp]i5c$4 ,! only /orm t ! comet w\ld h met )1 at lea/ 9 s f> z our pres5t object is conc]n$1 0 ! tr\ble t x _h ) ,m]cury4 ,! mass ( ,m]cury 01 !re=e1 involv$ 9 ! delay ( ! comet4 ,9 fact1 ! delay 0 a measure ( ! mass ( ! planet4 ,i d n attempt to describe to y all ! long "w ?r\gh :i* ! ma!matician _h to plod be=e he c\ld asc]ta9 ! mass ( ,m]cury4 ,x 0 a v t$i\s & a v h>d sum1 b at la/ 8 calculations arriv$ at ! answ]1 & %[$ t ,m]cury mu/ be a light globe comp>$ to ! e>?4 ,9 fact1 x w\ld take tw5ty-five globes1 ea* equal to ,m]cury1 to weigh z mu* z ! e>?4 ,i d>e say y w ?9k t ?is 0 a v long & r\ndab\t way ( weigh+4 ,suppos+1 h[ev]1 we _h to weigh a m\nta91 or r a body :i* 0 bigg] ?an fifty ?\s& m\nta9s1 & :i* 0 also _m millions ( miles away1 all sorts ( exp$i5ts w\ld h to be resort$ to4 ,i h told y "o ( !m4 ,if y feel any d\bts z to ! accuracy ) :i* su* weigh+s c be made1 !n ,i mu/ tell y t !re are _m o!r me?ods1 & t ^! all agree 9 giv+ concordant results4 ,illu/ration3 ,,fig4 #di4--,relative ,weights ( ,m]cury & ! ,e>?4 ,we h>dly "k any?+ z to :at ! globe ( ,m]cury may be l4 ,we c see little or no?+ ( ! nature ( its surface4 ,we only p]ceive ! planet to be a ball1 brightly light$ by ! sun1 & we _c satisfactorily disc]n p]man5t features !reon1 z we are able to d on "s ( ! o!r planets4 ,,! ,,planet ,,v5us4 ,y w h no difficulty 9 recogniz+ ,v5us1 b y mu/ *oose ! "r "t to look out = h]4 ,9 ! fir/ place1 y ne$ nev] expect to see ,v5us v late at night4 ,y %\ld look = ! planet 9 ! ev5+1 z soon z x is d>k1 t[>ds ! we/1 or 9 ! morn+1 a little be=e sunrise1 t[>ds ! ea/4 ,i d n1 h[ev]1 say t y c always see ,v5us1 ei!r be=e sunrise or aft] sunset4 ,9 fact1 = a l>ge "p ( ! ye>1 ?is planet is n to be se5 at all4 ,y %\ld !re=e consult ! almanac1 & unless y f9d t ,v5us is /at$ to be an ev5+ /> or a morn+ />1 y ne$ n tr\ble to se>* = x4 ,i may1 h[ev]1 tell y t ,v5us c nev] be an ev5+ /> & a morn+ /> at ! same "t4 ,if y c see x ?is ev5+ aft] sund[n1 !re is no use 9 gett+ up e>ly 9 ! morn+ to look out = x aga94 ,! planet w rema9 = sev]al weeks a spl5did object aft] sunset1 & !n w gradually disappe> f ! we/1 & 9 a c\ple ( mon?s lat] w be ! morn+ /> 9 ! ea/4 ,v5us requires a ye> & sev5 mon?s to run ?r\gh h] *anges1 s t if y f9d h] a bright ev5+ /> to-night1 y may feel sure t %e 0 a bright ev5+ /> a ye> & sev5 mon?s ago1 & t %e w be a bright ev5+ /> 9 a ye> & sev5 mon?s to come4 ,nor mu/ y ev] expect to see h] "r ov]head2 %e is always to ! we/ or to ! ea/4 ,! spl5dor ( ,v5us1 :5 at h] be/1 w prev5t y at su* times f mi/ak+ ?is planet = an ord9>y />4 ,%e is !n m ?an tw5ty times z bright z any /> 9 ! heav5s4 ,! mo/ conclusive pro( ( ! unrivall$ brightness ( ,v5us is f\nd 9 ! fact t %e c be recogniz$ 9 broad daylight )\t a telescope4 ,ev5 on ! brighte/ ,june aft]noons ! lovely planet is sometimes to be disc]n$ l a morsel ( :ite cl\d on ! p]fect azure ( ! sky4 ,v5us is s brilliant t p]haps y w h>dly cr$it me :5 ,i tell y t %e has no m light ( h] own ?an has a /one or a h&ful ( e>?1 or a button4 ,is x possible t ?is is ! case1 y w say1 = z we see ! planet s exquisitely beautiful1 h[ c %e be m]ely a huge /one high up 9 ! heav5s8 ,! fact is t ,v5us %9es by light n h] own1 b by light :i* falls ^u h] f ! sun4 ,%e is light$ up j z ! moon1 or j z our own e>? is light$4 ,h] radiance m]ely arises f ! sunbeams :i* fall ^u h]4 ,x seems at fir/ surpris+ t m]e sunbeams on ! planet c give h] ! brilliancy t is sometimes s attractive4 ,let me %[ y an illu/ration :i* w1 ,i tru/1 conv9ce y t sunbeams w be adequate ev5 = ! glory ( ,v5us4 ,"h is a button4 ,i hang x by a piece ( f9e ?read1 & :5 ,i dip x into ! beam f ! electric lamp1 look at ! brilliancy ) :i* ! mimic planet glitt]s4 ,y _c see ! %ape ( ! button2 x is too small = t2 y m]ely see x z a brilliant gem1 radiat+ light all ar\nd4 ,!re=e1 we ne$ n be surpris$ to le>n t ! brilliancy ( ! ev5+ /> is borr[$ f ! sun1 & t if1 :ile we are look+ at ! planet 9 ! ev5+1 ! sun 7 to be sudd5ly ext+ui%$1 ! planet w\ld also vani% f view1 ?\gh ! />s w\ld %9e z be=e4 ,?us we expla9 ! appe>ance ( ,v5us4 ,! ev5+ /> is a beautiful1 lum9\s po9t1 b x has no %ape :i* c be disc]n$ ) ! unaid$ eye4 ,:51 h[ev]1 ! telescope is turn$ t[>ds ,v5us we h ! delightful spectacle ( a t9y moon1 :i* goes ?r\gh its phases j z does our own satellite4 ,:5 fir/ se5 z an ev5+ /> ,v5us w (t5 be l ! moon at ! qu>t]1 & !n x w pass to ! cresc5t %ape4 ,!n ! cresc5t becomes gradually ?9n]1 & next w foll[ a brief p]iod ( invisibility be=e ! appe>ance ( ,v5us z ! morn+ />4 ,x seems at fir/ a little /range t ,v5us :5 brighte/ %\ld n be full l ! moon1 :i* 9 simil> circum/ances is1 ( c\rse1 a complete circle ( light4 ,! planet1 h[ev]1 has a v m>k$ cresc5t-%ap$ =m 9 ^! circum/ances4 ,b at ?is "t ! planet is s ne> u t ! ga9 ( brilliancy f ! dim9ution ( di/ance m ?an comp5sates = ! small "p ( ! illum9at$ side :i* is turn$ t[>ds u4 ,y ought all to try to get "s "o to %[ y ,v5us ?r\gh a telescope4 ,a v l>ge in/rum5t is n necess>y1 & ,i feel sure y w be delight$ to see ! beautiful moon-%ap$ planet4 ,y w !n h no difficulty 9 und]/&+ h[ ! brightness ( ! planet has come f ! sun4 ,! *anges 9 ! cresc5t m]ely dep5d ^u ! proportion ( ! illum9at$ side :i* is turn$ t[>ds u4 ,7 ,v5us itself a sunlike body we %\ld1 ( c\rse1 see no cresc5t1 b only a bright circle ( light4 ,9 ,fig4 #ej y w notice an imag9>y picture ( a "y a/ronom] survey+ ,v5us ) a telescope4 ,i h n1 z is obvi\s1 attempt$ to %[ ! diff]5t objects 9 _! prop] proportions4 ,! sun is suppos$ to h set1 s t 8 beams d n rea* ! a/ronom]4 ,night has begun at 8 obs]vatory2 b ! sunbeams fall on ,v5us1 & light h] up on t side turn$ t[>ds ! sun4 ,a "p ( ?is light$ side is1 ( c\rse1 se5 by ! telescope :i* ! a/ronom] is us+1 & ?us ! planet seems to him l a cresc5t ( light4 ,illu/ration3 ,,fig4 #ej4--,to %[ t ,v5us %9es by ,sunlight4 ,,! ,,transit ,,( ,,v5us4 ,we might naturally ?9k f ,fig4 #df t ,v5us mu/ pass at e revolution directly betwe5 ! e>? & ! sun2 & !re=e x might appe> t :at is call$ ! transit ( ,v5us across ! sun ought to occur e "t betwe5 ! appe>ance ( ! planet z ! ev5+ /> & ! next foll[+ appe>ance z ! morn+ />4 ,no d\bt on ea* ( ^! occasions ,v5us seems to approa* ! sun closely2 b ! orbits ( ,v5us & ! ,e>? d n lie q 9 ! same plane1 & h5ce ! planet usually passes j ov] or j "u ! sun1 s t x is a v r>e ev5t inde$ = h] to come "r 9 front ( ! sun4 ,b ?is does sometimes happ54 ,x happ5$1 = in/ance1 9 ! ye> #ahgd1 & aga9 9 ! ye> #ahhb2 b1 alas6 ,i _c hold out to y ! prospect ( ev] see+ ano!r su* spectacle4 ,!re w be no fur!r occurr5ce ( ! transit ( ,v5us until ! ye> #bjjd1 ?\gh !re w be ano!r eight ye>s lat]1 9 #bjab4 ,x seems r odd t "o transit ( ,v5us %\ld be foll[$ by ano!r aft] an int]val ( eight ye>s1 & t !n a p]iod ( mu* m ?an a c5tury %\ld h to elapse be=e !re w be a repetition ( a simil> pair4 ,?is is 9 consequ5ce ( a curi\s relation betwe5 ! motion ( ,v5us & ! motion ( ! ,e>?1 :i* ,i mu/ endeavor to expla9 ) ! help ( a little illu/ration4 ,let u suppose a clock ) ord9>y numb]s r\nd ! dial1 b s arrang$ t ! sl[ly mov+ %ort h& requires #cfe4bf days to complete "o revolution r\nd ! dial1 :ile ! m rapidly mov+ long h& revolves 9 #bbd4gj days4 ,! %ort h& w !n g r\nd once 9 a ye>1 & ! long h& once dur+ ! revolution ( ,v5us4 ,let u suppose t bo? h&s />t toge!r f ,,xii1 !n 9 #bbd4gj days ! long h& is r\nd to ,,xii aga91 b ! %ort h& w h only advanc$ to ab\t ,,vii1 & by ! "t x rea*es ,,xii ! long h& w h complet$ a l>ge "p ( a second circuit4 ,x happ5s t ! two numb]s #bbd4gj & #cfe4bf are v ne>ly 9 ! ratio ( #h to #ac4 ,9 fact1 if ! numb]s _h only be5 #bbd4h & #cfe4c respectively1 !y w\ld be exactly 9 ! proportion ( #h to #ac4 ,x1 !re=e1 foll[s t eight revolutions ( ! %ort h& mu/ occupy v ne>ly ! same "t z ?irte5 revolutions ( ! long h&4 ,aft] eight ye>s ! %ort h& w ( c\rse be f\nd aga9 at ,,xii2 & at ! same mom5t ! long h& w also be back at ,,xii1 aft] complet+ ?irte5 revolutions4 ,we c n[ und]/& :y ! transits1 :5 !y d occur1 g5]ally arrive 9 pairs at an int]val ( eight ye>s4 ,suppose t at a c]ta9 "t ,v5us happ5s to int]pose itself directly betwe5 ! e>? & ! sun1 !n1 :5 eight ye>s h elaps$1 ! e>? is1 ( c\rse1 re/or$ = ! eigh? "t s9ce ! fir/ transit to ! same place1 & ,v5us has return$ to almo/ ! same spot = ! ?irte5? "t4 ,! two bodies are practically 9 ! same condition z !y 7 at fir/1 &1 !re=e1 ,v5us aga9 int]v5es1 & ! planet is beheld z a black spot on ! sun's surface4 ,we mu/ n pu% ?is argum5t too f>2 ! relation betwe5 ! two p]iods ( revolution1 ?\gh ne>ly1 is n exactly #h to #ac4 ,! consequ5ce is t :5 ano!r eight ye>s h elaps$1 ! planet passes a little above ! sun or a little bel[ ! sun1 & ?us a ?ird occurr5ce ( ! transit is avoid$ = m ?an a c5tury4 ,! next transit w take place at ! opposite side ( ! pa?4 ,we 7 =tunate en\gh to be able to see ! transit ( ,v5us 9 #ahhb f ,great ,brita94 ,p]haps ,i %\ld say a "p ( ! transit1 = ! sun _h set long be=e ! planet _h f9i%$ its j\rney across ! disk4 ,v5us look$ l a small r\nd black spot1 /eal+ 9 on ! bright surface ( ! sun & gradually advanc+ along ! %ort *ord t =m$ its track4 ,illu/ration3 ,,fig4 #ea4--,v5us 9 ,transit across ! ,sun4 ,an imm5se deal ( tr\ble 0 tak5 9 #ahhb1 z well z 9 #ahgd1 to obs]ve ?is r>e occurr5ce4 ,exp$itions 7 s5t to v>i\s places ov] ! e>? :]e ! circum/ances 7 favorable4 ,inde$1 ,i d n suppose t !re 0 ev] any o!r cele/ial ev5t ab\t :i* s mu* int]e/ 0 creat$4 ,! reason :y ! ev5t attract$ s mu* att5tion 0 n solely on acc\nt ( its beauty or its s+ul>ity2 x 0 because ! transit ( ,v5us af=ds u a valuable means ( le>n+ ! di/ance ( ! sun4 ,:5 obs]vations ( ! transit ( ,v5us made at opposite sides ( ! e>? are br\ght toge!r1 we are enabl$ to calculate f !m ! di/ance ( ,v5us1 & kn[+ t1 we c f9d ! di/ance ( ! sun & ! di/ances & ! sizes ( ! planets4 ,?is is v valuable in=mation2 b y w\ld h to read "s r h>d books on a/ronomy if y want$ to und]/& cle>ly h[ x is t ! transit ( ,v5us tells u all ^! wond]ful ?+s4 ,i may1 h[ev]1 say t ! pr9ciple ( ! me?od is really ! same z t m5tion$ on pp4 #ai-be4 ,:5 y rememb] t n we ourselves1 nor our *ildr51 & h>dly our gr&*ildr51 w ev] be able to see ano!r transit ( ,v5us1 y w1 p]haps1 n be surpris$ t we tri$ to make ! mo/ ( su* transits z h occurr$ 9 our "t4 ,,v5us ,,z ,a ,,_w4 ,?\gh ,v5us exhibits su* pretty cresc5ts 9 ! telescope1 yet ,i mu/ say t 9 o!r respects a view ( ! planet is r disappo9t+4 ,v5us is adorn$ by su* a v bright dress ( sunbeams t we c see b little m ?an ^? sunbeams1 & we c h>dly make out any?+ ( ! actual nature ( ! planet itself4 ,we c sometimes disc]n fa9t m>ks ^u ! globe1 b x is impossible ev5 to make a conjecture ( :at ! ,v5us c\ntry is l4 ,?is is greatly to be regrett$1 = ,v5us approa*es comp>atively close to ! e>?1 & is a _w s l our own 9 size & o!r circum/ances t we feel a legitimate curiosity to le>n some?+ m ab\t h]4 ,b ! m>ks on ! planet1 ?\gh v fa9t1 are /ill suffici5tly def9ite to h enabl$ "s %>p-sight$ a/ronom]s to answ] a "q ( mu* int]e/4 ,!y h made x pla9 t 9 "o mo/ important respect ,v5us is v unlike our ,e>?4 ,our globe1 ( c\rse1 rotates on its axis once ea* day1 b ,v5us requires no less ?an #bbe days to complete ea* rotation4 ,9 fact1 ?is planet rotates 9 su* a fa%ion t %e always keeps ! same face to ! sun4 ,! inhabitants ( ,v5us w !re=e f9d t x is p]5nial day on "o side ( ?is globe & ev]la/+ night on ! o!r4 ,v5us is "o ( ! few globes :i* might conceivably be ! abode ( be+s n v widely diff]5t f ourselves4 ,9 "o condition especially--namely1 t ( weight--%e resembles ! e>? s closely t ^? bodies :i* we actually possess w\ld probably be adapt$1 s f> z /r5g? is conc]n$1 = a resid5ce on ! si/] planet4 ,our pres5t muscles w\ld n be unnecess>ily /rong1 z !y w\ld be on ! moon1 nor %\ld we f9d !m too weak1 z !y w\ld c]ta9ly prove to be 7 we plac$ on "o ( ! v heavy bodies ( our sy/em4 ,nor ne$ ! temp]ature ( ,v5us be reg>d$ z pres5t+ any insup]able difficulties4 ,%e is1 ( c\rse1 ne>] to ! sun ?an we are1 b !n climate dep5ds on o!r conditions besides ne>ness to ! sun1 s t ! "q z to :e!r ,v5us w\ld be too hot = our abode c\ld n be readily decid$4 ,! composition ( ! atmosph]e surr\nd+ ! planet w\ld be ! mo/ mat]ial po9t 9 decid+ :e!r t]re/rial be+s c\ld live !re4 ,i ?9k x to be 9 ! highe/ degree unlikely t ! atmosph]e ( ,v5us %\ld *ance to suit u 9 ! requisite p>ticul>s1 & !re=e ,i ?9k !re is n mu* likelihood t ,v5us is inhabit$ by any m51 wom51 or *ildr5 resembl+ ^? on ?is e>?4 ,,! ,,planet ,,m>s ,,& ,,8 ,,movem5ts4 ,! pa? ( ! e>? lies betwe5 ! orbits ( ! planets ,v5us & ,m>s4 ,x is natural = u to endeavor to le>n :at we c ab\t our neighbors4 ,we ought to "k some?+1 at all ev5ts1 z to ! p :o live next door to u on ea* side4 ,i h1 h[ev]1 already said t we _c obs]ve v mu* ^u ,v5us4 ,! case is v diff]5t ) respect to ,m>s4 ,he is a planet :i* we are =tunately enabl$ to /udy m9utely1 & he is full ( int]e/ :5 we exam9e him ?r\gh a good telescope4 ,! "r season = obs]v+ ,m>s mu/1 ( c\rse1 be await$1 z he is n always visible4 ,su* seasons recur ab\t e two ye>s1 & !n = mon?s toge!r ,m>s w be a brilliant object 9 ! skies e night4 ,nor has ,m>s necess>ily to be s\ght 9 ! e>ly morn or imm$iately aft] sunset1 9 ! mann] we h already describ$ = ,v5us & ,m]cury4 ,at ! "t ,m>s is at 8 be/ he comes into ! highe/ position at midnight1 & he c g5]ally be se5 = h\rs be=e1 & be foll[$ = h\rs subsequ5tly4 ,y may1 h[ev]1 f9d "s difficulty 9 recogniz+ him4 ,y probably w\ld n at fir/ be able to di/+ui% ,m>s f a fix$ />4 ,no d\bt ?is planet is a ruddy object1 b "s />s are also ruddy1 & ?is is at ! be/ a v insecure *>act]i/ic = id5tification4 ,i _c give y any m g5]al directions1 except t y %\ld get y\r papa to po9t out ,m>s to y ! next "t x is visible4 ,x is j conceivable t papa himself might n "k h[ to f9d ,m>s4 ,if s1 ! soon] he gets a set ( /> maps & beg9s to tea* himself & to tea* y1 ! bett] x w be = y bo?4 ,m>s1 ?\gh app>5tly s l a />1 diff]s 9 "s ess5tial po9ts f any /> 9 ! sky4 ,! />s prop] are all fix$ 9 ! con/ellations1 & !y nev] *ange _! relative positions4 ,! gr\ps :i* =m ! ,great ,be> or ! ,belt ( ,orion d n alt]1 !y are j ! same n[ z !y 7 c5turies ago4 ,b ! case is v diff]5t ) a planet su* z ,m>s4 ,! v ^w planet means a w&]]1 & x is ju/ly appli$1 because ,m>s1 in/ead ( /ay+ p]man5tly 9 any "o con/ellation1 goes con/antly roam+ f "o gr\p to ! o!r4 ,he is a v re/less body2 sometimes he pays 8 respects to ! heav5ly ,tw9s1 & is f\nd ne> ,ca/or & ,pollux 9 ,gem9i1 !n he goes (f & has a brief soj\rn ) ! ,bull1 b x looks z if t fi]ce animal got tir$ ( 8 company & hunt$ him (f to ! ,lion4 ,8 qu>t]s !n become /ill m critical4 ,sometimes x looks z if he desir$ to seek = peace b5ea? ! wat]s1 & s he visits ,aqu>ius1 :ile at o!r times he is f\nd 9 dang]\s proximity to ! claws ( ! ,crab4 ,m>s _c ev5 make up 8 m9d to run /eadily r\nd ! heav5s 9 "o direction2 sometimes he w bolt (f rapidly1 !n pause = a :ile1 & turn back aga92 !n ! orig9al impulse w return1 & he w resume 8 j\rney 9 ! direction he at fir/ int5d$4 ,x is no wond] t ,i am n able to give y v explicit directions z to h[ y may secure a sight ( a truant ^: w&]+s are app>5tly s unc]ta94 ,yet !re is a def9ite ord] und]ly+ all 8 movem5ts4 ,a/ronom]s1 :o make x _! bus9ess to /udy ! movem5ts ( ,m>s1 c foll[ him on 8 way2 !y "k exactly :]e he is n[1 & :]e he w be e night = ye>s & ye>s to come4 ,! p :o make ! almanacs come to ! a/ronom]s & get h9ts f !m z to :at ,m>s int5ds to d1 s t ! almanacs ann\nce ! positions 9 :i* ! planet w be f\nd ) z mu* regul>ity z if he 0 9 ! habit ( behav+ ) ! ord]ly propriety ( ! sun or ! moon4 ,we mu/ n lay all ! blame on ,m>s = ! ecc5tricities ( 8 movem5ts4 ,our e>? is to a v l>ge ext5t responsible4 ,:at we ?9k to be ,m>s' vag>ies are (t5 to be expla9$ by ! fact t we ourselves on ! e>? are rapidly %ift+ ab\t & alt]+ our po9t ( view4 ,illu/ration3 ,,fig4 #eb4--;,h[ ! ,tree seems to move ab\t4 ,i 0 driv+ d[n a pretty c\ntry road ) a little girl ?ree ye>s old beside me1 :5 ,i 0 address$ ) ! little rem>k1 8,look at ! tree go+ ab\t 9 ! field40 ,n[1 y or ,i1 ) our long] exp]i5ce ( ! _w ar\nd u1 "k t x is n ! cu/om ( trees to take !mselves up & walk ab\t ! fields4 ,b ?is 0 :at ?is little girl saw1 or r :at %e ?\ght %e saw2 & v (t5 :at we d see is some?+ v diff]5t f :at we ?9k we see4 ,we ?9k we see ,m>s p]=m+ all ^! extraord9>y movem5ts1 z ! little girl ?\ght %e saw ! tree mov+ ab\t4 ,b j z t little girl1 :5 %e grew to be a big girl1 f\nd t :at %e ?\ght 0 a tree walk+ across ! field mu/ really h "s q diff]5t explanation1 s we1 too1 f9d t :at ,m>s seems to d is "o ?+1 & :at ,m>s actually does is q ano!r ?+4 ,let u see :at ! little girl notic$4 ,%e 0 look+ at ! tree1 & fir/ %e saw x on "o side ( ! h\se1 & !n %e saw x on ! opposite side 7,fig4 #eb74 ,if x _h be5 a c[ in/ead ( a tree1 ( c\rse ! natural supposition w\ld h be5 t ! c[ _h walk$4 ,our little fri5d may1 p]haps1 h ?\ght x unusual = a tree to walk1 b /ill %e saw ! und\bt$ fact t ! tree _h %ift$ to ! o!r side ( ! h\se1 & !re=e1 p]haps1 rememb]+ :at ! c[ c\ld d1 %e said ! tree _h mov$4 ,illu/ration3 ,,fig4 #ec4--;,a ,specim5 ( ! ,track ( ,m>s4 ,! little girl did n /op to reflect t %e h]self _h entirely *ang$ h] position1 & h5ce arose ! surpris+ ph5om5on ( a tree t c\ld move ab\t4 ,y w und]/& ?is1 at once1 f ! two positions ( ! c> "h %[n4 ,9 ! fir/ position1 z ! girl looks at ! tree1 ! dott$ l9e %[s ! direction ( h] glance1 & ! o!r dott$ l9e %[s h[ ! app>5t places ( ! tree & ! h\se h alt]$4 ,x is h] *ange ( place t has accompli%$ ! trans=mation4 ,obs]ve also t ! tree appe>$ to h] to move 9 ! direction opposite to t 9 :i* %e is go+4 ,m>s g5]ally appe>s to move r\nd among ! />s f we/ to ea/4 ,9 fact1 if we 7 view+ him f ! sun he w\ld always seem to move 9 ?is mann]4 ,b at c]ta9 seasons our e>? is mov+ v fa/ pa/ ,m>s1 & ?is w make him appe> to move 9 ! opposite direction4 ,?is app>5t motion is sometimes s mu* 9 excess ( 8 real motion1 t x may give u an entirely incorrect idea ( :at ! planet is actually do+4 ,?us1 not)/&+ t ,m>s is mov+ "o way1 he may appe> to u :o dwell on ! e>? to be go+ 9 ! opposite way4 ,?is illusion only happ5s = a %ort "t1 j :5 we are pass+ ,m>s1 z we d e two ye>s4 ,! effect on ! planet is to make ! pa? he pursues at ?is "t some?+ l t %[n 9 ,fig4 #ec4 ,! planet is ne>e/ to u at ! "t he is mov+ 9 ?is loop4 ,he is !n to be se5 at 8 be/ 9 ! telescope1 s t x is especially int]e/+ to wat* ,m>s ?r\gh ?is critical "p ( 8 c>e]4 ,i want to %[ y h[ to make a little calculation :i* w expla9 ! law by :i* ! seasons :5 we c see ,m>s be/ w foll[ ea* o!r4 ,! p]iod he requires = a voyage r\nd ! sun is n q two ye>s1 = t w\ld be #gcj days1 & ,m>s only takes #fhg days = 8 j\rney4 ,x is1 h[ev]1 true t #a-ae_/ag ye>s is v ne>ly ! p]iod ( ,m>s4 ,h5ce1 e #cb ye>s ,m>s w complete #ag r\nds4 ,f ?is we %all be able to see h[ long x w take aft] ! e>? once passes ,m>s be=e !y pass aga94 ,i %all suppose !re is a circul> c\rse1 ar\nd :i* two boys />t toge!r to run a race4 ,"o ( ^! boys is su* a good runn] t he w get q r\nd 9 #ag m9utes2 b ! o!r boy c h>dly run m ?an half z quickly1 = he w require #cb m9utes to complete "o circle4 ,"h !n is ! "q4 ,suppose ! two boys to />t toge!r3 h[ long w x be be=e ! fa/] runn] ga9s "o complete circuit on ! o!r8 ,by ! "t ! good runn] 7,a7 has complet$ "o circuit1 ! bad runn] 7,b7 has only got a little m ?an halfway4 ,:5 ,a has complet$ 8 second circuit1 he has1 ( c\rse1 run = twice #ag m9utes--t is1 = #cd m9utes4 ,?is is two m9utes long] ?an ! "t ,b requires to get r\nd once2 !re=e ,b is only ahead by a di/ance :i* ,a c\ld cov] 9 ab\t "o m9ute2 b ,b w h advanc$ dur+ ?is m9ute a di/ance = :i* ,a w require ano!r half-m9ute1 dur+ :i* ,b cov]s a di/ance = :i* ,a w ne$ a fur!r qu>t]1 & s on4 ,b all ^! int]vals--"o m9ute1 half a m9ute1 a qu>t] ( a m9ute1 "o-eigh?1 "o-sixte5?1 & s on--add$ toge!r am\nt to two m9utes1 & h5ce x foll[s t ,b w n be ov]tak5 until ab\t two m9utes aft] ,a has complet$ 8 second r\nd--t is1 9 #cf m9utes altoge!r4 ,we c pass f ?is illu/ration to ! case ( ! planet ,m>s & ! e>?4 ,! orbit ( ! e>? is trav]s$ 9 a ye>1 & !re=e1 aft] ! e>? has once pass$ ,m>s1 :i* is !n1 z a/ronom]s w\ld say1 9 opposition1 ab\t two ye>s & ! eigh? ( a ye>--t is1 two ye>s & six or sev5 weeks--w elapse be=e ,m>s is aga9 favorably plac$4 ,y w ?us see t we ne$ n expect to obs]ve ,m>s "u ! be/ conditions e ye>4 ,besides1 ! di/ance ( ! planet f ! e>? at opposition v>ies s greatly t "s oppositions are m favorable ?an o!rs4 ,! "t has come :5 ,i mu/ tell y some?+ ab\t ! %apes ( ! pa?s 9 :i* ! e>? & ! o!r planets p]=m _! great j\rneys r\nd ! sun4 ,p]haps y w ?9k t ,i am go+ to contradict "s ( ! ?+s t ,i h told y be=e4 ,i h (t5 repres5t$ ! orbits ( ! planets z circles1 & n[ ,i am go+ to tell y t ?is is n correct4 ,! fact is t ! pa?s are ne>ly circles2 b1 /ill1 !re is "s dep>ture f ! exact circul> %ape4 ,m>s1 9 p>ticul>1 moves 9 a pa? :i* is m diff]5t f a circle ?an ! pa? ( ! e>?1 & consequ5tly x is appropriate to introduce ?is subject :5 we are engag$ ab\t ,m>s4 ,illu/ration3 ,,fig4 #ed4--;,h[ to draw an ,ellipse4 ,we mu/ fir/ take ano!r lesson 9 draw+1 & ! appliances ,i want y to use = ! purpose are v simple4 ,y mu/ h a smoo? bo>d & "s tacks or draw+-p9s1 besides pap]1 p5cil1 & tw9e4 ,illu/ration3 ,,fig4 #ee4--,specim5s ( ,ellipses4 ,we fir/ lay a %eet ( pap] on ! bo>d1 & !n put 9 two tacks ?r\gh ! pap] & into ! bo>d4 ,x does n mu* matt] :]e we put !m 94 ,next we take a piece ( tw9e & tie ! two ends toge!r s z to =m a loop1 :i* we pass r\nd ! two tacks 7,fig4 #ed74 ,9 ! loop ,i place ! p5cil1 & !n y see ,i move x r\nd1 tak+ c>e to keep ! tw9e /ret*$4 ,?us ,i produce a pretty curve1 :i* we call ! ellipse4 ,i mu/ ask all ( y to practise ?is exp]im5t4 ,try ) diff]5t l5g?s ( /r+1 & try us+ diff]5t di/ances betwe5 ! tacks4 ,"h are "s sket*es ( two %apes ( ellipse & a p>abola 7,fig4 #ee74 ,elliptic curves c be made almo/ circles by putt+ ! two tacks close toge!r1 or !y c be made v long 9 comp>ison ) _! wid?4 ,!y are all pretty & graceful figures1 & are (t5 useful = ornam5tal "w4 ,! ellipse is a pretty %ape = b$s ( fl[]s 9 a grass-plot4 ,! importance ( ! ellipse to a/ronom]s is great] ?an t ( any o!r geometrical figure4 ,9 fact1 all ! planets1 z !y p]=m _! long & unceas+ j\rneys r\nd ! sun1 move 9 ellipses2 & ?\gh x is true t ^! ellipses are v ne>ly circles1 yet ! diff]5ce is q appreciable4 ,x is also important to obs]ve t ! sun is n 9 ! c5tre ( ! ellipse :i* ! planet describes4 ,! sun is ne>] to "o end ?an to ! o!r4 ,& ! actual position ( ! sun mu/ be p>ticul>ly not$4 ,suppose t "s mighty giant 7 prep>+ to draw an exact pa? = ! e>?1 or = ,m>s1 ( c\rse he w\ld want to h millions ( miles ( /r+ = produc+ a big en\gh curve1 & "o ( ! nails t he us$ w\ld h to be driv5 "r into ! sun4 ,! foll[+ is ! a/ronom]'s m accurate me?od ( /at+ ! facts4 ,he calls ea* ( ! po9ts repres5t$ by ! tacks ar\nd :i* ! /r+ is loop$ a focus ( ! ellipse2 ! two po9ts toge!r are said to be ! foci2 & z ! planet is describ+ its orbit1 ! position ( ! sun w lie exactly at "o ( ! foci4 ,! ellipse is a curve t nature is v fond ( reproduc+4 ,f an electric light1 a brilliant beam w div]ge4 ,if y hold a globe 9 ! beam1 & let ! %ad[ fall on a %eet ( pap]1 x =ms an ellipse4 ,if y hold ! %eet squ>ely1 ! %ad[ is a circle2 b z y incl9e x1 y obta9 a beautiful oval1 & by gradually alt]+ ! position1 y c get a greatly elongat$ curve4 ,inde$1 y c ?us produce an ellipse ( almo/ any =m4 ,! electric light is n indisp5sable = ?is purpose2 any ord9>y bright lamp ) a small flame w answ]1 & by tak+ diff]5t siz$ balls & putt+ !m 9 v>i\s positions1 y c make _m ellipses1 great & small4 ,,! ,,discov]ies ,,made ,,by ,,ty*o ,,& ,,kepl]4 ,x 0 by ! obs]vations ( a celebrat$ old a/ronom]1 nam$ ,ty*o ,brahe1 t ! true %ape ( a planet's pa? came to be aft]w>ds det]m9$4 ,ty*o liv$ 9 days be=e telescopes 7 inv5t$4 ,he _h few ( ! excell5t contrivances = measur+ :i* we h 9 our obs]vatories4 ,we %all take a look at ?is f9e old a/ronom]1 z he sits amid 8 curi\s a/ronomical ma*9es4 ,illu/ration3 ,,fig4 #ef4--,ty*o ,brahe 9 8 ,obs]vatory4 ,he liv$ on an isl& ne> ,cop5hag51 & he has giv5 u a picture ( himself 7,fig4 #ef71 z he is seat$ ) 8 qua9t app>atus1 & 8 assi/ants ar\nd him1 busily engag$ 9 obs]v+ ! heav5s4 ,y see ! walls ( 8 obs]vatory are decorat$ ) pictures2 & "o ( ! great ,dani% h\nds :i* ! ,k+ ( ,d5m>k _h pres5t$ to him lies asleep at 8 feet4 ,i d n ?9k we %\ld n[ enc\rage big dogs 9 ! obs]vatory at night4 ,nor d mod]n a/ronom]s put on _! velvet robes ( /ate1 z ,ty*o 0 said to h done :5 he ent]$ into ! pres5ce ( ! />s1 z1 by s do+1 he %[$ 8 respect = ! heav5s4 ,a/ronom]s1 n[adays1 r pref] to we> "s com=table coat :i* %all keep out ! cold1 no matt] :at may be its appe>ance f ! picturesque po9t ( view4 ,9 ?is wond]ful contrivance1 y see ,ty*o ,brahe did n use any actual telescope4 ,he obs]v$ ?r\gh a small op5+ 9 ! wall1 & le/ !re %\ld be any mi/ake z to :at is go+ on1 y see he is po9t+ t[>ds x1 & giv+ 8 ?ree assi/ants _! in/ructions4 ,! mo/ important "w is be+ done by ! man on ! "r4 ,he is engag$ 9 mak+ ! actual obs]vation4 ,b he has no aid f magnify+ l5ses4 ,all he c d is to slide a po9t] up or d[n till x is j 9 l9e ) ! planet or /> z he sees x ?r\gh ! hole opposite4 ,on ! circle a numb] ( m>ks h be5 engrav$1 & !re are numb]s plac$ opposite to ! m>ks2 x is by ^! t ! position ( ! object is to be asc]ta9$4 ,if ! object is high1 !n ! po9t] w be l[2 & if ! object is l[1 !n ! po9t] w be high4 ,! obs]v] calls out ! position :5 he has f\nd x1 & !re1 y see1 is a man ready ) writ+ mat]ials to take d[n ! obs]vation4 ,notice also ! o!r a/ronom] :o is look+ at ! clock4 ,he gives ! "t1 :i* mu/ also be record$ accurately4 ,9 fact1 ! entire process ( f9d+ ! place ( a heav5ly body consi/s 9 two obs]vations--"o f ! circle & ! o!r f ! clock2 s t ?\gh ,ty*o _h no telescope to aid 8 vision1 yet ! pr9ciple on :i* 8 "w 0 done 0 ! same z t :i* we use 9 our obs]vatories at ?is mom5t4 ,y may ?9k t su* a conc]n w\ld h>dly be capable ( produc+ mu* reliable "w4 ,h[ev]1 ,ty*o comp5sat$ 9 a great degree = ! imp]fection ( 8 in/rum5t by ! skill ) :i* he us$ x4 ,he _h a noble det]m9ation to d 8 v be/4 ,p]sev]ance w accompli% wond]s ev5 ) v imp]fect means4 ,a great a/ronom] has said t a skilful obs]v] ought to be able to make valuable measurem5ts ) a common c>t-:eel6 ,x 0 ) in/rum5ts on ! pr9ciple ( t :i* ,i h "h %[n t ,ty*o made 8 celebrat$ obs]vations ( ,m>s4 ,week aft] week1 mon? aft] mon?1 ye> aft] ye>1 did ! pati5t old a/ronom] track ! planet ?r\gh 8 caprici\s w&]+s4 ,be=e we try to expla9 any?+1 x is ( c\rse necess>y to asc]ta91 ) all available accuracy1 :at ! ?+ actually is4 ,!re=e1 :5 we seek to expla9 ! irregul> movem5ts ( a planet1 ! fir/ ?+ to be done is to make a c>eful exam9ation ( ! nature ( ^? irregul>ities4 ,& ?is 0 :at ,ty*o /rove to d ) ! be/ means at 8 disposal4 ,! full b5efit ( ,ty*o's "w 0 realiz$ by ,kepl] :5 he comm5c$ to se>* out ! k9d ( figure 9 :i* ,m>s 0 mov+4 ,fir/ he tri$ v>i\s circles1 & !n he s\ght1 by plac+ ! c5tre 9 diff]5t positions1 to see :e!r x w\ld n be possible to acc\nt ?us = ! irregul>ities ( ! wayw>d planet4 ,x w\ld n d2 ! movem5t 0 n circul>4 ,?is 0 ?\ght v /range 9 ^? days1 = ! circle 0 reg>d$ z ! only p]fect curve1 & x 0 consid]$ q impossible = a planet to h any motion except x 7 ! mo/ p]fect4 ,!re 01 h[ev]1 no help = x2 s ,kepl] sagaci\sly tri$ ! ellipse1 :i* he consid]$ to be ! mo/ p]fect curve next to ! circle4 ,he cont9u$ 8 long calculations1 until at la/ he succe$$ 9 f9d+ "o p>ticul> ellipse1 plac$ 9 "o p>ticul> position1 :i* w\ld j expla9 ! /range w&]+s ( our erratic neighbor4 ,x 0 n alone t ! motion ( ! planet trac$ out an ellipse2 x 0 fur!r discov]$ t ! sun lies at "o ( ! foci ( ! curve4 ,if ! sun 7 any:]e else1 ! motion ( ! planet w\ld h be5 diff]5t f t :i* ,ty*o _h f\nd x to be4 ,y mu/ "k t ?is discov]y is "o ( ! v greate/ t h ev] be5 made 9 ! :ole ext5t ( human k4 ,aft] x _h be5 prov$ t ! orbit ( ,m>s 0 elliptic1 x became pla9 t ! same pa? mu/ be trac$ by e planet4 ,!re are v big planets1 & !re are small ones2 !re are planets :i* move 9 v l>ge orbits1 & !re are planets ^: pa?s are comp>atively small4 ,9 all cases ! high road :i* ! planet foll[s is inv>iably an ellipse1 & ! sun is inv>iably to be f\nd situat$ at ! focus4 ,x is surely int]e/+ to f9d t ^! beautiful ellipses :i* we c draw s simply ) a piece ( tw9e & a p5cil %\ld be also ! v same figures :i* our great e>? & all ! o!r bodies :i* revolve ar\nd ! sun are ev] compell$ to foll[4 ,kepl] also made ano!r great discov]y 9 connection ) ! same subject4 ,if ! planet mov$ 9 a circle ) ! sun 9 ! c5tre1 !n !re w\ld be v good reason to expect t x w\ld always move at ! same spe$1 = !re w\ld be no reason :y x %\ld g fa/] at "o place ?an at ano!r4 ,9 fact1 ! planet w\ld !n be revolv+ always at ! same di/ance f ! sun1 & e "p ( its pa? w\ld be exactly l e o!r "p4 ,b :5 we consid] t ! motion is p]=m$ 9 an ellipse1 s t ! planet is curv+ r\nd m rapidly at ! extremities ( its pa? ?an 9 ! o!r p>ts :]e ! curvature is less p]ceptible1 we h no reason to expect t ! spe$ %all rema9 ! same all r\nd4 ,we "k t ! eng9e-driv] ( a railway tra9 always has to slack5 spe$ :5 he is go+ r\nd a %>p curve4 ,if he did n d s1 8 tra9 w\ld be v likely to run (f ! l9e1 & a dreadful accid5t w\ld foll[4 ,! eng9e-driv] is well aw>e t ! conditions ( pace are dep5d5t on ! curvature ( 8 l9e4 ,! planet f9ds t x1 too1 mu/ pay att5tion to ! curves2 b ! extraord9>y po9t is t ! planet acts exactly 9 ! opposite way to ! eng9e-driv]4 ,! planet puts on its highe/ pace at "o ( ! mo/ critical curves 9 ! :ole j\rney4 ,!re are two specially %>p curves 9 ! planet's pa?4 ,^! are1 ( c\rse1 ! two extremities ( ! ellipse :i* x foll[s4 ,! cauti\s eng9e-driv] w\ld1 ( c\rse1 creep r\nd ^! ) equal c>e1 & no d\bt ! planet goes sl[ly en\gh ab\t t end ( ! ellipse :i* is f>!/ f ! sun4 ,!re its pace is sl[] ?an any:]e else2 b f t mom5t onw>ds ! planet /eadily applies itself to gett+ up m & m spe$4 ,z x trav]ses ! comp>atively /raight portion ( ! cele/ial road1 ! pace is ev] accel]at+ until ! %>p curve ne> ! sun is be+ approa*$2 !n ! velocity gets m & m al>m+1 until at la/1 9 utt] defiance ( all rules ( eng9e-driv+1 ! planet ru%es r\nd "o ( ! wor/ p>ts ( ! orbit at ! highe/ possible spe$4 ,& yet no accid5t happ5s1 ?\gh ! planet has no nicely laid l9es to keep x on ! track4 ,if l9es are necess>y to save a railway tra9 f de/ruction1 h[ c we possibly escape :5 we h no simil> assi/ance to keep u f fly+ away f ! sun & (f into inf9ite space8 ,kepl] has taught u to measure ! *anges 9 ! spe$ ( ! body ) precision4 ,he has %[n t ! planet mu/1 at e po9t ( its long j\rney1 possess exactly ! "r spe$2 o!rwise ev]y?+ w\ld g wrong4 ,i d>e say y h se51 at diff]5t po9ts along a l9e ( railway1 bo>ds put up "h & !re1 ) notices l1 8,t5 miles an h\r40 ,^! words are1 ( c\rse1 an intimation to ! eng9e-driv] t he is n to v>y f ! spe$ ?us /at$4 ,kepl] has giv5 u a law :i* is equival5t to a l>ge numb] ( caution bo>ds1 fix$ all r\nd ! planet's pa?1 indicat+ ! safe spe$ = ! j\rney at e /age4 ,x is =tunate = u t ! planet is c>eful to obs]ve ^! regulations4 ,if ! e>? 7 to leave h] track1 ! consequ5ces w\ld be f> worse ?an ^? ( ! mo/ frightful railway accid5t t ev] happ5$4 ,:i*ev] side we took w\ld be almo/ equally disa/r\s4 ,if we w5t inw>ds we %\ld plunge into ! sun1 & if we w5t outw>ds we %\ld be froz5 by cold4 ,we owe our safety to ! c>e ) :i* ! spe$ ( ! e>? is prescrib$4 ,:5 ne> ! sun1 ! e>? is pull$ inw>ds ) exceptionally /rong attraction4 ,we are (t5 told t :5 a /rong temptation seizes u1 ! wise/ ?+ t we c d is to run away z h>d z possible4 ,?is is j :at ! laws ( dynamics cause ! e>? to d at ?is critical "t4 ,%e puts on h] v be/ pace1 & only slack5s :5 %e has got well away f ! dang]4 ,! p]il t we are expos$ to :5 ! e>? is at ! o!r end ( ! orbit is ( an opposite "*4 ,we are !n a long way f ! sun1 & ! pull :i* x c ex]cise ^u ! e>? is correspond+ly less5$4 ,c>e is !n requir$ le/ we %\ld escape altoge!r f ! sun's w>m? & 8 guidance4 ,we mu/ !re=e give "t to ! sun to ex]cise 8 p[]1 s z to enable ! e>? to be recall$2 accord+ly we move z sl[ly z possible until ! sun conqu]s ! e>?'s disposition to fly (f1 & we beg9 to return4 ,y may rememb] t :5 we 7 speak+ ab\t ! moon1 ,i %[$ y h[ a body might revolve ar\nd ! e>? 9 a circle "u ! influ5ce ( an attraction t[>ds ! e>?'s c5tre4 ,s long z ! pa? is really a circle1 !n ! p[] ) :i* ! e>? is draw+ ! body rema9s ! same4 ,9 a precisely simil> way1 a body c\ld revolve ar\nd ! sun 9 a circle1 9 :i* case also ! attraction ( ! sun w rema9 ! same all r\nd4 ,b n[ we h a v mu* m difficult case to consid]4 ,if ! body does n always rema9 at ! same di/ance1 ! p[] ( ! sun w n be ! same at ! diff]5t places4 ,:5ev] ! object is ne> ! sun1 ! attraction w be great] ?an :5 x is f>!r (f4 ,= example1 :5 ! di/ance betwe5 ! two bodies is d\bl$1 !n ! pull is r$uc$ to ! f\r? "p ( :at x 0 be=e4 ,,! ,,discov]ies ,,made ,,by ,,newton4 ,i h n[ "s great discov]ies to talk to y ab\t1 :i* 7 made by ,sir ,isaac ,newton4 ,he 0 n an a/ronom] :o look$ mu* ?r\gh a telescope1 ?\gh he made _m rem>kable exp]im5ts4 ,he us$ to sit 9 8 /udy & ?9k1 & !n he us$ to draw figures ) 8 p5cil1 & make long calculations4 ,at la/ he 0 able to give answ]s to ! que/ions3 ,:at is ! reason :y ! planet moves 9 an ellipse8 ,:y %\ld x move 9 ?is curve r ?an 9 any o!r8 ,:y %\ld ?is ellipse be s plac$ t ! sun lies at "o ( ! foci8 ,if ! planet _h run uni=mly r\nd its c\rse1 ,newton w\ld h f\nd 8 task an impossible "o4 ,b ,i h already expla9$ t ! motion is n uni=m4 ,i describ$ h[ ! planet hurri$ along ) extra spe$ at c]ta9 p>ts ( its pa?2 h[ x l+]$ at o!r p>ts2 h[1 9 fact1 x nev] pres]v$ ! same rate = ev5 a s+le m9ute dur+ ! :ole j\rney4 ,kepl] _h %[n h[ to make a "t-table = ! :ole j\rney4 ,9 fact1 j z a capta9 on a long voyage keeps a record ( ea* day's run1 & %[s h[ to-day he makes #agj miles1 & to-morr[ p]haps #bjj1 & ! next day #baj1 :ile ! day aft] he may fall back to #abj1 s ,kepl] gave rules by :i* ! log ( a planet 9 its voyage r\nd ! sun might be s fai?fully kept t e day's run w\ld be accurately record$4 ,:5 ,newton comm5c$ 8 "w1 "o ( ! fir/ que/ions he _h to consid] 0 ! foll[+3 ,suppose t a great globe l a planet1 or a small globe l a m>ble1 or an irregul> body l an ord9>y /one1 7 to be ?r[n into space1 & 7 !n to be left to foll[ its c\rse )\t any =ce :atev] act+ ^u x1 :]e w\ld x g to8 ,y may say1 at once1 t a body "u su* circum/ances w pres5tly fall d[n to ! gr\nd2 & s1 ( c\rse1 x w1 if x be ne> ! e>?4 ,i am n1 h[ev]1 talk+ ( any?+ ne> ! e>?2 ,i want y to imag9e a body f> (f 9 ! dep?s ( space1 among ! />s4 ,su* a body ne$ n necess>ily fall d[n "h1 = y see ! moon does n fall1 & ! sun does n4 ,if y 7 at a great di/ance f our globe & f all o!r l>ge globes--s f>1 inde$1 t _! attractions 7 imp]ceptible--y c\ld try ! exp]im5t t ,i wi% n[ to describe4 ,?r[ a /one z h>d z ev] y c1 & :at w happ58 ,( c\rse1 :5 y d x d[n "h1 x moves 9 a pretty curve ?r\gh ! air1 & tumbles to ! gr\nd2 b away 9 op5 space1 :at w ! /one d8 ,!re w be no su* motion z up or d[n1 z we ord9>ily und]/& x2 = ?\gh ! e>?1 no d\bt1 w lie 9 "o p>ticul> direction at a great di/ance1 yet !re w be o!r bodies j z l>ge 9 o!r directions2 & !re is no reason :y ! /one %\ld move t[>ds "o ( ^! r ?an to ano!r2 9 fact1 if !y are all f> en\gh1 z ! />s are f u1 _! attractions w be q inappreciable4 ,!re is1 !re=e1 n ! slighte/ reason :y ! /one %\ld sw]ve to "o side m ?an to ano!r4 ,!re is no m reason :y x %\ld turn to ! "r ?an :y x %\ld turn to ! left4 ,nor c\ld y ?r[ ! /one s z to make x foll[ a curv$ pa?4 ,y c1 ( c\rse1 make x describe a curve :ile x rema9s 9 y\r h&1 b ! mom5t ! /one has left y\r h&1 x proce$s on its j\rney by a law ov] :i* y h no control4 ,z ! direction _c be *ang$ t[>ds "o side m ?an t[>ds ! o!r1 ! /one mu/ simply foll[ a /raight l9e f ! v mom5t :5 x is releas$ f y\r h&4 ,! spe$ ) :i* ! /one is />t$ w also n *ange4 ,y might at fir/ ?9k t x w\ld gradually abate1 & ultimately cease4 ,no d\bt a /one ?r[n along ! road w behave 9 ?is way1 b t is because ! /one rubs aga9/ ! gr\nd4 ,if y ?r[ a /one across a %eet ( ice1 !n x w run a v long di/ance be=e x /ops1 & all ! "t x w be mov+ 9 a /raight l9e4 ,9 ?is case !re is b little loss by rubb+ aga9/ ! ice1 because x is s smoo?4 ,?us we see t if ! pa? be exce$+ly smoo?1 ! body w run a long way be=e x /ops4 ,?9k ( ! di/ance a railway tra9 w run if1 :ile travell+ at full spe$ along a level l9e1 ! /eam is turn$ (f4 ,^! illu/rations all %[ t if y let a body alone1 aft] hav+ once />t$ x1 & d n try to pull x ?is way or t way1 & d n make x rub aga9/ ?+s1 t body w move on cont9ually 9 a /raight l9e1 & w keep up a uni=m spe$4 ,we c apply ?is reason+ to a /one out 9 space4 ,x w\ld c]ta9ly move 9 a /raight l9e1 & w\ld g on & on =ev]1 )\t los+ any ( its pace4 ,i ne$ h>dly tell y t no "o has ev] be5 able to try ?is exp]im5t4 ,9 ! fir/ place1 we reside ^u ! surface ( ! e>?1 & we h no means ( asc5d+ into ^? elevat$ regions :]e ! /one is suppos$ to be project$4 ,!re is also ano!r difficulty :i* we _c entirely avoid1 & t arises f ! resi/ance ( ! air4 ,all movem5ts d[n "h are imp$$ because ! body has to =ce its way ?r\gh ! air2 & 9 do+ s x inv>iably loses "s ( its spe$4 ,out 9 op5 space !re is1 ( c\rse1 no air1 & no loss ( spe$ c !re=e arise f ?is cause4 ,illu/ration3 ,,fig4 #eg4--,! ,humm+-top4 ,!re are1 h[ev]1 sev]al actual exp]im5ts by :i* we c assure ourselves ( ! g5]al tru?4 ,set a humm+-top sp9n+ 7,fig4 #eg72 x gradually comes to re/1 p>tly because ( ! rubb+ ( its po9t on ! table1 & p>tly because x has to =ce its way ?r\gh ! air4 ,9 fact1 ! hum ( ! top t y he> is only produc$ at ! exp5se ( its motion4 ,suppos+ ,i use a mu* heavi] top2 if ,i set x sp9n+ x w keep up = _m m9utes1 because its weight gives x a bett] /ore ( p[] :]e) to ov]come ! resi/ance ( ! air4 ,i rememb] he>+ a /ory ab\t ,pr(essor ,cl]k-,maxwell4 ,he _h1 :5 at ,cambridge1 inv5t$ "o ( ^! l>ge & heavy tops1 :i* w\ld sp9 = a long "t4 ,"o ev5+ ! top 0 left sp9n+ on a plate 9 8 room :5 8 fri5ds took _! dep>ture1 & no d\bt x came to re/ 9 due "t4 ,e>ly ! next morn+1 ,pr(essor ,maxwell1 he>+ ! same fri5ds com+ up to 8 rooms aga91 jump$ out ( b$1 set ! top sp9n+1 & !n got back to b$1 & pret5d$ to be asleep4 ,he ?us a/\nd$ 8 fri5ds1 :o1 ( c\rse1 imag9$ t ! top mu/ h be5 sp9n+ all ! night long6 ,if we sp9 a top "u ! receiv] ( an air pump 7,fig4 #eh71 x w keep up its motion = a v mu* long] "t aft] ! air has be5 exhau/$ ?an x w\ld 9 ord9>y circum/ances4 ,su* exp]im5ts prove t ! motion ( a body w n ( itself naturally die out1 & t if we c\ld only keep away ! int]f]+ =ces altoge!r1 ! motion w\ld cont9ue indef9itely ) unabat$ spe$4 ,:at ,i h be5 endeavor+ to illu/rate is call$ ! fir/ law ( motion4 ,x is writt5 ?us3-- 8,e body cont9ues 9 its /ate ( re/ or ( uni=m motion 9 a /raight l9e1 except 9 s f> z x may be compell$ by impress$ =ces to *ange t /ate40 ,illu/ration3 ,,fig4 #eh4--,to illu/rate ! ,fir/ ,law ( ,motion4 ,i w\ld recomm5d y to le>n ?is by he>t4 ,i c assure y x is q z well wor? kn[+ z ^? rules 9 ! ,lat9 ,gramm> ) :i* _m ( y1 ,i h no d\bt1 are acqua9t$4 ,! be/ pro( ( ! fir/ law ( motion is d]iv$1 n f any exp]im5ts1 b f a/ronomy4 ,we make _m calculations ab\t ! movem5ts ( ! sun1 ! moon1 ! />s1 & !n we v5ture on pr$ictions1 & we f9d ^? pr$ictions v]ifi$4 ,?us we _h a transit ( ,v5us across ! sun 9 #ahhb1 & e a/ronom] knew t ?is 0 go+ to occur1 & _m w5t to ! ends ( ! e>? s t !y might see x favorably4 ,_! anticipations 7 realiz$2 !y always are4 ,a/ronom]s make no mi/akes 9 ^! matt]s4 ,!y "k t !re w be ano!r transit ( ,v5us 9 ! ye> #bjjd1 b n soon]4 ,! calculations by :i* ^! accurate prophecies are made involve ?is fir/ law ( motion2 & z we f9d t su* prophecies are always fulfill$1 we "k t ! fir/ law ( motion mu/ be true also4 ,newton knew t if a planet 7 m]ely left alone 9 space1 x w\ld cont9ue to move on =ev] 9 a /raight l9e4 ,b ,kepl] _h %[n t ! planet did n move 9 a /raight l9e1 b t x describ$ an ellipse4 ,"o conclusion 0 obvi\s4 ,!re mu/ be "s =ce act+ ^u ! planet :i* pulls x away f ! /raight l9e x w\ld o!rwise pursue4 ,we may1 = ! sake ( illu/ration1 imag9e ?is =ce to be appli$ by a rope atta*$ to ! planet s t at e mom5t x is dragg$ by "s unse5 h&4 ,to f9d ! direction ?is rope mu/ h1 we take ! law ( ,kepl]1 :i* expla9s ! rules accord+ to :i* ! planet v>ies its spe$4 ,i _c ent] into ! "q fully1 z x w\ld be too difficult = u to discuss n[4 ,i %\ld h to talk a great deal m ab\t ma!matics ?an w\ld be conv5i5t j at pres5t2 b ,i ?9k y c all und]/& ! result to :i* ,newton 0 l$4 ,he %[$ t ! rope mu/ always be direct$ t[>ds ! sun4 ,9 o!r words1 suppose t !re 0 no sun1 b t 9 ! place :i* x occupi$ !re 0 a /rong en\gh giant con/antly pull+ away at ! planet1 !n we %\ld f9d t ! spe$ ( ! planet w\ld alt] j 9 ! way x actually does4 ,?us we le>n t "s =ce mu/ reside 9 ! sun by :i* ! planet is drawn1 & ?is =ce is ex]t$1 al?\gh !re is no visible bond betwe5 ! sun & ! planet4 ,!re is ano!r fact to be le>n$ ab\t ! sun's attraction1 & ?is "t we obta9 x by kn[+ ! %ape ( ! curve foll[$ by ! planet4 ,! laws by :i* ! planet's spe$ is regulat$ prove t ! =ce emanates f ! sun4 ,we %all n[ le>n mu* m :5 we take into acc\nt t ! pa? ( ! planet is an ellipse1 ( :i* ! sun lies at ! focus4 ,no?+ has be5 said z yet reg>d+ ! magnitude ( ! pull :i* is be+ ex]t$ by ! sun4 ,is t pull to be always ! same1 or is x to be great] at "s times ?an at o!r times8 ,newton %[$ t no ellipse o!r ?an a circle c\ld be describ$1 if ! pull f ! sun 7 always ! same4 ,its magnitude mu/ be cont9ually *ang$1 & ! ne>] ! planet lies to ! sun1 ! m vehem5t is ! pull x receives4 ,newton laid d[n ! exact law by :i* ! =ce on ! planet at any "o place 9 its pa? c\ld be comp>$ ) ! =ce at any o!r position4 ,let u suppose t ! planet is 9 a c]ta9 position1 & t x !n passes into a second position1 :i* is twice z f> f ! sun4 ,! pull ^u ! planet at ! %ort] di/ance is n only great] ?an ! pull at ! long] di/ance1 b x is actually f\r times z mu*4 ,/at+ ?is result a little m g5]ally1 we ass]t1 9 ! language ( a/ronom]s1 t ! attraction v>ies inv]sely z ! squ>e ( ! di/ance4 ,if ?is law 7 dep>t$ f1 !n ,i d n say t x w\ld be impossible = ! planet to revolve ar\nd ! sun 9 "s fa%ion1 b ! motion w\ld n be p]=m$ 9 an ellipse describ$ ar\nd ! sun 9 ! focus4 ,y see h[ v in/ructive are ! laws :i* ,kepl] discov]$4 ,f ! fir/ ( !m we 7 able to inf] t ! sun attracts ! planets2 f ! second1 we h le>n$ h[ ! magnitude ( ! attract+ =ce v>ies4 ,! true importance ( ^! great discov]ies w be manife/ :5 we comp>e !m ) :at we h already le>n$ ) reg>d to ! movem5ts ( ! moon4 ,z ! moon revolves ar\nd ! e>? x is held by ! e>?'s attraction1 & ! moon foll[s a pa? :i*1 ?\gh ne>ly a circle1 is really an ellipse4 ,?is orbit is describ$ ar\nd ! e>? j z ! e>? describes its pa? ar\nd ! sun4 ,t law by :i* a /one falls to ! gr\nd 9 consequ5ce ( ! e>?'s attraction is m]ely an illu/ration ( a great g5]al pr9ciple4 ,e body 9 ! :ole univ]se attracts e o!r body4 ,?9k ( two weights ly+ on ! table4 ,!y no d\bt attract ea* o!r1 b ! =ce is an extremely small "o--s small1 inde$1 t y c\ld n measure x by any ord9>y appliance4 ,"o or bo? ( ! attract+ masses mu/ be enorm\sly big if _! mutual gravitation is to be readily appreciable4 ,! attraction ( ! e>? on a /one is a consid]able =ce1 because ! e>? is s l>ge1 ev5 ?\gh ! /one may be small4 ,imag9e a pair ( colossal solid iron cannon-balls1 ea* #ec y>ds 9 diamet]1 & weigh+ ab\t #dag1jjj tons4 ,suppose ^! two globes 7 plac$ a mile ap>t1 ! pull ( "o ( !m on ! o!r by gravitation w\ld be j a p\nd weight4 ,not)/&+ ! size ( ^! masses1 ! h& ( a *ild c\ld prev5t any motion ( "o ball by ! attraction ( ! o!r4 ,if1 h[ev]1 !y 7 q free to move1 & !re 0 absolutely no friction1 ! balls w\ld beg9 to draw toge!r2 at fir/ !y w\ld creep s sl[ly t ! motion w\ld h>dly be notic$4 ,! pace w\ld no d\bt cont9ue to improve sl[ly1 b /ill n less ?an ?ree or f\r days mu/ elapse be=e !y w h come toge!r4 ,by ! k9dness ( ,pr(essor ,dew>1 ,i am enabl$ to exhibit a contrivance ) :i* we c illu/rate ! motion ( a planet ar\nd ! sun4 ,"h is a long wire susp5d$ f ! ro( ( ?is !atre1 & atta*$ to its l[] end is an iron ball1 made holl[ = ! sake ( lightness4 ,:5 ,i draw ! ball aside1 x sw+s to & fro ) ! regul>ity ( a great p5dulum4 ,b :5 ,i place a p[]ful magnet 9 its neighborhood 7,fig4 #ei71 y see t z soon z ! ball gets ne> ! magnet x is viol5tly drawn to "o side1 & foll[s a curv$ pa?4 ,?is magnet may be tak5 to repres5t ! sun1 :ile ! ball is l our e>?1 or any o!r planet1 :i* w\ld move 9 a /raight l9e 7 x n = ! attraction ( ! sun :i* draws ! body aside4 ,illu/ration3 ,,fig4 #ei4--,! ,effect ( ,attraction4 ,,! ,,geography ,,( ,,m>s4 ,we w n[ say some?+ ) respect to ! geography ( our fell[-planet1 a subject :i* seems all ! m int]e/+ because ,m>s is s l ! e>? 9 _m respects4 ,we require a fairly good telescope = ! purpose ( see+ him well1 b :5 su* an in/rum5t is direct$ to ! planet1 a beautiful picture ( ano!r _w is unfold$ 7,fig4 #fj74 ,!re are _m ?+s visible on 8 surface1 b we mu/ always rememb] t ev5 ) our mo/ p[]ful telescopes ! planet /ill appe>s a long way (f4 ,illu/ration3 ,,fig4 #fj4--,views ( ,m>s4 ,illu/ration3 ,,fig4 #fa4--,m>s4 7,by ,d\glass1 ,l[ell ,obs]vatory47 ,9 ! mo/ favorable circum/ances1 ,m>s is at lea/ "o hundr$ times z f> f u z ! moon4 ,b we "k t an object on ! moon mu/ be z l>ge z ,/4 ,paul's ,ca!dral if x is to be visible 9 our telescopes4 ,an object on ,m>s mu/ be1 !re=e1 at lea/ "o hundr$ times z broad & "o hundr$ times z long z ,/4 ,paul's ,ca!dral if x is to be disc]nible by a/ronom]s on our e>?4 ,we c1 !re=e1 only expect to see ! g5]al features ( our fell[-planet4 ,7 we look+ at our e>? f a simil> di/ance1 & ) equally good telescopes1 ! cont95ts & oceans1 & ! l>g] seas & isl&s1 w\ld all be l>ge en\gh to be conspicu\s4 ,x is1 h[ev]1 d\btful :e!r !y c\ld ev] be prop]ly reveal$ ?r\gh ! s]i\s imp$im5t to vision :i* our atmosph]e w\ld (f]4 ,x =tunately happ5s t ! surface ( ,m>s is only obscur$ by cl\ds to a v trifl+ ext5t1 & we are ?us able to see a panorama ( our neighbor+ globe laid be=e u4 ,m>s is n ne>ly s l>ge z our e>?1 ! diamet]s ( ! two bodies be+ ne>ly z two to "o4 ,x foll[s t ! numb] ( acres on ! planet is only a qu>t] ( ! numb] ( acres on ! e>?4 ,c>eful telescopic scrut9y %[s t ! *ief features :i* we see on ,m>s are ( a p]man5t "*4 ,9 ?is respect ,m>s is mu* m l ! moon ?an ! sun4 ,! latt] pres5ts to u m]ely gl[+ vapors1 ) h>dly m p]man5ce ?an is possess$ by ! cl\ds 9 our own sky4 ,on ! o!r h&1 ! entire abs5ce ( cl\ds f ! moon enables u to see ! p]man5t features on its surface4 ,mo/ ( ! visible features on ,m>s are also inv>iable2 ?\gh occasionally x w\ld seem t ! climate produces "s *anges 9 its appe>ance4 ,illu/ration3 ,,fig4 #fb4--,! ,s\? ,pole ( ,m>s1 ,septemb]1 #ahgg 7,gre574 ,we fir/ notice t !re are diff]5tly color$ p>ts on ,m>s4 ,! d>ki% or blui% regions are usually spok5 ( z seas or oceans2 ?\gh we %\ld be go+ beyond our /rict k 7 we to ass]t t wat] is actually f\nd !re4 ,look at ! horn-%ap$ object 9 ! c5tre ( ! l[] picture 9 ,fig4 #fj4 ,we call x ! ,kais] ,sea1 & x is s /rongly m>k$ t ev5 9 a small telescope x c be (t5 se54 ,y mu/ n1 h[ev]1 always expect to notice ?is feature :5 y look at ! planet ?r\gh a telescope1 = x turns r\nd & r\nd4 ,we c make a globe repres5t+ ,m>s4 ,on ?is are to be depict$ ?is great sea & ! o!r *>act]i/ic objects4 ,b z we turn ! globe ar\nd1 ! opposite side ( ! planet is br\ght into view1 & o!r features are reveal$ l ^? repres5t$ 9 ! upp] figure4 ,m>s requires #bd h\rs #cg m9utes #bb4g seconds to complete a s+le rotation4 ,x is some:at rem>kable t ?is only diff]s f ! e>?'s p]iod ( rotation by a little m ?an half an h\r4 ,m>s conta9s :at we call cont95ts z well z oceans1 & we also f9d !re lakes & seas & /raits4 ,^! objects are indicat$ 9 ! draw+s t are "h repres5t$4 ,b ! mo/ /rik+ features :i* ! planet displays are ! m>vell\s :ite regions1 :i* are se5 bo? at its ,nor? ,pole & at its ,s\? ,pole 7,fig4 #fb74 ,if we 7 able to so> al(t above our e>? & take a bird's-eye view ( our own pol> regions1 we %\ld see a :ite cap at ! middle ( ! arctic circle4 ,?is appe>ance w\ld be produc$ by ! et]nal ice & sn[4 ,x w\ld increase dur+ ! long1 d>k w9t]1 & be some:at r$uc$ by melt+ dur+ ! cont9u\sly bright summ]4 ,?\gh we _c ?us see our e>?1 yet we c sometimes obs]ve "o ,pole ( ,m>s & sometimes ! o!r1 & we f9d ea* ( ^! ,poles cr[n$ ) a d5se :ite cap1 :i* increases dur+ ! sev]ity ( its w9t]1 & :i* decl9es aga9 ) ! w>m? ( ! ensu+ summ]4 ,sket*es ( ,m>s h be5 made by _m a/ronom]s2 among !m we may m5tion ,mr4 ,gre51 :o made a beautiful s]ies ( pictures at ,madeira 9 #ahgg4 ,^! may be supplem5t$ by ! draw+s ( ,mr4 ,knobel 9 #ahhd1 :5 ! opposite ,pole ( ! planet 0 turn$ to view4 ,! draw+s %[ ! pol> sn[s1 & !re seem to be "s elevat$ di/ricts 9 8 arctic regions :i* reta9 a little pat* ( sn[ aft] ! ma9 body ( ! ice cap has %runk )9 its summ] limits4 ,an int]e/+ case ( ?is k9d is %[n 9 ,fig4 #fb1 :i* has be5 copi$ f "o ( ,mr4 ,gre5's draw+s4 ,x has lately be5 surmis$ t ! cont95ts on ,m>s are occasionally inundat$ by floods ( wat]4 ,!re are also indications ( cl\ds hang+ ov] ! ,m>tian l&s1 b ! inhabitants ( t planet1 9 ?is respect1 escape mu* bett] ?an we d4 ,a c]ta9 am\nt ( atmosph]e always surr\nds ,m>s1 ?\gh x is mu* less copi\s ?an t we h "h4 ,z to ! composition ( ?is atmosph]e we "k no?+4 ,= any?+ we c tell1 x might be a gas s poison\s t a s+le inspiration w\ld be fatal to u2 or if x conta9$ oxyg5 9 mu* l>g] proportion ?an our air does1 x might be fatal f ! m]e excitem5t to our circulation :i* an ov]-supply ( /imulant w\ld produce4 ,i d n ?9k x ! lea/ likely t our exi/5ce c\ld be support$ on ,m>s1 ev5 if we c\ld get !re4 ,we also require c]ta9 conditions ( climate1 :i* w\ld probably be totally diff]5t f ^? we %\ld f9d on ,m>s4 ,_m rem>kable obs]vations ( ,m>s h be5 lately made by ,mr4 ,p]cival ,l[ell4 ,x seems v d\btful h[ f> our =m] division ( cont95ts & oceans on ,m>s c be ma9ta9$4 ,mr4 ,l[ell has paid special att5tion to a wond]ful sy/em ( l9es on ! planet's surface to :i* ! "n ( 8canals0 has be5 giv51 :i* (t5 %[ su* a degree ( regul>ity z w\ld almo/ sugge/ ! idea t !y _h be5 laid d[n by intellig5t guidance4 ,,! ,,satellites ,,( ,,m>s4 ,:5 ,m>s appe>$ 9 8 full spl5dor 9 #ahgg1 he 0 = ! fir/ "t honor$ ) ! notice ( in/rum5ts capable ( do+ him ju/ice4 ,i d n1 h[ev]1 mean t 9 =m] app>itions he 0 n also c>efully obs]v$1 b a great improvem5t _h rec5tly tak5 place 9 telescopes1 & x 0 ?us "u specially favorable auspices t 8 return 0 welcom$ 9 #ahgg4 ,?is ye> w be always celebrat$ 9 a/ronomical hi/ory = a beautiful discov]y made by ,pr(essor ,asaph ,hall1 ! illu/ri\s a/ronom] at ,wa%+ton4 ,be=e ,i c expla9 :at ?is discov]y 01 ,i mu/ h a little talk ab\t moons1 or satellites z !y are (t5 call$4 ,y "k t we h "o moon1 :i* is con/antly revolv+ r\nd ! e>?1 & accompanies ! e>? 9 its long voyage r\nd ! sun4 ,b ! e>? is only a planet1 & !re are _m o!r planets :i* are worlds l ours4 ,x is natural to comp>e ^! worlds1 & z we h "o moon1 :y %\ld n ! o!r planets also h moons8 ,if !re are *ildr5 9 "o h\se 9 a squ>e1 :y %\ld !re n be *ildr5 9 ! o!r h\ses8 ,we f9d t "s ( ! o!r planets h satellites1 b !y d n seem to be di/ribut$ v regul>ly4 ,9 fact1 !y are almo/ z caprici\sly allott$ z ! *ildr5 w\ld be 9 eight h\ses t y might take at r&om4 ,illu/ration3 ,,fig4 #fc4--,m>s & 8 ,two ,satellites4 ,9 ,numb] ,"o !re lives an old ba*elor1 & 9 ,numb] ,two a s+le lady4 ,^! are ,m]cury & ,v5us1 & ( c\rse !re are no *ildr5 9 ei!r ( ^! h\ses4 ,numb] ,?ree is inhabit$ by old "m ,e>?1 & %e has got a f9e big son1 call$ ! ,moon4 ,numb] ,f\r is a nice little h\se inhabit$ by ,m>s4 ,!re are to be f\nd a pair ( little tw9s1 & nimble creatures !y are too4 ,numb] ,five is a great mansion4 ,a v big man lives "h1 call$ ,jupit]1 ) f\r robu/ sons & daught]s t ev]ybody kn[s4 ,i fancy !y mu/ g to _m danc+ p>ties1 = e night !y may be se5 :irl+ r\nd & r\nd4 ,= ?ree hundr$ ye>s ^! f\r moons h be5 kn[n to a/ronom]s1 b 9 #ahib !re 0 an addition to ! family 9 ! %ape ( a t9y moon :i* _h nev] be5 se5 up to t "t4 ,numb] ,six is also a f9e big h\se1 ?\gh n q s big z ,numb] ,five1 b l>g] ?an any ( ! o!rs4 ,x is inhabit$ by ,saturn1 & conta9s ! bigge/ family ( all4 ,up till ! o!r day eight sons & daught]s 7 kn[n to live "h1 b !y are n ne>ly s /urdy z ,jupit]'s *ildr52 9 fact1 ! "y ,saturns d n make mu* display1 & "s ( !m are s delicate t !y are h>dly ev] se54 ,9 ?is h\sehold1 too1 a new memb] has rec5tly appe>$4 ,= fifty ye>s ! family 0 kn[n to consi/ ( ^! eight sons & daught]s1 b 9 ,augu/1 #ahih1 :5 !y 7 be+ photograph$ 9 a gr\p1 x 0 discov]$ t a n9? moon _h be5 add$4 ,numb] ,sev5 is also a f9e l>ge h\se2 b ,uranus1 :o lives !re1 is su* a recluse t unless y c>efully keep y\r eye on 8 h\se1 y w h>dly ev] cat* a glimpse ( him4 ,!re are f\r *ildr5 9 t h\se1 ,i believe1 b we h>dly "k !m4 ,!y move 9 circles ( _! own1 & app>5tly h se5 a good deal ( tr\ble4 ,only "o m h\se is to be m5tion$1 & t is ,numb] ,eight1 inhabit$ by ,neptune4 ,x conta9s "o *ild1 b we are h>dly on visit+ t]ms ) ?is h\sehold1 & we "k next to no?+ ab\t x4 ,be=e #ahgg1 ,m>s appe>$ to be 9 ! same condition z ,v5us or ,m]cury--t is1 devoid ( ! dignity ( att5dants4 ,!re 01 h[ev]1 good reason = ?9k+ t !re might be "s satellites to ,m>s1 only t we _h n se5 !m4 ,y see t1 z ,numb] ,?ree _h "o *ild1 & ,numb]s ,five1 ,six1 ,sev51 & ,eight _h ea* "o1 or m ?an "o1 x seem$ h>d t poor ,numb] ,f\r %\ld h none at all4 ,x 01 h[ev]1 c]ta9 t if !re 7 any satellites to ,m>s1 !y mu/ be comp>atively small ?+s2 = if ,m>s _h ev5 "o consid]able moon1 x mu/ h be5 discov]$ long ago4 ,on ! memorable occasion 9 #ahgg1 ,pr(essor ,hall discov]$ t ! ruddy planet ,m>s 0 att5d$1 n alone by "o moon1 b by two4 ,_! behavior 0 mo/ extraord9>y4 ,x appe>$ to him at fir/ almo/ z if "o ( ^! little moons 0 play+ at hide-&-seek4 ,sometimes x w\ld peep out at "o side ( ! planet1 & sometimes at ! o!r side4 ,i h "h a picture 7,fig4 #fc7 :i* %[s h[ ^! moons ( ,m>s revolve4 ,t is ! globe ( ! planet himself 9 ! middle1 & he is turn+ r\nd /eadily 9 a p]iod :i* is ne>ly ! same z our day4 ,b ! rem>kable po9t is t ! inn] ( ! moons ( ,m>s runs r\nd ! planet 9 #g h\rs #ci m9utes4 ,x w\ld seem v /range 9 our sky if we _h a little moon :i* rose 9 ! we/ in/ead ( 9 ! ea/1 & :i* gallop$ "r across ! heav5s ?ree times e day--& ?is is :at ,m>s has4 ,! out] moon takes a m leisurely j\rney1 = he requires #cj h\rs #ah m9utes to complete a circuit4 ,if = no o!r reason ?an to see ^! wond]ful moons1 x w\ld be v int]e/+ to visit ,m>s4 ,! satellites ( ?is planet are 9 contra/ to our moon4 ,9 ! fir/ place1 our moon takes #bg days to g r\nd ! e>?1 & is comp>atively a long way (f4 ,! moons ( ,m>s are mu* ne>] to _! planet1 & !y g r\nd mu* m quickly4 ,!re is also ano!r diff]5ce4 ,! moons ( ,m>s are mu* small] bodies ?an our moon4 ,if we repres5t ,m>s by a good-siz$ football1 8 moons1 on ! same scale1 w\ld be h>dly s big z ! smalle/-siz$ gra9s ( %ot4 ,does x n speak well = ! p[] ( telescopes 9 ^! mod]n days t objects s small z ! satellites ( ,m>s %\ld be se5 at all8 ,y rememb]1 ( c\rse1 t nei!r ,m>s himself nor 8 moons h any light ( _! own4 ,!y %9e solely 9 consequ5ce ( ! sunlight :i* falls ^u !m4 ,!y are m]ely light$ l ! e>? itself1 or l ! moon4 ,! difficulty ab\t obs]v+ ! satellites is all ! great] because !y are se5 9 ! telescope close to su* a brilliant body z ,m>s4 ,! gl>e f ! bright planet is su* t :5 we want to see fa9t objects l ! satellites we h to hide ,m>s1 s z to get a comp>atively d>k space 9 :i* to se>*4 ,n[ t !y "k exactly :at to look =1 a good _m a/ronom]s h obs]v$ ! satellites ( ,m>s4 ,a sup]b telescope is nev]!less requir$4 ,&1 9 fact1 y c\ld n f9d a bett] te/ = ! excell5ce ( an in/rum5t ?an to try if x w %[ ^! delicate objects4 ,b d n imag9e t m]ely hav+ a good telescope & a cle> sky is all t is requisite = mak+ a/ronomical discov]ies4 ,y might j z well say t by putt+ a fir/-rate cricket-bat 9 any man's h&s w ensure 8 mak+ a gr& score4 ,e boy kn[s t ! bat does n make ! cricket]1 & ,i c assure him t nei!r w ! telescope make ! a/ronom]4 ,9 bo? cases1 no d\bt1 !re is "s elem5t ( luck4 ,b ( ?is y may be c]ta93 t z x is ! man t makes ! score1 & n ! bat1 s x is ! a/ronom] t makes ! discov]y1 & n 8 telescope4 ,deimos & ,phobos 7 ! names ( ! two p]sonages1 accord+ to ,hom]1 ^: duty x 0 to att5d on ! god ,m>s1 & to yoke 8 /e$s4 ,a conclave ( classical s*ol>s & a/ronom]s appropriately decid$ t ,deimos & ,phobos mu/ be ! names ( ! two satellites to ! planet :i* be>s ! "n ( ,m>s4 ,,h[ ,,! ,,telescope ,,aids ,,9 ,,view+ ,,fa9t ,,objects4 ,we h be5 hi!rto talk+ ab\t l>ge planets1 :i*1 if n z big z our e>?1 are at lea/ z big z our moon4 ,b n[ we h to say a few words ab\t a numb] ( little planets1 _m ( !m be+ s v small t a million roll$ toge!r w\ld n =m a globe s big z ?is e>?4 ,^! little objects y _c see ) y\r unaid$ eye1 & ev5 ) a telescope !y only look l v small />s4 ,i h (t5 be5 ask$ :y x is t a telescope enables u to see objects1 bo? fa9t & small1 :i* our unaid$ eyes fail to %[4 ,p]haps ?is w be a good opportunity to say a few words on ! subject4 ,i ?9k we c expla9 ! utility ( ! telescope by exam9+ our own eyes4 ,! eye und]goes a rem>kable trans=mation :5 its own] passes f d>kness into a brilliantly light$ room 7,fig4 #fd74 ,"h y see two views ( an eye1 & y notice ! great diff]5ce betwe5 !m4 ,!y are n int5d$ to be ! eyes ( two diff]5t p1 or ! two eyes ( ! same p]son2 !y are m]ely two conditions ( ! same eye4 ,!y are int5d$ to illu/rate two diff]5t /ates ( ! eye ( a colli]4 ,! "r %[s 8 eye :5 he is above gr\nd 9 bright daylight2 ! left is 8 eye :5 he has gone d[n ! coal-pit to 8 useful "w 9 ! d>k regions bel[4 ,i rememb] :5 ,i w5t d[n a coal-pit ,i 0 l[]$ d[n a long %aft1 & :5 ! bottom 0 rea*$ a safety lamp 0 h&$ to me4 ,! gloom 0 su*1 t at fir/ ,i f\nd "s little difficulty 9 guid+ my /eps1 b ! capable guide beside me said 9 an enc\rag+ voice1 8,y w be all "r1 sir1 9 a few mom5ts1 = y w get y\r pit-eyes40 ,i did get my 8pit-eyes10 z he promis$1 & 0 able to see my way along suffici5tly to enjoy ! wond]ful sights t are met ) 9 ! dep?s bel[4 ,illu/ration3 ,?is %[s ! ,eye 9 ! ,d>k4 ,?is %[s ! ,eye 9 ! ,daylight4 ,,fig4 #fd4 ,! *ange t came ov] my eyes is t :i* ^! two pictures illu/rate3 ! black1 r\nd spot 9 ! c5tre is an op5+ cov]$ ) a transp>5t w9d[1 by :i* light ent]s ! eye2 ! black spot is call$ ! pupil1 & nature has provid$ a beautiful contrivance by :i* ! pupil c get l>g] or small]1 s z to make vision agreeable4 ,:5 !re is a great deal ( light we limit ! am\nt t ent]s by contract+ ! pupil s z to make ! op5+ small]4 ,?us ! picture ) ! small pupil repres5ts ! /ate ( ! colli]'s eye :5 he is above gr\nd 9 bright sunlight4 ,:5 he desc5ds into ! pit1 :]e ! light is v scanty1 !n he wants to grasp z mu* ( x z ev] he c1 & consequ5tly 8 pupil enl>ges s z to make a wid] op5+1 & ?is is :at he calls gett+ 8 8pit-eyes40 ,b y ne$ n g d[n a coal-m9e to see ! use ( ! iris--= s t pretty membrane is call$ :i* surr\nds ! pupil4 ,e "t y pass f light into d>kness ! same ?+ c be p]ceiv$4 ,:5 we turn d[n ! lights 9 a room1 s t we are 9 comp>ative d>kness1 our pupils gradually exp&4 ,z soon z ! lights are turn$ up aga91 !n our pupils beg9 to contract4 ,o!r animals h ! same contrivance 9 _! eyes4 ,y may notice 9 ! ,zological ,g>d5s h[ quickly ! pupil ( ! lion contracts :5 he raises 8 eyes to ! light4 ,! p[] ( rapidly *ang+ ! pupil might be ( s]vice to a bea/ ( prey4 ,imag9e him cr\*+ 9 a d5se %ade to wait = 8 d9n]2 !n ( c\rse ! pupil w be l>ge f defici5cy ( light2 b :5 he spr+s out sudd5ly on 8 victim1 9 bright light1 x w\ld surely be ( advantage to him to be able at once to see cle>ly4 ,accord+ly 8 pupil adju/s itself to ! alt]$ conditions ) a rapidity t might n be necess>y = creatures ( less pr$ace\s habits4 ,^! *anges ( ! pupil expla9 h[ ! telescope aids our eyes :5 we want to disc]n any fa9t objects1 l ! little planets4 ,su* bodies are n visible to ! unaid$ eyes1 because our pupils are n l>ge en\gh to grasp suffici5t light = ! purpose4 ,ev5 :5 !y are op5$ to ! utmo/1 we want some?+ t %all enable !m to op5 wid] /ill4 ,we mu/ !re=e borr[ assi/ance f "s device :i* %all h an effect equival5t to an enl>gem5t ( ! pupil beyond ! limits t nature has actually assign$ to x4 ,:at we want is some?+ l a funnel :i* %all trans=m a l>ge beam ( rays into a small "o4 ,i may expla9 :at ,i mean by ! foll[+ illu/ration3 ,suppose t x is ra9+ heavily1 & t y want to fill a bucket ) wat]4 ,if y m]ely put ! bucket out 9 ! middle ( a field1 x w nev] be fill$2 b br+ x to :]e ! ra9-%oot f a h\se-top is runn+ d[n1 & !n y\r bucket w be runn+ ov] 9 a few mom5ts4 ,! reason1 ( c\rse1 is t ! broad top ( ! h\se has caught a va/ numb] ( drops & br\ght !m toge!r 9 ! n>r[ %oot1 & s ! bucket is fill$4 ,9 ! same way ! telescope ga!rs ! rays ( light t fall on ! object glass1 & cond5ses !m into a small beam :i* c ent] ! eye4 ,we ?us h :at is ne>ly equival5t to an eye ) a pupil z big z ! object glass4 ,?us ! effect ( a gr& telescope am\nts to a practical increase ( ! pupil f ! size ( a ?reep5ny-piece up to t ( a d9n]-plate1 or ev5 mu* l>g] /ill4 ,,! ,,a/]oids ,,or ,,small ,,planets4 ,an a/]oid is l a t9y />1 & 9 fact ! two bodies are v (t5 mi/ak54 ,if we c\ld get close to ! objects1 we %\ld see a wide diff]5ce betwe5 !m4 ,we %\ld f9d ! a/]oid to be a d>k planet l our e>?1 light$ only by ! rays f ! sun4 ,! />1 small & fa9t ?\gh x may seem1 is itself a bright sun1 at su* a va/ di/ance t x is only visible z a small po9t4 ,! /> is millions ( times z f> f u z ! planet1 & utt]ly diff]5t 9 e respect4 ,x is a curi\s fact t ! planets %\ld happ5 to resemble ! />s s closely4 ,we c f9d an analog\s fact 9 q ano!r "p ( nature4 ,9 visit+ a good entomological collection1 y w be %[n "s ( ! wond]ful leaf-l insects4 ,^! creatures h w+s1 exactly =m$ to imitate leaves ( trees1 ) ! /alks & ve9s completely repres5t$4 ,:5 "o ( ^! insects lies at re/1 ) its w+s fold$1 among a numb] ( leaves1 x w\ld be almo/ impossible to p5etrate ! disguise4 ,?is mimicry is no d\bt an +5i\s artifice to deceive ! birds or o!r enemies t want to eat ! insect4 ,!re is1 h[ev]1 "o te/ :i* ! cunn+ bird c\ld apply3 ! leaves d n move ab\t ( _! own accord1 b ! leaf-insects d4 ,if !re=e ! bird w only h ! pati5ce to wait1 he w see a pair ( ! seem+ leaves move1 & !n ! deception w be to him a deception no long]1 & he w gobble up ! poor insect4 ,9 our attempts to discov] ! planets we exp]i5ce j ! same difficulties z ! insect-eat+ bird4 ,wide z is ! true diff]5ce betwe5 a planet & a />1 !re is yet su* a seem+ resemblance betwe5 !m t we are (t5 puzzl$ to "k :i* is :i*4 ,! planets imitate ! />s s successfully1 t :5 "o ( !m is pres5t$ to u among myriads ( />s x is impossible = u to detect ! planet by its appe>ance4 ,b we c be cunn+--we c /eadily wat*1 & ! mom5t we f9d "o ( ^! />-l po9ts beg9n+ to creep ab\t we c p\nce ^u x4 ,we "k by its movem5ts t x is only disguis$ z a />1 b t x is really "o ( ! planets4 ,x is n always easy to discov] ! a/]oids ev5 by ?is pr9ciple1 = un=tunately ^! bodies move v sl[ly4 ,if y h a planet 9 ! field ( view1 x w creep along s gradually t an h\r or m mu/ h elaps$ be=e x has %ift$ its position ) respect to ! neighbor+ />s to any appreciable ext5t4 ,! se>* = su* little planets is !re=e a t$i\s "o1 b !re are two me?ods ( conduct+ x3 ! new "o1 :i* has only rec5tly come into use1 & ! old "o4 ,i %all speak ( ! old "o fir/4 ,al?\gh ! body's motion is s sl[1 yet :5 suffici5t "t is all[$1 ! planet w n only move away f ! />s close by1 b w ev5 j\rney r\nd ! entire heav5s4 ,! sure/ way ( mak+ ! discov]y is to /udy a small "p ( ! heav5s n[ & to exam9e ! same locality aga9 mon?s or ye>s aft]w>ds4 ,memory w n suffice = ?is purpose4 ,no "o c\ld recollect all ! />s he saw ) suffici5t di/9ctness to be confid5t t ! field ( ! telescope on ! second occasion conta9$ ei!r m or few] />s ?an x did on ! fir/4 ,! only way ( do+ ?is "w is to draw a map ( ! />s v c>efully4 ,?is is a t$i\s bus9ess1 = ! />s are s num]\s t ev5 9 a small "p ( ! heav5s !re w be _m ?\s&s ( />s visible 9 ! telescope4 ,all ( ^! w h to be ent]$ fai?fully 9 _! true places on ! map4 ,:5 ?is has be5 done ! map mu/ be laid aside = a season1 & !n x is br\ght out aga9 & comp>$ ) ! sky4 ,no d\bt ! great majority ( ! objects w be f\nd j z !y 7 be=e4 ,^! are ! />s1 ! di/ant suns1 & our conc]n is n at pres5t ) !m4 ,sometimes x w happ5 t an object m>k$ on ! fir/ map has left a vacant place on ! second4 ,?is1 h[ev]1 does n help u mu*1 =1 :atev] ! object 01 x has vani%$ into obscurity1 & a new planet c\ld h>dly be discov]$ 9 ?is way4 ,b sometimes x w happ5 t !re is a small po9t ( light se5 9 ! second map :i* has no correspond+ po9t 9 ! fir/4 ,!n1 inde$1 ! expectation ( ! a/ronom] is ar\s$2 he may be on ! br9k ( a discov]y4 ,( c\rse he wat*es accurately ! little /rang]4 ,x might be "s /> t _h be5 accid5tally ov]look$ :5 =m+ ! map1 or x might possibly be a /> t has become bright 9 ! int]val4 ,b "h is a ready te/3 is ! body mov+8 ,he looks at x v c>efully1 & notes its position ) respect to ! adjac5t />s4 ,9 an h\r or two 8 suspicions may be confirm$2 if ! object be 9 motion1 !n x is really a planet4 ,a few fur!r obs]vations1 made on subsequ5t days1 w %[ ! pa? ( ! body4 ,& ! a/ronom] has only to assure himself t ! object is n "o ( ! planets t h be5 already f\nd be=e he ann\nces 8 discov]y4 ,! new me?od ( se>*+ = small planets1 :i* has only come into use 9 rec5t ye>s1 is a v beautiful "o1 & r5d]s ! process ( mak+ su* discov]ies mu* m easy ?an ! old] me?od :i* ,i h j describ$4 ,we c take photographs ( ! heav5ly bodies by adju/+ a s5sitive plate 9 ! telescope s t ! images ( ! objects we desire to see %all fall ^u x4 ,! me?od w apply to v small />s1 if by excell5t clockwork & c>eful guid+ we c keep ! telescope con/antly po9t+ to ! same spot until ! />s h _h "t to impr9t _! little images4 ,?us we obta9 a map ( ! heav5s1 made 9 a ?or\ghly accurate mann]4 ,inde$1 ! delicacy ( photography = ?is purpose is s great1 t ! plates %[ _m />s :i* _c be se5 ) ev5 ! greate/ ( telescopes4 ,suppose t a little planet happ5$ to lie among ! />s :i* are be+ photograph$4 ,all ! "t t ! plate is be+ expos$ ! w&]] is1 ( c\rse1 creep+ along1 & aft] an h\r 7exposures ev5 long] are (t5 us$71 x may h mov$ ?r\gh a di/ance suffici5t to ensure its detection4 ,! plate w1 !re=e1 %[ ! />s z po9ts1 b ! planet w betray its pres5ce by produc+ a /reak4 ,! a/]oids n[ kn[n numb] betwe5 #djj & #ejj4 ,out ( ?is ho/ a few af=d "s in=mation to ! a/ronom]1 b ! majority ( !m are objects possess+ individually only ! slighte/ int]e/4 ,no small planet is wor? look+ at z a telescopic picture4 ,we %\ld consid] t a/]oid to be a l>ge "o :i* possess$ a surface altoge!r z great z ,engl& or ,france4 ,_m ( ^! planets h a sup]ficial ext5t n s l>ge z "s ( our great c\nties4 ,a globe :i* 0 j big en\gh to be cov]$ by ,york%ire--if y c\ld imag9e t l>ge c\nty neatly fold$ r\nd x--w\ld make a v respectable m9or planet4 ,we "k h>dly any?+ ( ! nature ( ^! small worlds1 b x is c]ta9 t any liv+ be+s !y c\ld support mu/ h a totally diff]5t nature f ! creatures t we "k on ?is e>?4 ,we c easily prove ?is by mak+ a calculation4 ,i %all suppose a small planet "o hundr$ miles wide1 its diamet] be+1 !re=e1 ! "o-eightie? "p ( ! diamet] ( ! e>?4 ,if we 7 l&$ on su* a globe1 we %\ld be f> m puzzl$ by ! extraord9>y lightness ( ev]y?+ ?an we %\ld be 9 ! simil> case ( ! moon to :i* ,i ref]r$ 7p4 #abd74 ,if we suppose ! planet to be con/ruct$ ( mat]ials :i* _h ! same d5sity z ^? ( :i* ! e>? is made1 !n e weight w\ld be r$uc$ to ! eightie? "p ( :at x is "h4 ,!re w\ld be "o curi\s consequ5ce ( resid5ce on su* a globe4 ,we h he>d ( attempts to make fly+ ma*9es1 or to provide a man ) w+s by :i* he %all so> al(t l ! birds4 ,all su* contrivances h hi!rto fail$4 ,x may be possible to make a pair ( w+s by :i* a man c fly d[n1 b x is q ano!r matt] :5 he tries to fly up aga94 ,suppose1 h[ev]1 we 7 liv+ on a small planet1 x w\ld be p]fectly easy to fly1 = z our bodies w\ld only seem to weigh a c\ple ( p\nds1 we ought to be able to flap a pair ( w+s /rong en\gh to ov]come s trivial a =ce4 ,i %\ld1 h[ev]1 add t ?is is on ! supposition t ! atmosph]e has ! same d5sity z our own4 ,life on ^! small planets w\ld inde$ be extraord9>y4 ,let u take1 = example1 ,flora1 & see h[ a game ( lawn t5nis on t body w\ld be manag$4 ,! v slighte/ bl[ ( ! racket w\ld drive ! ball a prodigi\s di/ance be=e x c\ld t\* ! gr\nd2 inde$1 unless ! c\rts 7 ab\t half a mile long1 x w\ld be impossible to s]ve any ball t 0 n a fault4 ,nor is !re any great ex]tion necess>y = play+ lawn t5nis on ,flora1 ev5 ?\gh ! c\rts are sev]al hundr$ acres 9 ext5t4 ,z a "y lady ran to meet ! ball & return x1 ea* ( h] /eps might cov] a hundr$ y>ds or s )\t extra ef=t2 & %\ld %e h ! mis=tune to get a fall1 h] desc5t to ! gr\nd w\ld be z g5tle z if %e 0 seek+ repose on a b$ ( ! s(te/ swan's-d[n4 ,^! little planets clu/] toge!r 9 a c]ta9 "p ( our sy/em4 ,inside are ! f\r inn] planets1 ( :i* we h already spok52 outside are ! f\r out] planets1 ( :i* we h soon to speak4 ,betwe5 ^! two gr\ps !re 0 a vacant space4 ,x seem$ unreasonable t :]e !re 0 room = planets1 planets %\ld n be f\nd4 ,accord+ly ! se>* 0 made1 & ^! objects 7 discov]$4 ,ev5 at ! pres5t day1 m & m are be+ con/antly add$ to ! li/4 ,up till q rec5tly all ! small planets :i* _h be5 discov]$ conf9$ !mselves to ! space ly+ betwe5 ! pa?s ( ! major planets ,m>s & ,jupit]4 ,?is inv>iable rule 01 h[ev]1 dep>t$ f 9 ! case ( "o ( ^! bodies :i* 0 discov]$ 9 ,augu/1 #ahih4 ,?is little body1 :i* 0 kn[n = "s "t by ! provisional appellation ( ,d ,q1 & :i* has n[ be5 def9itely *ri/5$ ,eros1 is an exception to ?is rule4 ,x travels at an av]age di/ance f ! sun actually less ?an t ( ,m>s1 & at ! ne>e/ po9t c come )9 #ae1jjj1jjj miles ( ! e>?4 ,we occasionally get in=mation f ^! little bodies2 = 9 _! revolutions ?r\gh ! sol> sy/em1 !y sometimes pick up scraps ( useful k1 :i* we c elicit f !m by c>eful exam9ation4 ,= example1 "o ( ! mo/ important problems 9 ! :ole ( a/ronomy is to det]m9e ! sun's di/ance4 ,i h already m5tion$ "o ( ! ways ( do+ ?is1 :i* is giv5 by ! transit ( ,v5us4 ,a/ronom]s nev] l to rely on a s+le me?od2 we are !re=e glad to discov] any o!r means ( solv+ ! same problem4 ,?is x is :i* ! little planets w sometimes d = u4 ,juno on "o occasion approa*$ v close to ! e>?1 & a/ronom]s 9 v>i\s p>ts ( ! globe obs]v$ h] at ! same "t4 ,:5 !y comp>$ _! obs]vations !y measur$ ! sun's di/ance4 ,b ,i am n go+ to tr\ble y n[ ) a matt] s difficult4 ,suffice x to say1 t = ?is1 z = all simil> inve/igations1 ! obs]v]s 7 con/ra9$ to use ! v same pr9ciple z t :i* we illu/rat$ 9 ,fig4 #e4 ,let me r close ?is lecture ) ! rem>k t we h "h be5 consid]+ only ! less] memb]s ( ! great family :i* circulate r\nd ! sun1 & t we %all speak 9 our next lecture ( ! giant memb]s ( our sy/em4 ,,lecture ,,iv4 ,,jupit]1 ,,saturn1 ,,uranus1 ,,neptune4 ,jupit]1 ,saturn1 ,uranus1 ,neptune--,jupit]--,! ,satellites ( ,jupit]--,saturn--,! ,nature ( ! ,r+s--,william ,h]s*el--,! ,discov]y ( ,uranus--,! ,satellites ( ,uranus--,! ,discov]y ( ,neptune4 ,our lecture to-day ought to make u take a v humble view ( ! size ( our e>?4 ,m]cury1 ,v5us1 & ,m>s may be reg>d$ z ! e>?'s pe]s1 ?\gh we are slightly l>g] ?an ,v5us1 & a good deal l>g] ?an ,m]cury or ,m>s2 b all ^! f\r globes are insignificant 9 comp>ison ) ! gigantic planets :i* lie 9 ! out] p>ts ( our sy/em4 ,^! great bodies d n enjoy ! b5efits ( ! sun to ! same ext5t t we are p]mitt$ to d2 !y are s f> (f t ! sun's rays become greatly enfeebl$ be=e !y c trav]se ! di/ance2 b ! gloom ( _! situation seems to matt] b little1 = x is highly improbable t any ( ^! bodies c\ld be inhabit$4 ,a view ( p>ts ( ! pa?s ( ^! f\r great planets is %[n 9 ,fig4 #fe4 ,! inn]mo/ is ,jupit]1 :i* completes a circuit 9 ab\t twelve ye>s2 !n comes ,saturn1 revolv+ 9 an orbit s great t tw5ty-n9e ye>s & a half are requir$ be=e ! complete j\rney is f9i%$4 ,/ill fur!r outside is ,uranus1 :i* has a long] j\rney ?an ,saturn1 & moves s mu* m sl[ly t a man w\ld h to live to ! ripe old age ( eighty-f\r if a complete revolution ( ,uranus 0 to be accompli%$ dur+ 8 lifetime4 ,at ! b\nd>y ( our sy/em revolves ! planet ,neptune1 & ?\gh x is a mighty globe1 yet we _c see x )\t a telescope4 ,x is invisible to ! nak$ eye = two reasons3 fir/ ( all1 because x is s f> f ! sun t ! light :i* illum9ates x is excessively feeble2 &1 secondly1 because x is s f> f u t :atev] brilliancy x has is l>gely r$uc$4 ,illu/ration3 ,,fig4 #fe4--,! ,orbits ( ! ,f\r ,giant ,planets4 ,,jupit]4 ,( all ^! bodies ,jupit] is by f> ! greate/2 he is1 inde$1 great] ?an all ! o!r planets roll$ into "o4 ,! relative insignificance ( ! e>? :5 comp>$ ) ,jupit] is well illu/rat$ by ! fact t if we took #abjj globes ea* z big z our e>?1 & made !m into a s+le globe1 x w\ld only be z l>ge z ! greate/ ( ! planets4 ,a view ( ! comp>ative sizes ( ! e>? & ,jupit] is %[n 9 ,fig4 #ff4 ,illu/ration3 ,,fig4 #ff4--;,jupit] & ! ,e>? comp>$4 ,fig4 #fg %[s a picture ( ,jupit] z se5 ?r\gh ! telescope4 ,fir/1 y w notice t ! outl9e ( ! planet's %ape is n circul>1 = x is pla9 t ! v]tical diamet] 9 ?is picture is %ort] ?an ! horizontal "o2 9 fact1 ,jupit] is flatt5$ at ! ,poles & bulges out at ! equator1 s t a section ?r\gh ! ,poles is an ellipse4 ,jupit] is turn+ r\nd rapidly on 8 axis1 & ?is w acc\nt = ! protub]ance4 ,we f9d t ! planet has assum$ almo/ ! same =m z if x 7 actually a liquid4 ,?is we c illu/rate by a globe ( oil :i* is pois$ 9 a mixture ( spirits ( w9e & wat] s c>efully adju/$ t ! oil has no t5d5cy to rise or fall4 ,z we make ! globe ( oil rotate1 :i* we c easily d by pass+ a sp9dle ?r\gh x1 we see t x bulges out 9 ! =m t ,jupit] z well z o!r planets h tak54 ,illu/ration3 ,,fig4 #fg4--,! ,cl\ds ( ,jupit]4 ,on ! picture ( ! planets y w see %ad$ b&s4 ,^! are con/antly *ang+ _! aspect1 & = a d\ble reason4 ,9 ! fir/ place1 !y *ange because ,jupit] is rotat+ s quickly t 9 five h\rs ! :ole side ( ! planet :i* is t[>ds u has be5 c>ri$ out ( sight4 ,9 ano!r five h\rs ! orig9al side ( ! globe w be back aga91 = ! entire rotation occupies ab\t #aj h\rs1 or1 m precisely1 #i h\rs #ee m9utes #ba seconds4 ,b ^! b&s are !mselves n p]man5t objects4 ,!y h no m p]man5ce ?an ! cl\ds ov] our own sky4 ,sometimes ,jupit]'s cl\ds are m /rongly m>k$ ?an on o!r occasions4 ,sometimes1 inde$1 !y are h>dly to be se5 at all4 ,x is f ?is we le>n t ^? m>k+s :i* we see :5 we look at ! great planet are m]ely ! masses ( cl\d :i* surr\nd & obscure :atev] may con/itute 8 int]ior4 ,!re is a circum/ance :i* demon/rates t ,jupit] mu/ be an object exce$+ly diff]5t f ! e>?1 ?\gh bo? bodies agree 9 s f> z hav+ cl\ds are conc]n$4 ,:at w\ld y ?9k :5 ,i tell y t we 7 able to weigh ,jupit] by ! aid ( 8 little moons1 ( :i* ,i %all aft]w>ds speak8 ,^! little bodies in=m u t ,jupit] is ab\t #cjj times z heavy z our e>?1 & we h no d\bt ab\t ?is1 = x has be5 confirm$ 9 o!r ways4 ,b we h f\nd by actual measurem5t t ,jupit] is #abjj times z big z ! e>?1 & !re=e1 if he 7 con/itut$ l ! e>?1 he ought to be #abjj times z heavy4 ,?is is1 ,i ?9k1 q pla92 = if two cakes 7 made ( ! same mat]ial1 & "o conta9$ twice ! bulk ( ! o!r1 !n x w\ld c]ta9ly be twice z heavy4 ,if !re be two balls ( iron1 "o twice ! bulk ( ! o!r1 !n1 ( c\rse1 "o has twice ! weight ( ! o!r4 ,b if a ball ( lead h twice ! bulk ( a ball ( iron1 !n ! lead5 ball w\ld be m ?an twice z heavy z ! iron1 because lead is ! heavi] mat]ial4 ,9 ! same way1 ! weights ( ! e>? & ,jupit] are n :at we might expect f _! relative sizes4 ,if ! two bodies 7 made ( ! same mat]ials & 9 ! same /ate1 !n ,jupit] w\ld be c]ta9ly f\r times z heavy z we f9d him to be4 ,we are1 !re=e1 l$ to ! belief t ,jupit] is n a solid body1 at lea/ 9 its out] portions4 ,! masses ( cl\d :i* surr\nd ! planet seem to be imm5sely ?ick1 & z cl\ds are1 ( c\rse1 light bodies 9 comp>ison ) _! bulk1 !y h ! effect ( l>gely increas+ ! app>5t size ( ,jupit]1 :ile add+ v little to 8 weight4 ,!re is ?us a great deal ( m]e inflation ab\t ?is planet1 by :i* he looks mu* bigg] ?an 8 actual mat]ials w\ld w>rant if he 7 con/itut$ l ! e>?4 ,^! facts sugge/ an int]e/+ "q4 ,:y has ,jupit] su* an imm5se atmosph]e1 if we may s call x8 ,! cl\ds we are s famili> ) d[n "h on ! e>? are produc$ by ! heat ( ! sun1 :i* beats d[n ^u ! wide surface ( ! ocean1 evaporates ! wat]1 & raises ! vapor up to :]e x =ms ! cl\ds4 ,heat1 !re=e1 is necess>y = ! =mation ( cl\d2 & ) cl\ds s d5se & s massive z ^? on ,jupit]1 m heat w\ld app>5tly be necess>y ?an is requir$ = ! mod]ate cl\ds on ?is e>?4 ,:5ce is ,jupit] to get ?is heat8 ,h we n se5 t ! great planet is f> m di/ant f ! sun ?an we are8 ,9 fact1 ! int5sity ( ! sun's heat on ,jupit] is n m ?an ! tw5ty-fif? "p ( :at we d]ive f ! same s\rce4 ,we c h>dly believe t ! sun suppli$ ! heat to make ^? big cl\ds on ! great planet2 s we mu/ ca/ ab\t = an additional s\rce1 :i* c only be inside ! planet itself4 ,s f> z 8 int]nal heat is conc]n$1 ,jupit] seems to be 9 mu* ! same condition n[ z our e>? 0 once1 ages ago1 be=e its surface _h cool$ d[n to ! pres5t temp]ature4 ,z ,jupit] is s mu* l>g] ?an ! e>?1 he has be5 sl[] 9 p>t+ ) 8 heat4 ,! planet seems n yet to h _h "t to cool suffici5tly to enable wat] to rema9 on 8 surface4 ,?us ! int]nal heat ( ! planet supplies an explanation ( 8 cl\ds4 ,we may also rem>k t z ! pres5t condition ( ,jupit] illu/rates ! e>ly condition ( our e>?1 s ! pres5t condition ( ! e>? =e%ad[s ! future res]v$ = ,jupit] :5 he %all h _h "t to cool d[n1 & :5 ! wat]s t n[ exi/ 9 ! =m ( vapor %all be cond5s$ into oceans on 8 surface4 ,,! ,,satellites ,,( ,,jupit]4 ,e own] ( a telescope delights to turn x on ! planet ,jupit]1 bo? = ! spectacle ! globe itself af=ds him1 & = a view ( ! wond]ful sy/em ( moons by :i* ! giant planet is att5d$4 ,=tunately ! f\r satellites ( ,jupit] lie )9 rea* ( ev5 ! mo/ mode/ telescope1 & _! incessant *anges relative to ,jupit] & ea* o!r give !m a nev]-end+ int]e/ = ! a/ronom]4 ,comp>$ ) ! torpid p]=mance ( our moon1 :i* requires a mon? to complete a circuit ar\nd ! e>?1 ,jupit]'s moons are wond]fully brisk & lively4 ,nor are !y small bodies l ! satellites ( ,m>s1 = ! second ( ,jupit]'s satellites is q z big z our moon1 & ! o!r ?ree are v mu* l>g]4 ,x is1 h[ev]1 true t 8 satellites appe> insignificant :5 comp>$ ) ,jupit]'s own enorm\s bulk4 ,! inn]mo/ ( ^! little bodies flies "r r\nd 9 a p]iod ( "o day & eighte5 or n9ete5 h\rs1 :ile ! out]mo/ ( !m takes a little m ?an a =tnight--t is1 r m ?an half ! "t t our moon dem&s = a complete revolution4 ,jupit]'s satellites are too f> (f = u to see mu* ) respect to _! /ructure or appe>ance ev5 ) mighty telescopes4 ,x is1 ( c\rse1 _! great di/ance f u t makes !m look insignificant4 ,!y w\ld1 h[ev]1 be bright en\gh to be se5 l small />s 7 x n t1 be+ s close to ,jupit]1 8 ov]p[]+ brightness r5d]s su* fa9t objects 9 8 vic9ity invisible4 ,x 0 by means ( ! satellites ( ,jupit] t "o ( ! mo/ beautiful sci5tific discov]ies 0 made4 ,z a satellite revolves r\nd ! giant planet x (t5 happ5s t ! little body ent]s into ! %ad[ ( ! great planet4 ,no sunlight w !n fall ^u ! satellite1 & z x has no light ( its own1 x disappe>s f sight until x has pass$ ?r\gh ! %ad[ & aga9 receives sunlight on ! o!r side4 ,we c wat* ^! eclipses ) our telescopes1 & !re c be no m int]e/+ employm5t = a small telescope4 ,! movem5ts ( ^! bodies are n[ kn[n s ?or\ghly t ! occurr5ce ( ! eclipses c be pr$ict$4 ,! almanacs w tell :5 ! satellite is calculat$ to disappe>1 & :5 x ought aga9 to return to visibility4 ,:5 a/ronom]s fir/ began to make ^! computations a c\ple ( hundr$ ye>s ago1 ! little satellites gave a great deal ( tr\ble4 ,!y w\ld n keep _! "t4 ,sometimes !y 7 a qu>t] ( an h\r too soon1 & sometimes a qu>t] ( an h\r too late4 ,at la/1 h[ev]1 ! reason = ^! irregul>ities 0 discov]$1 & a wond]ful reason x 04 ,suppose !re 7 a numb] ( cannons all ov] ,hyde ,p>k1 & t ^! cannons 7 fir$ at ! same mom5t by electricity4 ,?\gh ! s\nds w\ld all be produc$ simultane\sly1 yet1 no matt] :]e y /ood1 y w\ld n he> !m altoge!r2 ! noise f ! cannons close at h& w\ld rea* y\r e>s fir/1 & ! m di/ant reports w\ld come 9 subsequ5tly4 ,y c calculate ! di/ance ( a fla% ( lightn+ if y all[ a mile = e five seconds t elapse betwe5 ! "t y saw ! fla% & ! "t y he>d ! peal ( ?und] :i* foll[$ x4 ,! light & ! noise 7 produc$ simultane\sly1 b ! s\nd takes five seconds to pass ov] e mile1 :ile ! light1 9 comp>ison to s\nd1 may be said to move in/antane\sly4 ,t s\nd travell$ ) a limit$ velocity 0 always obvi\s1 b nev] until ! discrepancies arose ab\t ,jupit]'s satellites 0 x le>n$ t light also takes "t to travel4 ,x is true t light travels mu* m quickly ?an s\nd--inde$1 ab\t a million times z fa/4 ,light goes s quickly1 t x w\ld ru% m ?an sev5 times ar\nd ! e>? 9 a s+le second4 ,s f> z t]re/rial di/ances are conc]n$1 ! velocity ( light is su* t ! "t requir$ = a j\rney is inappreciable4 ,! di/ances1 h[ev]1 betwe5 "o cele/ial body & ano!r are s enorm\s1 t ev5 a ray ( light1 mov+ z quickly z x alone c move1 w occupy a measurable "t on ! way4 ,our moon is comp>atively s ne> u1 t light takes little m ?an a second to cov] t %ort di/ance4 ,eight m9utes are1 h[ev]1 requir$ = light to travel f ! sun to ! e>?2 9 fact1 ! sunbeams t n[ come into our eyes left ! sun eight m9utes ago4 ,if ! sun 7 to be sudd5ly ext+ui%$1 x w\ld /ill seem to %9e z brightly z ev] 9 ! eyes ( ! inhabitants ( ?is e>? = eight m9utes long]4 ,z ,jupit] is five times z f> f ! sun z we are1 x foll[s t ! light f ! sun to ,jupit] w sp5d =ty m9utes on ! j\rney1 & ! light f ,jupit] to ! e>? w take a some:at simil> "t4 ,:5 we look at ,jupit] & 8 moons1 we d n see him z he is n[1 we see him z he 0 m ?an half an h\r ago1 b ! int]val w v>y some:at accord+ to our diff]5t di/ances f ! planet4 ,sometimes ! light f ,jupit] w rea* u 9 z little z ?irty-two m9utes1 :ile sometimes x w take z mu* z =ty-eight--t is1 ! light sometimes requires = its j\rney a qu>t] ( an h\r m ?an is suffici5t at o!r times4 ,we c !re=e und]/& t irregul>ity ( ,jupit]'s satellites :i* puzzl$ ! e>ly a/ronom]s4 ,an eclipse sometimes appe>$ a qu>t] ( an h\r be=e x 0 expect$2 because ! e>? 0 !n z ne> z x c\ld be to ,jupit]1 :ile ! calculations _h be5 made f obs]vations :5 ,jupit] 0 at 8 greate/ di/ance4 ,x 0 ^! eclipses ( ! satellites :i* fir/ sugge/$ ! possibility t light mu/ h a measurable spe$4 ,:5 ?is 0 tak5 into acc\nt1 !n ! occasional delay ( ! eclipses 0 f\nd to be satisfactorily expla9$4 ,confirmation fl[$ 9 f o!r s\rces1 & ?us ! discov]y ( ! velocity ( light 0 completely e/abli%$4 ,pr(essor ,b>n>d1 :5 /udy+ ,jupit] 9 #ahib ) ! spl5did refractor at ! ,lick ,obs]vatory1 saw a v small po9t ( light ne>] to ! planet ?an ! ne>e/ ( ! f\r satellites already kn[n4 ,fur!r exam9ation %[$ t ?is little object 0 inde$ ano!r satellite4 ,?us ,jupit] has a fif? moon 9 addition to ! f\r :i* h be5 kn[n s long4 ,?is little body is s small & fa9t t x c only be disc]n$ "u ! mo/ favorable conditions by ! mo/ p[]ful telescopes4 ,,saturn4 ,next outside ,jupit]1 on ! conf9es ( ! anci5t planet>y sy/em1 revolves ano!r gr& planet1 call$ ,saturn4 ,8 di/ance f u is sometimes ne>ly a ?\s& millions ( miles1 & he requires m ?an a qu>t] ( a c5tury = ! completion ( ea* revolution4 ,sometimes p d n pron\nce ! names ( ! planets q correctly4 ,i h he>d ( a g>d5] :o has a ta/e = a/ronomy1 & sometimes beg9s to talk ab\t ! planets ,junip] & ,citron4 ,probably y w "k :at he meant to say4 ,! anci5ts _h discov]$ ,saturn to be a planet1 = ?\gh he look$ l a />1 yet 8 movem5t ?r\gh ! con/ellations c\ld n escape _! notice :5 att5tion 0 paid to ! heav5s4 ,illu/ration3 ,,fig4 #fh4--,saturn & ! ,e>? comp>$4 ,9 ! matt] ( size ,saturn is only surpass$ by ,jupit] among ! planets4 ,he is ab\t #fjj times z l>ge z ! e>?2 ! small object1 ,e1 %[n 9 ,fig4 #fh1 repres5ts our e>? 9 its true comp>ative size to ! r+$ planet2 b ,saturn is s f> (f1 t ev5 at 8 be/ he is nev] s bright z ,v5us1 or ,m>s1 or ,jupit] become :5 !y are favorably situat$4 ,on ! globe ( ,saturn we c sometimes see a few b&s1 b !y are fa9t comp>$ ) ^? on ,jupit]4 ,!re is1 h[ev]1 no d\bt t :at we see ^u ,saturn is a d5se mass ( cl\d4 ,inde$1 he c h comp>atively little solid matt] inside1 = ?is planet does n weigh s mu* z a ball ( wat] ! same size w\ld d4 ,saturn1 l ,jupit]1 mu/ be highly heat$ 9 8 int]ior4 ,! r+1 or r s]ies ( r+s1 by :i* ! planet is surr\nd$ are also %[n 9 ,fig4 #fh3 ^! app5dages are n fa/5$ to ! globe ( ,saturn by any mat]ial bonds2 !y are pois$ 9 space1 )\t any support1 :ile ! globe or planet prop] is plac$ symmetrically 9 ! int]ior4 ,i h made a model :i* %[s ,saturn ) 8 r+s1 b x is necess>y = me to fa/5 ! r+s by little pieces ( wire to ! globe1 = !re is no me*anical means by :i* ! r+s ( ! model c\ld be pois$ )\t support1 z !y are ar\nd ! planet4 ,if we ?r[ ! beam ( ! electric lamp on ! little planet1 we see ! %ad[ :i* ! planet ca/s on its r+4 ,simil> %ad[s c be obs]v$ 9 ! actual ,saturn ( ! sky1 & ?is is a pro( t ! planet does n %9e by its own light1 b by ! light ( ! sun :i* falls ^u x4 ,"h aga9 we illu/rate ! wide diff]5ce betwe5 a planet & a />1 = 7 our sun to be put out1 ,saturn & all ! o!r planets 9 ! sky w\ld vani% f sight1 :ile ! />s w\ld1 ( c\rse1 tw9kle on z be=e4 ,!re are ?ree r+s r\nd ,saturn2 !y all lie 9 ! same plane1 & !y are s ?91 t :5 turn$ edgewise t[>ds u ! :ole sy/em almo/ disappe>s1 except 9 v p[]ful telescopes4 ,! out] & ! inn] bright r+s are divid$ by a d>k l9e1 :i* c be trac$ entirely r\nd4 ,at ! inn] edge ( ! inn] r+ beg9s t /range /ructure call$ ! crape r+1 :i* ext5ds halfway t[>ds ! globe ( ! planet4 ,! mo/ rem>kable po9t ab\t ! crape r+ is its semi-transp>5cy1 = we c sometimes see ! globe ( ! planet ?r\gh ?is /range curta94 ,! crape r+ c only be obs]v$ ) a p[]ful telescope4 ,! o!r two r+s are )9 ! p[] ( v mod]ate in/rum5ts4 ,,! ,,nature ,,( ,,! ,,r+s4 ,= ! explanation ( ! nature ( ,saturn's r+s we are indebt$ to ! calculations ( ma!maticians4 ,y might h ?\ght1 p]haps1 t no?+ w\ld be simpl] ?an to suppose ! r+s 7 /iff plates made f solid mat]ial4 ,b ! "q _c be ?us settl$4 ,we "k t ! r+ c\ld n be> ! /ra9 ( ! planet's attraction ^u x if x 7 a solid body4 ,i may illu/rate ! argum5t by famili> facts ab\t bridges4 ,:]e ! span is b a small "o1 z1 = in/ance1 :5 a road has to cross a railway1 a canal1 or a riv]1 ! ar* is1 ( c\rse1 ! prop] k9d ( /ructure4 ,!re is1 = example1 a specially beautiful ar* ov] ! riv] ,dee at ,*e/]4 ,b if ! bridge be long] ?an ?is1 masonry ar*es are n suitable4 ,:]e a consid]able span has to be cross$1 z at ! ,m5ai ,/raits1 or a gigantic "o1 z at ! ,fir? ( ,=?1 !n ar*es h to be ab&on$1 & iron bridges ( a totally diff]5t con/ruction h to be employ$4 ,ar*es _c be us$ beyond a limit$ span1 because ! /ra9 ^u ! mat]ials becomes too great = _! p[]s ( resi/ance to )/&4 ,ea* ( ! /ones 9 an ar* is squeez$ by int5se pressure1 & !re is a limit beyond :i* ev5 ! /\te/ /ones _c be reli$ ^u4 ,z soon1 !re=e1 z ! span ( ! ar* is s great t ! /ones x conta9s are squeez$ z f> z is compatible ) safety1 !n ! limit ( size = t =m ( ar* has be5 rea*$4 ,suppose t y /ood on ,saturn at 8 equator1 & look$ up at ! mighty r+ :i* w\ld /ret* edgewise across y\r sky4 ,x w\ld rise up f ! horizon on "o side1 &1 pass+ ov] y\r head1 w\ld slope d[n to ! horizon on ! o!r4 ,y w\ld1 9 fact1 be "u an ar* ( :i* ! span 0 ab\t #ajj1jjj miles4 ,ow+ to ! attraction ( ,saturn1 e "p ( t /ructure w\ld be pull$ =cibly t[>ds 8 surface1 & ?us ! mat]ials ( ! ar*1 if x 7 a solid body1 w\ld be compress$ ) t]rific =ce4 ,x does n really signify t ! ar* ,i am n[ speak+ ( is half ( a r+ ! o!r half ( :i* is bel[ ! globe ( ! planet4 ,t is only a diff]5ce ) respect to ! support ( two ends ( ! ar*1 & does n affect ! "q z to ! pressure ^u its mat]ials2 nor does ! fact t ! r+ is revolv+ remove ! difficulty1 ?\gh x und\bt$ly less5s x4 ,we "k no solid sub/ance :i* c\ld endure ! pressure4 ,ev5 ! t\ghe/ /eel t ev] 0 made w\ld b5d up l d\gh "u su* conditions4 ,we _c1 !re=e1 acc\nt = ,saturn's r+ by suppos+ x to be a solid1 = no solid w\ld be /rong en\gh4 ,d y n rememb] ! old fable ( ! oak tree & ! pliant re$--h[ :5 ! /orm 0 ab\t to arise ! oak laugh$ at ! poor re$1 & said x w\ld nev] be able to )/& ! bla/s8 ,b matt]s did n s turn out4 ,! mighty oak1 :i* w\ld n yield to ! /orm1 0 bl[n d[n1 :ile ! sl5d] re$ b5t to ! w9d & suff]$ no injury4 ,?is gives u a h9t z to ! true con/itution ( ,saturn's r+2 x is n a solid body1 try+ to resi/ by m]e /r5g?2 x is r to be expla9$ z an excessively pliant /ructure4 ,inde$1 ,i ought n to call x a /ructure at all2 x is r a multitude ( small bodies n 9 ! lea/ atta*$ toge!r4 ,i d n "k :at ! size ( ^! bodies may be4 ,= any?+ we c tell1 !y may be no l>g] ?an ! pebbles y f9d on a gravel walk4 ,let u see h[ we c\ld encircle our e>? ) r+s l ^? :i* surr\nd ,saturn4 ,i %all ask y to be provid$ ) a suffici5tly l>ge numb] ( pebbles1 & y mu/ also imag9e t ,i h ! means ( asc5d+ high up into space1 halfway f "h to ! moon4 ,suppose ,i w5t up !re & simply dropp$ ! pebble1 ( c\rse1 x w\ld tumble /raight d[n to ! e>? aga94 ,if1 h[ev]1 ,i ?rew x out ) prop] spe$ & 9 ! prop] direction1 ,i c\ld />t x (f l a little moon1 & x w\ld g on r\nd & r\nd our e>? 9 a circle4 ,i m5tion a pebble1 b really x is little matt] :at ! size ( ! object may be--x may be z small z a gra9 ( %ot or z big z a cannon-ball4 ,n[ take ano!r pebble4 ,ca/ x also 9 a some:at simil> pa?1 tak+ c>e1 h[ev]1 t ! planes ( ! two orbits %all be ! same4 ,ea* ( ^! little bodies %all pursue its j\rney )\t int]f]5ce f ! o!r4 ,!n proce$ 9 ! same way ) a ?ird1 a f\r?1 ) ?\s&s & millions & billions ( pebbles1 until at la/ ! small bodies w become s num]\s t !y almo/ fill a l>ge "p ( ! plane ) a cont9u\s %oal4 ,ea* little object1 guid$ entirely by ! e>?'s attraction1 w pursue its pa? ) undeviat+ regul>ity4 ,its neighbors w n int]f]e ) x1 nor w x int]f]e ) !m4 ,let u circumscribe ! limits ( our flat %oal ( moonlets4 ,we fir/ take away all ^? t lie outside a c]ta9 l>ge circle2 !n we %all cle> away suffici5t to make a vacant space betwe5 ! out] r+ & ! inn] r+1 & ?us ! two conspicu\s r+s h be5 made2 at ! inside ( ! inn] r+ we %all take out numb]s ( pebbles "h & !re1 s z to make ?is "p mu* less d5se ?an ! out] portions1 & ?us produce a semi-transp>5t crape r+2 !n we %all cle> away ^? t come too close to ! planet1 & =m a neat inn] b\nd>y4 ,c\ld we !n view our h&iwork f ! /&po9t ( ano!r planet1 :at appe>ance w\ld our e>? pres5t8 ,! sev]al pebbles1 ?\gh individually s small1 w\ld yet1 by _! c\ntless numb]s1 reflect ! sun's light s z to produce ! appe>ance ( a cont9u\s %eet4 ,?us we %\ld f9d a l>ge bright out] r+ surr\nd+ ! e>?1 sep>at$ by a d>k int]val f ! inn] r+1 & at ! m>g9 ( ! inn] r+ ! pebbles w\ld be s mu* m sp>sely di/ribut$ t we %\ld be able to see ?r\gh !m to "s ext5t4 ,t beautiful sy/em ( r+s :i* ,saturn displays is und\bt$ly ( a simil> "* to ! hypo!tical sy/em :i* ,i h endeavor$ to describe4 ,no o!r explanation w acc\nt = ! facts1 especially = ! semi-transp>5cy ( ! crape r+4 ,! sep>ate bodies f :i* ,saturn's r+s are con/itut$ seem1 h[ev]1 s small t we are n able to see !m individually4 ,!re are "s o!r f9e l9es runn+ r\nd ! r+s beside ! great division1 & ^! c also be expla9$ by ! !ory ,i h /at$4 ,saturn has o!r claims on our att5tion besides ^? ( its r+s4 ,x has an elaborate ret9ue ( satellites--no few]1 inde$1 ?an n9e2 b "s ( !m are v fa9t objects1 & n by any means s int]e/+ z ! sy/em by :i* ,jupit] is att5d$4 ,! n9? ( ^! 0 discov]$ q rec5tly by ,pr(essor ,w4 ,h4 ,pick]+1 ( ,h>v>d ,college ,obs]vatory4 ,?is little moon1 = :i* ! "n 8,phoebe0 has be5 sugge/$1 is fur!r f ! planet ?an any ( ! o!rs4 ,x is a m9ute object %9+ z a /> ( ! #ae? or #af? magnitude1 & moves ar\nd ! planet 9 a p]iod ( ab\t sixte5 mon?s4 ,saturn 0 ! la/ & out]mo/ ( ! planets ) :i* ! anci5ts 7 acqua9t$4 ,its pa? lay on ! fronti]s ( ! !n kn[n sol> sy/em1 & ! magnific5ce ( ! planet itself1 ) its att5dant lum9>ies & its m>vell\s r+s1 r5d]$ x wor?y inde$ ( a position s dignifi$4 ,^! five planets--namely1 ,m]cury1 ,v5us1 ,m>s1 ,jupit]1 & ,saturn--made up ) ! sun & ! moon ! sev5 8planets0 ( ! anci5ts4 ,!y 7 suppos$ to complete ! sol> sy/em1 &1 fur!rmore1 ! exi/5ce ( o!r memb]s 0 ?\ght to be impossible4 ,9 mod]n times x has be5 discov]$ t !re are yet two m planets4 ,i d n n[ ref] to ^? little bodies :i* run ab\t 9 scores betwe5 ,m>s & ,jupit]4 ,i mean two gr& fir/-class planets1 f> bigg] ?an our e>?4 ,"o ( !m is ,uranus1 :i* revolves f> outside ,saturn1 & ! o!r is ,neptune1 :i* is mu* fur!r /ill1 & ^: mighty orbit includes ! :ole planet>y sy/em 9 its circuit4 ,to complete its j\rney r\nd ! sun n less ?an #afe ye>s is requir$4 ,,william ,,h]s*el4 ,i h to beg9 ! acc\nt ( ?is discov]y by tell+ y a little /ory4 ,9 ! middle ( ! la/ c5tury !re liv$ at ,hanov] a tea*] ( music ^: "n 0 ,isaac ,h]s*el4 ,he _h a family ( t5 *ildr51 & he did ! be/ = !m t 8 scanty means w\ld p]mit4 ,( 8 *ildr5 ,william 0 ! f\r?1 & he inh]it$ 8 fa!r's tal5ts = music1 z did mo/ ( 8 bro!rs & si/]s4 ,he 0 a bright1 clev] boy at s*ool1 & he made su* good progress 9 8 music t by ! "t he 0 f\rte5 ye>s old he 0 able to play 9 ! milit>y b& ( ! ,hanov]ian ,gu>ds4 ,w> broke out betwe5 ,france & ,engl&1 & z ,hanov] 0 !n "u ! ,engli% cr[n1 ! ,fr5* invad$ x1 & a battle 0 f\ght 9 :i* ! poor ,hanov]ian ,gu>ds suff]$ v t]ribly4 ,"y ,h]s*el sp5t ! night aft] ! battle 9 a dit*1 & he came to ! conclusion t he did n l fight+1 ?\gh he 0 only a memb] ( ! b&1 & he resolv$ to *ange 8 pr(ession4 ,t 0 n s easy to d j !n1 = ev5 a b&sman _c leave ! s]vice 9 w> "t at 8 own free w4 ,william ,h]s*el1 h[ev]1 %[$ all ?r\gh 8 life t he 0 n ! man to be baffl$ by difficulties4 ,i d n "k :e!r he ask$ = leave1 b at all ev5ts he took x4 ,he des]t$1 9 fact1 & 8 fri5ds succe$$ 9 s5d+ him away to ,engl&4 ,he 0 n9ete5 ye>s old :5 he comm5c$ to look = a c>e] ov] "h1 & c]ta9ly he f\nd 8 prospects 9 ! musical pr(ession v disc\rag+4 ,h]s*el 01 h[ev]1 v indu/ri\s2 & at la/ he succe$$ 9 gett+ appo9t$ z organi/ ( ! ,octagon ,*apel at ,ba?4 ,he gradually became fam\s = 8 musical skill1 & _h numb]s ( pupils4 ,he us$ also to conduct conc]ts & oratorios1 & 0 well kn[n 9 ?is way ov] ! ,we/ ( ,engl&4 ,busy z ,h]s*el 0 ) 8 pr(ession1 he /ill reta9$ 8 love ( read+ & /udy4 ,e mom5t he c\ld sp>e f 8 duties he devot$ to 8 books4 ,x 0 natural t a musician %\ld specially desire to /udy ! !ory ( music1 & to und]/& x prop]ly y %\ld "k ,euclid & algebra1 &1 inde$1 high] bran*es ( ma!matics z well4 ,h]s*el did n "k ^! ?+s at fir/2 he _h n ! means ( le>n+ !m :5 he 0 a boy1 s he work$ v h>d aft] he became a man4 ,& he /udi$ ) su* success t he made fair progress 9 ma!matics1 & !n x appe>$ to him t x w\ld be int]e/+ to le>n some?+ ab\t a/ronomy4 ,aft] he _h begun to read ab\t ! />s1 he ?\ght he w\ld l to see !m1 & s he borr[$ a telescope4 ,x 0 only a little in/rum5t1 b x delight$ him s mu* t he said he mu/ h "o = himself4 ,s he wrote to ,london to make inquiries4 ,telescopes 7 mu* de>] 9 ^? days ?an !y are n[1 & ,h]s*el c\ld n give ! price t ! opticians dem&$4 ,"h aga9 8 inv9cible det]m9ation came to 8 aid4 ,:at 0 !re to prev5t him f mak+ a telescope8 he ask$ himself2 & =?) he began ! attempt4 ,y w ?9k x /range1 p]haps1 t a music-tea*] :o _h no special tra9+ z a me*anic %\ld at once comm5ce s delicate & difficult a task2 b x is n really s h>d to make a telescope z might be imag9$4 ,! amateur _c make su* a pretty-look+ in/rum5t z he is able to buy at ! %ops--! tubes w n be s beautifully poli%$ & ! f9i% w be su* z a tra9$ workman w\ld be a%am$ (--b ! ess5tial "p ( a telescope is comp>atively easy to make2 at lea/1 ,i %\ld say ( a reflect+ telescope1 :i* is ! k9d ,h]s*el attempt$ to make1 & succe$$ 9 mak+4 ,y mu/ "k t !re are two k9ds ( telescopes4 ,! common] "o ) :i* y are m famili> is call$ ! refract+ telescope1 & x has glass l5ses4 ,x 0 an in/rum5t con/ruct$ on ?is pr9ciple t we spoke ( 9 a =m] lecture 7p4 #ig74 ,! reflect+ telescope dep5ds = its p[] ^u a bright mirror at ! l[] end1 & :5 us+ ?is in/rum5t y look at ! reflection ( ! />s 9 ! mirror4 ,x 0 a reflector l ?is t ,h]s*el began to con/ruct1 & he engag$ 9 ! task ) en?usiasm4 ,8 si/] ,c>ol9e _h come to live ) him1 & %e us$ to help him at 8 "w4 ,s mu* 9 e>ne/ 0 he t he us$ to ru% into 8 work%op directly he came home f a conc]t1 & )\t tak+ (f 8 be/ clo!s he w\ld plunge into ! gr9d+ & poli%+ ( 8 mirrors4 ,8 si/] tri$ to keep ! h\se z tidy z possible1 b ,h]s*el put up a c>p5t]'s %op 9 ! draw+-room1 & turn+-la!s 9 ! be/ b$room4 ,at la/ he succe$$4 ,he made a mirror ( ! "r %ape1 & f\nd t x exhibit$ ! />s prop]ly4 ,x 0 n a look+-glass 9 ! ord9>y s5se1 ) glass on "o side & quicksilv] on ! o!r4 ,! mirror t ,h]s*el con/ruct$ 0 entirely ( metal4 ,x consi/$ ( a mixture ( two p>ts ( copp] ) "o ( t94 ,illu/ration3 ,,fig4 #fi4--,! ,mirror4 ,! copp] has fir/ to be melt$ 9 a furnace1 = ! metal mu/ be above a r$ heat be=e x w beg9 to run4 ,!n ! t9 has to be c>efully add$1 & ! ca/+ ( ! mirror is effect$ by p\r+ ! molt5 metal into a flat m\ld4 ,?us ! r\gh mirror is obta9$1 :i* 9 ,h]s*el's e>li] telescopes seems to h be5 ab\t six or sev5 in*es 9 diamet]1 & ne>ly an in* ?ick4 ,?\gh copp] is su* a t\gh sub/ance1 & ?\gh t9 is also t\gh1 yet :5 melt$ toge!r to make speculum metal1 z ?is alloy is call$1 !y produce an exce$+ly h>d & brittle mat]ial4 ,:5 we rememb] t we c\ld nev] break a copp] p5ny piece by ?r[+ x d[n on ! flags1 x may seem /range t ! 8speculum metal0 %\ld be s exce$+ly brittle4 ,a piece ! size ( a p5ny w\ld be m brittle ?an a bit ( glass ( ! same dim5sions1 & :5 ! speculum is ca/1 unless x is cool$ v c>efully1 x w fly into pieces4 ,h]e9 lay "o ( ! difficulties t ,h]s*el enc\nt]$4 ,speculum metal mu/ be put into an ov5 z soon z ! ca/+ has become solid1 & !n ! heat is gradually all[$ to abate4 ,:5 ! speculum has be5 at la/ obta9$1 next foll[s ! labor ( giv+ x ! true figure & poli%4 ,x is n only m fragile ?an glass1 b x is also q z h>d1 & !re=e ! gr9d+ is a t$i\s op]ation4 ,fir/ ! surface has to be gr\nd ) co>se s&1 & !n ) em]y1 :i* is gradually made f9] & f9] until ! true figure has be5 giv5 7,fig4 #fi74 ,! mirror is !n some:at bas9-%ap$1 b ! depression is v slight4 ,= example1 9 a mirror six in*es across ! depression at ! c5tre w\ld p]haps be n m ?an ! tw5tie? ( an in*4 ,small ?\gh ?is depression is1 yet x has to be made ) exactness4 ,9 fact1 if x 7 wrong at any po9t by s mu* z ! t5? ( ! ?ickness ( ?is %eet ( pap]1 ! telescope w\ld n p]=m accurately4 ,! tool t is us$ 9 gr9d+ is made ( ca/ iron1 & has be5 turn$ 9 a la! to ! "r %ape4 ,x is divid$ into squ>es 9 ! mann] %[n 9 ,fig4 #gj4 ,aft] ! gr9d+ comes ! poli%+1 & ?is is effect$ ) a tool l ! gr9d] 9 %ape4 ,?is has to be cov]$ ov] ) little squ>es ( pit*1 s t :5 w>m$ & put d[n on ! mirror x is s(t en\gh to receive ! "r %ape4 ,"s r\ge & wat] is spread ov] ! mirror1 & ! poli%] is work$ backw>d & =w>d ) ! h& until a brilliant surface is obta9$4 ,illu/ration3 ,,fig4 #gj4--,! ,gr9d+ ,tool4 ,:5 ! amateur a/ronom] has complet$ ?is "p ( ! task1 all ! great difficulties ab\t 8 telescope are conqu]$4 ,! tube may be made ( wood1 &1 inde$1 a squ>e tube w d j z well z a r\nd "o4 ,he mu/ also provide = ! top ( ! tube a small mirror1 :i* has to be p]fectly flat4 ,! prep>ation ( ?is requires mu* c>e1 because x is n s easy z "o might suppose to obta9 an accurately flat surface4 ,"o way ( do+ ?is is to get ?ree pieces1 & gr9d ea* two ( !m toge!r until e pair w t\* all ov]2 !n !y w c]ta9ly all be flat4 ,"o m "p y want1 & t is an eyepiece4 ,?is pres5ts no difficulty4 ,a s+le glass l5s c be made to answ] & y\r telescope is complete4 ,,! ,,discov]y ,,( ,,uranus4 ,x 0 9 ! ye> #aggd t ,h]s*el fir/ _h a view ( ! heav5s ?r\gh ! telescope he _h himself con/ruct$4 ,dur+ ! e>ly "p ( 8 c>e] he does n seem to h made any important discov]ies4 ,he 0 gradually prep>+ himself = ! great a*ievem5t by :i* 8 "n became fam\s4 ,x 0 on ! #ac? ( ,m>*1 #agha1 t ! organi/ ( ! ,octagon ,*apel at ,ba? turn$ 8 telescope on ! con/ellation ( ! ,tw9s1 & began to look at "o /> aft] ano!r4 ,y mu/ "k t a /> m]ely looks l a little po9t 9 a telescope2 ev5 ! greate/ in/rum5t w only make a /> look bright]1 & w nev] %[ x ) a p]ceptible disk4 ,9 look+ ov] ! />s t night1 ,h]s*el's att5tion 0 arre/$ by "o object t did look l>g] :5 magnifi$1 & !re=e 0 n a />4 ,! only o!r objects :i* w\ld behave 9 ?is way 7 ! planets1 or possibly a comet4 ,inde$1 at fir/ ,h]s*el imag9$ t :at he saw mu/ be a comet4 ,x c\ld h>dly h occurr$ to him t he 0 to h su* good =tune z to discov] a new planet4 ,! five great planets _h be5 kn[n f all antiquity4 ,0 x reasonable to suppose t !re c\ld be yet ano!r t _h nev] be5 p]ceiv$8 ,=tunately1 !re 0 a te/ available4 ,a /> rema9s 9 ! same place f night to night & f ye> to ye>2 :ile a planet1 z we h already _h occasion to m5tion1 is a body :i* is w&]+ ab\t4 ,! movem5ts ( a planet are1 h[ev]1 n at all l ^? ( a comet4 ,to decide on ! nature ( ,h]s*el's newly discov]$ body1 x 0 suffici5t to obs]ve ! "* ( its motion4 ,a few nights suffic$ to d ?is4 ,! position ( ! body 0 c>efully m>k$ relatively to ! neighbor+ />s1 & x 0 soon %[n t x 0 a planet4 ,"h1 !n1 a great discov]y 0 made4 ,a new planet1 n[ call$ ,uranus1 0 add$ to our sy/em4 ,x w\ld be no?+ to discov] a new />4 ,y might z well talk ( discov]+ a new gra9 ( s& on ! sea%ore4 ,! />s are 9 untold myriads4 ,!y are s f> (f t !y h no relation :atev] to our sy/em1 :i* is presid$ ov] by ! sun4 ,b by ! detection ( a new planet1 revolv+ f> outside ,saturn1 ,h]s*el %[$ t a new & mo/ int]e/+ memb] _h to be add$ to ! five old planets :i* h be5 kn[n f ! e>lie/ records ( hi/ory4 ,x may well be imag9$ t a discov]y s />tl+ z ?is excit$ a/oni%m5t ?r\gh\t ! sci5tific _w4 8,:o is ?is ,ba? organi/80 ev]ybody ask$4 ,acc\nts ( him & 8 discov]ies appe>$ 9 ! pap]s4 ,8 fell[-citiz5s 7 n s famili> ) ! "n z we are1 happily1 n[2 & ! spell+ ( ! unusual "n %[$ _m v>ieties4 ,:5 ,george ,,iii4 he>d ( ,h]s*el's great a*ievem5t1 he direct$ ! a/ronom] to be summon$ to ,w9dsor1 t ! ,k+ might receive an acc\nt ( ! wond]ful discov]y f ! lips ( ! discov]] himself4 ,h]s*el ( c\rse obey$1 & he br\ght ) him 8 fam\s telescope1 & also a map ( ! :ole sol> sy/em1 to %[ to ! ,k+4 ,no d\bt he ?\ght t 8 ,maje/y _h probably n paid mu* att5tion to a/ronomy4 ,h]s*el 01 !re=e1 prep>$ to expla9 to ! ,k+ :at x w\ld be necess>y = him to "k be=e he c\ld fully appreciate ! magnitude ( ! discov]y4 ,y w rememb] t ,h]s*el :ile /ill a boy _h des]t$ f ! army1 _m ye>s previ\sly4 ,x appe>s t ! ,k+ _h le>n$ ?is fact 9 "s way1 s t :5 ,h]s*el 0 u%]$ into 8 pres5ce 8 ,maje/y said t be=e ! great a/ronom] c\ld discuss sci5ce !re 0 a little matt] ( bus9ess t mu/ be dispos$ (4 ,! ,k+ accord+ly h&$ ,h]s*el a pap]1 9 :i* he 01 ,i d>e say1 greatly surpris$ to f9d a p>don to ! des]t] writt5 out by ! ,k+ himself4 ,!n ,h]s*el unfold$ 8 wond]ful discov]y1 :i* ! ,k+ ?or\ghly appreciat$1 & 9 ! ev5+ ! telescope 0 set up 9 ! g>d5s1 & ! glories ( ! heav5s 7 display$4 ,h]s*el made a mo/ favorable impression on 8 ,maje/y1 & :5 ! ,k+ told ! ladies ( ! ,ca/le next day ( all t ,h]s*el _h %[n him1 _! a/ronomical ardor 0 also ar\s$1 & !y ask$ to see ?r\gh ! m>vell\s tube4 ,( c\rse ,h]s*el 0 ready to comply1 & ! telescope 0 accord+ly c>ri$ to ! w9d[s ( ! ,que5's ap>tm5ts at ,w9dsor1 :i* w\ld h comm&$ a f9e view if ! cl\ds _h n be5 9 ! way1 :i* !y un=tunately 74 ,ev5 = royalty ! cl\ds w\ld n disp]se1 s :at 0 to be done8 ,h]s*el 0 equal to ! occasion4 ,he specially want$ to exhibit ,saturn1 = x is "o ( ! mo/ beautiful objects 9 ! sky1 & w fasc9ate any intellig5t behold]4 ,no a/ronom]s w\ld h be5 able to see ,saturn ?r\gh ! cl\ds1 b ,h]s*el did n disappo9t 8 visitors2 he direct$ ! in/rum5t1 n to ! sky 7no?+ 0 !re to be se572 he turn$ x t[>ds a di/ant g>d5 wall4 ,n[ :at w\ld y expect to see by look+ ?r\gh a telescope at a g>d5 wall--bricks1 p]haps1 or ivy8 ,:at ^! ladies saw 0 a beautiful image ( ,saturn1 8 globe 9 ! c5tre & 8 r+s all complete1 =m+ s true a resemblance to ! planet t ev5 an exp]i5c$ a/ronom] might h be5 deceiv$4 ,9 ! aft]noon ,h]s*el _h se5 t ! cl\ds 7 ?ick1 & t !re w\ld be little probability ( us+ ! telescope prop]ly4 ,accord+ly he cut out a little image ( ,saturn1 illum9at$ x by lamps1 & set x up at a suitable di/ance on a g>d5 wall4 ,h]s*el's visit to ,w9dsor 0 productive ( important consequ5ces4 ,! ,k+ said x 0 a pity t s great an a/ronom] %\ld devote himself to music1 & t x w\ld be f> bett] = him to give up t pr(ession & come & live at ,w9dsor4 ,8 ,maje/y promis$ t he w\ld pay him a sal>y1 & he also und]took to provide ! co/ ( erect+ great telescopes4 ,8 fai?ful si/] ,c>ol9e came ) him z 8 assi/ant1 & also receiv$ "s b\nty f ! ,k+4 ,f t mom5t ,h]s*el r5\nc$ all 8 musical bus9ess1 & devot$ himself to 8 great life-task ( obs]v+ ! heav5s4 ,he built telescopes ( proportions f> exce$+ ^? t _h ev] be5 !n ?\ght (4 ,he us$ to /& at night 9 ! op5 air f dusk to dawn gaz+ d[n ! tube ( 8 mighty reflector1 wat*+ ! />s & o!r objects 9 ! heav5s z !y mov$ pa/4 ,he w\ld dictate :at he saw to ,c>ol9e1 :o sat ne> him4 ,x 0 h] bus9ess to write d[n 8 notes & to record ! position ( ! objects :i* he 0 describ+4 ,sometimes1 %e tells u1 ! cold 0 s great t ! ink us$ to freeze 9 h] p5 :5 %e 0 at ?is "w4 ,until he became a v old man1 ,h]s*el devot$ himself to 8 a/ronomical labors4 ,8 discov]ies are to be c\nt$ by ?\s&s1 ?\gh n "o ( !m 0 s /rik+ or s important z ! detection ( ! new planet :i* fir/ br\ght him fame4 ,! "q ( a "n = ! addition to ! sun's family _h1 ( c\rse1 to be settl$4 ,h]s*el _h surely a "r to be he>d at ! *ri/5+1 & z a complim5t to 8 ,maje/y he nam$ ! /rang] ! ,georgium ,sidus4 ,s1 inde$1 = a brief :ile1 ! planet 0 actually /yl$4 ,! ,cont95tal a/ronom]s1 h[ev]1 w\ld n accept ?is designation2 all ! o!r planets 7 nam$ aft] anci5t div9ities1 & x 0 ?\ght t ! ,k+ ( ,engl& w\ld seem oddly associat$ ) ,jupit] & ,saturn2 p]haps also !y consid]$ t ! ,briti% dom9ions1 on :i* ! sun nev] sets1 7 already q l>ge en\gh1 )\t fur!r ext5sion to ! cele/ial regions4 ,accord+ly a consultation 0 held1 ! result ( :i* 0 t ,george ,,iii4 0 depriv$ ( 8 planet>y honors1 & ! body 0 giv5 ! "n ( ,uranus1 :i*1 by univ]sal cons5t1 x n[ be>s4 ,! planet ,uranus lies j on ! v]ge ( visibility ) ! unaid$ eye4 ,x c sometimes be glimps$ l a fa9t />1 &1 ( c\rse1 ) a telescope x is readily p]ceiv$4 ,_m g5]ations ( a/ronom]s be=e ,h]s*el's "t _h be5 obs]v+ ! heav5s1 mak+ maps ( ! />s1 & compil+ great catalogues 9 :i* ! places ( ! />s 7 accurately put d[n4 ,x (t5 happ5$ t ,uranus came "u _! notice1 b x nev] occurr$ to !m t :at seem$ s l a /> 0 really a planet4 ,i h1 no d\bt1 said t ,uranus look$ unlike a /> :5 ,h]s*el exam9$ x2 b !n t 0 because ,h]s*el 0 a p>ticul>ly skilful a/ronom]4 ,to an obs]v] ( a m ord9>y type ,uranus w\ld n pres5t any v rem>kable appe>ance1 & w\ld be pass$ ov] m]ely z a small />4 ,9 fact1 ! planet 0 ?us obs]v$ n once or twice1 b no few] ?an sev5te5 times1 be=e ! acute eye ( ,h]s*el p]ceiv$ its true "*4 ,on _m previ\s occasions ! planet _h be5 not$ z a /> by a/ronom]s :o are 9 e way entitl$ to our respect4 ,x requir$ a ,h]s*el1 det]m9$ to see ev]y?+ 9 ! v be/ mann]1 to grasp ! discov]y :i* elud$ s _m o!rs4 ,:5 ,uranus 0 obs]v$ on ^! =m] occasions & mi/ak5 = a />1 its place _h be5 c>efully put d[n4 ,^! records are at pres5t ( ! utmo/ use1 because !y %[ ! pa/ hi/ory ( ! planet2 & !y appe> all ! m valuable :5 we rememb] t ,uranus requires no less ?an eighty-f\r ye>s to accompli% a s+le revolution ar\nd ! sun4 ,?us1 s9ce ! planet 0 discov]$ 9 #agha1 x _h complet$ "o revolution by #ahfe1 & is n[ 7#ahii7 ab\t "o-?ird ( ! way ar\nd ano!r4 ,! e>li] obs]vations ext5d backw>ds almo/ #bjj ye>s1 s t altoge!r we h m or less in=mation ab\t ! movem5ts ( ! planet dur+ ! completion ( two circuits & a half4 ,uranus is a great deal bigg] ?an ! e>?1 z y w see 9 ! view ( ! comp>ative sizes ( ! planets 7,fig4 #dg74 ,x appe>s to be ( a blui% hue1 b we _c tell :e!r x turns r\nd on its axis1 or r1 ,i %\ld say1 we are n able to see :e!r x turns r\nd on its axis2 = we c h>dly d\bt t x does s4 ,not)/&+ t ,uranus is at s great a di/ance f ! e>?1 we h be5 able to put ?is planet1 no less ?an ! ne>] ones1 9 ! weigh+ scales1 & we ass]t ) confid5ce t ,uranus is fifte5 times z heavy z our e>?4 ,we are indebt$ to ! satellites = ?is in=mation4 ,,! ,,satellites ,,( ,,uranus4 ,y mu/ use a v good telescope to see ! satellites ( ,uranus4 ,!y are f\r 9 numb]1 be>+ ! names ( ,ariel1 ,umbriel1 ,titania1 & ,ob]on4 ,! inn]mo/ ( ^!1 ,ariel1 completes a j\rney r\nd ! planet 9 two days & a half2 ,ob]on1 ! mo/ di/ant1 requires ?irte5 days & a half4 ,a planet is always t5d+ to pull its satellite d[n1 & ! satellite is kept f fall+ by ! spe$ ) :i* x revolves4 ,! heavi] ! planet1 ! fa/] mu/ its satellites g r\nd4 ,?us1 to take an illu/ration f our own moon1 we "k t1 if ! e>? 7 to be made f\r times heavi] ?an x is1 ! moon w\ld h to sp9 r\nd twice z fa/ z x does1 9 ord] to rema9 9 ! same orbit4 ,! spe$ ) :i* ! satellites ( ,uranus revolve accord+ly af=ds a measure ( ! mass ( ! planet4 ,7 ,uranus heavi] ?an he is1 8 satellites w\ld revolve m quickly ?an !y d2 7 he light]1 ! satellites w\ld take a long] p]iod to g r\nd4 ,uranus also seems to be greatly swoll5 by cl\ds1 9 ! same mann] z are bo? ,jupit] & ,saturn2 9 fact1 if our e>? 0 z big z ,uranus1 x w\ld weigh f\r or five times z mu* z ,uranus does4 ,h5ce we are c]ta9 t ,uranus mu/ consi/ ( mat]ials less d5se on ! :ole ?an are ^? ( :i* our e>? is made4 ,!re is ano!r s+ul> circum/ance connect$ ) ! moons ( ,uranus4 ,i h told y h[ e body revolv+ r\nd ano!r by gravitation w describe an ellipse2 b1 ( c\rse1 !re are _m diff]5t k9ds ( ?is curve1 & "s may be ne>ly circles4 ,!re is no?+ :atev] to prev5t a satellite f revolv+ ar\nd its prim>y 9 an exact circle if x be />t$ prop]ly2 t is1 9 ! "r direction & ) ! "r spe$4 ,all ! f\r satellites ( ?is planet seem to revolve 9 circles s p]fect t we c make an accurate picture ( ?is sy/em ) a pair ( compasses4 ,x is fur!r to be notic$ t ! f\r circles seem to lie exactly 9 ! same plane4 ,! orbits ( ! o!r great planets & ( _! satellites lie 9 planes incl9$ at angles ( less ?an #ce to ! ecliptic1 ! plane 9 :i* ! e>? moves4 ,"h aga9 ! satellites ( ,uranus are exceptional4 ,! plane 9 :i* !y are conta9$ /&s up almo/ squ>ely to ! plane 9 :i* ! motion ( ! planet is p]=m$4 ,! moons ( ,uranus seem to h got a twi/1 f "s accid5tal circum/ance = :i* we are n able to acc\nt4 ,,! ,,discov]y ,,( ,,neptune4 ,! b\nd>ies ( ! sol> sy/em _h be5 mu* ext5d$ by ! discov]y ( ,uranus1 b !y 7 de/9$ to receive /ill fur!r enl>gem5t by ! detection ( ano!r va/ planet1 revolv+ f> outside ,uranus1 ! orbit ( :i* =ms1 accord+ to our pres5t k1 ! outl9e ( ! planet>y sy/em4 ,i h "h to describe "o ( ! greate/ discov]ies t h ev] be5 made4 ,x is n ! magnific5ce ( ! out]mo/ planet itself t ,i ref] to1 ?\gh1 inde$1 x is bigg] ?an ,uranus4 ,i am r ?9k+ ( ! way 9 :i* ! discov]y 0 made4 ,i d n mean any disrespect to ,h]s*el :5 ,i say t ! discov]y ( ,uranus 0 *iefly a /roke ( good =tune2 b ,i may be p]mitt$ to describe x 9 ?is mann] by way ( emphasiz+ z /rongly z ,i c h[ utt]ly diff]5t 0 ! tra9 ( ideas :i* l$ to ! discov]y ( ,neptune4 ,h]s*el m]ely look$ at "o /> aft] ano!r till sudd5ly he dropp$ on ! planet1 hav+ be=eh& n ! slighte/ notion t any su* planet 0 likely to exi/4 ,b ,neptune 0 %[n to exi/ be=e x 0 ev] se51 &1 9 fact1 ! man t fir/ saw ! planet1 & knew x to be a planet1 0 n ! discov]]4 ,?is is r a difficult subject2 & x w\ld take y ye>s ( h>d /udy to be able to und]/& ! tra9 ( reason+ by :i* ,neptune 0 f\nd4 ,i %all1 h[ev]1 make an attempt to expla9 ?is matt] suffici5tly to give at lea/ "s idea ( ! k9d ( problem t _h to be solv$4 ,y w rememb] t law ( ,kepl] :i* tells u t e planet moves r\nd ! sun 9 an ellipse4 ,if ! planet be un9t]f]$ ) 9 any way & guid$ only by ! attraction ( ! sun1 x w =ev] cont9ue to describe precisely ! same ellipse )\t ! slighte/ alt]ation4 ,x 0 asc]ta9$ t ! pa? :i* ,uranus foll[$ 0 n always regul>4 ,! e>ly obs]vations ( ! planet1 :5 x 0 mi/ak5 = a />1 h "h be5 ( ! utmo/ s]vice4 ,!y h indicat$ ! ellipse :i* ,uranus describ$ ! la/ "t x w5t r\nd1 & our mod]n obs]vations h taught u ! pa? :i* ! planet is at pres5t describ+4 ,^! two ellipses are slightly diff]5t1 & ! consequ5ce is t1 suppos+ we take ! obs]vations ( ,uranus made #ajj ye>s ago1 & calculate f !m :]e ,uranus ought to be n[1 we f9d t ! planet is a little a/ray4 ,a/ronom]s are n accu/om$ to be wrong 9 su* calculations1 & :5 discrepancies arise1 ! fir/ ?+ to be done is to see :at has caus$ !m4 ,x is c]ta9 t ! position 9 :i* ,uranus is f\nd ?is v night1 = example1 is n :at x w\ld h be5 _h ! sun alone be5 guid+ ! planet4 ,p]haps y w ?9k t x is impossible = reliable computations to be made ab\t su* matt]s2 b ,i assure y !y c1 & ! v fact t ! motion ( ,uranus appe>$ to be irregul> made x int]e/+ to try & f9d out ! cause ( ! di/urbance4 ,i h already expla9$1 :5 speak+ ab\t ,m>s 7p4 #ahg71 t !re is an attraction betwe5 e two bodies1 b 9 ! gr\p ( planets to :i* ! e>? belongs ! sun's attraction is s mu* /rong] ?an any o!r =ce t all ! movem5ts are guid$ ma9ly by x4 ,nev]!less x is true t n only does ! sun pull our e>? & all ! o!r planets z well1 b all ! planets1 includ+ ! e>?1 are pull+ "o ano!r4 ,9 fact1 !re is an incessant /ruggle go+ on 9 ! family p>ty4 ,=tunately ! sun is s mu* m p[]ful ?an any o!r memb]1 t he keeps !m all pretty well 9 ord]2 & unless y look v c>efully y w n see ! effects ( ! little /ruggles t are go+ on betwe5 e pair ( ! sy/em4 ,our e>? itself is pull$ & sway$ to & fro by ! actions ( its bro!rs & si/]s4 ,x is dragg$ p]haps a ?\s& or two ?\s& miles ?is way by ,jupit]1 or x gets a good tug 9 ! o!r direction by ,v5us4 ,m>s & ,saturn also d _! little be/ to =ce ! e>? away f its /rict pa?4 ,h[ev]1 our e>? does n suff] mu* f ^! irregul>ities4 ,x pursues its r\te fairly en\gh1 j z a coa* f ,london to ,brighton w get safely to its de/9ation not)/&+ ! fact t x has to sw]ve a little f its pa? :5ev] x meets o!r vehicles on ! way1 or :5 ! coa*man wi%es to avoid a piece ( ! road on :i* /ones h be5 fre%ly laid d[n4 ,! track foll[$ by ,uranus 0 f\nd to be some:at irregul>1 l t ( e o!r planet4 ,jupit] gave x a pull1 & s did ,saturn1 & at fir/ x 0 ?\ght t ! irregul>ities :i* 7 p]ceiv$ c\ld be expla9$ by ! action ( ^! planets1 s big & s well kn[n4 ,"h is a "q = calculation2 x involves a v long & a v h>d piece ( "w1 b x is possible to e/imate h[ f> ea* ( ! o!r planets is capable ( dragg+ ,uranus f its pa?4 ,is x n rem>kable t by work+ out long calculations we %\ld be able to f9d :at "o planet hundr$s ( millions ( miles away 0 able to d to ano!r planet /ill fur!r (f1 & n only = to-day or ye/]day1 b = pa/ "t ext5d+ ov] m ?an a c5tury8 ,if1 h[ev]1 y w li/5 to me a little long]1 ,i ?9k ,i %all give y a pro( t ^! sums c\ld be work$ out correctly4 ,:5 ! calculations _h be5 made :i* %[$ h[ mu* ! kn[n planets c\ld di/urb ,uranus1 x 0 f\nd t !re 7 /ill "s deviations ( ! planet t rema9$ unexpla9$4 ,!y 7 n l>ge2 !y only am\nt$ to %[+ t ! body 0 j a little a/ray f ! spot :]e ! calculations indicat$ x %\ld be4 ,! re/ ( a/ronomy 0 s p]fect1 & ! law ( attraction prevail$ s univ]sally1 t x 0 ?\ght ! law ( attraction mu/ provide "s way ( expla9+ ! behavior ( ,uranus4 ,he c\ld n h left 8 track ( 8 own accord2 !re=e !re mu/ be "s ag5cy at "w ^u him ( :i* we did n "k4 ,:at c\ld ?is unkn[n s\rce ( di/urbance be8 ,e su* tr\ble _h hi!rto be5 f\nd to be a consequ5ce ( ! attraction ( gravitation2 !re=e !re mu/ be "s unkn[n body pull+ at ,uranus :i* no "o _h ev] se54 ,:]e c\ld x be8 ,h[ 0 x to be discov]$8 ,su* 7 ! que/ions t 7 ask$1 & !y 7 answ]$ 9 a mo/ satisfactory mann]4 ,fir/ ( all1 :at sort ( body c\ld x be t 0 pull+ ,uranus8 ,x is obvi\s t none ( ! />s w\ld be compet5t to produce s great an effect2 !y are all s f> (f t !y h no?+ :atev] to say to any ( ! dome/ic matt]s 9 our little sol> sy/em1 :i* is simply a gr\p by itself4 ,x w\ld be m reasonable to suppose t !re mu/ be yet ano!r planet :i* nobody _h ev] recogniz$1 b :i* affect$ ,uranus s z to acc\nt = 8 truant behavior4 ,to beg9 to se>* = ?is planet ) telescopes )\t "s guidance w\ld be futile2 9 fact1 a/ronom]s _h be5 scann+ ! heav5s = planets = ne>ly fifty ye>s1 & ?\gh sev]al _h be5 discov]$1 !y all belong$ to ! zone ( little planets1 & none ( !m 7 big en\gh to pull ,uranus ab\t appreciably4 ,( c\rse1 if all ! />s c\ld be blott$ out ( ! sky1 s t no?+ b planets 7 left1 !n1 by sweep+ ! telescope ov] ! heav5s1 e planet t exi/s might be spe$ily f\nd4 ,! difficulty is t ! planets1 :i* are ei!r small or v di/ant1 look s l ! />s t x is impossible to recognize !m among ! millions ( glitt]+ po9ts 9 ! sky4 ,x 01 h[ev]1 hop$ t ! unkn[n planet w\ld be l>ge en\gh to be visible 9 ! telescope1 if only we knew exactly :]e to po9t x4 ,two illu/ri\s a/ronom]s1 ,adams ( ,cambridge1 & ,lev]ri] ( ,p>is1 bo? sep>ately und]took an a/oni%+ piece ( calculation4 ,!y tri$ to f9d out ! position ( ! unkn[n planet f ! m]e fact t x d]ang$ ,uranus 9 a p>ticul> way4 ,i d>e say _m ( ^? :o are read+ ?is book h le>n$ simple equations 9 algebra1 & !y h work$ su* que/ions z to f9d ! l5g? ( a pole1 half ( :i* is 9 mud1 a qu>t] 9 wat]1 & t5 feet above ! wat]4 ,^? :o "k ?is mu* c p]haps realize ! problem t _h to be solv$ 9 try+ to discov] ! unkn[n planet4 ,s difficult a "q z ?is _h to be solv$ 9 a way t y\r ma/]s w\ld h>dly all[ y to use :5 work+ y\r sums 9 algebra4 ,i d n ?9k !y w\ld let y make a s]ies ( guesses4 ,let u try #bj feet1 = in/ance1 z ! l5g? ( ! pole2 t w make #aj feet 9 ! mud1 #e feet 9 ! wat]1 & #e feet outside4 ,?is w n d2 x is n en\gh2 we mu/ try aga92 & aft] ano!r guess or two1 we see t a pole #dj feet long w exactly answ]4 ,we d n use ?is me?od ( guess+ 9 algebra1 because solv+ ! simple equation is a mu* bett] me?od4 ,adams & ,lev]ri] f\nd t to discov] ! unkn[n planet 0 a "q s v difficult1 t !y 7 oblig$ to use a sort ( guess+1 b v intellig5t guess+1 ,i ne$ h>dly assure y4 ,!y proce$$ 9 ?is way 7,fig4 #ga74 ,!y w\ld draw a circle outside ! pa? ( ,uranus1 & !n suppose t a planet 0 revolv+ 9 t circle4 ,its effect ^u ,uranus w\ld !n be calculat$1 & x w\ld be f\nd :e!r ! obs]v$ irregul>ities c\ld be 9 ?is mann] acc\nt$ =4 ,! fir/ planet !y tri$ 0 n ! "r "o2 !n !y began aga9 ) ano!r1 until at la/1 aft] _m trials & mu* v h>d "w1 !y saw t !re might be a planet 9 a p>ticul> pa? f> outside ,uranus1 su* t if ?is planet 7 ( ! "r weight & mov+ ) ! "r spe$1 !n x w\ld pull ,uranus exactly 9 ! way t a/ronom]s _h obs]v$ x to be pull$4 ,!y f\nd at la/ t !re c\ld be little d\bt ab\t ! matt]2 = ?is unkn[n body w\ld acc\nt = all ! facts4 ,!n1 inde$1 !y _h solv$ _! equation2 !y _h f\nd ! unkn[n4 ,illu/ration3 ,,fig4 #ga4--,orbits ( ,uranus & ,neptune4 ,! two great a/ronom]s _h ?us discov]$ a planet1 b z yet x 0 only a planet on pap]4 ,^? :o c\ld judge ( ! subject _h no d\bt t ! planet 0 really 9 ! sky2 b j z y l to prove t y h f\nd ! correct answ] to y\r sum1 s p 7 naturally anxi\s to prove ! tru? ( ?is wond]ful sum t ,adams & ,lev]ri] _h work$ out4 ,?is 0 to be done by actually see+ ! planet ( :i* ! a/ronom]s _h ass]t$ ! exi/5ce4 ,lev]ri] calculat$ t ! new planet 9 a c]ta9 night w\ld be 9 a p>ticul> position on ! sky4 ,accord+ly he wrote to ,dr4 ,galle1 ( ! obs]vatory at ,b]l91 reque/+ him on ! ev5+ 9 "q to po9t 8 telescope to ! v spot indicat$1 & !re he w\ld see a planet :i* human eyes _h nev] be=e beheld4 ,( c\rse1 ,dr4 ,galle 0 only too delight$ to und]take s m>vell\s a commission4 ,! ev5+ 0 f9e2 ! telescope 0 op5$2 x 0 direct$ t[>ds ! heav5s2 & !re1 9 ! v spot :i* ! calculations ( ,lev]ri] _h indicat$1 %one ! beautiful little planet4 ,at ,cambridge arrangem5ts _h also be5 made to se>* = ! new memb] ( ! sol> sy/em1 9 accordance ) ,pr(essor ,adams' calculations4 ,!re also ! planet t _h giv5 all ?is tr\ble to ,uranus 0 br\ght to light4 ,at fir/ x look$ l a />1 z all su* planets d2 b t x 0 n a /> 0 spe$ily prov$1 by ! two te/s :i* are sure indications ( a planet4 ,fir/ ! body 0 s mov+ t its position ) respect to ! adjac5t />s 0 con/antly *ang+4 ,!n1 :5 a /rong magnify+ p[] 0 plac$ on ! telescope1 ! little object 0 se51 n to be a m]e />like po9t1 b to exp& into ! little disk :i* %[s u we are n look+ at a di/ant sun1 b at a _w l our own4 ,0 n ?is truly a great discov]y8 ,h we n %[n y h[ entitl$ ! calculations ( a/ronom]s are to our respect1 :5 we f9d t !y actually discov]$ ! exi/5ce ( a maje/ic planet be=e ! telescope _h reveal$ x8 ,see also ! greatly increas$ int]e/ t belongs to ,h]s*el's discov]y ( ,uranus4 ,we c h>dly imag9e any?+ t w\ld h giv5 m gratification to ?is old a/ronom] ?an to ?9k t 8 ,uranus %\ld h giv5 rise to a discov]y ev5 m spl5did ?an 8 own4 ,he di$1 h[ev]1 m ?an tw5ty ye>s be=e ?is a*ievem5t4 ,! au?orities :o decide on su* matt]s *ri/5$ ! new planet ,neptune2 & ?is body w&]s r\nd on ! outskirts ( our sol> sy/em1 requir+ = ea* j\rney a p]iod ( no less ?an #afe ye>s4 ,! circle ?us describ$ has a radius ?irty times z great z t ( ! e>?'s track4 ,neptune is altoge!r invisible to ! unaid$ eye1 b x is suffici5tly bright to h be5 occasionally record$ z a />4 ,inde$1 ne>ly fifty ye>s be=e x 0 actually discov]$ to be a planet x _h be5 includ$ by ! a/ronom] ,lal&e 9 a li/ ( />s he 0 obs]v+4 ,a curi\s circum/ance 0 aft]w>ds br\ght to light4 ,:5 ref]5ce 0 made to ! books 9 :i* ,lal&e's obs]vations 7 writt51 x 0 f\nd t he _h obs]v$ ?is object twice1 namely1 on ,may #h & ,may #aj1 #aghe4 ,( c\rse1 if ! object _h inde$ be5 a /> its position on ! two days w\ld h be5 ! same1 b be+ a planet x _h mov$4 ,:5 ,lal&e1 on look+ ov] 8 pap]s1 saw t ! places ( ?is suppos$ /> 7 diff]5t on ! two nights1 he conclud$ t he mu/ h made a mi/ake on ! fir/ night1 & accord+ly treat$ ! object z if ! place on ! #aj? 0 ! "r "o4 ,j ?9k h[ n>r[ly ,lal&e miss$ mak+ a discov]y6 ,unhappily = 8 r5[n1 he took x = grant$ t "o or bo? ( 8 obs]vations 7 errone\s1 & s !y mu/ h be5 if ! object _h be5 a />4 ,b !y 7 bo? "r2 x 0 ! planet :i* _h mov$ 9 ! int]val4 ,z ,neptune is half z f> aga9 f ! e>? z ,uranus1 we c h>dly expect to le>n mu* ab\t ! actual nature ( ! planet4 ,we d "k t x has f\r times ! diamet] ( ! e>?1 s t x exce$s ! e>? 9 ! same proportion t ! e>? is l>g] ?an ! moon4 ,l ! o!r great planets1 ,neptune is also envelop$ ) copi\s cl\ds2 9 fact1 x only weighs "o-fif? "p z mu* z x w\ld d if x 7 made ( mat]ials z sub/antial z are ^? ( ! e>?4 ,l our e>?1 ,neptune is att5d$ by "o moon1 :i* revolves r\nd ! planet 9 a little m ?an six days4 ,! orbit ( ?is great planet m>ks ! b\nd>y ( our kn[n sy/em ( planets4 ,we h se5 h[ ! five great planets ( antiquity h be5 increas$ 9 ^! mod]n days by ! addition ( two m1 ,uranus & ,neptune1 :ile ! discov]y ( a multitude ( small planets has giv5 a fur!r increase to ! numb] ( ! sun's family4 ,we h /ill "s o!r objects 9 our sol> sy/em to describe2 "s ( !m are excessively big2 ^! are ! comets4 ,"s ( !m are exce$+ly small2 !y are ! %oot+ />s4 ,we %all talk ab\t comets & %oot+ />s 9 our next lecture4 ,,lecture ,v4 ,,comets ,,& ,,%oot+ ,,/>s4 ,! ,movem5ts ( a ,comet--,encke's ,comet--,! ,great ,comet ( ,halley--,h[ ! ,telegraph is us$ = ,comets--,! ,p>abola--,! ,mat]ials ( a ,comet--,meteors--,:at becomes ( ! ,%oot+ ,/>s--,gr& ,meteors--,! ,great ,novemb] ,%[]s--,o!r ,great ,%[]s--,meteorites4 ,,! ,,movem5ts ,,( ,a ,,comet4 ,! planets are all massive globes1 m or less flatt5$ at ! ,poles2 b n[ we h to talk ab\t a multitude ( objects ( ! mo/ irregul> %apes1 & ( ! mo/ flimsy description4 ,we call !m comets1 & !y exi/ 9 su* numb]s t an old a/ronom] has said 8!re 7 m comets 9 ! sky ?an fi%es 9 ! sea10 ?\gh ,i ?9k we _c q believe him4 ,!re is also ano!r wide diff]5ce betwe5 planets & comets3 planets move r\nd 9 ne>ly circul> ellipses1 & n only d we "k :]e a planet is to-night1 b we "k :]e x 0 a mon? ago1 or a hundr$ ye>s ago1 or :]e x w be 9 a hundr$ ye>s or a ?\s& ye>s to come4 ,all su* movem5ts are conduct$ ) conspicu\s regul>ity & ord]2 b n[ we are to speak ( bodies :i* g5]ally come 9 ^u u 9 ! mo/ unc]ta9 & irregul> fa%ion4 ,!y visit u we h>dly "k :5ce1 except t x is f out] space1 & !y are adorn$ 9 a glitt]+ raim5t1 almo/ spiritual 9 its texture4 ,!y are always *ang+ _! appe>ance 9 a baffl+1 b /ill v fasc9at+ mann]4 ,if an arti/ tries to draw a comet1 he w h h>dly f9i%$ 8 picture ( x 9 "o *>m+ robe be=e he f9ds x array$ 9 ano!r4 ,! a/ronom] has also 8 compla9ts to make aga9/ ! comets4 ,i h told y h[ ?or\ghly we c rely on ! movem5ts ( ! planets1 b comets (t5 play sad pranks ) our calculations4 ,!y sometimes take ! a/ronom]s by surprise1 & blaze out ) _! long tails j :5 we d n expect !m4 ,!n by way ( comp5sation !y frequ5tly disappo9t u by n appe>+ :5 !y h be5 mo/ anxi\sly look$ =4 ,aft] a voyage ?r\gh space ! comet at l5g? beg9s to draw 9 t[>ds ! c5tral p>ts ( our sy/em1 & z x approa*es ! sun1 its pace becomes gradually great] & great]2 9 fact1 z ! body sweeps r\nd ! sun ! spe$ is sometimes #bj1jjj times fa/] ?an t ( an express tra94 ,x is sometimes m ?an #ajjj times z fa/ z ! swifte/ ( rifle bullets1 occasionally atta9+ ! rate ( #bjj miles a second4 ,! clos] ! comet goes to ! sun1 ! fa/] x moves2 & a case has be5 kn[n 9 :i* a comet1 aft] com+ 9 = an incalculable duration ( "t t[>ds ! sun1 has acquir$ a spe$ s trem5d\s1 t 9 two h\rs x has :irl$ r\nd ! sun & has comm5c$ to return to ! dep?s ( out] space4 ,?is t]rific outbur/ ( spe$ does n la/ long4 ,a pace :i* ne> ! sun is #bj1jjj times t ( our express tra9s dim9i%es to #aj1jjj times1 to fifty times1 to t5 times t pace2 :ile 9 ! out]mo/ "p ( its pa? ! comet seems to creep along s sl[ly t we might ?9k x _h be5 fatigu$ by its previ\s ex]tions4 ,illu/ration3 ,,fig4 #gb4--;,h[ ! ,comet's ,tail is dispos$4 ,we h s (t5 se5 a /ream ( sp>ks /ret*+ out along ! track ( a sky-rocket1 t we might naturally suppose ! tail ( a comet /ream$ out along its pa? 9 a some:at simil> mann]4 ,?is w\ld be q wrong4 ,y see f ,fig4 #gb t ! tail does n lie along ! comet's pa?1 b is always direct$ outw>ds f ! sun4 ,if y w draw a l9e f ! sun to ! head ( ! comet & foll[ ! direction ( ! l9e1 x %[s ! way 9 :i* ! tail is arrang$4 ,y w also notice h[ ! tail ( ! comet seems to gr[ 9 l5g? z x approa*es ! sun4 ,:5 ! comet is fir/ se51 ! tail is (t5 a v insignificant affair1 b x %oots out ) enorm\s rapidity until x becomes _m millions ( miles long by ! "t ! comet is :irl+ r\nd ! sun4 ,^? glories soon beg9 to wane z ! comet flies outw>d2 ! tail gradually vani%es1 & ! w&]] retreats aga9 to ! dep?s ( space 9 ! same undecorat$ condition z t 9 :i* x fir/ approa*$4 ,:5 a comet appe>s1 x is always a matt] ( int]e/ to see :e!r x is an entirely new object1 or :e!r x may n be only ano!r return ( a comet :i* has paid u "o or m previ\s visits4 ,! "q !n arises z to h[ !y are to be id5tifi$4 ,"h we see a wide contra/ betwe5 unsub/antial bodies l comets & ! weighty & /ately planets4 ,sket*es ( ! v>i\s planets or ( ! face ( ! sun1 ?\gh !y might %[ slight diff]5ces f "t to "t1 are /ill always suffici5tly *>act]i/ic1 j z a photographic portrait w id5tify ! individual1 ev5 ?\gh ! lapse ( ye>s w br+ "s *anges 9 8 appe>ance4 ,b ! draw+ ( a comet is almo/ useless = id5tification4 ,y might z well try to id5tify a cl\d or a puff ( smoke by mak+ a picture ( x4 ,make a draw+ ( a comet at "o appe>ance1 & sket* p>ticul>ly ! ample tail ) :i* x is provid$4 ,! next "t ! comet comes r\nd x may v possibly h two tails1 or possibly no tail at all4 ,we are !re=e unable to place any reliance on ! comet's p]sonal appe>ance 9 our ef=ts to id5tify x4 ,! highway :i* x foll[s ?r\gh ! sky af=ds ! only means ( recognition2 = ! comet1 if undi/urb$ by o!r objects1 w nev] *ange its actual orbit4 ,b ev5 ?is me?od ( id5tification (t5 fails1 = x n unfrequ5tly happ5s t dur+ its erratic movem5ts ! comet gets into fe>ful tr\ble ) o!r heav5ly bodies4 ,9 su* cases ! poor comet is sometimes driv5 s completely out ( its road t x has to make = itself an entirely new pa?1 & our ef=ts to id5tify x are plung$ 9 confusion4 ,x has happ5$ t a second comet or ev5 a ?ird w be f\nd 9 ne>ly ! same track1 b :e!r ^! are :olly diff]5t1 or :e!r !y are m]ely p>ts ( ! same orig9al object1 x is (t5 impossible to det]m9e4 ,! great majority ( comets are only to be se5 ) a telescope1 & h>dly a ye> passes )\t ! detection ( at lea/ a few ( ^! fa9t objects4 ,! numb] ( really brilliant comets t c be se5 9 a lifetime c\ld1 h[ev]1 be c\nt$ on ! f+]s4 ,,encke',s ,,comet4 ,we h already allud$ to a little body call$ ,encke's comet1 :i* 0 discov]$ by an a/ronom] at ,m>seilles4 ,x 0 9 ! ye> #ahah t he 0 scann+ ! heav5s ) a small telescope1 :5 an object attract$ 8 att5tion4 ,x 0 n "o ( ^? gr& long-tail$ comets :i* e "o notices2 ?is body 0 s fa9t t x m]ely appe>$ z a v small cl\d ( light1 & 0 recogniz$ z a comet by ! fact t x 0 mov+4 ,x happ5s t !re are o!r bodies 9 ! sky v l comets2 we call !m nebul1 & we %all h some?+ to say ab\t !m aft]w>ds4 ,b x is rem>kable t j z a planet is liable to be mi/ak5 = a />1 s a comet is liable to be mi/ak5 = a nebula4 ,h[ev]1 9 ea* case ! fact ( its movem5t is ! te/ by :i* ! planet or ! comet is at once detect$4 ,a nebula /ays always 9 ! same spot1 l a />1 :ile a comet is incessantly mov+4 ,9 fact1 ) a telescope y c actually wat* a comet /eal+ pa/ ! />s t lie ne> x4 ,y "k t an object a v long way (f may appe> to move sl[ly1 ?\gh 9 reality x is mov+ v rapidly4 ,look at a /eam] ne> ! horizon at sea4 ,9 ! c\rse ( a m9ute or two x w n appe> to h %ift$ its position to any appreciable ext5t1 b t is because x is f> (f4 ,if y 7 ne> ! %ip1 y w\ld see t x 0 da%+ along at ! rate ( p]haps fifte5 or tw5ty miles an h\r4 ,9 a simil> mann] ! comet seems to move sl[ly1 because x is at su* a great di/ance4 ,z a matt] ( fact x is mov+ fa/] at ! "t we see x ?an any /eam]1 fa/] ?an any express tra91 fa/] ?an any cannon-ball4 ,!re 7 special reasons :y ! movem5ts ( ,encke's comet %\ld be wat*$ ) peculi> c>e1 & ! track :i* x pursu$ be asc]ta9$4 ,if y c obs]ve a comet ?ree times & measure its position 9 ! sky1 ! movem5t ( t comet is completely det]m9$4 ,p]haps ,i %\ld say w\ld be det]m9$ if ! comet 7 let alone1 :i*1 un=tunately1 is n (t5 ! case4 ,inde$1 y may rememb] h[ ,i told y "s ( ! misadv5tures ( ?is v comet :5 we 7 speak+ ab\t ! planet ,m]cury4 ,encke's comet comes r\nd 9 a p]iod ( a little m ?an ?ree ye>s1 & x gives u "s curi\s in=mation t has be5 asc]ta9$ dur+ its j\rneys4 ,"o ( ! facts we h ?us le>n$ is s important t we _c omit to notice x 7,fig4 #gc74 ,illu/ration3 ,,fig4 #gc4--,! ,orbit ( ,encke's ,comet4 ,at increas+ heights above ! e>?'s surface !re is gradually less & less air2 until at la/1 at ab\t #bjj or #cjj miles above ! surface on :i* we dwell1 !re w\ld be none4 ,y might z well try to qu5* y\r ?ir/ by dr9k+ out ( an empty cup z attempt to brea! 9 ! op5 space :i* beg9s a few hundr$ miles al(t4 ,9 op5 space motion c\ld take place q freely4 ,d[n "h ! resi/ance ( ! air is a great imp$im5t to movem5t1 especially :5 v rapid4 ,a heavy cannon-ball is *eck$ & robb$ ( its pace by hav+ to pl\gh its way ?r\gh our d5se atmosph]e4 ,! motion is arre/$ 9 ! same way1 ?\gh n ( c\rse to ! same degree1 z if ! cannon-ball _h be5 fir$ into wat]4 ,unsub/antial objects are1 ( c\rse1 imp$$ by ! air to a f> great] ext5t ?an su* heavy bodies z cannon-balls4 ,y "k t y _c ?r[ a h&ful ( fea!rs across ! road 9 ! same way t y c\ld ?r[ a h&ful ( gravel4 ,! light fea!rs _c =ce _! way ?r\gh ! air s well z ! pebbles4 ,a body s flimsy z a comet w\ld nev] be able to pu% its way ?r\gh an atmosph]e l ours2 b out 9 empty space ! comet meets ) no resi/ance dur+ ! great] "p ( its pa?4 ,accord+ly1 ?\gh x has little m sub/ance ?an a w-o'-!-wisp1 ! comet pursues its j\rney ) z mu* resolute dignity z if x 7 made ( ca/ iron4 ,if 9 any "p ( its track ! body %\ld h to pi]ce its way ?r\gh any mat]ial l ev5 ! ?9ne/ possible air1 !n ! unsub/antial nature ( ! comet>y mat]ials w\ld be at once %[n4 ,! motion w\ld be imp$$1 & ! body's pa? w\ld be *ang$4 ,9 ?is way a comet may be made v in/ructive1 = x w %[ :e!r space is really s empty z we sometimes suppose x to be4 ,dur+ ! great] "p ( its c\rse ! flimsy little ,encke te>s along ) su* ease & spe$ t !re seems to be no?+ to imp$e x1 & ?us we le>n t space is g5]ally empty4 ,h[ev]1 :5 ! comet beg9s to :eel ar\nd ! sun1 ! fre$om ( its movem5ts seems to receive a *eck4 ,! unsub/antial object has to =ce its way ) a difficulty t x did n exp]i5ce s long z x 0 mov+ r\nd ! great] "p ( its orbit4 ,we ?us le>n t !re is a ?9 diffus$ atmosph]e surr\nd+ ! sun4 ,we _c1 inde$1 say t x is l our air4 ,its composition is q diff]5t1 & almo/ ! only way we "k ( its exi/5ce is by ! evid5ce :i* ?is comet af=ds4 ,9 a =m] lecture ,i %[$ h[ ,encke's comet told u ! mass ( ! planet ,m]cury4 ,n[ we see h[ ! travels ( ! same body give u in=mation ab\t ! sun himself4 ,i ought1 h[ev]1 to add t "s m rec5t obs]vations seem n to h confirm$ ! belief t !re is ! resi/ance ( ! k9d we h j be5 consid]+4 ,,! ,,great ,,comet ,,( ,,halley4 ,i d>e say y w\ld ?9k x m int]e/+ to talk ab\t "s big & bright comets r ?an ab\t objects s fa9t z t ( ,encke4 ,x un=tunately happ5s t mo/ ( ! f9e comets pay our sy/em only a s+le visit4 ,!re is only "o ( ! really spl5did objects ( ?is k9d t comes back to u ) any?+ l regul>ity4 ,x 0 la/ se5 9 ! ye> #ahce1 & ,i am glad to tell y t x is com+ aga92 x is expect$ ab\t ! ye> #aiaj4 ,y may ask1 ,h[ c we feel sure t su* a pr$iction z ,i h m5tion$ w turn out correctly8 ,! fact is t ?is comet has be5 wat*$ = a great _m c5turies4 ,we f9d anci5t records1 "s ( !m ne>ly #bjjj ye>s old1 ( ! appe>ance ( gr& comets1 & sev]al ( ^! are f\nd to fit 9 ) ! supposition t !re is a body :i* accompli%es its j\rney 9 a p]iod ( ab\t sev5ty-five or sev5ty-six ye>s4 ,( c\rse !re are ?\s&s ( o!r comets record$ 9 ^! old books z well2 b :at ,i mean is t among ! records _m are f\nd :i* cle>ly indicate "s successive returns ( ?is p>ticul> body4 ,i w expla9 h[ ! movem5ts ( ?is comet 7 discov]$4 ,!re 0 a great a/ronom] call$ ,halley1 :o liv$ two hundr$ ye>s ago1 & 9 ! ye> #afhb he1 l e "o else1 0 look+ ) admiration at a spl5did comet ) a magnific5t tail :i* adorn$ ! sky 9 t ye>4 ,at ! obs]vatories1 ( c\rse1 !y dilig5tly set d[n ! positions ( ! comet1 :i* !y asc]ta9$ by c>efully measur+ x ) telescopes4 ,halley fir/ calculat$ ! highway :i* ?is comet foll[$ ?r\gh ! heav5s1 & !n he look$ at ! li/ ( old comets t _h be5 se5 be=e4 ,he ?us f\nd t 9 #afjg--t 01 sev5ty-five ye>s e>li]--a great comet _h also appe>$1 ! pa? ( :i* seem$ mu* ! same z t :i* he f\nd = ! body t he _h himself obs]v$4 ,?is 0 a rem>kable fact1 & x became /ill m significant :5 he discov]$ t sev5ty-six ye>s e>li]--namely1 9 #aeca--;ano!r great comet _h be5 record$1 :i* mov$ 9 a pa? also agree+ ) ^? ( #afjg & #afhb4 ,x !n occurr$ to ,halley t possibly ^! 7 n ?ree diff]5t objects1 b only diff]5t exhibitions ( "o & ! same1 :i* mov$ r\nd 9 ! p]iod ( sev5ty-five or sev5ty-six ye>s4 ,!re is a te/ :i* an a/ronom] c (t5 apply 9 ! pro( ( 8 !ory1 & x is a v sev]e te/4 ,he w n only %[ himself to be wrong if x fails1 b he w also make himself some:at ridicul\s4 ,halley v5tur$ to submit 8 reputation to ?is ordeal4 ,he prophesi$ t ! comet w\ld appe> aga9 9 ano!r sev5ty-five or sev5ty-six ye>s4 ,he knew t he w\ld1 ( c\rse1 be dead long be=e #ageh %\ld arrive2 b :5 he v5tur$ to make ! pr$iction1 he said t he hop$ po/]ity w\ld n refuse to admit t ?is discov]y _h be5 made by an ,engli%man4 ,y c easily imag9e t z #ageh drew ne>1 great int]e/ 0 excit$ among a/ronom]s to see if ! pr$iction ( ,halley w\ld be fulfill$4 ,we are accu/om$ 9 ^! days to f9d _m a/ronomical ev5ts =etold ) ! same sort ( punctuality z we expect 9 railway "t-tables4 ,! ,nautical ,almanac is full ( su* prophecies1 & we f9d !m univ]sally fulfill$4 ,ev5 n[1 h[ev]1 we are n able to set =? our "t-tables = comets ) ! same confid5ce t we %[ :5 issu+ !m = ! sun1 ! moon1 or ! />s4 ,h[ a/oni%+1 !n1 mu/ ,halley's pr$iction h seem$6 ,"h 0 a va/ comet :i* _h to make a voyage ?r\gh space to ! ext5t ( _m hundr$s ( millions ( miles4 ,= ?ree-qu>t]s ( a c5tury x w\ld be utt]ly invisible 9 ! greate/ telescopes1 & ! only way 9 :i* x c\ld be p]ceiv$ 0 by figures & calculations :i* enabl$ ! m9d's eye to foll[ ! hidd5 body all ar\nd its my/]i\s track4 ,= fifty1 or sixty1 or sev5ty ye>s no?+ _h be5 se5 ( ! comet1 nor1 inde$1 0 any?+ expect$ to be se5 ( x2 b z sev5ty-"o1 & sev5ty-two1 & sev5ty-?ree ye>s _h pass$1 x 0 felt t ! w&]]1 ?\gh /ill unse51 mu/ be rapidly draw+ ne>4 ,! problem 0 made m difficult = ^? skilful ma!maticians :o essay$ to calculate x by ! fact t ! comet approa*$ ! ?or\ghf>es :]e ! planets circulate2 &1 ( c\rse1 ! flimsy object w\ld be pull$ hi!r & ?i!r out ( its pa? by ! attractions ( ! weighty bodies4 ,x 0 comput$ t ! influ5ce ( ,saturn alone 0 suffici5t to delay ! comet = m ?an ?ree mon?s1 :ile x appe>$ t ! attraction ( ,jupit] 0 pot5t en\gh to ret>d ! expect$ ev5t = a ye> & a half m4 ,0 x n wond]ful t ma!maticians %\ld be able to f9d out all ^! facts f m]ely kn[+ ! track :i* ! comet 0 expect$ to foll[8 ,clairaut1 :o devot$ himself to ?is problem1 sugge/$ t !re might also be "s di/urbances f o!r causes ( :i* he did n "k1 & t consequ5tly ! expect$ return ( ! comet might be a mon? wrong ei!r way4 ,great inde$ 0 ! admiration 9 a/ronomical circles :51 true to pr$iction1 ! comet blaz$ ^u ! _w )9 ! limits ( "t ,clairaut _h specifi$4 ,! rem>kable fulfilm5t ( ?is prophecy entitles u to speak ) confid5ce ab\t ! pa/ p]=mances ( ?is comet4 ,among all ! app>itions ( ,halley's comet = ! la/ two ?\s& ye>s1 p]haps ! mo/ rem>kable is t :i* took place 9 ! ye> #ajff4 ,i am sure y w all rememb] ?is date 9 y\r ,engli% hi/ory2 x 0 ! ye> ( ! ,conque/4 ,9 ^? days !y did n und]/& a/ronomy z we und]/& x n[2 !y us$ to ?9k ( a comet z a fe>ful port5t ( evil1 s5t to ?reat5 "s frightful calamity2 su* z a pe/il5ce1 a w>1 a fam9e1 or some?+ else equally disagreeable4 ,h5ce 9 ! ye> ( ! ,conque/ ! appe>ance ( s t]rific an object 9 ! sky 0 a v significant om54 ,att5tion 0 conc5trat$ ^u ! spectacle1 & a picture ( ,halley's comet z x appe>$ to ! some:at t]rifi$ imag9ations ( ! p ( ^? days has be5 pres]v$4 ,!re is a celebrat$ tape/ry at ,bayeux on :i* hi/orical incid5ts are repres5t$ by beautifully work$ pictures4 ,on ?is fabric we h a view ( ,halley's comet 9 a qua9t & r ludicr\s aspect4 ,y w read ( ?is comet also 9 ! e>ly pages ( ,t5nyson's 8,h>old40 ,,h[ ,,! ,,telegraph ,,is ,,us$ ,,= ,,comets4 ,9 ^! days ! /udy ( comets is prosecut$ ) en]gy4 ,ov] ! _w obs]vatories are situat$1 & :5ev] a comet is discov]$1 tid+s ( ! ev5t are diffus$ among ^? likely to be int]e/$4 ,suppose t "o is discov]$ 9 ! s\!rn hemisph]e1 ! a/ronom]s !n write to w>n ! nor!rn obs]vatories ( ! ev5t4 ,b comets (t5 move fa/] ?an h] ,maje/y's mails1 s t ! telegraph has to be put into requisition4 ,! k9d ( message is "o :i* %all %[ ! position & ! movem5ts ( ! body4 ,x necess>ily involves a good _m figures & words1 & consequ5tly x is desirable to abbreviate z mu* z possible = ! sake ( economy4 ,!re is a fur!r difficulty 9 us+ ! telegraph1 because ! messages are n ( an intelligible description to ^? n specially v]s$ 9 a/ronomy4 ,skilful z ! telegraph cl]ks are1 !y c h>dly be expect$ to be famili> ) ! te*nicalities ( a/ronom]s4 ,! cl]k at ! receiv+ end is h&$ a message :i* he does n und]/& v cle>ly4 ,! cl]k at ! o!r end does n und]/& ! message :i* is deliv]$ to him1 & betwe5 !m x has happ5$ t !y h trans=m$ ! message into some?+ :i* n only !y d n und]/&1 b :i*1 un=tunately1 nobody else c und]/& ei!r4 ,^! difficulties h be5 surm\nt$ by an agreem5t betwe5 a/ronom]s1 :i* is s simple & int]e/+ t ,i mu/ m5tion x4 ,! k9d ( message t expresses ! place ( a comet w consi/ ( s5t5ces some?+ ( ?is k9d3 8,"o hundr$ & tw5ty-?ree degrees & =ty-five m9utes40 ,surely x w\ld be an advantage to be able to replace all ^! words by a s+le ^w1 p>ticul>ly if by do+ s ! risk ( error w\ld be dim9i%$4 ,?is is :at ! a/ronom]s' telegraphic arrangem5t enables !m to accompli%4 ,!re is a c]ta9 excell5t ,diction>y kn[n z ,worce/]'s4 ,i am sure :5 ,mr4 ,worce/] arrang$ ?is "w1 he _h n ! slighte/ anticipation ( an odd use to :i* x w\ld occasionally be put4 ,e a/ronom] :o is co-op]at+ 9 ! comet s*eme mu/ h a copy ( ! book4 ,to s5d ! message ,i h j ref]r$ to1 he has to take up 8 ,diction>y & look out page #abc4 ,!n he w c\nt d[n ! column until he comes to ! =ty-fif? ^w on t page1 :i* he f9ds to be 8con/itu5t10 & accord+ to ?is plan ! message1 or at lea/ ?is "p ( x1 is m]ely t "o ^w1 8con/itu5t40 ,! a/ronom] :o receives ?is message & wi%es to int]pret x takes up 8 copy ( ,worce/]'s ,diction>y & looks out = 8con/itu5t40 ,he sees t x is on page #abc1 & t x is ! =ty-fif? ^w d[n on t page2 & !re=e he kn[s t ! int]pretation ( ! message is to be "o hundr$ & tw5ty-?ree degrees & =ty-five m9utes4 ,,! ,,p>abola4 ,g5]ally speak+1 great comets come to u once & are !n nev] se5 aga94 ,su* bodies d n move 9 clos$ ovals or ellipses1 !y foll[ ano!r k9d ( curve1 l t repres5t$ 9 ,fig4 #gd4 ,x is "o t e boy ought to "k4 ,9 fact1 9 "o ( 8 e>lie/ accompli%m5ts he le>n$ h[ to make a p>abola4 ,x is true he did n call x by any "n s f9e z ?is1 b e "t a ball is ?r[n into ! air x describes a "p ( ! beautiful curve :i* geomet]s "k by ?is ^w 7,fig4 #gd74 ,9 fact1 y c\ld n ?r[ a ball s t x %\ld describe any o!r curve except a p>abola4 ,no boy c\ld ?r[ a /one 9 a truly horizontal l9e4 ,x w always curve d[n a little1 w always1 9 fact1 be a portion ( a p>abola4 ,illu/ration3 ,,fig4 #gd4--,! ,pa? ( a ,projectile is a ,p>abola4 ,!re are big p>abolas & !re are small ones4 ,"o ( ! %ells :i* are ?r[n into a t[n :5 bomb>d$ f a di/ance describes1 z x rises & !n slopes d[n aga91 "p ( a mighty p>abola4 ,s does a t5nis ball ?r[n by ! h& or /ruck by ! racket2 ?\gh "h1 inde$1 ,i admit t a sp9 may be giv5 to ! ball :i* w some:at detract f ! simplicity ( its movem5t4 ,9 play+ baseball1 a l>ge "p ( ! skill ( ! pit*] consi/s 9 ?r[+ ! ball 9 su* a way t x %all n move 9 a p>abola1 b 9 "s twi/+ curve by :i* he hopes to baffle 8 adv]s>y4 ,sett+ aside ^! exceptions1 & su* ano!r z ! case ( a body toss$ /raight up or dropp$ /raight d[n1 we may ass]t t ! pa? ( a projectile is a p>abola4 ,illu/ration3 ,,fig4 #ge4--,! ,ligh?\se ,reflector4 ,!re are "s rem>kable applications ( ! same curve = practical purposes4 ,f our ligh?\ses we want to s5d beams (f to sea1 s z to guide %ips into port4 ,if we m]ely employ$ a lamp )\t conc5trat+ its rays1 we %\ld h a v imp]fect ligh?\se1 = ! lamp scatt]s light ab\t 9 all directions4 ,mu* ( x goes /raight up into ! air1 mu* ( x w\ld be direct$ inl&2 9 fact1 !re is only an extremely small "p ( ! entire numb] ( rays t w naturally take ! useful direction4 ,we !re=e require some?+ r\nd ! lamp :i* %all cat* ! truant rays t are runn+ away to idl5ess & loss1 & %all conc5trate !m into ! direction 9 :i* !y w be useful to ! m>9]4 ,an effective way ( do+ ?is is to furni% ! lamp ) a reflector4 ,on its bright surface 7,fig4 #ge7 all ! rays fall :i* w\ld o!rwise h gone a/ray1 & ea* ( !m is prop]ly r$irect$1 :]e ! sailors c see x4 ,x is ess5tial t ! mirror %all d ?is "w accurately1 & ?is x w only d :5 x has be5 truly %ap$ s z to be a p>abola4 ,y w rememb]1 also1 h[ ,i describ$ to y ! reflector :i* ,h]s*el made = 8 great telescope4 ,! %ape ( ! mirror mu/ be mo/ accurately work$1 & x1 too1 mu/ h a p>abola = its section2 s t y see ?is curve is "o ( importance 9 a v>iety ( ways4 ,b ! gr&e/ ( all p>abolas are ^? :i* ! comets pursue4 ,unlike ! ellipse1 ! p>abola is an op5 curve2 x has two bran*es /ret*+ away & away =ev]1 & always gett+ fur!r ap>t4 ,( c\rse1 9 ! examples ( ?is curve t ,i h giv5 x is only a small "p ( ! figure t is conc]n$4 ,:5 y ?r[ a /one x only describes t "p ( ! p>abola t lies betwe5 y\r h& & ! spot :]e ! /one hits ! gr\nd4 ,x is j a "p ( ! curve 9 ! same way t a cresc5t may be a bit ( a circle4 ,x is to comets t we mu/ look = ! mo/ complete illu/ration ( ! ample ext5t ( a p>abola4 ,! %ape ( ?is gr& curve w expla9 :y s _m comets only appe> to u once4 ,x is q cle> t if y beg9 to run r\nd a clos$ racec\rse1 y may1 if y cont9ue y\r c>e] long en\gh1 pass & repass ! />t+-po/ ?\s&s ( times4 ,?us1 comets :i* move 9 ellipses1 & are consequ5tly trac+ clos$ curves1 w pass ! e>? times )\t numb]4 ,= ?is reason we may see !m ov] & ov] aga91 z we d ,encke's comet or ,halley's comet4 ,b suppose y 7 travell+ along a road :i*1 no matt] h[ x may turn1 nev] leads aga9 into itself1 !n x is q pla9 t1 ev5 if y 7 to cont9ue y\r j\rney =ev]1 y c nev] twice pass ! same h\se on ! roadside4 ,t is exactly ! condition 9 :i* mo/ ( ! comets are mov+4 ,_! orbits are p>abolas :i* b5d r\nd ! sun2 &1 g5]ally speak+1 ! sun is v close to ! turn+-po9t4 ,! e>? is also1 comp>atively speak+1 close to ! sun2 s t :ile ! comet is 9 t neighborhood we c sometimes see x4 ,we d n see ! comet = a long "t be=e x approa*es ! sun1 or = a long "t aft] x has pass$ ! sun4 ,all we "k1 !re=e1 ( its j\rney is t ! two ends ( ! p>abola /ret* on & on =ev] into space4 ,! comet is fir/ p]ceiv$ com+ 9 along "o ( ^! bran*es to :irl r\nd ! sun2 & aft] do+ s1 x retreats along ! o!r bran*1 & gradually s9ks into ! dep?s ( space4 ,:y "o ( ^! my/]i\s w&]]s %\ld approa* 9 su* a hurry1 & !n :y x %\ld fly back aga91 c be p>tially expla9$ )\t ! aid ( ma!matics4 ,let u suppose t1 at a di/ance ( ?\s&s ( millions ( miles1 !re float$ a mass ( flimsy mat]ial resembl+ t f :i* comets are made4 ,not)/&+ its va/ di/ance f ! sun1 ! attraction ( t great body w ext5d ?i!r4 ,x is true ! pull ( ! sun on ! comet w be ( ! feeble/ & slighte/ description1 on acc\nt ( ! enorm\sly great di/ance4 ,/ill1 ! comet w respond 9 "s degree1 & w comm5ce gradually to move 9 ! direction 9 :i* ! sun invites x4 ,p]haps c5turies1 or p]haps ?\s&s1 or ev5 t5s ( ?\s&s1 ( ye>s w elapse be=e ! object has ga9$ ! sol> sy/em4 ,by t "t its spe$ w be augm5t$ to su* a degree1 t aft] a t]rific :irl ar\nd ! sun1 x w at once fly (f aga9 along ! o!r bran* ( ! p>abola4 ,p]haps y w wond] :y x does n tumble /raight into ! sun4 ,x w\ld d s1 no d\bt1 if x />t$ at fir/ f a position ( re/2 g5]ally1 h[ev]1 ! comet has a motion to beg9 ) :i* w\ld n be direct$ exactly to ! lum9>y4 ,?is x is :i* causes ! comet to miss actually hitt+ ! sun4 ,x may also be difficult to und]/& :y ! sun does n keep ! comet :5 at la/ x has arriv$4 ,:y %\ld ! w&]+ body be 9 su* a hurry to rec$e8 ,surely x might be expect$ t ! attraction ( ! sun ought to hold x4 ,if some?+ 7 to *eck ! pace ( ! comet 9 its t]rific da% r\nd ! sun1 !n1 no d\bt1 ! object w\ld simply tumble d[n into ! sun & be lo/4 ,! sun has1 h[ev]1 n "t to pull 9 ! comet :5 x comes up ) a spe$ #bj1jjj times t ( an express tra94 ,b ! sun does succe$ 9 alt]+ ! direction ( ! motion ( ! comet1 & ! attraction has %[n itself 9 t way4 ,i c illu/rate :at happ5s 9 ?is mann]4 ,"h is a heavy weight susp5d$ f ! ceil+ by a wire2 x hangs /raight d[n1 ( c\rse1 & !re x is kept by ! pull ( ! e>?4 ,suppos+ ,i draw ! weight aside & all[ x to sw+ to & fro1 !n ! motion cont9ues l ! beat ( a p5dulum4 ,! weight is always pull$ d[n z ne> to ! e>? z possible1 b :5 x gets to ! l[e/ po9t1 x does n /ay !re1 x goes ?r\gh t po9t1 & rises up at ! o!r side4 ,! reason is t ! weight has acquir$ spe$ by ! "t x rea*es ! l[e/ po9t2 & t1 9 virtue ( its spe$1 x passes ?r\gh ! position 9 :i* x w\ld naturally re/1 & actually asc5ds ! o!r side 9 opposition to ! e>?'s pull1 :i* is dragg+ x back all ! "t4 ,?is w illu/rate h[ ! comet c pass by & ev5 rec$e f ! body :i* is cont9ually attract+ x4 ,j a few words ( caution mu/ be add$4 ,suppose y _h an ellipse s long t ! comet w\ld take ?\s&s & ?\s&s ( ye>s to complete a circuit1 !n ! "p ( ! ellipse 9 :i* ! comet moves dur+ ! "t :5 we c see x is s l a p>abola1 t we might possibly be mi/ak5 9 ! matt]4 ,9 fact1 a geomet] w tell u t if "o end ( an ellipse 0 to g fur!r & fur!r away1 ! end t /ay$ ) u w\ld gradually become m & m l ?is curve4 ,!re=e1 "s ( ^? comets :i* seem to move 9 p>abolas may really be mov+ 9 extremely elongat$ ellipses1 & ?us1 aft] excessively long p]iods ( "t1 may come back to revisit u4 ,,! ,,mat]ials ,,( ,a ,,comet4 ,a comet is made ( v unsub/antial mat]ial4 ,?is we c %[ 9 a v int]e/+ mann]1 :5 we see x mov+ ov] ! sky betwe5 ! e>? & ! />s4 ,sometimes a comet w pass ov] a clu/] ( v small />s1 s fa9t t ! v lighte/ cl\d t is ev] 9 ! sky w\ld be q suffici5t to hide !m4 ,yet ! />s are di/9ctly visible "r ?r\gh ! comet1 not)/&+ t x may be hundr$s ( ?\s&s ( miles ?ick4 ,?is %[s u h[ excessively flimsy is ! sub/ance ( a comet1 = :ile a few feet ( haze or mi/ suffice to ext+ui% ! brighte/ ( />s1 ?is imm5se curta9 ( comet /uff1 :atev] x may be made (1 is practically transp>5t4 ,i h (t5 told y t we are able to weigh ! heav5ly bodies1 b a comet gives u a great deal ( tr\ble4 ,y see t ! weigh+ ma*9e mu/ be ( a v delicate k9d if y are go+ to weigh a v light object4 ,take1 = example1 a little lock ( gold5 hair1 :i* no d\bt has g5]ally a value q indep5d5t ( ! numb] ( gra9s t x conta9s4 ,suppose1 h[ev]1 t we are s curi\s z to desire to "k its weight1 !n "o ( ^? beautiful balances 9 our laboratories w tell u4 ,9 fact1 if y snipp$ a little fragm5t f a s+le hair1 ! balance w\ld be s5sitive en\gh to weigh x4 ,if1 h[ev]1 y 7 only provid$ ) a common pair ( scales l ^? :i* are suit$ = ! p>cel po/1 !n y c\ld nev] weigh any?+ s light z a lock ( hair4 ,y h n small en\gh weights to beg9 )1 & ev5 if y _h !y w\ld be ( no use1 = ! scale is too co>se to e/imate su* a trifle4 ,?is is precisely ! sort ( difficulty we exp]i5ce :5 we try to weigh a comet4 ,! body1 ?\gh s big1 is v light1 & our scales are s cumb]some t we are 9 a position ( "o :o w\ld try to weigh a lock ( hair ) a p>cel-po/ balance4 ,we _c always f9d suitable scales = weigh+ cele/ial bodies4 ,we h to use = ! purpose :atev] me?ods ( discov]+ ! weights happ5 to be available4 ,s f>1 ! me?ods ,i h m5tion$ are ( ! rude/ description2 !y s]ve well en\gh = weigh+ heavy masses l planets1 b !y w n d = su* unsub/antial bodies z comets4 ,b1 ?\gh we fail 9 ?is endeavor1 i4e4 to weigh comets1 yet skilful a/ronom]s h succe$$ 9 some?+ :i* at fir/ y might ?9k to be almo/ impossible4 ,!y h actually be5 able to discov] "s ( ! +r$i5ts ( :i* a comet is made4 ,?is is s important a subject t ,i mu/ expla9 x fully4 ,! mo/ in/ructive comet :i* we h se5 9 mod]n days is t :i* appe>$ 9 ! ye> #ahhb4 ,x 0 an object s great t its tail alone 0 d\ble z long z f ! e>? to ! sun4 ,x 0 discov]$ at ! obs]vatories 9 ! s\!rn hemisph]e e>ly 9 ,septemb] ( t ye>4 ,a little lat] x 0 obs]v$ 9 ! nor!rn hemisph]e 9 extraord9>y circum/ances4 ,x mu/ be rememb]$ t a comet is g5]ally a fa9t object1 & t ev5 ^? comets :i* are l>ge en\gh & bright en\gh to =m glori\s spectacles 9 ! sky at night are usually invisible dur+ ! brightness ( day4 ,= a comet to be se5 9 daylight 0 inde$ an unusual occurr5ce2 b on ! =5oon ( ,sunday1 ,septemb] #ag1 ,mr4 ,common at ,eal+ saw a great comet close to ! sun4 ,un=tunately cl\ds int]v5$1 & he 0 prev5t$ f obs]v+ ! critical occurr5ce j approa*+4 ,an a/ronom] at ! ,cape ( ,good ,hope--,mr4 ,f9lay--:o _h also be5 "o ( ! e>lie/ discov]]s ( ! comet1 0 wat*+ ! body on ! same day4 ,he foll[$ x z x advanc$ close up to ! sun2 bright inde$ mu/ t comet h be5 :i* p]mitt$ su* a wond]ful obs]vation4 ,at ! sun's edge ! comet disappe>$ in/antly2 9 fact1 ! obs]v]s ?\ght t x mu/ h gone beh9d ! sun4 ,!y c\ld n o!rwise acc\nt = ! sudd5ness ) :i* x vani%$4 ,?is 0 n :at really happ5$4 ,x 0 aft]w>ds asc]ta9$ t ! comet _h n pass$ beh9d ! sun2 x _h1 inde$1 come betwe5 u & our lum9>y4 ,9 its fur!r progress ?is body %[$ 9 a /rik+ degree ! incoh]5t nature ( ! mat]ials ( :i* a comet is compos$4 ,x seem$ to ?r[ (f portions ( its mass along its track1 ea* ( :i* cont9u$ an indep5d5t j\rney4 ,ev5 ! c5tral "p 9 ! head ( ! comet--! nucleus1 z x is call$--%[$ itself to be ( a widely diff]5t nature f a sub/antial planet>y body4 ,! nucleus divid$ into two1 ?ree1 f\r1 or ev5 five di/9ct p>ts1 :i* seem$1 9 ! words ( "o obs]v]1 to be connect$ toge!r l pe>ls on a /r+4 ,! comet ( #ahhb 0 also v in/ructive ) reg>d to ! actual mat]ials f :i* su* bodies are made4 ,a/ronom]s h a beautiful me?od by :i* !y f9d out ! sub/ances pres5t 9 a heav5ly body1 ev5 ?\gh !y nev] c get a specim5 ( ! body into _! h&s4 ,we "k at lea/ ?ree mat]ials :i* 7 pres5t 9 ?is comet4 ,! fir/ ( !m is an +r$i5t :i* is v commonly f\nd 9 comets--a *emi/ calls x c>bon4 ,x is an extremely famili> mat]ial on ! e>?2 = in/ance1 coal is *iefly compos$ ( c>bon4 ,*>coal :5 burn$ leaves only a few a%es4 ,all ! sub/ance t has vani%$ dur+ combu/ion is c>bon2 9 fact1 x is n too mu* to say t c>bon is f\nd abundantly n only 9 wood1 b 9 almo/ e =m ( vegetable matt]4 ,! food we eat conta9s abundant c>bon1 & x is an important con/itu5t 9 ! build+ up ( our own bodies4 ,g5]ally speak+1 c>bon is n f\nd 9 a pure /ate--x is associat$ ) o!r sub/ances4 ,soot & lampblack are l>gely compos$ ( x2 b ! pure/ =m ( ?is elem5t c>bon t we "k is ! diamond4 ,x is int]e/+ to note t c>bon is c]ta9ly f\nd z a frequ5t con/itu5t ( comets4 ,! great comet ( #ahhb und\bt$ly conta9$ x1 z well z c]ta9 o!r sub/ances4 ,( ^! we "k two3 ! fir/ is ! elem5t sodium1 an extremely abundant mat]ial on e>?1 inasmu* z ! salt 9 ! sea is ma9ly compos$ ( x4 ,x 0 also discov]$ t ! same great comet conta9$ ano!r sub/ance v common "h & extremely useful to mank9d4 ,dr4 ,copel& & ,dr4 ,lohse at ,dune*t %[$ t iron 0 pres5t 9 ?is body :i* _h come 9 to visit u f ! dep?s ( space4 ,^! discov]ies are especially int]e/+ because !y seem to %[ ! uni=mity ( mat]ial compos+ our sy/em4 ,we already knew t sodium & iron ab\nd$ 9 ! sun1 & n[ we h le>n$ t ^! bodies & c>bon z well are pres5t 9 ! comets4 ,9 ! next *apt] we %all le>n t ! v same mat]ials--sodium & iron--are met ) 9 bodies f> m remote f u ?an any bodies ( our own sy/em4 ,comets h su* a caprici\s habit ( da%+ into ! sol> sy/em at any "t & f any direction1 t x is wor? :ile ask+ :e!r a comet might n sometimes happ5 to come into collision ) ! e>?4 ,!re is no?+ impossible 9 su* an occurr5ce4 ,!re is1 h[ev]1 no reason to appreh5d t any disa/r\s consequ5ces w\ld ensue to ! e>?4 ,man has liv$ on ?is globe = _m1 _m ?\s&s ( ye>s1 & ! rocks are full ( ! rema9s ( fossil animals :i* h fl\ri%$ dur+ pa/ ages2 inde$1 we _c possibly e/imate ! numb] ( millions ( ye>s t h elaps$ s9ce liv+ ?+s fir/ crawl$ ab\t ?is globe4 ,!re has nev] be5 any complete break 9 ! succession ( life1 consequ5tly dur+ all ^? millions ( ye>s we are c]ta9 t no su* dire calamity has happ5$ to ! e>? z a frightful collision w\ld h produc$1 & we ne$ n appreh5d any su* cata/rophe 9 ! future4 ,i d n mean1 h[ev]1 t h>mless collisions ) comets may n h occasionally happ5$2 9 fact1 !re is good reason = kn[+ t !y h actually tak5 place4 ,9 ! ye> #ahfa a f9e comet appe>$2 & x is n s well rememb]$ z its m]its des]ve1 because x happ5$1 un=tunately = its own r5[n1 to appe> j ?ree ye>s aft] ! comet ( #aheh1 :i* 0 "o ( ! mo/ gorge\s objects ( ?is k9d 9 mod]n times4 ,b 9 #ahfa we _h a novel exp]i5ce4 ,on a ,sunday ev5+ 9 midsumm] ( t ye>1 we da%$ into ! comet1 or x da%$ into u4 ,we 7 n1 x is true1 9 collision ) its d5se/ "p2 x 0 r ! end ( ! tail :i* we enc\nt]$4 ,!re 71 =tunately1 no v s]i\s results4 ,inde$1 mo/ ( u nev] knew t any?+ _h happ5$ at all1 & ! re/ only le>n$ ( ! accid5t long aft] x 0 all ov]4 ,= a c\ple ( h\rs t night x w\ld seem t we 7 actually 9 ! tail ( ! comet1 b s f> z ,i "k no "o 0 injur$ or exp]i5c$ any al>m+ inconv5i5ce4 ,inde$1 ,i h only he>d ( "o calamity aris+ f ! collision4 ,a cl]gyman tells u t at midsumm] he 0 always able 9 ord9>y ye>s to read 8 s]mon at ev5+ s]vice )\t artificial light4 ,on ?is p>ticul> occasion1 h[ev]1 ! sky 0 ov]ca/ ) a peculi> gl[1 :ile ! ord9>y light 0 s mu* int]f]$ ) t ! sexton _h to provide a pair ( c&les to enable him to get ?r\gh ! s]mon4 ,! exp5se ( ^? c&les 01 ,i believe1 ! only loss to ! e>? 9 consequ5ce ( its collision ) ! comet ( #ahfa4 ,illu/ration3 ,,fig4 #gf4--;,h[ ! ,tail ( a ,comet arises4 ,! tail ( a comet appe>s to develop "u ! influ5ce ( ! sun4 ,z ! w&]+ body approa*es ! s\rce ( c5tral heat x gr[s w>m1 & z x gets clos] & clos] to ! sun1 ! f]vor becomes great] & great]1 until sometimes ! comet exp]i5ces a heat m viol5t ?an any we c\ld produce 9 our furnaces4 ,! mo/ infusible sub/ances1 su* z /ones or e>?1 w\ld be heat$ :ite-hot & melt$1 & ev5 driv5 (f into vapor1 "u ! int5se heat to :i* a comet is sometimes expos$4 ,comets1 inde$1 h be5 kn[n to sweep r\nd ! sun s closely z to pass )9 a sev5? "p ( its radius f ! surface4 ,x seems t c]ta9 mat]ials pres5t 9 ! comet1 :5 heat$ to ?is extraord9>y temp]ature1 are driv5 away f ! head1 & ?us =m ! tail 7,fig4 #gf74 ,h5ce we see t ! tail consi/s ( a /ream ( vapor\s p>ticles1 da%+ away f ! sun z if ! heat :i* _h call$ !m into be+ 0 a torm5t f :i* !y 7 endeavor+ to escape4 ,! tail ( a comet is1 !re=e1 n a p]man5t "p ( ! body4 ,x is m l ! smoke f a great *imney4 ,! smoke is be+ incessantly r5ew$ at "o end z ! column gets disp]s$ into ! air at ! o!r4 ,z ! comet retreats1 ! sun's heat loses its p[]4 ,9 ! *ills ( space !re is1 !re=e1 no tail-mak+ 9 progress1 :ile ! small mass ( ! comet r5d]s x unable to ga!r back aga9 by its attraction ! mat]ials :i* h be5 expell$4 ,%\ld x happ5 t ! comet moves 9 an elliptic orbit1 & ?us comes back "t aft] "t to be invigorat$ by a good roa/+ f ! sun1 x w1 ( c\rse1 endeavor to manufacture a tail ea* "t t x approa*es ! s\rce ( heat4 ,! quantity ( mat]ial available = ! =mation ( tails is limit$ to ! am\nt ) :i* ! comet orig9ally />t$2 no fre% supply c be add$4 ,if1 !re=e1 ! comet exp5ds a portion ( ?is e "t x comes r\nd1 an inevitable consequ5ce seems to foll[4 ,suppose a boy receives a sov]eign :5 he goes back to s*ool1 & t e "t he passes ! pa/ry-cook's %op "s ( 8 money disappe>s 9 a mann] t ,i d>e say y c conjecture1 ,i ne$ n tell y t be=e long ! sov]eign w h totally vani%$4 ,9 a simil> way comets _c escape ! natural consequ5ces ( _! extravagance2 _! /ore ( tail-mak+ sub/ance mu/1 !re=e1 gradually dim9i%4 ,at ea* successive return ! tails produc$ mu/ g5]ally decl9e 9 size & magnific5ce1 until at la/ ! necess>y mat]ials h be5 all squ&]$1 & we h ! pitiful spectacle ( a comet )\t any tail at all4 ,! gigantic size ( comets mu/ excite our a/oni%m5t4 ,a pebble toss$ into a riv] w\ld n be m completely engulf$ ?an is our :ole e>? :5 x ent]s ! tail ( "o ( ^! bodies4 ,b we n[ pass by a sudd5 transition to speak ( ! v smalle/ bodies1 ( little objects s m9ute t y c\ld c>ry !m 9 y\r wai/coat pocket4 ,y w p]haps be surpris$ t su* ?+s c play an important "p 9 our sy/em & h a mom5t\s connection ) mighty comets4 ,,meteors4 ,if y look out f y\r w9d[ at ! midnight sky1 or take a walk on a f9e cle> night1 y w occasionally see a /reak ( light da% ov] ! heav5s1 ?us =m+ :at is call$ a fall+1 or a %oot+1 /> 7,fig4 #gg74 ,x is n really "o ( ! regul> />s t has d>t$ f its place4 ,! objects we are n[ talk+ ( are q diff]5t f />s prop]4 ,to beg9 )1 ! %oot+ />s are comp>atively close to u :5 we see !m1 & !y are v small1 :]eas ! />s !mselves are enorm\s globes1 f> bigg] ?an our e>?1 or (t5 ev5 bigg] ?an ! sun4 ,sometimes a great %oot+ /> is se5 :i* makes a trem5d\s blaze ( light z bright z ! moon1 or ev5 bright] /ill4 ,^! objects we call meteors1 & y w be v =tunate if y c ev] see a really f9e "o4 ,a/ronom]s _c pr$ict ^! ?+s z !y pr$ict ! appe>ance ( ! planets4 ,bright meteors consequ5tly appe> q unexpect$ly1 & x is a matt] ( *ance z to :o %all enjoy ! privilege ( behold+ !m4 ,b x is n ab\t ! great meteors t we are n[ go+ to speak p>ticul>ly2 !y are (t5 n s int]e/+ z ! small ones4 ,illu/ration3 ,,fig4 #gg4--;,a ,brilliant ,meteor4 ,^! little meteoroids1 z we %all call !m1 h a curi\s hi/ory4 ,!y become visible to u only at ! v la/ mom5t ( _! exi/5ce--9 fact1 ! /reak ( light :i* =ms a %oot+ /> is m]ely ! de/ruction ( a meteoroid4 ,y mu/ always rememb] t we are "h liv+ at ! bottom ( a great ocean ( air1 & above ! air ext5ds ! empty space4 ,air is a great imp$im5t to motion2 a l>ge "p ( ! p[] ( a locomotive eng9e has to be exp5d$ solely 9 pu%+ ! air out ( ! way s z to all[ ! tra9 to get ?r\gh4 ,! fa/] ! spe$1 ! great] is ! tax :i* ! air imposes on ! mov+ body4 ,a cannon-ball1 = in/ance1 loses an imm5sity ( its spe$1 & consequ5tly ( its p[]1 by hav+ to bore its way ?r\gh ! air4 ,9 out] space beyond ! limits ( ?is atmosph]e1 a fre$om ( movem5t c be enjoy$ ( :i* we "k no?+ d[n "h4 ,i spoke ( ?is :5 discuss+ ! movem5ts ( ,encke's comet4 ,ev5 ?is v unsub/antial body c\ld da% along )\t appreciable resi/ance until x trav]s$ ! atmosph]e surr\nd+ ! sun4 ,b n[ we h to speak ( ! motion ( a little object bo? small & d5se1 resembl+ p]haps a pebble or a fragm5t ( iron1 or "s sub/ance ( t description4 ,x is a little body su* z ?is :i* produces a %oot+ />4 ,= ages & ages ! meteoroid has be5 mov+ freely ?r\gh space4 ,! spe$ ) :i* x da%es along greatly exce$s t ( any ( ! motions ) :i* we are famili>4 ,x is ab\t #ajj times z swift z ! pace ( a rifle-bullet4 ,ab\t tw5ty miles w\ld be cov]$ 9 a second4 ,y c h>dly imag9e :at t spe$ is capable (4 ,suppose t y put "o ( ^! fly+ meteoroids beside an express tra9 to race f ,london to ,ed9burgh1 ! meteoroid w\ld h won ! race be=e ! tra9 _h got out ( ! /ation4 ,or suppose t a %oot+ /> det]m9$ to make ! circuit ( ! e>?1 x might1 s f> z pace is conc]n$1 g entirely ar\nd ! globe & back to ! po9t f :i* x />t$ 9 a little m ?an tw5ty m9utes4 ,b ! fact is1 y c\ld n make any object d[n "h move z fa/ z a %oot+ />4 ,no gunp[d] t c\ld be made w\ld be /rong en\gh1 9 ! fir/ place1 & ev5 if ! body c\ld once receive ! spe$1 x w\ld nev] be able to =ce its way ?r\gh ! air un9jur$4 ,s long z a little %oot+ /> is te>+ away ?r\gh op5 space we are n able to see x4 ,! l>ge/ telescope 9 ! _w w\ld n reveal a glimpse ( any?+ s small4 ,! meteoroid has no light ( its own1 & x is n big en\gh to exhibit ! light reflect$ f ! sun 9 ! same mann] z a little planet w\ld d4 ,x is only at ! mom5t :5 x beg9s to be de/roy$ t its visibility comm5ces4 ,if ! little object c succe$ 9 da%+ pa/ our e>? )\t becom+ entangl$ 9 ! atmosph]e1 !n x w pursue its track ) p]haps only a slight alt]ation 9 its pa?1 due to ! pull ex]cis$ by ! e>?4 ,! air :i* surr\nds our globe may be lik5$ to a va/ net1 9 :i* if any little meteor becomes caught its c>e] is ov]4 ,= :5 ! little body1 aft] rejoic+ 9 ! fre$om ( op5 space1 da%es into air1 imm$iately x exp]i5ces a t]rific resi/ance2 x has to =ce ! p>ticles ( air out ( ! way s z to make room = itself1 & 9 do+ s x rubs aga9/ !m ) su* vehem5ce t heat is produc$4 ,i am sure e boy kn[s t if he rubs a button ^u a bo>d x becomes v hot1 9 consequ5ce ( ! friction4 ,!re are _m o!r ways 9 :i* we c illu/rate ! production ( heat 9 ! same mann]4 ,"o is a contrivance by :i* we sp9 r\nd rapidly a piece ( /ick press$ aga9/ a bo>d4 ,quantities ( heat are ?us produc$ by ! friction1 & volumes ( smoke rise up4 ,we h read h[ "s savages are able to produce fire by means ( friction 9 a some:at simil> mann]1 b to d s requires a r>e am\nt ( skill & pati5ce4 ,!re is ano!r illu/ration by :i* to %[ h[ heat c be produc$ by friction4 ,a brass tube full ( wat] is s arrang$ t x c be turn$ ar\nd v rapidly by ! :irl+ table4 ,we apply pressure to ! tube1 & aft] a m9ute or two ! wat] beg9s to get hot1 & !n at la/ to boil1 until ultimately ! cork is driv5 out & a dim9utive &1 =tunately1 h>mless explosion ( ! friction boil] takes place4 ,eng9e]s are aw>e h[ frequ5tly heat is produc$ by friction1 :5 x is v inconv5i5t or dang]\s4 ,inde$1 unless ! :eels ( railway c>riages are kept well greas$1 ! rubb+ ( ! axle may g5]ate s mu* heat t conflagrations 9 ! c>riage w ensue4 ,nature1 9 ! little %oot+ />1 gives u a /rik+ illu/ration ( ! same fact4 ,p]haps y may be surpris$ to he> t ! :ole brilliancy ( ! %oot+ /> is simply due to friction4 ,z ! little body da%es ?r\gh ! air x becomes fir/ r$-hot1 !n :ite-hot1 until at la/ x is melt$ & turn$ into vapor4 ,?us is =m$ t gl[+ /reak :i* we1 /&+ v _m miles bel[1 see z a %oot+ />4 ,a bullet :5 fir$ f a rifle w fly into pieces aft] x has /ruck aga9/ ! t>get1 & if y quickly pick up "o ( ^! pieces y w g5]ally f9d x q hot4 ,:5ce comes ?is heat8 ,! bullet1 ( c\rse1 0 cold be=e ! rifleman pull$ ! trigg]4 ,no d\bt !re 0 a consid]able am\nt ( heat develop$ by ! burn+ ( ! gunp[d]1 b ! bullet 0 s %ort a "t 9 contact ) ! wad1 ?r\gh :i* s little heat w\ld pass1 t we mu/ look to "s o!r s\rce = ! w>m? t has be5 acquir$4 ,friction aga9/ ! b>rel z ! bullet pass$ to ! m\? mu/ h w>m$ ! missile a good deal1 & :5 rubb+ aga9/ ! air ! same influ5ce mu/ h add$ /ill fur!r to its temp]ature1 :ile ! bl[ aga9/ ! t>get w\ld f9ally w>m x yet m4 ,9 comp>+ ! %oot+ /> ) ! rifle-bullet we mu/ rememb] t ! cele/ial object is travell+ ) a pace #ajj times z swift z ! utmo/ velocity t ! rifle c produce1 & ! heat :i* is g5]at$ by friction is increas$ 9 /ill great] proportion4 ,if we d\ble ! spe$1 we %all increase ! quantity ( heat by friction f\rfold2 if we increase ! spe$ ?ree times1 !n friction w be capable ( produc+ n9e times z mu* heat4 ,9 fact1 we mu/ multiply ! numb] express+ ! relative spe$ by itself--t is1 we mu/ =m its squ>e--if we want to f9d an accurate measure = ! quantity ( heat :i* friction is able to produce :5 a rapidly mov+ body is be+ /opp$ by its aid4 ,! %oot+ /> may h a pace #ajj times t ( ! rifle-bullet1 & if we multiply #ajj by #ajj we get #aj1jjj2 consequ5tly we see t ! heat produc$ by ! %oot+ /> be=e its motion 0 arre/$ 9 da%+ ?r\gh ! air w\ld be #aj1jjj times t ga9$ by ! rifle-bullet 9 its flight4 ,if ! temp]ature ( ! rifle-bullet only rose a s+le degree by friction1 x w\ld ?us be possible = ! %oot+ /> to ga9 #aj1jjj degrees1 & ?is w\ld be en\gh to melt & boil away any object :i* ev] exi/$4 ,?us we ne$ n be surpris$ t friction ?r\gh ! air1 & friction alone1 has prov$ an adequate cause = ! production ( all ! heat necess>y to acc\nt = ! mo/ brilliant ( meteors4 ,x is r =tunate = u t ! meteors d da% 9 ) ?is frightful spe$2 _h ! little bodies only mov$ z quickly z a rifle-bullet1 or ev5 only f\r or five times z fa/1 !y w\ld h pelt$ d[n on ! e>? 9 solid =m4 ,inde$1 on r>e occasions x does happ5 t bodies f ! heav5s /rike d[n on ! gr\nd4 ,! great majority ( ^? t fall on ! gr\nd1 h[ev]1 become entirely trans=m$ into h>mless vapor4 ,! e>? w\ld1 inde$1 be almo/ un9habitable f ?is cause alone 7 x n = ! protection t ! air af=ds u4 ,all day & all night innum]able missiles w\ld be :izz+ ab\t u1 & ?\gh _m ( !m are und\bt$ly v small1 yet z _! spe$ is #ajj times t ( a rifle-bullet1 ! fusillade w\ld be v unpleasant4 ,x is1 inde$1 ! int5se hurry ( ^! cele/ial bullets to get at u :i* is ! v s\rce ( our safety4 ,x dissipates ! meteors into /reaks ( h>mless vapor4 ,,:at ,,becomes ,,( ,,! ,,%oot+ ,,/>s4 ,:5 we ?r[ a lump ( coal on ! fire1 all t is soon left is a little p9* ( a%es1 & ! re/ ( ! coal has vani%$4 ,y might ?9k x _h be5 altoge!r annihilat$1 b t is n nature's way4 ,no?+ is ev] completely de/roy$2 x is m]ely trans=m$ or *ang$ into some?+ else4 ,! great] "p ( ! coal has unit$ ) ! oxyg5 :i* x has obta9$ f ! air1 & has =m$ a new gas1 :i* has asc5d$ ! *imney4 ,e p>ticle t 0 9 ! coal c be ?us acc\nt$ =1 & 9 ! act ( trans=mation heat is giv5 out4 ,a meteor also becomes trans=m$1 b ! sub/ance x conta9s is n lo/1 ?\gh x is *ang$ into gl[+ vapors4 ,x is kn[n t ) heat en\gh any sub/ance c be turn$ into vapor1 j z wat] c be boil$ into /eam4 ,look at an electric light fla%+ betwe5 two pieces ( c>bon4 ,?\gh c>bon is "o ( ! mo/ difficult sub/ances to melt1 yet su* is ! int5se heat g5]at$ by ! electric curr5t t ! c>bon is n only melt$1 b is actually turn$ into a vapor1 & x is ?is vapor gl[+ ) heat t gives u ! brilliant light4 ,9 a simil> mann] iron c be r5d]$ r$-hot1 :ite-hot1 & !n boil$ & trans=m$ into an iron vapor1 if we may s call x4 ,!re is1 inde$1 pl5ty ( su* iron vapor 9 ! univ]se4 ,quantities ( x surr\nd ! sun & "s ( ! />s4 ,:5 ord9>y /eam is *ill$ x cond5ses into little drops ( wat]4 ,s1 too1 if iron be heat$ until x is trans=m$ into vapor1 & if t vapor be all[$ to cond5se1 x w ultimately =m a du/1 consi/+ ( bits ( iron s small t y w\ld require a microscope to exam9e !m4 ,!re is iron pres5t 9 ! small %oot+ />s4 ,o!r sub/ances are also conta9$ !re91 & all ^! mat]ials1 aft] be+ boil$ by ! int5se heat1 are trans=m$ into vapor4 ,:5 ! heat subsides1 ! vapor cond5ses aga9 into f9e du/1 s t ! ultimate effect ( ! atmosph]e on a %oot+ /> is to gr9d ! little object into excessively f9e p[d]1 :i* is scatt]$ along ! track :i* ! object has pursu$4 ,sometimes ?is p[d] w cont9ue to gl[ = m9utes aft] ! meteor has vani%$1 & 9 ! case ( "s great meteors ?is /ream ( lum9\s du/ 9 ! air =ms a v /rik+ spectacle4 ,a great meteor1 or fire-ball z x is (t5 call$1 appe>$ on ! #f? ( ,novemb]1 #ahfi4 ,x flew ov] ,devon%ire & ,cornwall1 & left a track fifty miles long & f\r miles wide4 ,! du/ rema9$ visible all along ! great highway = ne>ly an h\r2 x =m$ a gl[+ cl\d hang+ 9 ! sky1 & ?\gh orig9ally ne>ly /raight1 x became b5t & twi/$ by ! w9ds be=e x f9ally disappe>$ f view4 ,we h n[ to see :at becomes ( ?is meteoric du/ :i* is be+ incessantly p\r$ into ! air f ext]nal space4 ,none ( x ev] gets away aga92 = :5ev] an un=tunate meteor j t\*es ! air x is inevitably captur$ & pulv]iz$4 ,t du/ subsides sl[ly1 b we d n f9d x easy to di/+ui% ! p>ticles :i* h come f ! %oot+ />s1 because !re is s mu* float+ du/ :i* has come f o!r s\rces4 ,a sunbeam is ! prettie/ way ( reveal+ ! exi/5ce ( ! motes ) :i* ! air is *>g$4 ,! sunbeam r5d]s ^! motes visible exactly 9 ! same way z planets become visible :5 sunbeams fall on !m 9 f>-di/ant space4 ,b if we h n ! sunbeams "h1 we c ?r[ across ! room a beam ( electric light1 & x is se5 gl[+ all along its track1 simply because ! air ( ! room1 l air ev]y:]e1 is *>g$ ) myriads ( small float+ p>ticles4 ,if y hold ! flame ( a _s-lamp b5ea? ?is beam1 y w see :at seems l columns ( black smoke asc5d+ ?r\gh x4 ,b ^! columns are n smoke1 !y are pure air1 or r air 9 :i* ! solid p>ticles h be5 trans=m$ into vapor by ! heat f ! _s-flame4 ,! motes ab\nd ev]y:]e 9 ! air4 ,we take ?\s&s ( !m into our lungs e "t we brea!4 ,!y are on ! :ole gradually s9k+ & subsid+ d[nw>ds1 b !y yield to e slighte/ curr5t1 s t :5 look+ at a sunbeam y w f9d !m mov+ 9 all directions4 ,x is sometimes h>d to believe t ! little objects are t5d+ d[nw>ds1 b if y look on ! top ( a book t has la9 = a "t on a book-%elf1 y f9d !re a quantity ( du/1 produc$ by ! motes :i* h gradually subsid$ :]e !y f\nd a quiet spot & 7 all[$ suffici5t "t to d s4 ,! great majority ( ^! p>ticles consi/1 no d\bt1 ( fragm5ts ( t]re/rial objects4 ,! du/ f ! roads1 ! smoke f ! factories1 & num]\s o!r s\rces1 are incessantly add+ _! objectionable p>ticles to ! air4 ,!re c be no d\bt t ! %oot+ />s also contribute _! mites to ! du/ ) :i* ! atmosph]e is ev] *>g$4 ,! motes 9 ! murky air ( our t[ns h no d\bt *iefly orig9at$ f s\rces on ?is e>?4 ,_m ( ^! s\rces x w\ld be impossible to reg>d z ( a romantic description4 ,we may1 h[ev]1 feel confid5t t among ^? teem+ myriads ( small float+ objects are _m little p>ticles :i*1 hav+ _h _! orig9 f %oot+ />s1 are n[ gradually s9k+ to ! e>?4 ,?is is n a m]e surmise1 = du/ has be5 collect$ f l(ty ,alp9e sn[s1 f ! dep?s ( ! sea1 & f o!r localities f> remov$ f ! haunts ( m54 ,f su* collections1 t9y p>ticles ( iron h be5 obta9$1 :i* h evid5tly be5 once 9 a molt5 condition4 ,!re is no conceivable explanation = ! orig9 ( iron fragm5ts 9 su* situations1 except t !y h be5 dropp$ f %oot+ />s4 ,i am sure y h (t5 help$ 9 ! mak+ ( a gigantic sn[ball4 ,y beg9 ) a small quantity ( sn[ t c be work$ ) y\r h&s4 ,!n y h roll$ x along ! gr\nd until x has become s big & s heavy t y mu/ get a few playmates to help y1 until at la/ x has gr[n s unwieldy t y c move x no long]1 & !n y apply y\r arti/ic p[]s to c>v+ out a /atue4 ,! sn[ball has gr[n by ! addition ( mat]ial to x f )\t1 & z x became heavi] & heavi]1 x lapp$ up m & m ( ! sn[ z x roll$ along2 s t ) ea* increase ( size1 its capacity = becom+ /ill l>g] has also increas$4 ,i want to lik5 our e>? to a sn[ball :i* goes roll+ on ?r\gh space1 & e day1 e h\r1 e m9ute1 is ga!r+ up & tak+ into x ! little %oot+ />s t x meets ) on its way4 ,no d\bt ! annual accumulation is a v small quantity :5 comp>$ ) ! :ole size ( ! e>?2 b ! e>? is always draw+ 91 & n[1 at all ev5ts1 nev] giv+ back aga92 s t :5 ?is process is c>ri$ on long en\gh1 a/oni%+ results may be obta9$4 ,y h all he>d _m maxims on ?is subject--h[ e little sav+ w at l5g? rea* a respectable or a gigantic total4 ,nature ab\nds ) illu/rations ( ! pr9ciple4 ,all ! wat] t ?und]s ov] ,niag>a is m]ely a suffici5t numb] ( little drops ( ra9 collect$ toge!r4 ,our e>? has be5 gradually ho>d+ up1 dur+ c\ntless ages1 all ! meteor du/ t has ra9$ ^u x2 & ! l>g] ! e>? gr[s1 ! bigg] is ! net :i* x spreads1 & ! great] is ! p[] x has to capture ! w&]+ bodies4 ,?us1 our e>?1 ages & ages ago1 may h be5 consid]ably small] ?an x is at pres5t2 9 fact1 a l>ge proportion ( ?is globe on :i* we dwell may h be5 d]iv$ f ! little %oot+ />s :i* incessantly ra9 9 ^u its surface4 ,,gr& ,,meteors4 ,i d>e say t _m ( ^? pres5t w1 9 ! c\rse ( _! lives1 h opportunities ( see+ "s ( ! great meteors1 or fire-balls1 :i* are occasionally display$4 ,g5]ally speak+1 ab\t "o hundr$ or s ( ^! spl5did objects are record$ e ye>4 ,we are nev] appris$ t !y are com+2 !y take u unaw>es1 & !re=e we h no opportunity to make prop] arrangem5ts = see+ !m4 ,!re is only ! *ance t su* p]sons z h be5 =tunate en\gh to see !m w h not$ ! circum/ances ) suffici5t accuracy to enable u to make use ( _! obs]vations4 ,illu/ration3 ,,fig4 #gh4--;,h[ to f9d ! ,height ( a ,meteor4 ,! *ief po9t to det]m9e is ! height ( ! meteor above ! e>?4 ,= ?is we mu/ h two obs]vations at lea/1 made 9 places z f> asund] z possible4 ,suppose an obs]v] at ,london & an obs]v] at ,york 7 bo? witnesses ( a spl5did meteor2 if !y f9d1 on subsequ5t comp>ison1 t _! obs]vations 7 made at ! same mom5t1 !re is no reasonable d\bt t x 0 ! same object !y bo? saw4 ,! obs]v] at ,york describes ! meteor z ly+ to ! s\?1 halfway d[n f ! po9t directly ov] 8 head t[>ds ! horizon4 ,! ,london obs]v] speaks ( ! meteor z be+ to ! nor?2 & to him also x appe>$ t ! object 0 halfway d[n t[>ds 8 horizon f ! po9t directly ov] 8 head4 ,if y "k a little ,euclid1 y c easily %[ f ^! facts t ! height ( ! meteor mu/ h be5 half ! di/ance betwe5 ,london & ,york1 t is1 #he miles 7,fig4 #gh74 ,i d n mean to say t ! mode ( discov]+ ! meteor's height w be always q su* a simple process z x has be5 9 ! case ( ! ,london & ,york obs]vations4 ,! pr9ciple is1 h[ev]1 ! same--t :5ev] f two suffici5tly di/ant positions ! direction ( ! meteor has be5 obs]v$1 its pa? is kn[n--j z on p4 #ba we %[$ h[ ! height ( ! susp5d$ ball 0 obta9$ f obs]vations at ea* end ( ! table4 ,g5]ally speak+1 bright meteors beg9 at an elevation ( betwe5 fifty & "o hundr$ miles1 & !y become ext+ui%$ be=e !y are )9 tw5ty miles ( ! gr\nd4 ,sometimes a trem5d\s explosion w take place dur+ ! passage ( a meteor ?r\gh ! air4 ,!re 0 a celebrat$ in/ance 9 ,am]ica on ! #ba/ ( ,decemb]1 #ahgf1 :i* w give an idea ( "o ( ^! objects possess+ exceptional magnific5ce4 ,x began 9 ,kansas ab\t sev5ty-five miles high1 & !nce x flew = a ?\s& miles at a spe$ ( t5 or fifte5 miles a second1 until x disappe>$ some:]e ne> ,lake ,ont>io4 ,ov] a c]ta9 region betwe5 ,*icago & ,/4 ,l\is1 ! great ball ( fire bur/ into a numb] ( pieces1 & =m$ a clu/] ( gl[+ />s t seem$ to *ase ea* o!r ov] ! sky4 ,?is clu/] mu/ h be5 ab\t =ty miles long & five miles wide1 & :5 ! explosion occurr$ a mo/ t]rific noise 0 produc$1 s l\d t _m ?\ght x 0 an e>?quake4 ,a rem>kable circum/ance illu/rates ! trem5d\s height at :i* ?is explosion occurr$4 ,! meteor _h bur/ into pieces1 ! display 0 all ov]1 & 0 beg9n+ to be =gott51 & yet no?+ _h be5 he>d4 ,x 0 n until a qu>t] ( an h\r aft] ! explosion _h be5 se5 t a fe>ful cra% 0 he>d at ,bloom+ton4 ,! explosion actually occurr$ #ahj miles f ! spot1 & z s\nd takes five seconds to travel a mile1 y c easily calculate t ! noise requir$ a qu>t] ( an h\r = its j\rney4 ,:at a trem5d\s noise x mu/ h be56 ,%oot+ />s are ( e grade ( brightness4 ,beg9n+ ) ! m gorge\s objects :i* h be5 comp>$ ) ! moon or ev5 ) ! sun himself1 we desc5d to o!rs z bright z ,v5us or z ,jupit]2 o!rs are z bright z />s ( v>i\s degrees ( brilliancy4 ,fa9t] %oot+ />s are mu* m num]\s ?an ! conspicu\s ones2 9 fact1 !re are multitudes ( ^! objects s extremely feeble t ! unaid$ eye w\ld n %[ !m4 ,!y only become p]ceptible 9 a telescope4 ,x is n uncommon :ile wat*+ ! heav5s at night to notice a fa9t /reak ( light da%+ across ! field ( ! in/rum5t4 ,?is is a %oot+ /> :i* is invisible except ?r\gh ! telescope4 ,,! ,,great ,,novemb] ,,%[]s4 ,illu/ration3 ,,fig4 #gi4--;,a ,great ,%[] ( ,%oot+ ,/>s4 ,occasionally we h ! sup]b spectacle ( a %[] ( %oot+ />s4 ,none ( y1 my "y fri5ds1 c z yet h _h ! good =tune to witness "o ( ! specially gr& displays1 b y may live 9 hope2 !re are /ill %[]s to come4 ,a/ronom]s h v5tur$ on ! prophecy t 9 or ab\t ! ye> #ahii y w h ! opportunity ( see+ a magnific5t exhibition ( ?is k9d4 ,!re is only "o gr\nd = anxiety1 & t is z to :e!r ! cl\ds w keep out ( ! way = ! occasion4 ,i ?9k ,i _c expla9 my subject bett] ?an by tak+ y into my confid5ce & %[+ y ! reasons on :i* we base ?is pr$iction4 ,! la/ great %oot+-/> %[] took place 9 ! ye> #ahff1 or1 p]haps1 ,i %\ld r say t ?is 0 ! la/ display f ! same %oot+-/> sy/em z t ab\t :i* we are n[ go+ to speak4 ,on ! night ( ! #ac? ( ,novemb]1 #ahff1 a/ronom]s 7 ev]y:]e delight$ by a sup]b spectacle4 ,enjoym5t ( ! wondr\s sight 0 n only = a/ronom]s4 ,e "o :o loves to see ! great sights ( nature w h good reason = rememb]+ t night4 ,i c]ta9ly %all nev] =get x4 ,x 0 ab\t t5 o'clock :5 a brilliant meteor or two fir/ fla%$ across ! sky1 !n pres5tly !y came 9 twos & ?rees1 & lat] on 9 doz5s1 9 scores1 9 hundr$s4 ,^! meteors 7 brilliant objects1 any "o ( :i* w\ld h extort$ admiration on an ord9>y night4 ,:at1 !n1 0 ! spl5dor ( ! display :5 !y came on 9 multitudes8 ,= two or ?ree h\rs ! great %[] la/$1 & !n gradually subsid$4 ,we 7 n tak5 unaw>es on ?is occasion1 = ! %[] 0 expect$1 & _h be51 9 fact1 await$ ) eag] anticipation4 ,x %\ld fir/ be notic$ t ea* ye> "s %oot+ />s may always be look$ = on or ab\t ! #ac? ( ,novemb]4 ,e ?irty-?ree ye>s1 or !reab\ts1 ! ord9>y spectacle breaks out into a magnific5t display4 ,x has also be5 f\nd t = ne>ly #ajjj ye>s !re h be5 occasional gr& %[]s ( meteors at ! "t ( ye> m5tion$1 & all ^! incid5ts agree ) ! supposition t !y are m]ely repetitions ( ! regul> ?irty-?ree-ye> %[]4 ,! fir/ 0 9 ! ye> ,a4,d4 #ijb1 :i* an old *ronicle speaks ( z ! 8ye> ( ! />s10 f ! extraord9>y display :i* !n took place4 ,i d n ?9k ! good p #ajjj ye>s ago fully appreciat$ ! a/ronomical int]e/ ( su* spectacles2 9 fact1 !y 7 (t5 fright5$ out ( _! wits1 & ?\ght ! end ( ! _w _h come4 ,d\btless _m anci5t %[]s h tak5 place ( :i* we h no record :atev]4 ,9 m mod]n days we h _h some:at full] in=mation2 = example1 on ! night betwe5 ! #ab? & #ac? ( ,novemb]1 #ahcc1 a %[] 0 magnific5tly se5 9 ,am]ica4 ,mr4 ,kirkwood tells u t a g5tleman ( ,s\? ,c>ol9a describ$ ! effect on ! negroes ( 8 plantation z foll[s3 8,i 0 sudd5ly awak5$ by ! mo/ di/ress+ cries t ev] fell on my e>s4 ,%rieks ( horror & cries = m]cy ,i c\ld he> f mo/ ( ! negroes ( ! ?ree plantations1 am\nt+ 9 all to ab\t #fjj or #hjj4 ,:ile e>ne/ly li/5+ = ! cause1 ,i he>d a fa9t voice ne> ! door call+ my "n4 ,i arose1 & tak+ my sword1 /ood at ! door4 ,at ?is mom5t ,i he>d ! same voice /ill besee*+ me to arise1 & cry+ out t ! _w 0 on fire4 ,i !n op5$ ! door1 & x is difficult to say :i* excit$ me ! mo/--! awfulness ( ! sc5e or ! di/ress$ cries ( ! negroes4 ,upw>ds ( a hundr$ lay pro/rate on ! gr\nd1 "s spee*less1 & "s ) ! bitt]e/ cries1 b ) _! h&s rais$ pray+ = m]cy4 ,! sc5e 0 truly awful1 = nev] did ra9 fall mu* ?ick] ?an ! meteors fell t[>ds ! e>?40 ,by ! /udy ( _m records ( great %[]s x 0 le>n$ t ! int]val at :i* ^! gr& displays succe$$ "o ano!r 0 ab\t ?irty-?ree ye>s2 & :5 x 0 rememb]$ t ! la/ great %[] 0 9 #ahcc x 0 confid5tly expect$ t ano!r simil> display w\ld take place 9 #ahff4 ,?is 0 fully confirm$4 ,yet ano!r ?irty-?ree ye>s br+s u to #ahii1 :5 we h good reason = look+ =w>d to a gr& %[] ( ^! bodies4 ,x may be expect$ to occur on ,novemb] #ad or ,novemb] #ae4 ,x may1 h[ev]1 possibly be t a %[] w occur on ! same days ( ! succe$+ ye>4 ,illu/ration3 ,,fig4 #hj4--,! ,e>? cross+ ! ,track ( ,meteors4 ,we "k a good deal n[ z reg>ds ! movem5ts ( ^! little objects4 ,i want y to ?9k ( a va/ sw>m1 some?+ l a flock ( birds1 :i* ,i d>e say y h (t5 se5 fly+ high 9 ! air2 ! diff]5ce1 h[ev]1 is t ! flock ( meteors is enorm\sly great] ?an any flock ( birds ev] 02 & ! meteors1 too1 are scatt]$ s widely ap>t1 t ea* "o may be miles away f its next neighbors4 ,usually ! meteoric %oal is _m millions ( miles long1 & p]haps a hundr$ ?\s& miles 9 wid?4 ,! great flock ( meteors travels ?r\gh space 9 a c]ta9 def9ite track4 ,we h le>n$ h[ ! sun guides a planet1 & =ces ! planet to move ar\nd him 9 an ellipse4 ,b our sun w also condesc5d to guide an object no bigg] ?an a %oot+ />4 ,a bullet1 a pea1 or ev5 a gra9 ( s& w be held to an elliptic c\rse ar\nd ! sun z c>efully z ! great ,jupit] himself4 ,! entire %oal ( meteors may !re=e pursue _! common j\rney ar\nd ! sun z if inspir$ by a common purpose1 ea* individual memb] ( ! ho/ be+1 h[ev]1 guid$ by ! sun1 & p]=m+ its pa? 9 real indep5d5ce ( its neighbors4 ,! orbit foll[$ by ?is %oal ( meteors is enorm\sly l>ge & wide4 ,"h is a sket* ( ! pa? 7,fig4 #hj71 & ,i h laid d[n ! position ( ! orbit ( ! e>?1 b n on ! same scale4 ,! ellipse is elongat$1 s t :ile ! %oal approa*es comp>atively close to ! sun at "o end ( its j\rney1 at ! o!r end x goes out to an enorm\s di/ance1 f> beyond ! orbit ( ! e>?--beyond1 inde$1 ! orbit ( ,jupit] or ,saturn2 9 fact1 x rea*es to ! pa? ( ,uranus4 ,to accompli% s va/ a j\rney z ?is ?irty-?ree ye>s & a qu>t] are requir$1 & n[ y w be easily able to see :y we get p]iodical visits f ! %oal4 ,x is1 h[ev]1 a m]e piece ( good =tune t we ev] enc\nt] ! ,novemb] meteors4 ,probably !re are num]\s o!r %oals ( meteors q z important :i* we nev] see1 j 9 ! same way z !re are _m %oals ( fi% 9 ! sea t nev] come into our net4 ,! e>? moves r\nd ! sun 9 a pa? :i* is v ne>ly a circle1 & ! %oal moves r\nd 9 ?is long oval4 ,we _c easily repres5t ! true /ate ( ?+s by m]e diagrams :i* %[ all ^! objects on ! same plane4 ,?is does n give an accurate repres5tation ( ! orbits4 ,i ?9k y w bett] und]/& :at ,i mean by means ( "s wire r+s4 ,make a r\nd "o to repres5t ! pa? ( ! e>?1 & a long oval "o to repres5t ! pa? ( ! meteors4 ,!re is to be a small op5+ 9 ! circul> r+ s t we c slip "o ( ! orbits inside ! o!r4 ,if we are to see ! meteors1 x is ( c\rse necess>y t !y %\ld /rike ! e>?'s atmosph]e1 = !y are n visible to u :5 !y lie at a di/ance l ! moon or l ! planets4 ,x is necess>y t !re be a collision betwe5 ! e>? & ! %oal ( meteors4 ,b !re nev] c\ld be a collision betwe5 two tra9s unless ! l9es on :i* ^! tra9s run meet ea* o!r2 !re=e1 x is necess>y t ?is long ellipse %all actually cross ! e>?'s track2 x w n d to h x pass inside l ! two l9ks ( a *a92 our e>? w\ld !n miss ! meteors altoge!r1 & we %\ld nev] see !m4 ,!re are v likely _m ( su* %oals ( meteors revolv+ 9 ?is way1 & ?us escap+ our notice entirely4 ,y w also und]/& :y !re is no use 9 look+ = ^! %[]s except on a p>ticul> day ( ,novemb]4 ,on t day1 & on t day alone1 ! e>? appe>s at t p>ticul> po9t ( its r\te :]e ! latt] crosses ! track ( ! %oal4 ,on ! #a/ ( ,novemb]1 = in/ance1 ! e>? has n yet rea*$ ! po9t :]e x c\ld meet ) ^! bodies4 ,by ! end ( ,novemb] x has pass$ too f>4 ,b ev5 suppos+ t ! e>? is cross+ ! track ( ! meteors on ! #ac? ( ,novemb]1 x is /ill possible t only a few1 or none at all1 %all be se54 ,! %oal may n happ5 to be at t spot at ! "r "t4 ,= a display ( meteors to occur1 x is !re=e necess>y t ! %oal %all happ5 to be pass+ ?is p>ticul> /age ( ! j\rney on ! #ac? ( ,novemb]4 ,9 #ahff ! e>? dipp$ ?r\gh ! %oal & caught a great _m ( ^! meteors 9 its net4 ,= a few h\rs ! e>? 0 engag$ 9 ! capture1 until x em]g$ on ! o!r side ( ! %oal1 & ! display 0 at an end4 ,sometimes x happ5s t 9 two ye>s foll[+ ea* o!r1 gr& %[]s ( meteors are se54 ,! reason ( ?is is t ! %oal is v long & ?91 & consequ5tly if ! e>? passes ?r\gh ! beg9n+ ( ! %oal "o ye>1 x may h return$ to ! same po9t next ye> be=e ! :ole l5g? ( ! %oal has completely pass$4 ,9 ?is case we %all h two great %[]s 9 consecutive ye>s4 ,?us a v f9e display 0 se5 9 ,am]ica on ! prop] day 9 #ahfg1 :ile _m /raggl]s 7 also obs]v$ dur+ ! ?ree subsequ5t recurr5ces ( ! same date4 ,:5ev] ! #ac? ( ,novemb] comes r\nd we g5]ally meet ) at lea/ five %oot+ />s belong+ to ?is same sy/em1 & we mu/ expla9 h[ ?is occurs4 ,suppose !re is a small racec\rse s t ! competitors w h to run a great _m times r\nd be=e ! race is ov]4 ,let !re be a v l>ge numb] ( entries1 & let ! majority ( ! a?letes be fairly good runn]s1 :ile a few are exceptionally good ) v>y+ degrees ( excell5ce1 & a few are v bad1 "s be+ worse ?an o!rs4 ,! :ole gr\p />ts toge!r 9 a clu/] at ! signal1 & p]haps = ! fir/ r\nd or two !y may keep tol]ably well toge!r4 ,x w be notic$ ! clu/] beg9s to elongate z "o circuit aft] ano!r is made2 ! bett] runn]s draw out to ! front1 & ! sl[] runn]s lag fur!r & fur!r beh9d2 at la/ x may happ5 t ^? at ! head w h ga9$ a :ole r\nd on ^? at ! tail1 :ile ! o!r runn]s ( v>y+ degrees ( spe$ w be scatt]$ all r\nd ! c\rse4 ,! majority ( ! runn]s1 if ( ne>ly equal spe$1 may cont9ue 9 a pretty d5se gr\p4 ,precisely simil> has be5 ! great cele/ial race :i* ^! meteors are runn+4 ,!y />t$ on _! gr& c>e] c5turies ago1 & ev] s9ce !n !y h be5 fly+ r\nd & r\nd _! mighty c\rse4 ,! great] proportion ( ! meteors /ill /ay close toge!r1 & _! pace is ne>ly uni=m4 ,! exceptionally sm>t ones h %ot ahead1 ! exceptionally sl[ ones h lagg$ beh9d1 & ?us x happ5s t1 aft] fifty or m revolutions h be5 complet$1 ! %ape ( ! orig9al sw>m has become consid]ably modifi$4 ,its l5g? has be5 drawn out1 :ile ! /raggl]s & ! fa/e/ runn]s h be5 scatt]$ all ar\nd ! pa?4 ,across ?is c\rse our e>? c>ries u e ,novemb]2 !re we usually enc\nt] "s ( ! memb]s ( ?is sw>m :i* h /ray$ f ! great ho/2 !y fla% into ! air1 & ?us x is t "s ( ^! bodies are g5]ally se5 e ,novemb]4 ,illu/ration3 ,,fig4 #ha4--,! ,radiant4 ,dur+ a %oot+-/> %[] x is int]e/+ to notice t all ! meteors seem to div]ge f a s+le po9t4 ,9 ! adjo9+ figure 7,fig4 #ha71 :i* %[s ! directions ( a numb] ( meteors' tracks1 y w notice t e "o seems to radiate f a c]ta9 po9t ( ! sky4 ,9 ! case ( ! %[] ( ! #ac?-#ae? ( ,novemb] ?is po9t lies 9 ! con/ellation ,leo4 ,i mu/ ref] y to ! ,app5dix = a description ( ! way to f9d ,leo or ! ,lion4 ,! radiant po9t1 z we t]m x1 ( ?is sy/em ( meteors is !re situat$4 ,x is true t ! meteors !mselves d n g5]ally seem to come all ! way f ?is place4 ,x is ! direction ( _! lum9\s trails produc$ backw>d t c>ries ! eye to ! radiant 7,fig4 #ha74 ,if a meteor 7 actually se5 !re1 x w\ld be c]ta9ly com+ /raight t[>ds u2 x w\ld n !n appe> z a /reak ( light at all2 x w\ld m]ely seem l a /> :i* sudd5ly blaz$ into spl5dor & !n aga9 sank d[n into invisibility4 ,e meteor :i* appe>$ ne> ?is po9t w\ld be direct$ v ne>ly at ! obs]v]1 & its pa? w\ld !re=e seem v mu* =e%ort5$4 ,i c illu/rate ?is ) a long /raight rod4 ,if ,i po9t x directly at y1 y c only see ! end4 ,if ,i po9t x ne>ly at y1 x w seem v mu* %ort5$4 ,dur+ ! great %[] 9 #ahff _m ( ! meteors c\ld be obs]v$ s close to ! radiant 9 ,leo t !y seem$ m]ely l v %ort m>ks 9 ! sky2 "s ( !m1 inde$1 seem$ to be m]ely />like po9ts swell+ up into brilliance & !n go+ out4 ,h5ce x is t we call ?is sy/em ( %oot+ />s ! 8,leonids40 ,!y be> ?is "n because _! radiant lies 9 ! con/ellation ,leo1 & unless ! direction ( a %oot+ /> emanates f ?is po9t x does n belong to ! ,leonids4 ,ev5 if x did s1 ! meteor w\ld n be a ,leonid unless ! date 0 "r1 namely1 on ! #ac? ( ,novemb]1 or )9 a day !re(4 ,we ?us h two *>act]i/ics :i* belong to a sy/em ( %oot+ />s2 !re is ! date on :i* !y occur & ! po9t f :i* !y radiate4 ,,o!r ,,great ,,%[]s4 ,to illu/rate :at ,i h said1 we w speak ab\t ano!r sy/em ( %oot+ />s2 !y are due e ,augu/1 f ! #i? to ! #aa?1 & _! directions div]ge f a po9t 9 ! con/ellation ( ,p]seus4 ,i may rem9d y ( ! dates ( ! recurr5ce ( ?is %[] z well z ( ! ,novemb] meteors ( :i* we h j spok51 by quot+ ! foll[+ production3-- ,if y ,novemb]'s />s w\ld see1 ,ab\t ! f\rte5? wat*+ be4 ,9 ,augu/1 too1 />s %9e ?r\gh heav51 ,on nights betwe5 n9e & elev54 ,x may be wor? y\r :ile to rememb] ^! l9es1 & always to keep a look-out on ! days nam$4 ,! ,augu/ meteors1 ! ,p]seids we (t5 call !m1 d n make gorge\s displays1 9 p>ticul> ye>s1 ) ! regul>ity ( ! ,leonids4 ,!re h be51 no d\bt1 "s exceptionally gr& %[]s betwe5 ! #i? & ! #aa? ( ,augu/1 b we _c pr$ict :5 ! next spl5did "o is due4 ,!re are va/ numb]s ( /raggl]s all r\nd ! track ( ! ,p]seids4 ,9 fact1 x w\ld seem z if ! great race _h gone on = su* a long p]iod t ! clu/] _h to a great ext5t brok5 up1 & t a l>ge proportion ( ! meteors 7 n[ scatt]$ ! :ole way ar\nd ! c\rse ) tol]able uni=mity4 ,?is be+ s1 x foll[s t e "t we cross ! track we are ne>ly c]ta9 to fall 9 ) a few ( ! /raggl]s1 ?\gh we may nev] enjoy ! trem5d\s spectacle ( a plunge ?r\gh a d5se ho/ ( meteoroids4 ,!re are _m o!r %[]s besides ! two ,i h m5tion$4 ,"s %oot+ />s are to be se5 almo/ e f9e night1 & ^? a/ronom]s :o pay p>ticul> att5tion to ?is subject are able to make out scores ( small %[]s :i* might n int]e/ y4 ,ea* ( ^! is fully def9$ by ! night ( ! ye> on :i* x occurs & ! position ( ! po9t 9 ! heav5s f :i* ! meteors radiate4 ,( ^! ,i mu/ m5tion "o4 ,x is n usually v attractive1 b x has a p>ticul> int]e/1 z ,i %all n[ expla94 ,on ! #bg? ( ,novemb]1 #ahgb1 a beautiful meteoric %[] took place4 ,y w notice t ?\gh ! mon? is ! same1 ! day is entirely diff]5t f t on :i* ! ,leonids appe>4 ,?is %[] ( ! #bg? is call$ ! ,&rom$es1 because ! l9es ( direction ( ! %oot+ />s ( :i* x is compos$ seem to div]ge f a po9t 9 ! con/ellation ,&rom$a4 ,ord9>ily speak+1 !re is no special display ( meteors connect$ ) ! annual return ( ?is day2 b 9 #ahgb a/ronom]s 7 a/oni%$ by an exhibition ( %oot+ />s belong+ to ?is sy/em4 ,!y 7 n at all bright :5 comp>$ ) ! ,leonid meteors4 ,!y 71 h[ev]1 suffici5tly num]\s to arre/ ! att5tion ( v _m1 ev5 among ^? :o d n usually pay mu* att5tion to ! heav5s4 ,! *ief int]e/ ( ! %[] ( ,&rom$es c5t]s 9 a rem>kable discov]y connect+ meteors & comets4 ,!re is a comet :i* 0 discov]$ by ! a/ronom] ,biela4 ,x is a small object1 requir+ a telescope to %[ x4 ,?is comet completes ea* revolution 9 a p]iod ( ab\t sev5 ye>s2 or r1 ,i %\ld say1 t 0 ! "t :i* ! comet us$ to sp5d on its j\rney1 = a life ( tr\ble & disa/] seems ( late to h ne>ly ext+ui%$ ! un=tunate object4 ,9 #ahgb ! comet 0 due 9 our neighborhood1 & on ! night ( ! #bg? ( ,novemb]1 9 ! same ye>1 ! e>? cross$ ! track1 &1 9 do+ s1 ! %[] ( %oot+ />s 0 se54 ,?is 0 a rem>kable co9cid5ce4 ,we cross$ ! pa? ( ! comet at ! "t :5 we knew ! comet ought to be !re2 & ?\gh we did n !n see ! comet1 we saw a %[] ( %oot+ />s1 & a wond]ful %[] too4 ,a circum/ance s peculi> sugge/$ at once t ! comet & ! %oot+ />s mu/ 9 "s way or o!r be connect$ toge!r4 ,?is is a sugge/ion we c te/ 9 ano!r mann]4 ,we "k ! hi/ory ( ! comet1 & we are aw>e t at ! v "t ( ! %[]1 ! comet 0 approa*+ f ! direction ( ! con/ellation ( ,&rom$a4 ,x 0 com+1 9 fact1 f ! v qu>t] :5ce ! %oot+ />s h !mselves travell$4 ,tak+ all ^! ?+s toge!r1 x seems impossible to d\bt t ! %oal ( %oot+ />s 01 if n actually ! comet itself1 some?+ closely connect$ ) t fam\s body4 ,,meteorites4 ,"s ye>s ago1 a f>m] liv+ ne> ,r[ton1 9 ,%rop%ire1 notic$ on a pa? 9 a field a hole :i* _h be5 sudd5ly made by "s my/]i\s & unkn[n ag5t4 ,! labor]s :o 7 ne> told him !y _h j he>d a rem>kable noise2 & :5 ! f>m] put 8 h& d[n into ! hole1 he felt some?+ hot at ! bottom ( x4 ,he took a spade & dug up ! /range body1 & f\nd x to be a piece ( iron1 weigh+ ab\t sev5 p\nds4 ,he 0 naturally amaz$ at su* an occurr5ce1 & br\ght ! body home ) him4 ,:]e did t piece ( iron come f8 ,x is pla9 t x c\ld n h be5 always 9 ! gr\nd4 ,! noise & ! rec5tly made hole %[$ t 0 n ! case1 & t is confirm$ by ! fact t ! iron 0 hot4 ,a piece ( iron )9 a few feet ( ! e>?'s surface _c h rema9$ w>m = any l5g? ( "t4 ,x is !re=e cle> t ! iron mu/ h tumbl$ f ! sky4 ,?is is a m>vell\s notion2 9 fact1 x seems s incr$ible t at fir/ p refus$ to believe t su* ?+s z /ones or solid lumps ( iron c\ld h fall5 f ! heav5s to ! e>?4 ,b !y _h to believe x2 ! evid5ce 0 too conclusive4 ,=tunately1 h[ev]1 ! occurr5ce is a comp>atively r>e "o2 inde$1 our life on ?is globe w\ld h an intol]able anxiety add$ to x if %[]s ( iron hail/ones l t at ,r[ton 7 at all ( frequ5t occurr5ce4 ,we %\ld want umbrellas ( a m sub/antial description ?an ^? :i* suffice = ! ra9s we actually exp]i5ce4 ,!re are1 inde$1 in/ances on record ( p]sons hav+ be5 kill$ by ! fe>ful bl[s giv5 by ^! bodies 9 fall+4 ,! ,r[ton sid]ite is a comp>atively small "o2 pieces weigh+ hundr$weights1 & ev5 tons1 h be5 collect$ toge!r 9 our museums4 ,i w\ld recomm5d y to pay a visit to t int]e/+ room 9 our great ,briti% ,museum 9 :i* ^! meteorites are exhibit$4 ,!re we see actual specim5s ( cele/ial bodies :i* we c feel or weigh1 & :i* our *emi/s c analyze4 ,x may be notic$ t !y only conta9 sub/ances t we already "k on ?is e>?4 ,?is cele/ial iron has (t5 be5 made use ( 9 primitive times be=e man und]/ood h[ to smelt iron f its ore & h[ to trans=m x f ca/ iron to wr\ght iron4 ,nature seems to h tak5 he$ ( _! wants1 & occasionally to h ?r[n d[n a lump or two = ! b5efit ( ^? :o 7 s =tunate z to secure !m4 ,t ^! /ones or irons drop f ! sky is absolutely c]ta91 b :5 we try to f9d out _! e>li] hi/ory we become involv$ 9 n a few difficulties4 ,nobody really kn[s ! true hi/ory ( ^! objects1 b ! view ( _! orig9 :i* seems to me to possess few] difficulties ?an any o!r view is t :i* we may call ! ,columbiad ,!ory4 ,i use ?is expression because e boy or girl li/5+ to me ought to h read ,jules ,v]ne's wond]ful book1 8,f ! ,e>? to ! ,moon10 & if any ( y h n read x1 ! soon] y d s ! bett]4 ,x is !re n>rat$ h[ ! gun club ( ,baltimore design$ a magnific5t cannon :i* 0 sunk deep into ! gr\nd1 & !n receiv$ a t]rific *>ge ( guncotton1 on :i* a great holl[ projectile 0 c>efully l[]$1 conta9+ inside ! ?ree adv5tur\s explor]s :o desir$ to visit ! moon4 ,calculations 7 produc$ ) a view ( %[+ t by fir+ on a p>ticul> day ! explosion w\ld drive ! projectile up to ! moon4 ,!re 01 h[ev]1 ! necess>y condition t ! spe$ ( projection %\ld be great en\gh4 ,! gun club 7 accurate 9 say+ t if ! cannon 7 able to dis*>ge ! projectile ) a spe$ tw5ty or ?irty times z great z t :i* _h ev] be5 obta9$ ) any o!r cannon1 !n ! missile w\ld asc5d up & up =ev] if no fur!r influ5ce 7 ex]t$ on x4 ,no d\bt we h to ov]look ! resi/ance on ! air & a few o!r little difficulties1 b to ?is ext5t1 at all ev5ts1 ! gun club 7 "r3 t a velocity ( ab\t six or sev5 miles a second w\ld suffice to c>ry a body away f ! gravitation ( ! e>?4 ,no "o supposes t !re 7 ev] ,columbiad cannons on our globe by :i* projectiles 7 %ot up into space2 b x seems possible t !re may h be5 9 v anci5t days volcanoes on ! e>? ) a %oot+ p[] z great z t :i* ,presid5t ,b>bicane design$ = ! big cannon4 ,ev5 n[ we h "s active volcanoes ( great en]gy on our e>?1 & we "k t 9 =m] days ! volcanoes mu/ h be5 /ill m p[]ful2 t1 9 fact1 ! ,vesuvius ( ! pres5t mu/ be m]ely a popgun 9 comp>ison ) volcanoes :i* h %ak5 ! e>? 9 ^? primitive days :5 x _h j cool$ d[n f its orig9al fi]y condition4 ,"s ( ^! e>ly volcanoes1 9 ! ?roes ( _! mighty eruptions1 appe> to h %ot =? pieces ( iron & volcanic sub/ances ) a viol5ce great en\gh to c>ry !m (f into space4 ,suppose t a missile 7 project$ upw>ds1 x w\ld asc5d high] & high]1 & gravity w\ld1 ( c\rse1 t5d to drag x back aga9 d[n to e>?4 ,x c be %[n t ) an initial spe$ ( six or sev5 miles a second ! missiles w\ld nev] return to ! e>? if only influ5c$ by its attraction4 ,! subsequ5t hi/ory ( su* a projectile w\ld be guid$ by ! laws accord+ to :i* a planet moves4 ,! body is und]/ood to escape ! de/9ation :i* 0 aim$ at by ! ,columbiad4 ,i mean1 ( c\rse1 t x is n suppos$ to hit ! moon4 ,( c\rse1 ?is might conceivably happ52 b mo/ ( ! projectiles w\ld g q wide ( ! m>k1 & w\ld travel (f into space4 ,?\gh ! e>? w\ld be unable to recall ! projectile1 ! attraction ( ! sun w\ld /ill guide x1 :e!r x 0 z big z a pav+-/one or ev] s mu* l>g] or small]4 ,! body w\ld be con/ra9$ to foll[ a pa? l a little planet ar\nd ! sun4 ,?is track x w\ld /eadily pursue = ages4 ,! w&]] w\ld1 h[ev]1 cross ! e>?'s track once dur+ ea* ( its revolutions at ! po9t f :i* x 0 project$4 ,( c\rse1 x w g5]ally happ5 t ! e>? w n be !re at ! "t ! meteorite is cross+1 & ! meteorite w n be !re at ! "t ! e>? is cross+4 ,no?+ w !re=e happ51 & ! object goes aga9 on its long r\nds4 ,b sometimes x mu/ occur t a meteor does n get pa/ ! junction )\t com+ s close to ! e>? t x plunges into ! air1 (t5 produc+ a noise & g5]at+ a /reak ( light l a %oot+ />4 ,!n x tumbles d[n1 & is re/or$ to t e>? :5ce x orig9ally came4 ,if ?is be ! true view--& ,i ?9k !re are less weighty objections to x ?an to any o!r ,i "k (--!n ! hi/ory ( ! piece ( iron t 0 f\nd 9 ,%rop%ire w\ld be some:at z foll[s4 ,_m millions ( ye>s ago1 :5 ! fires ( our e>? 7 mu* m vigor\s ?an !y are 9 ^! dull times1 a t]rific volcanic outbreak took place1 & va/ quantities ( mat]ial 7 %ot into space1 ( :i* ?is is "o ( ! fragm5ts4 ,dur+ all ! ages t h s9ce elaps$ ?is piece ( iron has foll[$ its lonely track4 ,9 a ?\s&? "p ( ! "t ru/ & decay w\ld h de/roy$ x _h x la9 on ! e>?1 b 9 ! solitudes ( space !re 0 f\nd no air or damp to produce corrosion4 ,at la/1 aft] ! completion ( its long travels1 x aga9 cra%$ d[n on ! e>?4 ,we h n[ briefly survey$ ! ext5t ( ! sol> sy/em4 ,we began ) ! sun1 :i* presides ov] all1 & !n we discuss$ ! v>i\s planets ) _! satellites1 next we consid]$ ! ecc5tric comets1 & f9ally ! m9ute bodies :i*1 z %oot+ />s or meteorites1 mu/ be reg>d$ z =m+ "p ( ! ,sun's sy/em4 ,9 our clos+ lecture we %all h to deal ) objects ( a f> m magnific5t "*4 ,,lecture ,,vi4 ,,/>s4 ,we try to make a ,map--,! ,/>s are ,suns--,! ,numb]s ( ! ,/>s--,! ,clu/]s ( ,/>s--,! ,rank ( ! ,e>? z a ,globe 9 ,space--,! ,di/ances ( ! ,/>s--,! ,brightness & ,color ( ,/>s--,d\ble ,/>s--,h[ we f9d :at ! ,/>s are made (--,! ,nebul--,:at ! ,nebul are made (--,photograph+ ! ,nebul--,conclusion4 ,,we ,,try ,,to ,,make ,a ,,map4 ,! gr\p ( bodies :i* clu/] ar\nd our sun =ms a little isl&1 s to speak1 9 ! ext5t ( inf9ite space4 ,we may illu/rate ?is by a map 9 :i* we %all endeavor to %[ ! />s plac$ at _! prop] relative di/ances4 ,we fir/ op5 ! compasses "o in*1 & ?us draw a little circle to repres5t ! pa? ( ! e>?4 ,we are n go+ to put 9 all ! planets4 ,we take ,neptune1 ! out]mo/1 at once4 ,to draw its pa? ,i op5 ! compasses to ?irty in*es1 & draw a circle ) t radius4 ,t w d = our sol> sy/em1 ?\gh ! comets no d\bt w roam beyond ^! limits4 ,to complete our map we ought ( c\rse to put 9 "s />s4 ,!re are a hundr$ million to *oose f1 & we %all beg9 ) ! brighte/4 ,x is (t5 call$ ! ,dog ,/>1 b a/ronom]s "k x bett] z ,sirius4 ,let u see :]e x is to be plac$ on our map4 ,sirius is beyond ,neptune1 s x mu/ be outside some:]e4 ,inde$1 x is a good deal fur!r (f ?an ,neptune2 s ,i try at ! edge ( ! draw+-bo>d2 ,i h got a me?od ( mak+ a little calculation t ,i d n int5d to tr\ble y )1 b ,i c assure y t ! results x leads me to are q correct2 !y %[ me t ?is bo>d is n big en\gh4 ,b c\ld a bo>d :i* 0 big en\gh fit into ?is lecture !atre8 ,"h1 aga91 ,i make my little calculations1 & ,i f9d t !re w\ld n be room = a bo>d suffici5tly great2 9 fact1 if ,i put ! sun "h at "o end1 ) its planets ar\nd x1 ,sirius w\ld be too ne> on ! same scale if x 7 at ! fur!r corn]4 ,! bo>d w\ld h to g out ?r\gh ! wall ( ! !atre1 out ?r\gh ,london4 ,inde$1 big z ,london is1 x w\ld n be l>ge en\gh to conta9 ! draw+-bo>d t ,i %\ld require4 ,x w\ld h to /ret* ab\t tw5ty miles f :]e we are n[ assembl$4 ,we may !re=e dismiss any hope ( mak+ a practical map ( our sy/em on ?is scale if ,sirius is to h its prop] place4 ,let u1 !n1 take "s o!r />4 ,we %all naturally try ) ! ne>e/ ( all4 ,x is "o t we d n "k 9 ?is "p ( ! _w1 b ^? t live 9 ! s\!rn hemisph]e are well acqua9t$ ) x4 ,! "n ( ?is /> is ,alpha ,c5tauri4 ,ev5 = ?is />1 we %\ld require a draw+ ?ree or f\r miles long if ! di/ance f ! e>? to ! sun is to be tak5 z "o in*4 ,y see :at an isolat$ position our sun & 8 planets occupy4 ,! memb]s ( ! family are all close toge!r1 & ! ne>e/ neighbors are situat$ at enorm\s di/ances4 ,!re is a good reason = ?is sep>ation4 ,! />s are v pretty & p]fectly h>mless to u :]e !y are at pres5t situat$4 ,!y might be v tr\blesome neighbors if !y 7 v mu* clos] to our sy/em4 ,x is !re=e well !y are s f> (f2 !y w\ld be con/antly mak+ di/urbance 9 ! sun's family if !y 7 ne> at h&4 ,sometimes !y w\ld be dragg+ u into unpleasantly great heat by br++ u too close to ! sun1 or produc+ a coolness by pull+ u away f ! sun1 :i* w\ld be q z disagreeable4 ,,! ,,/>s ,,are ,,suns4 ,we are ab\t to discuss "o ( ! gr&e/ tru?s 9 ! :ole ( nature4 ,we h _h occasion to see t ?is sun ( ours is a magnific5t globe imm5sely l>g] ?an ! greate/ ( 8 planets1 :ile ! greate/ ( ^! planets is imm5sely l>g] ?an ?is e>?2 b n[ we are to le>n t our sun is1 inde$1 only a /> n ne>ly s bright z _m ( ^? :i* %9e ov] our heads e night4 ,we are comp>atively close to ! sun1 s t we are able to enjoy 8 beautiful light & *e]+ heat4 ,ea* ( ^? o!r myriads ( />s is a sun1 & ! spl5dor ( ^? di/ant suns is (t5 f> great] ?an t ( our own4 ,we are1 h[ev]1 s enorm\sly f> f !m t !y appe> dw9dl$ d[n to insignificance4 ,to judge imp>tially betwe5 our sun or /> & su* a sun or /> z ,sirius we %\ld /& halfway betwe5 ! two2 x is impossible to make a fair e/imate :5 we f9d ourselves situat$ close to "o /> & a million times z f> f ! o!r4 ,aft] all[ance is made = ! imp]fections ( our po9t ( view1 we are enabl$ to realize ! maje/ic tru? t ! sun is no m ?an a />1 & t ! o!r />s are no less ?an suns4 ,?is gives u an impos+ idea ( ! ext5t & ! magnific5ce ( ! univ]se 9 :i* we are situat$4 ,look up at ! sky at night--y w see a ho/ ( />s2 try to ?9k t e "o ( !m is itself a sun4 ,x may probably be t ^? suns h planets circulat+ r\nd !m1 b x is hopeless = u to expect to see su* planets4 ,7 y /&+ on "o ( ^? />s & look+ t[>ds our sy/em1 y w\ld n p]ceive ! sun to be ! brilliant & gorge\s object t we knew s well4 ,if y c\ld see him at all1 he w\ld m]ely seem l a />1 n ne>ly s bright z _m ( ^? y c see at night4 ,ev5 if y _h ! bigge/ ( telescopes to aid y\r vision1 y c\ld nev] disc]n f "o ( ^! bodies ! planets :i* surr\nd ! sun4 ,no a/ronom] 9 ! />s c\ld see ,jupit] ev5 if 8 sight 7 a ?\s& times z good or 8 telescopes a ?\s& times z p[]ful z any sight or telescope t we "k4 ,s m9ute an object z our e>? w\ld1 ( c\rse1 be /ill m hopelessly beyond ! possibility ( vision4 ,,! ,,numb]s ,,( ,,! ,,/>s4 ,to c\nt ! />s involves a task :i* lies beyond ! p[] ( man to accompli%4 ,ev5 )\t ! aid ( any telescope1 we c see a great multitude ( />s f ?is "p ( ! _w4 ,!re are also _m con/ellations 9 ! s\!rn hemisph]e :i* nev] appe> above our horizon4 ,if1 h[ev]1 we 7 to g to ! equator1 !n1 by wait+ !re = a twelve-mon?1 all ! />s 9 ! heav5s w\ld h be5 successively expos$ to view4 ,an a/ronom]1 ,h\zeau1 ) ! pati5ce to c\nt !m1 enum]at$ ab\t #fjjj4 ,?is is ! nak$-eye e/imate ( ! />-population ( ! heav5s2 b if1 in/ead ( rely+ on unaid$ vision1 y get ! assi/ance ( a little telescope1 y w be a/\nd$ at ! enorm\s multitude ( />s :i* are disclos$4 ,illu/ration3 ,,fig4 #hb4--,! ,great ,be> & ! ,pole4 ,an ord9>y op]a-glass or b9ocul> is a v useful in/rum5t = look+ at ! />s 9 ! heav5s4 ,if y employ an in/rum5t ( ?is sort1 y w be amaz$ to f9d t ! heav5s teem ) additional ho/s ( />s t y\r unaid$ vision w\ld nev] h giv5 y k (4 ,any "p ( ! sky may be obs]v$2 b1 j to give an illu/ration1 ,i %all take "o special region1 namely1 t ( ! ,great ,be> 7,fig4 #hb74 ,! sev5 well-kn[n />s are "h %[n1 f\r ( :i* =m a sort ( oblong1 :ile ! o!r ?ree repres5t ! tail4 ,i w\ld l y to make ?is little exp]im5t4 ,on a f9e cle> night1 c\nt h[ _m />s !re are )9 ?is oblong2 !y are all v fa9t1 b y w be able to see a few1 &1 ) good sight1 & on a cle> night1 y may see p]haps t54 ,next take y\r op]a-glass & sweep x ov] ! same region2 if y w c>efully c\nt ! />s x %[s1 y w f9d fully #bjj2 s t ! op]a-glass has1 9 ?is "p ( ! sky1 reveal$ ne>ly tw5ty times z _m />s z c\ld be se5 )\t its aid4 ,z #fjjj />s c be se5 by ! eye all ov] ! heav5s1 we may fairly expect t tw5ty times t numb]--t is to say1 #abj1jjj />s--c\ld be %[n by ! op]a-glass ov] ! entire sky4 ,let u g a /ep fur!r1 & employ a telescope1 ! object-glass ( :i* is ?ree in*es across4 ,?is is a useful telescope to h1 &1 if a good "o1 w %[ multitudes ( pleas+ objects1 ?\gh an a/ronom] w\ld n consid] x v p[]ful4 ,an in/rum5t l ?is1 small en\gh to be c>ri$ 9 ! h&1 has be5 appli$ to ! task ( enum]at+ ! />s 9 ! nor!rn half ( ! sky1 & #cbj1jjj />s 7 c\nt$4 ,inde$1 ! actual numb] t might h be5 se5 ) x is consid]ably great]1 = :5 ! a/ronom] ,argel&] made ?is memorable inve/igation he 0 unable to reckon _m ( ! />s 9 localities :]e !y lay v close toge!r4 ,?is gr& c\nt only ext5d$ to half ! sky1 &1 assum+ t ! o!r half is z ri*ly inlaid ) />s1 we see t a little telescope l t we h suppos$ w1 :5 swept ov] ! heav5s1 reveal a numb] ( />s :i* exce$s t ( ! population ( any city 9 ,engl& except ,london4 ,x exhibits m ?an "o hundr$ times z _m />s z our eyes c\ld possibly reveal4 ,/ill1 we are only at ! beg9n+ ( ! c\nt2 ! v great telescopes add l>gely to ! numb]4 ,!re are multitudes ( />s :i* 9 small in/rum5ts we _c see1 b :i* are di/9ctly visible f our great obs]vatories4 ,t telescope w\ld be /ill b a comp>atively small "o :i* w\ld %[ z _m />s 9 ! sky z !re are p liv+ 9 ?is mighty city ( ,london2 & ) ! greate/ in/rum5ts1 ! tale ( />s has ris5 to a numb] f> great] ?an t ( ! entire population ( ,great ,brita94 ,9 addition to ^? />s :i* ! l>ge/ telescopes %[ u1 !re are myriads :i* make _! pres5ce evid5t 9 a :olly diff]5t way4 ,x is only 9 q rec5t times t an attempt has be5 made to develop fully ! p[]s ( photography 9 repres5t+ ! cele/ial objects4 ,on a photographic plate :i* has be5 expos$ to ! sky 9 a great telescope ! />s are record$ by ?\s&s4 ,_m ( ^! may1 ( c\rse1 be obs]v$ ) a good telescope1 b !re are n a few o!rs :i* no "o ev] saw 9 a telescope1 :i* app>5tly no "o ev] c\ld see1 ?\gh ! photograph is able to %[ !m4 ,we d n1 h[ev]1 employ a cam]a l t :i* ! photograph] uses :o is go+ to take y\r portrait4 ,! a/ronom]'s plate is put into 8 telescope1 & !n ! telescope is turn$ t[>ds ! sky4 ,on t plate ! />s produce _! images1 ea* by its own light4 ,"s ( ^! images are excessively fa9t1 b we give a v long exposure ( an h\r or two h\rs2 sometimes z mu* z f\r h\rs' exposure is giv5 to a plate s s5sitive t a m]e fraction ( a second w\ld suffici5tly expose x dur+ ! ord9>y practice ( tak+ a photograph 9 daylight4 ,we ?us af=d suffici5t "t to enable ! fa9t] objects to indicate _! pres5ce ^u ! s5sitive film4 ,ev5 ) an exposure ( a s+le h\r a picture exhibit+ #af1jjj />s has be5 tak5 by ,mr4 ,isaac ,rob]ts1 ( ,liv]pool4 ,yet ! portion ( ! sky :i* x repres5ts is only "o t5-?\s&? "p ( ! entire heav5s4 ,x %\ld be add$ t ! region :i* ,mr4 ,rob]ts has photograph$ is furni%$ ) />s 9 r exceptional pr(usion4 ,"h1 at la/1 we h obta9$ "s conception ( ! sublime scale on :i* ! /ell> univ]se is con/ruct$4 ,yet ev5 ^! plates _c repres5t all ! />s t ! heav5s conta94 ,we h e reason = kn[+ t ) l>g] telescopes1 ) m s5sitive plates1 ) m prolong$ exposures1 ev] fre% myriads ( />s w be br\ght )9 our view4 ,y mu/ rememb] t e "o ( ^! />s is truly a sun1 a lamp1 z x 71 :i* d\btless gives light to o!r objects 9 its neighborhood z our sun %$s light ^u ?is e>? & ! o!r planets4 ,9 fact1 to realize ! glories ( ! heav5s y %\ld try to ?9k t ! brilliant po9ts y see are m]ely ! lum9\s po9ts ( ! o!rwise invisible univ]se4 ,/&+ "o f9e night on ! deck ( a ,cun>d] we pass$ 9 op5 ocean ano!r great ,atlantic /eam]4 ,! vessel 0 ne> en\gh = u to see n only ! light f ! ma/-head b also ! little beams f ! sev]al cab9 ports2 & we c\ld see no?+ ( ! %ip h]self4 ,h] v exi/5ce 0 only kn[n to u by ! tw9kle ( ^! lights4 ,d\btless h] pass5g]s c\ld see1 & did see1 ! simil> lights f our own vessel1 & !y probably drew ! correct inf]5ce t ^! lights indicat$ a great %ip4 ,consid] ! multiplicity ( be+s & objects 9 a %ip3 ! capta9 & ! crew1 ! pass5g]s1 ! cab9s1 ! eng9es1 ! boats1 ! rigg+1 & ! /ores4 ,?9k ( all ! v>i$ int]e/s !re collect$ & !n reflect t out on ! ocean1 at night1 ! sole indication ( ! exi/5ce ( ?is elaborate /ructure 0 giv5 by ! few beams ( light t happ5$ to radiate f x4 ,n[ raise y\r eyes to ! />s2 !re are ! tw9kl+ lights4 ,we _c see :at ^? lights illum9ate1 we c only conjecture :at untold weal? ( non-lum9\s bodies may also lie 9 _! vic9ity2 we may1 h[ev]1 feel c]ta9 t j z ! few gleam+ lights f a %ip are utt]ly inadequate to give a notion ( ! nature & ! cont5ts ( an ,atlantic /eam]1 s are ! tw9kl+ />s utt]ly inadequate to give ev5 ! fa9te/ conception ( ! ext5t & ! int]e/ ( ! univ]se4 ,we m]ely see self-lum9\s bodies1 b ( ! multitudes ( objects & ! elaborate sy/ems ( :i* ^! bodies are only ! conspicu\s po9ts we see no?+ & we "k v little4 ,we are1 h[ev]1 entitl$ to inf] f an exam9ation ( our own />--! sun--& ( ! beautiful sy/em by :i* x is surr\nd$1 t ^! o!r suns may be also spl5didly att5d$4 ,?is is q z reasonable a supposition z t a set ( lights se5 at night on ! ,atlantic ,ocean indicates ! exi/5ce ( a f9e %ip4 ,,! ,,clu/]s ,,( ,,/>s4 ,on a cle> night y c (t5 see1 /ret*+ across ! sky1 a track ( fa9t light1 :i* is kn[n to a/ronom]s z ! 8,milky ,way40 ,x ext5ds bel[ ! horizon & !n r\nd ! e>? to =m a girdle ab\t ! heav5s4 ,:5 we exam9e ! ,milky ,way ) a telescope we f9d1 to our amazem5t1 t x consi/s ( myriads ( />s1 s small & s fa9t t we are n able to di/+ui% !m individually2 we m]ely see ! gl[ produc$ f _! collective rays4 ,rememb]+ t our sun is a />1 & t ! ,milky ,way surr\nds u1 x w\ld almo/ seem z if our sun 7 b "o ( ! ho/ ( />s :i* =m ?is clu/]4 ,illu/ration3 ,,fig4 #hc4--;,globul> ,clu/] 9 ! ,c5taur4 ,!re are also o!r clu/]s ( />s1 "s ( :i* are exquisitely beautiful telescopic spectacles4 ,i may m5tion a celebrat$ pair ( ^! objects :i* lies 9 ! con/ellation ( ,p]seus4 ,! sight ( !m 9 a great telescope is s impos+ t no "o :o is fit to look ?r\gh a telescope c\ld resi/ a %\t ( wond] & admiration :5 fir/ !y bur/ on 8 view4 ,b !re are o!r clu/]s4 ,"h is a picture ( "o :i* is kn[n z ! 8,globul> ,clu/] 9 ! ,c5taur0 7,fig4 #hc74 ,x consi/s ( a ball ( />s1 s f> (f t1 h[ev] l>ge ^! sev]al suns may actually be1 !y h dw9dl$ d[n to extremely small po9ts ( light4 ,a homely illu/ration may s]ve to %[ ! appe>ance :i* a globul> clu/] pres5ts 9 a good telescope4 ,i take a pepp]-ca/or & on a %eet ( :ite pap] ,i beg9 to %ake out ! pepp] until !re is a little heap at ! c5tre & o!r gra9s are scatt]$ loosely ab\t4 ,imag9e t e "o ( ^? gra9s ( pepp] 0 to be trans=m$ into a t9y electric light1 & !n y h "s idea ( :at a clu/] ( />s w\ld look l :5 view$ ?r\gh a telescope ( suffici5t p[]4 ,!re are multitudes ( su* gr\ps scatt]$ ?r\gh ! dep?s ( space4 ,!y require our bigge/ telescopes to %[ !m adequately4 ,we h se5 t our sun is a />1 be+ only "o ( a magnific5t clu/] t =m ! ,milky ,way4 ,we h also se5 t !re are o!r gr\ps scatt]$ ?r\gh ! l5g? & dep? ( space4 ,x is ?us we obta9 a notion ( ! rank :i* our e>? holds 9 ! s*eme ( ?+s cele/ial4 ,,! ,,rank ,,( ,,! ,,e>? ,,z ,a ,,globe ,,9 ,,space4 ,let me give an illu/ration ) ! view ( expla9+ m fully ! nature ( ! relation :i* ! e>? be>s to ! o!r globes :i* ab\nd ?r\gh space1 & y mu/ all[ me to draw a little ^u my imag9ation4 ,i %all suppose t ,h] ,maje/y's mails ext5d n only ov] ?is globe1 b t !y also communicate ) o!r worlds2 t po/al arrangem5ts exi/ betwe5 ,m>s & ! e>?1 betwe5 ! sun & ,orion--9 fact1 ev]y:]e ?r\gh\t ! :ole ext5t ( ! univ]se4 ,we %all consid] h[ our lett]s are to be address$4 ,let u take ! case ( ,mr4 ,john ,smi?1 m]*ant1 :o lives at #ajja1 ,piccadilly2 & let u suppose t ,mr4 ,john ,smi?'s bus9ess transactions are ( su* an ext5sive nature t !y rea* n only all ov] ?is globe1 b away ?r\gh\t space4 ,i %all suppose t ! firm has a correspond5t resid+--let u say 9 ! con/ellation ( ! ,great ,be>2 & :5 ?is man ( bus9ess wants to write to ,mr4 ,smi? f ^! remote regions1 :at address mu/ he put ^u ! lett]1 s t ! ,po/ma/]-,g5]al ( ! univ]se %all make no mi/ake ab\t its deliv]y8 ,he w write z foll[s3-- ,,mr4 ,,john ,,smi?1 #ajja ,piccadilly1 ,london1 ,engl&1 ,europe1 ,e>?1 ,ne> ! ,sun1 ,milky ,way1 ,! ,univ]se4 ,let u n[ see :at ! sev]al l9es ( ?is address mean4 ,( c\rse we put d[n ! "n ( ,mr4 ,john ,smi? 9 ! fir/ l9e1 & !n we w add 8#ajja ,piccadilly0 = ! second2 b z ! p 9 ! ,great ,be> are n likely to "k :]e ,piccadilly is1 we %all add 8,london0 und]nea?4 ,z ev5 ,london itself _c be well kn[n ev]y:]e1 x is bett] to write 8,engl&40 ,?is w\ld surely f9d ,mr4 ,john ,smi? f any po/-(fice on ?is globe4 ,f o!r globes1 h[ev]1 ! supreme importance ( ,engl& may n be s imm$iately recogniz$1 & !re=e x is z well to add ano!r l9e1 8,europe40 ,?is ought to be suffici5t1 ,i ?9k1 = any po/-(fice 9 ! sol> sy/em4 ,europe is big en\gh to be visible f ,m>s or ,v5us1 & %\ld be kn[n to ! po/-(fice p !re1 j z we "k & h names = ! cont95ts on ,m>s4 ,b fur!r away !re might be a little difficulty2 f ,uranus & ,neptune ! diff]5t regions on our e>? c nev] h be5 di/+ui%$1 & !re=e we mu/ add ano!r l9e to indicate ! p>ticul> globe ( ! sol> sy/em :i* conta9s ,europe4 ,m>k ,twa9 tells u t !re 0 always "o ?+ 9 a/ronomy :i* specially puzzl$ him1 & t 0 to "k h[ we f\nd out ! names ( ! />s4 ,we are1 ( c\rse1 9 hopeless ignorance ( ! "n by :i* ?is e>? is call$ among o!r intellig5t be+s else:]e :o c see x4 ,i c only adopt ! title ( 8,e>?10 & !re=e ,i add ?is l9e4 ,n[ our address is s complete t f any:]e 9 ! sol> sy/em--f ,m]cury1 f ,jupit]1 or ,neptune--!re ought to be no mi/ake ab\t ! lett] f9d+ its way to ,mr4 ,john ,smi?4 ,b f 8 correspond5t 9 ! ,great ,be> ?is address w\ld be /ill incomplete2 !y _c see our e>? f !re1 & ev5 ! sun himself only looks l a small />--l "o1 9 fact1 ( ?\s&s ( />s else:]e4 ,h[ev]1 ea* /> c be di/+ui%$1 & our sun may1 = in/ance1 be recogniz$ f ! ,great ,be> by "s designation4 ,we %all add ! l9e 8,ne> ! ,sun10 & !n ,i ?9k t f ?is con/ellation1 or f any ( ! o!r />s ar\nd u1 ! address ( ,mr4 ,john ,smi? may be reg>d$ z complete4 ,b ,mr4 ,smi?'s correspond5ce may be /ill wid]4 ,he may h an ag5t liv+ 9 ! clu/] ( ,p]seus or on "s o!r objects /ill fa9t] & m di/ant2 !n 8,ne> ! ,sun0 is utt]ly inadequate z a conclud+ l9e to ! address1 = ! sun1 if x c be se5 at all f !nce1 w be only ( ! significance ( an excessively m9ute />1 no m to be designat$ by a special "n ?an are ea* ( ! sev]al leaves on ! trees ( a =e/4 ,:at ?is di/ant correspond5t w be acqua9t$ ) is n ! e>? or ! sun1 b only ! clu/] ( />s among :i* ! sun is b a unit4 ,aga9 we use our own "n to d5ote ! clu/]1 & we call x ! 8,milky ,way40 ,:5 we add ?is l9e1 we h made ! address ( ,mr4 ,john ,smi? z complete z circum/ances w p]mit4 ,i ?9k a lett] po/$ to him any:]e ought to rea* its de/9ation4 ,to p]fect x1 h[ev]1 we w f9i% up ) "o l9e m--8,! ,univ]se40 ,,! ,,di/ances ,,( ,,! ,,/>s4 ,i mu/ n[ tell y some?+ ab\t ! di/ances ( ! />s4 ,i %all n make ! attempt to expla9 fully h[ a/ronom]s make su* measurem5ts1 b ,i w give y "s notion ( h[ x is done4 ,y may rememb] ,i %[$ y h[ we f\nd ! di/ance ( a globe t 0 hung f ! ceil+4 ,! pr9ciple ( ! me?od = f9d+ ! di/ance ( a /> is some:at simil>1 except t we make ! two obs]vations n f ! two ends ( a table1 n ev5 f opposite sides ( ! e>?1 b f two opposite po9ts on ! e>?'s orbit1 :i* are !re=e at a di/ance ( #ahf1jjj1jjj miles4 ,imag9e t on ,midsumm] ,day1 :5 /&+ on ! e>? "h1 ,i measure ) a piece ( c>d ! angle betwe5 ! /> & ! sun4 ,six mon?s lat]1 on ,midw9t] ,day1 :5 ! e>? is at ! opposite po9t ( its orbit1 ,i aga9 measure ! angle betwe5 ! same /> & ! sun1 & we c n[ det]m9e ! />'s di/ance by mak+ a triangle4 ,i draw a l9e a foot long1 & we w take ?is foot to repres5t #ahf1jjj1jjj miles1 ! di/ance betwe5 ! two /ations2 !n plac+ ! c>ds at ! corn]s1 ,i rule ! two sides & complete ! triangle1 & ! /> mu/ be at ! rema9+ corn]2 !n ,i measure ! sides ( ! triangle1 & f9d h[ _m feet !y conta91 & recollect+ t ea* foot corresponds to #ahf1jjj1jjj miles1 we discov] ! di/ance ( ! />4 ,if ! />s 7 comp>atively ne> u1 ! process w\ld be a v simple "o2 b1 un=tunately1 ! />s are s extremely f> (f t ?is triangle1 ev5 ) a base ( only "o foot1 mu/ h its sides _m miles long4 ,inde$1 a/ronom]s w tell y t !re is no m delicate or tr\blesome "w 9 ! :ole ( _! sci5ce ?an t ( discov]+ ! di/ance ( a />4 ,9 all su* measurem5ts we take ! di/ance f ! e>? to ! sun z a conv5i5tly long measur+-rod1 :]eby to express ! results4 ,! ne>e/ />s are /ill hundr$s ( ?\s&s ( times z f> (f z ! sun4 ,let u pond] = a little on ! va/ness ( ^! di/ances4 ,we %all fir/ express !m 9 miles4 ,tak+ ! sun's di/ance to be #ic1jjj1jjj miles1 !n ! di/ance ( ! ne>e/ fix$ /> is ab\t tw5ty millions ( millions ( miles--t is to say1 we express ?is by putt+ d[n a #b fir/1 & !n writ+ ?irte5 ciph]s aft] x4 ,x is1 no d\bt1 easy to speak ( su* figures1 b x is a v diff]5t matt] :5 we endeavor to imag9e ! awful magnitude :i* su* a numb] indicates4 ,i mu/ try to give "s illu/rations :i* w enable y to =m a notion ( x4 ,at fir/ ,i 0 go+ to ask y to try & c\nt ?is numb]1 b :5 ,i f\nd x w\ld require at lea/ #cjj1jjj ye>s1 c\nt+ day & night )\t /opp+1 be=e ! task 0 ov]1 x became necess>y to adopt "s o!r me?od4 ,:5 on a visit 9 ,lanca%ire ,i 0 once k9dly p]mitt$ to visit a cotton mill1 & ,i le>n$ t ! cotton y>n !re produc$ 9 a s+le day w\ld be long en\gh to w9d r\nd ?is e>? tw5ty-sev5 times at ! equator4 ,x appe>s t ! total production ( cotton y>n ea* day 9 all ! mills toge!r w\ld be on ! av]age ab\t #aee1jjj1jjj miles4 ,9 fact1 if !y w\ld only sp9 ab\t "o-fif? m1 we c\ld ass]t t ,great ,brita9 produc$ en\gh cotton y>n e day to /ret* f ! e>? to ! sun & back aga96 ,x is n h>d to f9d f ^! figures h[ long x w\ld take = all ! mills 9 ,lanca%ire to produce a piece ( y>n long en\gh to rea* f our e>? to ! ne>e/ ( ! />s4 ,if ! sp9n]s work$ z h>d z ev] !y c\ld = a ye>1 & if all ! pieces 7 !n ti$ toge!r1 !y w\ld ext5d to only a small fraction ( ! di/ance2 nor if !y work$ = t5 ye>s1 or = tw5ty ye>s1 w\ld ! task be fully accompli%$4 ,inde$1 upw>ds ( #djj ye>s w\ld be necess>y be=e en\gh cotton c\ld be gr[n 9 ,am]ica & spun 9 ?is c\ntry to /ret* ov] a di/ance s enorm\s4 ,all ! sp9n+ t has ev] yet be5 done 9 ! _w has n =m$ a long en\gh ?read6 ,!re is ano!r way 9 :i* we c =m "s notion ( ! imm5sity ( ^! sid]eal di/ances4 ,y w recollect t1 :5 we 7 speak+ ( ,jupit]'s moons 7p4 #bai71 ,i told y ( ! beautiful discov]y :i* _! eclipses enabl$ a/ronom]s to make4 ,x 0 ?us f\nd t light travels at ! enorm\s spe$ ( ab\t #ahe1jjj miles p] second4 ,x moves s quickly t )9 a s+le second a ray w\ld fla% two hundr$ times f ,london to ,ed9burgh & back aga94 ,we said t a meteor travels "o hundr$ times z swiftly z a rifle-bullet2 b ev5 ?is great spe$ seems almo/ no?+ :5 comp>$ ) ! spe$ ( light1 :i* is #aj1jjj times z great4 ,suppose "s brilliant outbreak ( light 7 to take place 9 a di/ant />--an outbreak :i* w\ld be ( su* int5sity t ! fla% f x w\ld ext5d f> & wide ?r\gh\t ! univ]se4 ,! light w\ld />t =? on its voyage ) t]rific spe$4 ,any neighbor+ /> :i* 0 at a di/ance ( less ?an #ahe1jjj miles w\ld1 ( c\rse1 see ! fla% )9 a second aft] x _h be5 produc$4 ,m di/ant bodies w\ld receive ! intimation aft] int]vals ( "t proportional to _! di/ances4 ,?us1 if a body 7 #a1jjj1jjj miles away ! light w\ld rea* x 9 f five to six seconds1 :ile ov] a di/ance z great z t :i* sep>ates ! e>? f ! sun ! news w\ld be c>ri$ 9 ab\t eight m9utes4 ,we c calculate h[ long a "t mu/ elapse ere ! light %all travel ov] a di/ance s great z t betwe5 ! /> & our e>?4 ,y w f9d t f ! ne>e/ ( ! />s ! "t requir$ = ! j\rney w be ov] ?ree ye>s4 ,pond] on all t ?is involves4 ,t outbreak 9 ! /> might be great en\gh to be visible "h1 b we c\ld nev] become aw>e ( x till ?ree ye>s aft] x _h happ5$4 ,:5 we are look+ at su* a /> to-night we d n see x z x is at pres5t1 = ! light t is at ?is mom5t ent]+ our eyes has travell$ s f> t x has be5 ?ree ye>s on ! way4 ,!re=e1 :5 we look at ! /> n[ we see x z x 0 ?ree ye>s previ\sly4 ,9 fact1 if ! /> 7 to g out altoge!r1 we might /ill cont9ue to see x tw9kl+ = a p]iod ( ?ree ye>s long]1 because a c]ta9 am\nt ( light 0 on its way to u at ! mom5t ( ext9ction1 & s long z t light keeps arriv+ "h1 s long %all we see ! /> %[+ z brightly z ev]4 ,:51 !re=e1 y look at ! ?\s&s ( />s 9 ! sky to-night1 !re is n "o t y see z x is n[1 b z x 0 ye>s ago4 ,i h be5 speak+ ( ! />s t are ne>e/ to u1 b !re are o!rs mu* f>!r (f4 ,x is true we _c f9d ! di/ance ( ^! m remote objects ) any degree ( accuracy1 b we c conv9ce ourselves h[ great t di/ance is by ! foll[+ reason+4 ,look at "o ( ! brighte/ />s4 ,try to conceive t ! object 0 c>ri$ away fur!r into ! dep?s ( space1 until x 0 t5 times z f> f u z x is at pres5t1 x w\ld /ill rema9 bright en\gh to be recogniz$ 9 q a small telescope2 ev5 if x 7 tak5 to "o hundr$ times its orig9al di/ance x w\ld n h )drawn f ! view ( a good telescope2 :ile if x retreat$ "o ?\s& times z f> z x 0 at fir/ x w\ld /ill be a recognizable po9t 9 our mightie/ in/rum5ts4 ,among ! />s :i* we c see ) our telescopes1 we feel confid5t !re mu/ be _m f :i* ! light has exp5d$ hundr$s ( ye>s1 or ev5 ?\s&s ( ye>s1 on ! j\rney4 ,:51 !re=e1 we look at su* objects1 we see !m1 n z !y are n[1 b z !y 7 ages ago2 9 fact1 a /> might h ceas$ to exi/ = ?\s&s ( ye>s1 & /ill be se5 by u e night z a tw9kl+ po9t 9 our great telescopes4 ,rememb]+ ^! facts1 y w1 ,i ?9k1 look at ! heav5s ) a new int]e/4 ,!re is a bright />1 ,vega or ,alpha ,lyr1 a beautiful gem1 s f> (f t ! light f x :i* n[ rea*es our eyes />t$ be=e _m ( my audi5ce 7 born4 ,suppose t !re are a/ronom]s resid+ on worlds amid ! />s1 & t !y h suffici5tly p[]ful telescopes to view ?is globe1 :at d y ?9k !y w\ld obs]ve8 ,!y w n see our e>? z x is at pres5t1 !y w see x z x 0 ye>s1 & sometimes _m ye>s1 ago4 ,!re are />s f :i*1 if ,engl& c\ld n[ be se51 ! :ole ( ! c\ntry w\ld be obs]v$ at ?is pres5t mom5t to be 9 a great /ate ( excitem5t at a v auspici\s ev5t4 ,di/ant a/ronom]s might notice a great procession 9 ,london1 & !y c\ld wat* ! coronation ( a y\?ful que5 amid ! en?usiasm ( a nation4 ,!re are o!r />s /ill fur!r1 f :i*1 if ! inhabitants _h good en\gh telescopes1 !y w\ld n[ see a mighty battle 9 progress n f> f ,brussels4 ,"o spl5did army c\ld be beheld hurl+ itself "t aft] "t aga9/ ! immovable ranks ( ! o!r4 ,!y w\ld n1 inde$1 be able to he> ! ev]-memorable1 8,up1 ,gu>ds1 & at !m60 b !re c be no d\bt t !re are />s s f> away t ! rays ( light :i* />t$ f ! e>? on ! day ( ! battle ( ,wat]loo are only j arriv+ !re4 ,fur!r (f /ill1 !re are />s f :i* a bird's-eye view c\ld be tak5 at ?is v mom5t ( ! sign+ ( ,magna ,*>ta4 ,!re are ev5 />s f :i* ,engl&1 if x c\ld be se5 at all1 w\ld n[ appe>1 n z ! great ,engl& we "k1 b z a c\ntry cov]$ by d5se =e/s1 & inhabit$ by pa9t$ savages1 :o wag$ incessant w> ) wild bea/s t roam$ ?r\gh ! isl&4 ,! geological problems t n[ puzzle u w\ld be quickly solv$ c\ld we only g f> en\gh into space & _h we only p[]ful en\gh telescopes4 ,we %\ld !n be able to view our e>? ?r\gh ! successive epo*s ( pa/ geological "t2 we %\ld be actually able to see ^? great animals ^: fossil rema9s are treasur$ 9 our museums tramp+ ab\t ov] ! e>?'s surface1 spla%+ across its swamps1 or swimm+ ) broad flipp]s ?r\gh its oceans4 ,inde$1 if we c\ld view our own e>? reflect$ f mirrors 9 ! />s1 we might /ill see ,moses cross+ ! ,r$ ,sea1 or ,adam & ,eve be+ expell$ f ,ed54 ,s important is ! subject ( /> di/ance t ,i am tempt$ to give "o m illu/ration 9 ord] to br+ be=e y "s conception ( h[ va/ su* di/ances are4 ,i %all take1 z be=e1 ! ne>e/ ( ! />s s f> z kn[n to u1 & ,i hope to be =giv5 = tak+ an illu/ration ( a practical & a comm]cial k9d in/ead ( "o m purely sci5tific4 ,i %all suppose t a railway is ab\t to be made f ,london to ,alpha ,c5tauri4 ,! l5g? ( t railway1 ( c\rse1 we h already /at$3 x is tw5ty billions ( miles4 ,s ,i am n[ go+ to ask y\r att5tion to ! simple "q z to ! f>e :i* x w\ld be reasonable to *>ge = ! j\rney4 ,we %all *oose a v *eap scale on :i* to compute ! price ( a ticket4 ,! p>liam5t>y rate "h is1 ,i believe1 a p5ny = e mile4 ,we w make our int]/ell> railway f>es mu* less ev5 ?an ?is2 we %all arrange to travel at ! rate ( "o hundr$ miles = e p5ny4 ,t1 surely1 is mod]ate en\gh4 ,if ! *>ges 7 s l[ t ! j\rney f ,london to ,ed9burgh only co/ f\rp5ce1 !n ev5 ! mo/ unreasonable pass5g] w\ld be surely cont5t$4 ,on ^! t]ms h[ mu* d y ?9k ! f>e f ,london to ?is /> ought to be8 ,i "k ( "o way 9 :i* to make our answ] intelligible4 ,!re is a ,national ,debt ) :i* y\r fa!rs are1 unhappily1 only too well acqua9t$2 y w "k q en\gh ab\t x y\rselves 9 ^? days :5 y h to pay income tax4 ,?is debt is s va/ t ! int]e/ ^u x is ab\t sixty ?\s& p\nds a day1 ! :ole am\nt ( ! ,national ,debt be+ six hundr$ & ?irty-eight millions ( p\nds 7,april1 #ahih74 ,if y w5t to ! book+ (fice ) ! :ole ( ?is mighty sum 9 y\r pocket--b /op a mom5t2 c\ld y c>ry x 9 y\r pocket8 ,c]ta9ly n1 if x 7 9 sov]eigns4 ,y w\ld f9d t aft] y _h z _m sov]eigns z y c\ld conv5i5tly c>ry !re w\ld /ill be "s left--s _m1 inde$1 t x w\ld be necess>y to get a c>t to help y on ) ! re/4 ,:5 ! c>t _h z great a load ( sov]eigns z ! horse c\ld draw !re w\ld be /ill "s m1 & y w\ld h to get ano!r c>t2 b t5 c>ts1 tw5ty c>ts1 fifty c>ts1 w\ld n be en\gh4 ,y w\ld want five ?\s& ( ^! be=e y w\ld be able to move (f t[>ds ! /ation ) y\r money4 ,:5 y did get !re & ask$ = a ticket at ! rate ( "o hundr$ miles = a p5ny1 d y ?9k y w\ld get any *ange8 ,no d\bt "s little "t w\ld be requir$ to c\nt ! money1 b :5 x 0 c\nt$ ! cl]k w\ld tell y t !re 0 n en\gh1 t he mu/ h ne>ly two hundr$ millions ( p\nds m4 ,t w give "s notion ( ! di/ance ( ! ne>e/ />1 & we may multiply x by t51 by "o hundr$1 & ev5 by "o ?\s&1 & /ill n atta9 to ! di/ance ( "s ( ! m remote />s t ! telescope %[s u4 ,on acc\nt ( ! imm5se di/ances ( ! />s we c only p]ceive !m to be m]e po9ts ( light4 ,we c nev] see a /> to be a globe ) m>ks on x l ! moon1 or l "o ( ! planets--9 fact1 ! bett] ! telescope ! small] does ! /> seem1 ?\gh1 ( c\rse1 its brightness is increas$ ) e addition to ! light-grasp+ p[] ( ! in/rum5t4 ,,! ,,brightness ,,& ,,color ,,( ,,/>s4 ,ano!r po9t to be notic$ is ! arrangem5t ( />s 9 classes1 accord+ to _! lu/re4 ,! brighte/ />s1 ( :i* !re are ab\t tw5ty1 are said to be ( ! fir/ magnitude4 ,^? j inf]ior to ! fir/ magnitude are rank$ z ! second2 & ^? j l[] ?an ! second are e/imat$ z ! ?ird2 & s on4 ,! smalle/ po9ts t y\r unaid$ eyes w %[ y are ( ab\t ! six? magnitude4 ,!n ! telescope w reveal />s /ill fa9t] & fa9t]1 d[n to :at we t]m ! sev5te5? or eighte5? magnitudes1 or ev5 l[] /ill4 ,! numb] ( />s ( ea* magnitude increases v mu* 9 ! classes ( small ones4 ,mo/ ( ! />s are :ite1 b _m are ( a some:at ruddy hue4 ,!re are a few telescopic po9ts :i* are int5sely r$1 "s exhibit beautiful gold5 t9ts1 :ile o!rs are blue or gre54 ,!re are "s curi\s />s :i* regul>ly *ange _! brilliancy4 ,let me try to illu/rate ! nature ( ^! v>iables4 ,suppose t y 7 look+ at a /reet gas-lamp f a v long di/ance1 s t x seem$ a little tw9kl+ light2 & suppose t "s "o 0 prep>+ to turn ! gas-cock up & d[n4 ,or1 bett] /ill1 imag9e a little ma*9e :i* w\ld act regul>ly s z to keep ! light fir/ ( all at its full brightness = two days & a half1 & !n gradually turn x d[n until 9 ?ree or f\r h\rs x decl9es to a feeble glimm]4 ,9 ?is l[ /ate ! light rema9s = tw5ty m9utes2 !n dur+ ?ree or f\r h\rs ! gas is to be sl[ly turn$ on aga9 until x is full4 ,9 ?is condition ! light w rema9 = two days & a half1 & !n ! same s]ies ( *anges is to recomm5ce4 ,?is w\ld be a v odd =m ( gas-lamp4 ,!re w\ld be p]iods ( two days & a half dur+ :i* x w\ld rema9 at its full2 ^! w\ld be sep>at$ by int]vals ( ab\t sev5 h\rs1 :5 ! gradual turn+ d[n & turn+ up aga9 w\ld be 9 progress4 ,illu/ration3 ,,fig4 #hd4--,p]seus & its ,neighbor+ ,/>s1 includ+ ,algol4 ,! imag9>y gas-lamp is exactly p>allel$ by a /> ,algol1 9 ! con/ellation ( ,p]seus 7,fig4 #hd71 :i* goes ?r\gh ! s]ies ( *anges ,i h indicat$4 ,ord9>ily speak+1 x is a bright /> ( ! second magnitude1 &1 :atev] be ! cause1 ! /> p]=ms its v>iations ) m>vell\s uni=mity4 ,9 fact1 ,algol has always arre/$ ! att5tion ( ^? :o obs]v$ ! heav5s1 & 9 e>ly times 0 look$ on z ! eye ( a ,demon4 ,!re are _m o!r />s :i* also *ange _! brilliancy4 ,mo/ ( !m require mu* long] p]iods ?an ,algol1 & sometimes a new /> :i* nobody has ev] se5 be=e w sudd5ly k9dle into brilliancy4 ,x is n[ kn[n t ! bright /> ,algol is att5d$ by a d>k companion4 ,?is d>k /> sometimes comes betwe5 ,algol & ! obs]v] & cuts (f ! light4 ,?us x is t ! dim9ution ( brightness is produc$4 ,,d\ble ,,/>s4 ,:5ev] y h a *ance ( look+ at ! heav5s ?r\gh a telescope1 y %\ld ask to be %[n :at is call$ a d\ble />4 ,!re are _m />s 9 ! heav5s :i* pres5t no rem>kable appe>ance to ! unaid$ eye1 b :i* a good telescope at once %[s to be ( q a complex nature4 ,^! are :at we call d\ble />s1 9 :i* two q di/9ct />s are plac$ s close toge!r t ! unaid$ eye is unable to sep>ate !m4 ,"u ! magnify+ p[] ( ! telescope1 h[ev]1 !y are se5 to be di/9ct4 ,9 ord] to give "s notion ( :at ^! objects are l1 ,i %all briefly describe ?ree ( !m4 ,! fir/ lies 9 t be/ kn[n ( con/ellations1 ! ,great ,be>4 ,if y look at 8 tail1 :i* consi/s ( ?ree />s1 y w see t ne> ! middle "o ( ! ?ree a small /> is situat$2 we call ?is little /> ,alcor1 b x is ! bright] "o ne> ,alcor to :i* ,i specially call y\r att5tion4 ,! %>pe/ eye w\ld nev] suspect t x 0 compos$ ( two />s plac$ close toge!r4 ,ev5 a small telescope w1 h[ev]1 %[ ?is to be ! case1 & ?is is ! easie/ & ! fir/ obs]vation t a "y a/ronom] %\ld make :5 beg9n+ to turn a telescope to ! heav5s4 ,( c\rse1 y w n imag9e t ,i mean ,alcor to be ! second compon5t ( ! d\ble />2 x is ! bright /> ne> ,alcor :i* is ! d\ble4 ,"h are two m>bles1 & ^! m>bles are fa/5$ an in* ap>t4 ,y c see !m1 ( c\rse1 to be sep>ate2 b if ! pair 7 mov$ fur!r & fur!r away1 !n y w\ld soon n be able to di/+ui% betwe5 !m1 ?\gh ! actual di/ance betwe5 ! m>bles _h n alt]$4 ,look at ^! two wax tap]s :i* are n[ light$2 ! little flames are an in* ap>t4 ,y w\ld h to view !m f a /ation a ?ird ( a mile away if ! di/ance betwe5 ! two flames 7 to appe> ! same z t betwe5 ! two compon5ts ( ?is d\ble />4 ,y\r eye w\ld nev] be able to discrim9ate betwe5 two lights only an in* ap>t at s great a di/ance2 a telescope w\ld1 h[ev]1 enable y to d s1 & ?is is ! reason :y we h to use telescopes to %[ u d\ble />s4 ,y might look at t d\ble /> ye> aft] ye> ?r\gh\t ! c\rse ( a long life )\t f9d+ any appreciable *ange 9 ! relative positions ( its compon5ts4 ,b we "k t !re is no su* ?+ z re/ 9 ! univ]se2 ev5 if y c\ld balance a body s z to leave x = a mom5t at re/1 x w\ld n /ay !re1 = ! simple reason t all ! bodies r\nd x 9 e direction are pull+ at x1 & x is c]ta9 t ! pull 9 "o direction w prepond]ate1 s t move x mu/4 ,especially is ?is true 9 ! case ( two suns l ^? =m+ a d\ble />4 ,plac$ comp>atively ne> ea* o!r !y c\ld n rema9 p]man5tly 9 t position2 !y mu/ gradually draw toge!r & come into collision ) an awful cra%4 ,!re is only "o way by :i* su* a disa/] c\ld be av]t$4 ,t is by mak+ "o ( ^! />s revolve ar\nd ! o!r j z ! e>? revolves ar\nd ! sun1 or ! moon revolves ar\nd ! e>?4 ,"s motion mu/1 !re=e1 be go+ on 9 e g5u9e d\ble />1 :e!r we h be5 able to see t motion or n4 ,let u n[ look at ano!r d\ble /> ( a diff]5t k9d4 ,?is "t x is 9 ! con/ellation ( ,gem9i4 ,! heav5ly tw9s are call$ ,ca/or & ,pollux4 ,( ^!1 ,ca/or is a v beautiful d\ble />1 consi/+ ( two bright po9ts1 a great deal clos] toge!r ?an 7 ^? 9 ! ,great ,be>2 consequ5tly a bett] telescope is requir$ = ! purpose ( %[+ !m sep>ately4 ,ca/or has be5 wat*$ = _m ye>s1 & x c be se5 t "o ( ^! />s is sl[ly revolv+ ar\nd ! o!r2 b x takes a v long "t1 am\nt+ to hundr$s ( ye>s1 = a complete circuit to be accompli%$4 ,?is seems v a/oni%+1 b :5 y rememb] h[ exce$+ly f> ,ca/or is1 y w p]ceive t t pair ( />s :i* appe> s close toge!r t x requires a telescope to %[ !m ap>t mu/ inde$ be sep>at$ by hundr$s ( millions ( miles4 ,let u try to conceive our own sy/em trans=m$ into a d\ble />4 ,if we took our out]mo/ planet--,neptune--& enl>g$ him a good deal1 & !n heat$ him suffici5tly to make him gl[ l a sun1 he w\ld /ill cont9ue to revolve r\nd our sun at ! same di/ance1 & ?us a d\ble /> w\ld be produc$4 ,an inhabitant ( ,ca/or :o turn$ 8 telescope t[>ds u w\ld be able to see ! sun z a />4 ,he w\ld n1 ( c\rse1 be able to see ! e>?1 b he might see ,neptune l ano!r small /> close to ! sun4 ,if g5]ations ( a/ronom]s 9 ,ca/or cont9u$ _! obs]vations ( our sy/em1 !y w\ld f9d a b9>y />1 ( :i* "o compon5t took a c5tury & a half to g r\nd ! o!r4 ,ne$ we !n be surpris$ t :5 we look at ,ca/or we obs]ve movem5ts t seem v sl[8 ,!re is (t5 s mu* diffus$ light ab\t ! bright />s se5 9 a telescope1 & s mu* tw9kl+ 9 "s /ates ( ! atmosph]e1 t />s appe> to dance ab\t 9 r a puzzl+ fa%ion1 especially to "o :o is n accu/om$ to a/ronomical obs]vations4 ,i rememb] he>+ h[ a g5tleman once came to visit an obs]vatory4 ,! a/ronom] %[$ him ,ca/or ?r\gh a p[]ful telescope z a f9e specim5 ( a d\ble />1 & !n1 by way ( improv+ 8 little lesson1 ! a/ronom] m5tion$ t "o ( ^! />s 0 revolv+ ar\nd ! o!r4 8,oh1 yes10 said ! visitor1 8,i saw !m go+ r\nd & r\nd 9 ! telescope40 ,he w\ld1 h[ev]1 h _h to wait = a few c5turies ) 8 eye to ! in/rum5t be=e he w\ld h be5 entitl$ to make ?is ass]tion4 ,d\ble />s also frequ5tly delight u by giv+ beautifully contra/$ colors4 ,i d>e say y h (t5 notic$ ! r$ & ! gre5 lights t are us$ on railways 9 ! signal lamps4 ,imag9e "o ( ^? r$ & "o ( ^? gre5 lights away f> up 9 ! sky & plac$ close toge!r1 !n y w\ld h "s idea ( ! appe>ance t a color$ d\ble /> pres5ts1 ?\gh1 p]haps1 ,i %\ld add t ! hues 9 ! heav5ly bodies are n s vividly diff]5t z are ^? :i* our railway p f9d necess>y4 ,!re is a p>ticul>ly beautiful d\ble /> ( ?is k9d 9 ! con/ellation ( ! ,swan4 ,y c\ld make an imitation ( x by bor+ two holes1 ) a r$-hot ne$le1 9 a piece ( c>d1 & !n cov]+ "o ( ^! holes ) a small bit ( ! topaz-color$ gelat9e ) :i* ,*ri/mas crack]s are made4 ,! o!r /> is to be simil>ly color$ ) blue gelat9e4 ,a slide made on ?is pr9ciple plac$ 9 ! lant]n gives a v good repres5tation ( ^! two />s on ! scre54 ,!re are _m o!r color$ d\bles besides ?is "o2 &1 inde$1 x is notewor?y t we h>dly ev] f9d a blue or a gre5 /> by itself 9 ! sky2 x is always z a memb] ( "o ( ^! pairs4 ,,h[ ,,we ,,f9d ,,:at ,,! ,,/>s ,,are ,,made ,,(4 ,"h is a piece ( /one4 ,if ,i want$ to "k :at x 0 compos$ (1 ,i %\ld ask a *emi/ to tell me4 ,he w\ld take x into 8 laboratory1 & fir/ cru% x into p[d]1 & !n1 ) 8 te/ tubes1 & ) ! liquids :i* 8 bottles conta91 & 8 weigh+ scales1 & o!r app>atus1 he w tell all ab\t x2 !re is s mu* ( ?is1 & s mu* ( t1 & pl5ty ( ?is1 & none at all ( t4 ,b n[1 suppose y ask ?is *emi/ to tell y :at ! sun is made (1 or "o ( ! />s4 ,( c\rse1 y h n a sample ( x to give him2 h[1 !n1 c he possibly f9d out any?+ ab\t x8 ,well1 he c tell y some?+1 & ?is is ! wond]ful discov]y t ,i want to expla9 to y4 ,we n[ put d[n ! gas1 & ,i k9dle a brilliant r$ light4 ,p]haps "s ( ^? :om ,i see be=e me h occasionally v5tur$ on ! some:at dang]\s practice ( mak+ fireworks4 ,if !re is any boy "h :o has ev] con/ruct$ sky-rockets1 & put ! little balls into ! top :i* are to burn ) su* vivid colors :5 ! explosion takes place1 he w "k t ! sub/ance :i* t+$ t r$ fire mu/ h be5 /rontium4 ,he w recognize x by ! color2 because /rontium gives a r$ light :i* no?+ else w give4 ,"h are "s ( ^! lightn+ pap]s1 z !y are call$2 !y are v pretty & v h>mless2 & ^!1 too1 give brilliant r$ fla%es z ,i ?r[ !m4 ,! r$ t9t has1 no d\bt1 be5 produc$ by /rontium also4 ,y see we recogniz$ ! sub/ance simply by ! color ( ! light x produc$ :5 burn+4 ,p]haps "s ( y h tri$ to make a gho/ at ,*ri/mas by dress+ up 9 a %eet1 & be>+ 9 y\r h& a ladle blaz+ ) a mixture ( common salt & spirits ( w9e1 ! effect produc$ be+ a mo/ gha/ly "o4 ,"s mammas w h>dly ?ank me = ?is sugge/ion1 unless ,i add t ! gho/ mu/ walk ab\t cauti\sly1 = o!rwise ! blaz+ _s w\ld be v apt to produce conflagrations ( a k9d m ext5sive ?an ^? int5d$4 ,h[ev]1 by ! k9dness ( ,pr(essor ,dew>1 ,i am enabl$ to %[ ! ph5om5on on a spl5did scale1 & also free f all dang]4 ,i k9dle a vivid flame ( an int5sely yell[ color1 :i* ,i ?9k ! ladies w unanim\sly agree is n at all becom+ to _! complexions1 :ile ! pretty dresses h lo/ _! v>iety ( colors4 ,"h is a nice b\quet1 & yet y c h>dly di/+ui% ! gre5 ( ! leaves f ! brilliant colors ( ! fl[]s1 except by trifl+ diff]5ces ( %ade4 ,expose to ?is light a numb] ( pieces ( v>i\sly color$ ribbon1 p9k & r$ & gre5 & blue1 & _! beauty is gone2 & yet we are told t ?is yell[ is a p]fectly pure color2 9 fact1 ! pure/ color t c be produc$4 ,i ?9k we h to be ?ankful t ! light :i* our good sun s5ds u does n possess purity ( t description4 ,!re is "o sub/ance :i* w produce t yell[ light2 x is a curi\s metal call$ sodium--a metal s s(t t y c cut x ) a knife1 & s light t x w float on wat]2 :ile1 /ill m /range1 x actually takes fire ! mom5t x is dropp$ on ! wat]4 ,x is only 9 a *emical laboratory t y w be likely to meet ) ! actual metallic sodium1 yet 9 o!r =ms ! sub/ance is "o ( ! mo/ abundant 9 nature4 ,inde$1 common salt is no?+ b sodium closely unit$ ) a mo/ poison\s gas1 a few respirations ( :i* w\ld kill y4 ,b ?is /range metal & ?is noxi\s gas1 :5 unit$1 become simply ! salt = our eggs at breakfa/4 ,?is pure yell[ light1 :]ev] x is se51 ei!r 9 ! flame ( spirits ( w9e mix$ ) salt or 9 t great blaze at :i* we h be5 look+1 is *>act]i/ic ( sodium4 ,:]ev] y see t p>ticul> k9d ( light1 y "k t sodium mu/ h be5 pres5t 9 ! body f :i* x came4 ,we h accord+ly le>n$ to recognize two sub/ances1 namely1 /rontium & sodium1 by ! diff]5t lights :i* !y give out :5 burn+4 ,to ^! two metals we may add a ?ird4 ,"h is a /rip ( :ite metallic ribbon4 ,x is call$ magnesium4 ,x seems l a bit ( t9 at ! fir/ glance1 b inde$ x is a v diff]5t sub/ance f t92 =1 look1 :5 ,i hold x 9 ! _s-lamp1 ! /rip ( metal imm$iately takes fire1 & burns ) a :ite light s dazzl+ t x pales ! gas-flames to insignificance4 ,!re is no o!r sub/ance :i* w1 :5 k9dl$1 give t p>ticul> k9d ( light :i* we see f magnesium4 ,i c recomm5d ?is little exp]im5t z q suitable = try+ at home2 y c buy a bit ( magnesium ribbon = a trifle at ! optician's2 x _c explode or d any h>m1 nor w y get into any tr\ble ) ! au?orities provid$ y hold x :5 burn+ ov] a tray or a newspap]1 s z to prev5t ! :ite a%es f fall+ on ! c>pet4 ,!re are1 9 nature1 a numb] ( simple bodies call$ elem5ts4 ,e "o ( ^!1 :5 ignit$ "u suitable conditions1 emits a light :i* belongs to x alone1 & by :i* x c be di/+ui%$ f e o!r sub/ance4 ,i d n say t we c try ! exp]im5ts 9 ! simple way ,i h "h indicat$4 ,_m ( ! mat]ials w yield light :i* w require to be /udi$ by mu* m elaborate artifices ?an ^? :i* h suffic$ = u4 ,b y see t ! me?od af=ds a means ( f9d+ out ! actual sub/ances pres5t 9 ! sun or 9 ! />s4 ,!re is a practical difficulty 9 ! fact t ea* ( ! heav5ly bodies conta9s a numb] ( diff]5t elem5ts2 s t 9 ! light x s5ds u ! hues aris+ f di/9ct sub/ances are bl5d$ into "o beam4 ,! fir/ ?+ to be done is to get "s way ( splitt+ up a beam ( light1 s z to discov] ! compon5ts ( :i* x is made4 ,y might h a ske9 ( silks ( diff]5t hues tangl$ toge!r1 & ?is w\ld be l ! sunbeam z we receive x 9 its unsort$ condition4 ,h[ %all we untangle ! light f ! sun or a />8 ,i w %[ y by a simple exp]im5t4 ,"h is a beam f ! electric light2 beautifully :ite & bright1 is x n8 ,x looks s pure & simple1 b yet t beam is compos$ ( all sorts ( colors m+l$ toge!r1 9 su* proportions z to =m :ite light4 ,i take a w$ge-%ap$ piece ( glass call$ a prism1 & :5 ,i introduce x into ! c\rse ( ! beam1 y see ! trans=mation t has tak5 place 7,fig4 #he74 ,in/ead ( ! :ite light y h n[ all ! colors ( ! ra9b[--r$1 orange1 yell[1 gre51 blue1 indigo1 violet1 m>k$ by _! initial lett]s 9 ! figure4 ,^! colors are v beautiful1 b !y are transi5t1 = ! mom5t we take away ! prism !y all unite aga9 to =m :ite light4 ,y see :at ! prism has done2 x has b5t all ! light 9 pass+ ?r\gh x2 b x is m effective 9 b5d+ ! blue ?an ! r$1 & consequ5tly ! blue is c>ri$ away mu* fur!r ?an ! r$4 ,su* is ! way 9 :i* we /udy ! composition ( a heav5ly body4 ,we take a beam ( its light1 we pass x ?r\gh a prism1 & imm$iately x is sep>at$ into its compon5ts2 !n we comp>e :at we f9d ) ! lights giv5 by ! diff]5t elem5ts1 & ?us we are enabl$ to discov] ! sub/ances :i* exi/ 9 ! di/ant object ^: light we h exam9$4 ,i d n mean to say t ! me?od is a simple "o2 all ,i am endeavor+ to %[ is a g5]al outl9e ( ! way 9 :i* we h discov]$ ! mat]ials pres5t 9 ! />s4 ,! in/rum5t t is employ$ = ?is purpose is call$ ! spectroscope4 ,& p]haps y may rememb] t "n by ^! l9es1 :i* ,i h he>d f an a/ronomical fri5d3-- ,illu/ration3 ,,fig4 #he4--;,h[ to split up a ,ray ( ,light4 8,tw9kle1 tw9kle1 little />1 ,n[ we f9d out :at y are1 ,:5 unto ! midnight sky1 ,we ! spectroscope apply40 ,i am sure x w int]e/ ev]ybody to "k t ! elem5ts :i* ! />s conta9 are n altoge!r diff]5t f ^? ( :i* ! e>? is made4 ,x is true !re may be sub/ances 9 ! />s ( :i* we "k no?+ "h2 b x is c]ta9 t _m ( ! mo/ common elem5ts on ! e>? are pres5t 9 ! mo/ di/ant bodies4 ,i %all only m5tion "o1 ! metal iron4 ,t useful sub/ance has be5 f\nd 9 "s ( ! />s :i* lie at almo/ incalculable di/ances f ! e>?4 ,,! ,,nebul4 ,9 draw+ t[>ds ! close ( ^! lectures ,i mu/ say a few words ab\t "s dim & my/]i\s objects to :i* we h n yet allud$4 ,!y are :at are call$ nebul1 or little cl\ds2 & 9 "o s5se !y are ju/ly call$ little1 = ea* ( !m occupies b a v small spot 9 ! sky z comp>$ ) t :i* w\ld be fill$ by an ord9>y cl\d 9 our air4 ,! nebul are1 h[ev]1 objects ( ! mo/ /up5d\s proportions4 ,7 our e>? & ?\s&s ( millions ( bodies q z big all put toge!r1 !y w\ld n be ne>ly s great z "o ( ^! nebul4 ,a/ronom]s reckon up ! v>i\s nebul by ?\s&s1 b ,i mu/ add t mo/ ( !m are app>5tly fa9t & un9t]e/+4 ,a nebula is sometimes liable to be mi/ak5 = a comet4 ,! comet is1 z ,i h already expla9$1 at once di/+ui%$ by ! fact t x is mov+ & *ang+ its appe>ance f h\r to h\r1 :ile scores ( ye>s elapse )\t *anges 9 ! aspect or position ( a nebula4 ,! mo/ p[]ful telescopes are employ$ 9 obs]v+ ^! fa9t objects4 ,i take ?is opportunity ( %[+ a picture ( an in/rum5t suitable = su* obs]vations4 ,x is ! great reflector ( ! ,p>is ,obs]vatory 7,fig4 #hg74 ,illu/ration3 ,,fig4 #hf4--,! ,r+ ,nebula 9 ,lyra1 "u ,diff]5t ,telescopic ,p[]s4 ,!re are su* multitudes ( nebul t ,i c only %[ a few ( ! m rem>kable k9ds4 ,9 ,fig4 #hf w be se5 pictures ( a curi\s object 9 ! con/ellation ( ,lyra se5 "u diff]5t telescopic p[]s4 ,?is is a gigantic r+ ( lum9\s gas4 ,to judge ( ! size ( ?is r+ let u suppose t a railway 7 laid across x1 & ! tra9 y ent]$ at "o side 0 n to /op until x rea*$ ! o!r side1 h[ long d y ?9k ?is j\rney w\ld require8 ,i recollect "s "t ago a picture 9 ,pun* :i* %[$ a tra9 ab\t to />t f ,london to ,brighton1 & ! gu>d walk+ up & d[n ann\nc+ to ! pass5g]s ! al>m+ fact t 8?is tra9 /ops n[h]e40 ,an old g5tleman 0 se5 va9ly ge/iculat+ out ( ! w9d[ & implor+ to be let out ere ! frightful j\rney 0 comm5c$4 ,9 ! nebul> railway ! pass5g]s w\ld almo/ require su* a w>n+4 ,illu/ration3 ,,fig4 #hg4--;,a ,great ,reflect+ ,telescope4 ,let ! tra9 />t at a spe$ ( a mile a m9ute1 y w\ld ?9k1 surely1 t x mu/ soon cross ! r+4 ,b ! m9utes pass1 an h\r has elaps$2 s ! di/ance mu/ be sixty miles1 at all ev5ts4 ,! h\rs creep on into days1 ! days advance into ye>s1 & /ill ! tra9 goes on4 ,! ye>s w\ld l5g!n out into c5turies1 & ev5 :5 ! tra9 _h be5 ru%+ on = a ?\s& ye>s ) an unabat$ spe$ ( a mile a m9ute1 ! j\rney w\ld c]ta9ly n h be5 complet$4 ,nor d ,i v5ture to say :at ages mu/ elapse ere ! t]m9us at ! o!r side ( ! r+ nebula w\ld be rea*$4 ,a clu/] ( />s view$ 9 a small telescope w (t5 seem l a nebula1 = ! rays ( ! />s become bl5d$4 ,a p[]ful telescope w1 h[ev]1 dispel ! illusion & reveal ! sep>ate />s4 ,x 01 !re=e1 ?\ght t all ! nebul might be m]ely clu/]s s exce$+ly remote t our mightie/ in/rum5ts fail$ to resolve !m into />s4 ,b ?is is n[ kn[n n to be ! case4 ,_m ( ^! objects are really masses ( gl[+ gas2 su* are1 = in/ance1 ! r+ nebul1 ( :i* ,i h j spok51 & ! =m ( :i* ,i c simulate by a pretty exp]im5t4 ,illu/ration3 ,,fig4 #hh4--;,h[ to make ! ,smoke-r+s4 ,we take a l>ge box ) a r\nd hole cut 9 "o face1 & a canvas back at ! opposite side4 ,i fir/ fill ?is box ) smoke1 & !re are diff]5t ways ( do+ s4 ,burn+ br[n pap] does n answ] well1 because ! supply ( smoke is too irregul> & ! pap] itself is apt to blaze4 ,a little bit ( phosphorus set on fire yields copi\s smoke1 b x w\ld be apt to make p c\gh1 &1 besides1 phosphorus is a dang]\s ?+ to h&le incauti\sly1 & ,i d n want to sugge/ any?+ :i* might be productive ( disa/] if ! exp]im5t 0 repeat$ at home4 ,a little wisp ( hay1 slightly damp$ & light$1 w safely yield a suffici5t supply1 & y ne$ n h an elaborate box l ?is2 any k9d ( old pack+-case1 or ev5 a b&-box ) a du/] /ret*$ across its op5 top & a r\nd hole cut 9 ! bottom1 w answ] capitally4 ,:ile ,i h be5 speak+1 my assi/ant has k9dly fill$ ?is box ) smoke1 & 9 ord] to h a suffici5t supply1 & "o :i* %all be z little disagreeable z possible1 he has mix$ toge!r ! fumes ( hydro*loric acid & ammonia f two retorts %[n 9 ,fig4 #hh4 ,a /ill simpl] way ( do+ ! same ?+ is to put a little common salt 9 a sauc] & p\r ov] x a little oil ( vitriol2 ?is is put into ! box1 & ov] ! floor ( ! box common smell+-salts is to be scatt]$4 ,y see !re are d5se volumes ( :ite smoke escap+ f e corn] ( ! box4 ,i uncov] ! op5+ & give a pu% to ! canvas1 & y see a beautiful r+ fly+ across ! room2 ano!r r+ & ano!r foll[4 ,if y 7 ne> en\gh to feel ! r+1 y w\ld exp]i5ce a little puff ( w9d2 ,i c %[ ?is by bl[+ out a c&le :i* is at ! o!r end ( ! table4 ,^! r+s are made by ! air :i* goes into a sort ( eddy z x passes ?r\gh ! hole4 ,all ! smoke does is to r5d] ! air visible4 ,! smoke-r+ is inde$ q ela/ic4 ,if we s5d a second r+ hurri$ly aft] ! fir/1 we c produce a collision1 & y see ea* ( ! two r+s rema9s unbrok51 ?\gh bo? are quiv]+ f ! effects ( ! bl[4 ,!y are beautifully %[n along ! beam ( ! electric lamp1 or1 bett] /ill1 along a sunbeam4 ,we c make _m exp]im5ts ) smoke-r+s4 ,"h1 = in/ance1 ,i take an empty box1 s f> z smoke is conc]n$1 b air-r+s c be driv5 =? f x1 ?\gh y _c see !m1 b y c feel !m ev5 at ! o!r side ( ! room1 & !y w1 z y see1 bl[ out a c&le4 ,i c also %oot invisible air-r+s at a column ( smoke1 & :5 ! missile /rikes ! smoke x produces a little commotion & em]ges on ! o!r side1 c>ry+ ) x en\gh ( ! smoke to r5d] itself visible1 :ile ! solid black look+ r+ ( air is se5 9 ! int]ior4 ,/ill m /rik+ is ano!r way ( produc+ ^! r+s1 = ,i *>ge ?is box ) ammonia1 & ! r+s f x y _c see4 ,!re is a column ( ! vapor ( hydro*loric acid t also y _c see2 b :5 ! invisible r+ ent]s ! invisible column1 !n a sudd5 union takes place betwe5 ! vapor ( ! ammonia & ! vapor ( ! hydro*loric acid2 ! result is a solid :ite sub/ance 9 extremely f9e du/ :i* r5d]s ! r+ in/antly visible4 ,,:at ,,! ,,nebul ,,are ,,made ,,(4 ,!re is a fundam5tal diff]5ce betwe5 ! illum9ation ( ^! little r+s t ,i h %[n y & ! great r+s 9 ! heav5s4 ,i _h to illum9ate our smoke ) ! help ( ! electric light1 =1 unless ,i _h done s1 y w\ld n h be5 able to see !m4 ,?is :ite sub/ance =m$ by ! union ( ammonia & hydro*loric acid has1 ( c\rse1 no m light ( its own ?an a piece ( *alk2 x requires o!r light fall+ ^u x to make x visible4 ,7 ! r+ nebula 9 ,lyra compos$ ( ?is mat]ial1 we c\ld n see x4 ,! sunlight :i* illum9ates ! planets might1 ( c\rse1 light up su* an object z ! r+1 if x 7 comp>atively ne> u2 b ,lyra is at su* a /up5d\s di/ance t any light :i* ! sun c\ld s5d out !re w\ld be j z feeble z ! light we receive f a fix$ />4 ,%\ld we be able to %[ our smoke-r+s1 = in/ance1 if1 in/ead ( hav+ ! electric light1 ,i m]ely cut a hole 9 ! ceil+ & all[$ ! feeble tw9kle ( a /> 9 ! ,great ,be> to %9e ?r\gh8 ,9 a simil> way ! sunbeams w\ld be utt]ly p[]less to effect any illum9ation ( objects 9 ^! /ell> di/ances4 ,if ! sun 7 to be ext+ui%$ altoge!r1 ! calamity w\ld no d\bt be a v dire "o s f> z we are conc]n$1 b ! effect on ! o!r cele/ial bodies 7moon & planets except$7 w\ld be ( ! slighte/ possible description4 ,all ! />s ( heav5 w\ld cont9ue to %9e z be=e4 ,n a po9t 9 "o ( ! con/ellations w\ld be alt]$1 n a v>iation 9 ! brightness1 n a *ange 9 ! hue ( any /> c\ld be notic$4 ,! ?\s&s ( nebul & clu/]s w\ld be absolutely unalt]$2 9 fact1 ! total ext9ction ( ! sun w\ld be h>dly rem>k$ 9 ! newspap]s publi%$ 9 ! ,pleiades or 9 ,orion4 ,!re might possibly be a little l9e some:]e 9 an odd corn] to ! effect 8,mr4 ,s-&-,s1 our well-kn[n a/ronom]1 has notic$ t a t9y />1 inconspicu\s to ! eye1 & absolutely ( no importance :atev]1 has n[ become invisible40 ,if1 !re=e1 x be n ! sun :i* lights up ?is nebula1 :]e else c be ! s\rce ( its illum9ation8 ,!re c be no o!r /> 9 ! neighborhood adequate to ! purpose1 =1 ( c\rse1 su* an object w\ld be brilliant to u if x 7 l>ge en\gh & bright en\gh to imp>t suffici5t illum9ation to ! nebula4 ,x w\ld be absurd to say t y c\ld see a man's face by ! light ( a c&le :ile ! c&le itself 0 too fa9t or too di/ant to be visible4 ,! actual facts are1 ( c\rse1 ! o!r way2 ! c&le might be visible1 :5 x 0 impossible to disc]n ! face :i* x light$4 ,h5ce we le>n t ! r+ nebula mu/ %9e by "s light ( its own1 & n[ we h to consid] h[ x c be possible = su* mat]ial to be self-lum9\s4 ,! light ( a nebula does n seem to be l flame2 x c1 p]haps1 be bett] repres5t$ by ! pretty electrical exp]im5t ) ,geissl]'s tubes4 ,^! are glass vessels ( v>i\s %apes1 & !y are all v ne>ly empty1 z y w und]/& :5 ,i tell y ! way 9 :i* !y h be5 prep>$4 ,a little gas 0 all[$ into ea* tube1 & !n almo/ all ! gas 0 tak5 out aga91 s t only a m]e trace 0 left4 ,i pass a curr5t ( electricity ?r\gh ^! tubes1 & n[ y see !y are gl[+ ) beautiful colors4 ,! diff]5t gases give out lights ( diff]5t hues1 & ! optician has ex]t$ 8 skill s z to make ! effect z beautiful z possible4 ,! electricity1 9 pass+ ?r\gh ^! tubes1 heats ! gas :i* !y conta91 & makes x gl[2 & j z ?is gas c1 :5 heat$ suffici5tly1 give out light1 s does ! great nebula1 :i* is a mass ( gas pois$ 9 space1 become visible 9 virtue ( ! heat :i* x conta9s4 ,we are n left q 9 d\bt z to ! con/itution ( ^! gase\s nebul1 = we c submit _! light to ! prism 9 ! way ,i expla9$ :5 we 7 speak+ ( ! />s4 ,di/ant ?\gh t r+ 9 ,lyra may be1 x is int]e/+ to le>n t ! +r$i5ts f :i* x is made are n entirely diff]5t f sub/ances we "k on our e>?4 ,! wat] 9 ?is glass1 & e drop ( wat]1 is =m$ by ! union ( two gases1 ( :i* "o is hydrog54 ,?is is an extremely light mat]ial1 z y see by a little balloon :i* asc5ds s prettily :5 fill$ ) x4 ,hydrog5 also burns v readily1 ?\gh ! flame is almo/ invisible4 ,:5 ,i bl[ a jet ( oxyg5 ?r\gh ! hydrog51 ,i produce a little flame ) a v int5se heat4 ,= in/ance1 ,i hold a /eel p5 9 ! flame1 & x gl[s & sputt]s1 & falls d[n 9 :ite-hot drops4 ,x is ne$less to say t1 z a con/itu5t ( wat]1 hydrog5 is "o ( ! mo/ important elem5ts on ?is e>?4 ,x is1 !re=e1 ( int]e/ to le>n t hydrog5 9 "s =m or o!r is a con/itu5t ( ! mo/ di/ant objects 9 space t ! telescope has reveal$4 ,,photograph+ ,,! ,,nebul4 ,( late ye>s we h le>n$ a great deal ab\t nebul1 by ! help :i* photography has giv5 to u4 ,look at ?is gr\p ( />s :i* con/itutes t beautiful little configuration kn[n z ! ,pleiades 7,fig4 #hi74 ,x looks l a m9iature repres5tation ( ! ,great ,be>2 9 fact1 x w\ld be f> m appropriate to call ! ,pleiades ! ,little ,be> ?an to apply t title to ano!r q diff]5t con/ellation1 z has un=tunately be5 done4 ,! ,pleiades =m a gr\p conta9+ six or sev5 />s visible to ! ord9>y eye1 ?\gh p]sons end[$ ) exceptionally good vision c usually see a few m4 ,9 an op]a-glass ! ,pleiades becomes a beautiful spectacle1 ?\gh 9 a l>ge telescope ! />s appe> too f> ap>t to make a really effective clu/]4 ,:5 ,mr4 ,rob]ts took a photograph ( ! ,pleiades he plac$ a highly s5sitive plate 9 8 telescope1 & on t plate ! ,pleiades engrav$ _! picture ) _! own light4 ,he left ! plate expos$ = h\rs1 & on develop+ x n only 7 ! />s se51 b !re 7 also pat*es ( fa9t light due to ! pres5ce ( nebula4 ,x c\ld n be said t ! objects on ! plate 7 fallaci\s1 = ano!r photograph 0 tak51 :5 ! same appe>ances 7 reproduc$4 ,illu/ration3 ,,fig4 #hi4--,! ,pleiades4 ,:5 we look at t pretty gr\p ( />s :i* has attract$ admiration dur+ all "t1 we are to ?9k t "s ( ^? />s are m]ely ! bright po9ts 9 a va/ nebula1 invisible to our unaid$ eyes or ev5 to our mighty telescopes1 ?\gh capable ( record+ its trace on ! photographic plate4 ,does n ?is give u a greatly increas$ notion ( ! ext5t ( ! univ]se1 :5 we reflect t by photography we are enabl$ to see mu* :i* ! mightie/ ( telescopes _h previ\sly fail$ to disclose8 ,( all ! nebul1 n[ numb]+ "s ?\s&s1 !re is b a s+le "o :i* c be se5 )\t a telescope4 ,x is 9 ! con/ellation ( ,&rom$a1 & on a cle> d>k night c j be se5 ) ! unaid$ eye z a fa9t /a9 ( light on ! sky4 ,x has happ5$ be=e n[ t p]sons notic+ ?is nebula = ! fir/ "t h ?\ght !y _h discov]$ a comet4 ,i w\ld l y to try & f9d out ?is object = y\rselves4 ,if y look at x ) an op]a-glass x appe>s to be di/9ctly elongat$4 ,y c see m ( its /ructure :5 y view x 9 l>g] in/rum5ts1 b its nature 0 nev] made cle> until "s beautiful photographs 7 tak5 by ,mr4 ,rob]ts 7,fig4 #ij74 ,un=tunately1 ! nebula 9 ,&rom$a has n be5 plac$ 9 ! be/ position = its portrait f our po9t ( view4 ,x seems z if x 7 a r flat-%ap$ object1 turn$ ne>ly edgewise t[>ds u4 ,to look at ! patt]n on a plate1 y w\ld naturally hold ! plate s z to be able to look at x squ>ely4 ,! patt]n w\ld n be se5 well if ! plate 7 s tilt$ t its edge 0 turn$ t[>ds y4 ,t seems to be ne>ly ! way 9 :i* we are =c$ to view ! nebula 9 ,&rom$a4 ,we c trace 9 ! photograph "s divisions ext5d+ entirely r\nd ! nebula1 %[+ t x seems to be =m$ ( a s]ies ( r+s2 & !re are "s outly+ portions :i* =m "p ( ! same sy/em4 ,truly ?is is a m>vell\s object4 ,x is impossible = u to =m any conception ( ! true dim5sions ( ?is gigantic nebula2 x is s f> (f t we h nev] yet be5 able to det]m9e its di/ance4 ,inde$1 ,i may take ?is opportunity ( rem>k+ t no a/ronom] has yet succe$$ 9 asc]ta9+ ! di/ance ( any nebula4 ,ev]y?+1 h[ev]1 po9ts to ! conclusion t !y are at lea/ z f> z ! />s4 ,illu/ration3 ,,fig4 #ij4--,! ,great ,nebula 9 ,&rom$a4 7,f ,mr4 ,rob]ts' ,photograph47 ,x is almo/ impossible to apply ! me?ods :i* we use 9 f9d+ ! di/ance ( a /> to ! discov]y ( ! di/ance ( ! nebul4 ,^! flimsy bodies are usually too ill-def9$ to admit ( be+ measur$ ) ! precision & ! delicacy requir$ = ! det]m9ation ( di/ance4 ,! measurem5ts necess>y = ?is purpose c only be made f "o />-l po9t to ano!r simil> po9t4 ,if we c\ld *oose a /> 9 ! nebula & det]m9e its di/ance1 !n1 ( c\rse1 we %\ld h ! di/ance ( ! nebula itself2 b ! difficulty is t we h1 9 g5]al1 no means ( kn[+ :e!r ! /> does actually lie 9 ! object4 ,x may1 = any?+ we c tell1 lie billions ( miles ne>] to u1 or billions ( miles fur!r (f1 &1 by m]ely happ5+ to lie 9 ! l9e ( sight1 appe> to glimm] 9 ! nebula itself4 ,illu/ration3 ,,fig4 #ia4--,to %[ h[ ,small ! ,sol> ,sy/em is comp>$ ) a ,great ,nebula4 ,if we h any assurance t ! /> is surr\nd$ by a mass ( ?is gl[+ vapor1 !n x may be possible to measure t nebula's di/ance4 ,x w occasionally happ5 t gr\nds c be f\nd = believ+ t a /> :i* appe>s to be 9 ! gl[+ gas does v]itably lie !re91 & is n m]ely se5 9 ! same direction4 ,!re are hundr$s ( />s visible on a good draw+ or a good photograph ( ! fam\s object 9 ,&rom$a1 & d\btless l>ge numb]s ( ^! are m]ely />s :i* happ5 to lie 9 ! same l9e ( sight4 ,! peculi> circum/ances att5d+ ! hi/ory ( "o /> seem1 h[ev]1 to w>rant u 9 mak+ ! assumption t x 0 c]ta9ly 9 ! nebula4 ,! hi/ory ( ?is /> is a rem>kable "o4 ,x sudd5ly k9dl$ f invisibility into brilliancy4 ,h[ is a *ange s rapid 9 ! lu/re ( a /> to be acc\nt$ =8 ,9 a few days its brightness _h und]gone an extraord9>y increase4 ,( c\rse1 ?is does n tell u = c]ta9 t ! /> lay 9 ! gl[+ gas2 b ! mo/ rational explanation t ,i h he>d (f]$ ( ?is occurr5ce is t due1 ,i believe1 to my fri5d ,mr4 ,monck4 ,he has sugge/$ t ! sudd5 outbreak 9 brilliancy might be acc\nt$ = on ! same pr9ciples z ^? by :i* we expla9 ! ignition ( meteors 9 our atmosph]e4 ,if a d>k />1 mov+ along ) t]rific spe$ ?r\gh space1 7 sudd5ly to plunge into a d5se region ( ! nebula1 heat & light mu/ be evolv$ 9 suffici5t abundance to trans=m ! /> into a brilliant object4 ,if1 !re=e1 we knew ! di/ance ( ?is /> at ! "t x 0 9 ,&rom$a1 we %\ld1 ( c\rse1 le>n ! di/ance ( t int]e/+ object4 ,?is has be5 attempt$1 & x has ?us be5 prov$ t ! ,great ,nebula mu/ be v mu* fur!r f u ?an is t /> ( ^: di/ance ,i attempt$ "s "t ago to give y a notion4 ,we ?us realize ! enorm\s size ( ! ,great ,nebula4 ,x appe>s t if1 on a map ( ?is object1 we 7 to lay d[n1 accurately to scale1 a map ( ! sol> sy/em1 putt+ ! sun 9 ! c5tre & all ! planets ar\nd 9 _! true proportions out to ! b\nd>y trac$ by ,neptune1 ?is area1 va/ ?\gh x is1 w\ld be a m]e speck on ! draw+ ( ! object4 ,our sy/em w\ld h to be enorm\sly bigg] be=e x suffic$ to cov] any?+ l ! area ( ! sky includ$ 9 "o ( ^! great objects4 ,"h is a sket* ( a nebula 7,fig4 #ia71 & ne> x ,i h m>k$ a dot :i* is to indicate our sol> sy/em4 ,we may feel confid5t t ! ,great ,nebula is at ! v lea/ z mighty z ?is proportion w\ld indicate4 ,,conclusion4 ,& n[1 my "y fri5ds1 ,i am draw+ ne> ! close ( t c\rse ( lectures :i* has occupi$ u1 ,i hope y w ?9k n unpr(itably1 = a portion ( our ,*ri/mas holidays4 ,we h spok5 ( ! sun & ( ! moon1 ( comets & ( />s1 & ,i h frequ5tly _h occasion to allude to ! relative position ( our e>? 9 ! univ]se4 ,no d\bt x is a noble globe :i* we inhabit1 b ,i h fail$ 9 my purpose if ,i h n %[n y h[ insignificant is ?is e>? :5 comp>$ ) ! va/ ext5t ( "s ( ! o!r bodies t ab\nd 9 space4 ,we h1 h[ev]1 be5 end[$ ) a feel+ ( curiosity :i* makes u long to "k ( ?+s beyond ! conf9es ( our own e>?4 ,a/ronom]s c tell u a little1 b too (t5 only a little4 ,!y w say--,t is a />1 & ,t is a planet1 & ,t is s big1 & ,t s f>2 su* is ! meagre /yle ( in=mation ) :i* we (t5 h to be cont5t4 ,! a/ronom]s :o live on o!r worlds1 if _! faculties be 9 any degree comp>able ) ours1 mu/ be simil>ly ignorant ) reg>d to ?is e>?4 ,inhabitants ( our fell[-planets c "k h>dly any?+ m ?an t ! e>? on :i* we dwell is a globe #hjjj miles across1 ) _m cl\ds ar\nd u4 ,"s ( ! planets w\ld n ev5 pay u ! complim5t ( recogniz+ our exi/5ce2 :ile f ! o!r sy/ems--! c\ntless o!r sy/ems--( space we are absolutely imp]ceptible & unkn[n4 ,out ( all ! millions ( bodies :i* we c see1 y c\ld v ne>ly c\nt on y\r f+]s ^? f :i* our e>? w\ld be visible4 ,?is reflection is calculat$ to %[ u h[ va/ mu/ be ! real ext5t ( t univ]se ar\nd u4 ,"h is our globe1 ) its inhabitants1 ) its great cont95ts1 ) its oceans1 ) its empires1 its k+doms1 ) its arts1 its comm]ce1 its lit]ature1 its sci5ces1 & yet x w\ld seem t all ^! ?+s are absolutely unkn[n to any inhabitants t may exi/ else:]e4 ,i d n ?9k t any reasonable p]son w d\bt t !re mu/ be inhabitants else:]e4 ,!re are millions ( globes1 _m ( !m m spl5did ?an ours4 ,surely x w\ld be presumptu\s to say t ?is is ! only "o ( all ! bodies 9 ! univ]se on ! surface ( :i* life1 ) all t life involves1 is manife/$4 ,y w r ?9k t our globe is b "o 9 ! mighty fabric1 & t o!r globes may teem ) int]e/ j z ours does4 ,we c1 ( c\rse1 make no conjecture z to :at ! nature ( ! life may be else:]e4 ,c\ld a travell] visit "s o!r globes & br+ back specim5s ( ! natural objects t he f\nd !re1 no collections t ! _w has ev] se5 c\ld rival !m 9 int]e/4 ,:5 ,i g into ! ,briti% ,natural ,hi/ory ,museum & look ar\nd t m>vell\s collection1 x awak5s 9 me a feel+ ( solemnity4 ,i see !re ! rema9s ( mighty ext9ct animals :i* once roam$ ov] ?is e>?2 also objects :i* h be5 dr$g$ f ! bottom ( ! sea at a dep? ( "s miles2 !re ,i c exam9e cry/als :i* h requir$ incalculable ages = _! =mation2 & !re ,i look at meteorites :i* h travell$ f ! heav5s above d[n on to ! e>? b5ea?4 ,su* sights1 & ! reflections !y awak51 br+ be=e u 9 an impos+ mann] ! ph5om5a ( our e>?1 & ! ext5t & int]e/ ( its pa/ hi/ory4 ,oliv] ,w5dell ,holmes said t ! only way to see ! ,briti% ,museum 0 to take lodg+s close by :5 y 7 a boy1 & to /ay 9 ! ,museum f n9e to five e day until y 7 an old man2 !n y w\ld beg9 to h "s notion ( :at ?is ,in/itution conta9s4 ,?9k :at millions ( ,briti% ,museums w\ld be requir$ 7 ! univ]se to be adequately illu/rat$3 "o museum = ! e>?1 ano!r = ,m>s1 ano!r = ,v5us--b x w\ld be useless attempt+ to enum]ate !m6 ,mo/ ( u mu/ be cont5t ) acquir+ ! m]e/ %r$ ( in=mation ) reg>d ev5 to our own e>?4 ,p]haps a s*oolboy w ?9k x =tunate t we are s ignorant ) respect to ! cele/ial bodies4 ,:at an awful vi/a ( lessons to be le>n$ w\ld op5 be=e 8 view1 if only we _h a compet5t k ( ! o!r globes :i* surr\nd u 9 space6 ,i %\ld l to illu/rate ! ext5t ( ! univ]se by foll[+ ?is reflection a little fur!r4 ,i %all j ask y to jo9 ) me 9 mak+ a little calculation z to ! ext5t ( ! lessons y w\ld h to le>n if a/ronom]s %\ld succe$ 9 discov]+ "s ( ! ?+s !y want to "k4 ,( c\rse1 all ( u le>n geography & hi/ory4 ,we mu/ "k ! geography ( ! lead+ c\ntries ( ! globe1 & we mu/ h "s k ( _! inhabitants & ( _! gov]nm5t1 _! res\rces & _! civilization4 ,x w\ld seem %ock+ly ignorant n to "k some?+ ab\t ,*9a1 or n to h "s ideas on ! subject ( ,india or ,egypt4 ,! discov]y ( ! ,new ,_w also involves matt]s on :i* e boy & girl has to be in/ruct$4 ,suppos+ we 7 s f> acqua9t$ ) ! o!r globes scatt]$ ?r\gh space t we 7 able to ga9 "s adequate k ( _! geography & natural hi/ory1 ( ! creatures t inhabit !m1 ( _! diff]5t products & climates1 !n ev]ybody w\ld be anxi\s to le>n ^? p>ticul>s2 & ev5 :5 ! novelty _h worn (f1 x w\ld /ill be "r = u to "k some?+ ab\t c\ntries p]haps m popul\s ?an ,*9a1 ab\t nations m opul5t ?an our own1 ab\t battles mighti] ?an ,wat]loo1 ab\t animals & plants f> /rang] ?an any we h ev] dreamt (4 ,an outl9e ( all su* matt]s %\ld1 ( c\rse1 be le>n$1 & z ! am\nt ( in=mation w\ld be r ext5sive1 we w try to cond5se x z mu* z possible4 ,to aid u 9 realiz+ ! full magnific5ce ( t s*eme 9 ! heav5s ( :i* we =m a "p1 ,i %all v5ture to give an illu/ration4 ,let u attempt to =m "s slight conception ( ! numb] & ( ! bulk ( ! books :i* w\ld be necess>y = convey+ an adequate description ( t m>vell\s univ]se ( />s :i* surr\nd u4 ,^! />s be+ suns1 & _m ( !m be+ bright] & l>g] ?an our own sun1 x is b reasonable to presume t !y may be att5d$ by planet>y sy/ems4 ,i d n say t we h any "r to inf] t su* sy/ems are l ours4 ,x is n improbable t _m ( ! suns ar\nd u h a mu* poor] ret9ue ?an t :i* dignifies our sun4 ,on ! o!r h&1 x is j z likely t _m ( ^! o!r suns may be ! c5tres ( sy/ems f> m brilliant & int]e/+1 ) f> great] div]sity ( /ructure1 ) f> m int5sity & v>iety ( life & intellig5ce ?an are f\nd 9 ! sy/em ( :i* we =m a "p4 ,x is only reasonable = u to suppose t1 z our e>? is an av]age planet1 s our sun is an av]age /> bo? 9 size & 9 ! importance ( its att5dants4 ,we may take ! numb] ( />s 9 ! sky at ab\t "o hundr$ millions2 & ?us we see t ! books :i* are to conta9 a description ( ! entire univ]se--or r1 ,i %\ld say1 ( ! entire univ]se t we see--mu/ describe #ajj1jjj1jjj times z mu* z is conta9$ 9 our s+le sy/em4 ,( c\rse1 we "k next to no?+ ( :at ! books %\ld conta92 b we c =m "s conjecture ( ! numb] ( ^? books1 & ?is is ! notion to :i* ,i n[ ask y\r att5tion4 ,s va/ is ! field ( k t has to be trav]s$1 t we %\ld be oblig$ to compress our descriptions into ! n>r[e/ compass4 ,we beg9 ) a description ( our e>?1 = ne>ly all ! books 9 ! libr>ies t exi/ at ?is mom5t are devot$ to subjects connect$ ) ?is e>?4 ,!y include v>i\s bran*es ( hi/ory1 innum]able languages & lit]atures & religions1 ev]y?+ relat+ to life on ?is globe1 to its hi/ory 9 pa/ geological times1 to its geography1 to its politics1 to e v>iety ( manufacture & agriculture1 & all ! innum]able matt]s :i* conc]n our e>?'s inhabitants1 pa/ & pres5t4 ,b ?is trem5d\s body ( k mu/ be mu* cond5s$ be=e x w\ld be small en\gh to retire to its j position 9 ! great cele/ial libr>y4 ,i c only all[ to ! e>? "o volume ( ab\t #ejj pages4 ,ev]y?+ t has to be said ab\t our e>? mu/ be pack$ )9 ?is compass4 ,all t]re/rial languages1 hi/ories1 & sci5ces t _c be includ$ betwe5 its cov]s c f9d no o!r place on our %elves4 ,i _c sp>e any m room4 ,our cele/ial libr>y w be big en\gh1 z y %all pres5tly see4 ,i am claim+ a good deal = our e>? :5 ,i reg>d x z "o ( ! mo/ important bodies 9 ! sol> sy/em4 ,( c\rse x is n ! bigge/--v f> f x2 b x seems z if ! big planets & ! sun 7 n likely to be inhabit$1 s t if we all[ "o o!r volume to ! re/ ( ! sol> sy/em1 x w p]haps be suffici5t1 ?\gh x mu/ be admitt$ t ,v5us1 ( :i* we "k next to no?+1 except t x is z l>ge z ! e>?1 may also be q z full ( life & int]e/4 ,m>s & ,m]cury are also among ! planets ) possible inhabitants4 ,we are1 !re=e1 re/rict+ ! importance ( ! sol> sy/em z mu* z possible1 p]haps ev5 too mu*1 by all[+ x two4 ,)9 ^? two volumes e conceivable ?+ ab\t ! entire sol> sy/em--sun1 planets 7great & small71 moons1 comets1 & meteors--mu/ be includ$1 or else x w\ld n be repres5t$ at all 9 ! great cele/ial libr>y4 ,we %all deal on simil> pr9ciples ) ! o!r sy/ems ?r\gh space4 ,ea* ( ! #ajj1jjj1jjj />s w h two volumes allott$ to x4 ,)9 ! two volumes devot$ to ea* /> we mu/ compress our description ( ! body itself & ( ! sy/em :i* surr\nds x2 ! planets1 _! inhabitants1 hi/ories1 arts1 sci5ces1 & all o!r in=mation4 ,i am n1 rememb]1 discuss+ ! cont5ts1 b only ! numb] ( books we %\ld h to read ere we c\ld obta9 ev5 ! m]e/ outl9e ( ! true magnific5ce ( ! heav5s4 ,let u try to =m "s e/imate z to ! k9d ( libr>y t w\ld be requir$ to accommodate #bjj1jjj1jjj volumes4 ,i suppose a long /raight hall1 s l(ty t !re c\ld be fifty %elves ( books on ea* side4 ,z y ent] y look on ! "r h& & on ! left1 & y see x pack$ f floor to ceil+ ) volumes4 ,we h arrang$ !m accord+ to ! con/ellations4 ,all ! %elves 9 "o "p conta9 ! volumes relat+ to ! worlds 9 ! ,great ,be>1 :ile ^u ! o!r side may repose ranks ^u ranks ( volumes relat+ to ! con/ellation ( ,orion4 ,i %all suppose t ! volumes are ea* ab\t an in* & a half ?ick1 & z !re are fifty %elves on ea* side1 y w easily see t = ea* foot ( its l5g? ! hall w accommodate #hjj books4 ,we c make a little calculation z to ! l5g? ( ?is libr>y1 :i*1 z we walk d[n ?r\gh x1 /ret*es out be=e u 9 a maje/ic corridor1 ) books1 books ev]y:]e4 ,let u cont9ue our /roll1 & z we pass by we f9d ! %elves on bo? sides pack$ ) _! ?\s&s ( volumes2 & we walk on & on1 & /ill see no end to ! vi/a t ev] op5s be=e u4 ,9 fact1 no build+ t 0 ev] yet con/ruct$ w\ld hold ?is /up5d\s libr>y4 ,let ! hall beg9 on ! fur!/ outskirts ( ! we/ ( ,london1 c>ry x ?r\gh ! he>t ( ! city1 & away to ! utmo/ limits ( ! ea/--n a half ( ! entire books c\ld be accommodat$4 ,! mighty corridor w\ld h to be fifty miles long1 & to be pack$ f floor to ceil+ ) fifty %elves ( books on ea* side1 if x is to conta9 ev5 ?is v inadequate description ( ! cont5ts ( ! visible univ]se4 ,imag9e ! solemn feel+s ) :i* we %\ld ent] su* a libr>y1 c\ld x be creat$ by "s miracle6 ,z we took d[n "o ( ! volumes1 ) :at my/]i\s awe %\ld we op5 x1 & read !re9 ( "s va/ _w :i* eye _h nev] se56 ,!re we might le>n /range problems 9 philosophy1 a/oni%+ developm5ts 9 natural hi/ory2 ) :at brea?less int]e/ we %\ld read ( inhabitants ( an organization utt]ly unkn[n to our m]ely t]re/rial exp]i5ce6 ,not)/&+ ! va/ size ( ! libr>y1 ! description ( ea* globe w\ld h to be v scanty4 ,?us1 = in/ance1 9 ! s+le book :i* ref]r$ to ! e>? ,i suppose a little *apt] might be sp>$ to an isl& call$ ,engl&1 & possibly a page or s to its capital1 ,london4 ,simil>ly meagre w\ld h to be ! acc\nts ( ! o!r bodies 9 ! univ]se2 & yet1 = ?is mo/ inadequate ( ab/racts1 a libr>y fifty miles long1 & l9$ closely ) fifty %elves ( books on ea* side1 w\ld be requir$6 ,me?uselah liv$1 we are told1 n9e hundr$ & sixty-n9e ye>s2 b ev5 if he _h atta9$ 8 ?\s&? bir?day he w\ld h _h to read ab\t #cjj ( ^! books ?r\gh e day ( 8 life be=e he accompli%$ ! task ( le>n+ ev5 ! m]e/ outl9e ab\t ! cont5ts ( space4 ,if1 inde$1 we 7 to h a compet5t k ( all ^! o!r globes1 ( all _! c\ntries1 _! geographies1 _! nations1 _! climates1 _! plants1 _! animals1 _! sci5ces1 languages1 arts & lit]atures1 x is n a volume1 or a score ( volumes1 t w\ld be requir$1 b ?\s&s ( books w\ld h to be devot$ to ! description ( ea* _w alone1 j z ?\s&s ( volumes h be5 devot$ to ! affairs ( ?is e>? )\t exhau/+ ! subjects ( int]e/ x pres5ts4 ,hundr$s ( ?\s&s ( libr>ies1 ea* z l>ge z ! ,briti% ,museum1 w\ld n conta9 all t %\ld be writt51 7 we to h any?+ l a detail$ description ( ! univ]se :i* we see4 ,i specially emphasize ! words j writt51 & ,i d s because ! gr&e/ ?\ght ( all1 & t ?\ght ) :i* ,i conclude1 br+s be=e u ! ov]:elm+ ext5t ( ! unse5 univ]se4 ,our telescopes c1 no d\bt1 c>ry our vision to an immeasurable di/ance into ! dep?s ( space4 ,b !re are1 d\btless1 />s beyond ! rea* ( our mightie/ telescopes4 ,!re are />s s remote t !y _c record !mselves on ! mo/ s5sitive ( photographic plates4 ,on ! blackbo>d ,i draw a little circle ) a piece ( *alk4 ,i ?9k ( our e>? z ! c5tre1 & ?is circle w m>k = u ! limit to :i* our greate/ telescopes c s\nd4 ,e /> :i* we see1 or :i* ! photographic plate sees1 lies )9 ?is circle2 b1 are !re no />s outside8 ,x is true t we c nev] see !m1 b x is impossible to believe t space is utt]ly void & empty :]e x lies beyond ! view ( our telescopes4 ,are we to say t inside ?is circle />s1 worlds1 nebul1 & clu/]s are cr[d$1 & t outside !re is no?+8 ,ev]y?+ tea*es u t ?is is n s4 ,we occasionally ga9 accession to our p[] by add+ p]haps an in* to ! diamet] ( our object-glass1 or by erect+ a telescope 9 an improv$ situation on a l(ty m\nta9 peak1 or by procur+ a photographic plate ( increas$ s5sibility4 ,x ?us happ5s t we are enabl$ to ext5d our vision a little fur!r & to make ?is circle a little l>g]1 & ?us to add a little m to ! kn[n inside :i* has be5 won f ! unkn[n outside4 ,:5ev] ?is is done we inv>iably f9d t ! new region ?us conqu]$ is also d5sely fill$ ) />s1 ) clu/]s1 & ) nebul2 x is ?us unreasonable to d\bt t ! re/ ( space also conta9s untold myriads ( objects1 ev5 ?\gh !y may nev]1 by any conceivable improvem5t 9 our in/rum5ts1 be br\ght )9 ! range ( our obs]vation4 ,reflect t ?is circle is comp>atively small ) respect to ! space outside4 ,x occupi$ b a small spot on ?is blackbo>d1 ! blackbo>d itself occupies only a small "p ( ! end ( ! !atre1 :ile ! end ( ! !atre is an area v small comp>$ ) t ( ,london1 ( ,engl&1 ( ! _w1 ( ! sol> sy/em1 ( ! actual di/ance ( ! />s4 ,9 a simil> way ! region ( space :i* is op5 to our inspection is an inconceivably small portion ( ! entire ext5t ( space4 ,! unkn[n outside is s mu* l>g] ?an ! kn[n inside1 x is impossible to express ! proportion4 ,i write d[n unity 9 ?is corn] & a ciph] aft] x to make t51 & six ciph]s aga9 to make t5 millions1 & aga91 six ciph]s m to make t5 billions2 b ,i might write six m1 ay1 ,i might cov] ! :ole ( ?is blackbo>d ) ciph]s1 & ev5 !n ,i %\ld n h got a numb] big en\gh to express h[ greatly ! ext5t ( ! space we _c see exce$s t ( ! space we see4 ,if1 !re=e1 we admit ! fact1 :i* no reasonable p]son c d\bt1 t ?is outside1 ?is unkn[n1 ?is unrea*able &1 to u1 invisible space does really conta9 worlds & sy/ems z does ?is small portion ( space 9 :i* we happ5 to be plac$--!n1 inde$1 we %all beg9 truly to compreh5d ! maje/y ( ! univ]se4 ,:at figures are to express ! myriads ( />s t %\ld =m a suitable population = a space inconceivably great] ?an t :i* conta9s #ajj1jjj1jjj />s8 ,b our imag9ation w ext5d /ill fur!r4 ,x br+s be=e u ^! myriads ( unse5 />s ) _! associat$ worlds1 x leads u to ?9k t ^! worlds may be full to ! brim ) int]e/s z great z ^? :i* exi/ on our _w4 ,:5 we rememb] t1 = an adequate description ( ! worlds :i* we c see1 "o hundr$ ?\s& libr>ies1 ea* great] ?an any libr>y on e>?1 w\ld be utt]ly insuffici5t1 :at conception are we to =m :5 we n[ le>n t ev5 ?is w\ld only am\nt to a description ( an inconceivably small fragm5t ( ! entire univ]se8 ,let u conceive t omnisci5ce grant$ to u an adequate revelation ( ! ample glories ( ! heav5s1 bo? 9 t univ]se :i* we d see & 9 t inf9itely great] univ]se :i* we d n see4 ,let a full inv5tory be made ( all ^? innum]able worlds1 ) descriptions ( _! features & acc\nts ( _! inhabitants & _! civilizations1 _! geology & _! natural hi/ory1 & all ! b\ndless po9ts ( int]e/ ( e k9d :i* a _w 9 ! s5se 9 :i* we und]/& x does mo/ naturally possess4 ,let ^? ?+s be writt5 e "o1 !n may we say t 7 ?is :ole e>? ( ours cov]$ ) va/ build+s1 l9$ f floor to ceil+ ) book-%elves--7 e "o ( ^! %elves /or$ full ) volumes1 yet1 ev5 !n ?is libr>y w\ld be inadequate to receive ! books t w\ld be necess>y to conta9 a description ( ! glories ( ! sid]eal heav5s4 ,,conclud+ ,,*apt]4 ,,h[ ,,to ,,"n ,,! ,,/>s4 ,e "o :o wi%es to le>n some?+ ab\t a/ronomy %\ld make a det]m9$ ef=t to become acqua9t$ ) ! pr9cipal con/ellations1 & to f9d out ! names ( ! bright] & m int]e/+ />s4 ,i h !re=e add$ to ,,/>-,,l& ?is little *apt]1 9 :i* ,i h tri$ to make ! /udy ( ! />s s simple t1 by tak+ advantage ( a few cle> nights1 !re ought to be no difficulty 9 obta9+ a k ( a few con/ellations4 ,! fir/ /ep is to become famili> ) ! ,great ,be>1 or ,ursa ,major1 z a/ronom]s m g5]ally call ! gr\p4 ,we beg9 ) ?is1 because aft] x has be5 once recogniz$1 !n y w f9d x q easy to make out ! o!r con/ellations & />s4 ,x may save y "s tr\ble if y c get "s "o to po9t out to y ! ,great ,be>2 b ev5 )\t su* aid1 ,i ?9k y w be able to make out ! sev5 bright />s :i* =m ?is rem>kable gr\p1 f ! figure "h giv5 7,fig4 #ib74 ,( c\rse1 ! position ( ?is con/ellation1 z ( e o!r 9 ! heav5s1 *anges ) ! h\r ( ! night1 & *anges ) ! seasons ( ! ye>4 ,ab\t ,april ! con/ellation at #aa o'clock at night is high ov] y\r head4 ,9 ,septemb] at ! same h\r1 ! ,great ,be> is l[ d[n 9 ! nor?4 ,x is to be se5 9 ! we/ 9 ,july1 & at ,*ri/mas x lies 9 ! ea/ at conv5i5t h\rs 9 ! ev5+ = obs]vation4 ,"o ( ! advantages ( us+ ! ,great ,be> z ! f\ndation ( our /udy ( ! />s arises f ! fact t to an obs]v] 9 ! ,briti% ,isl&s or 9 simil> latitudes ?is gr\p nev] sets4 ,:5ev] ! sky is cle> aft] nightfall1 ! ,great ,be> is to be se5 some:]e1 :ile ! brightness ( its compon5t />s makes x a conspicu\s object4 ,inde$1 !re is only "o con/ellation 9 ! sky1 namely1 t ( ,orion1 :i* is a m brilliant gr\p ?an ! ,great ,be>4 ,we %all tell y ab\t ,orion pres5tly1 b x does n suit to beg9 )1 because x c only be se5 9 w9t]1 & is !n plac$ v l[ d[n 9 ! heav5s4 ,illu/ration3 ,,fig4 #ib4--,! ,great ,be> & ! ,pole ,/>4 ,y\r next lesson w be to utilize ! ,great ,be> = ! purpose ( po9t+ out ! ,pole ,/>4 ,look at ! two />s m>k$ & 4 ,!y are call$ ! 8,po9t]s10 because if y foll[ ! direction !y indicate along ! dott$ l9e 9 ! figure1 !y w conduct y\r glance to ! ,pole4 ,?is is ! mo/ important /> 9 ! heav5s to a/ronom]s1 because x happ5s to m>k v ne>ly ! position ( ! ,pole on ! sky4 ,y w easily note ! peculi>ity ( ! ,pole ,/> if y w look at x two or ?ree times 9 ! c\rse ( ! night4 ,x w appe> to rema9 9 ! same place 9 ! sky1 :ile ! o!r />s *ange _! places f h\r to h\r4 ,x is v =tunate t we h a /> l ?is 9 ! nor!rn heav5s2 ! a/ronom]s 9 ,au/ralia or ,new ,zeal& c see no bright /> ly+ ne> ! ,s\!rn ,pole :i* w answ] ! purposes t ! ,pole ,/> does s conv5i5tly = u 9 ! nor?4 ,! ,pole ,/> belongs to a con/ellation :i* we call ! ,little ,be>2 two o!r conspicu\s memb]s ( ?is gr\p are ! two 8,gu>ds02 y w see h[ !y are situat$ f ,fig4 #hb1 p4 #cbb4 ,!y lie ne>ly midway betwe5 ! ,pole ,/> & ! la/ ( ! ?ree />s :i* =m ! ,great ,be>'s ,tail4 ,! same figure w also introduce u to ano!r beautiful con/ellation1 namely1 ,cassiopeia4 ,y w nev] f9d any difficulty 9 id5tify+ ! figure t m>ks ?is gr\p if y w notice t ! ,pole lies midway betwe5 x & ! ,great ,be>4 ,illu/ration3 ,,fig4 #ic4--,! ,great ,squ>e ( ,pegasus4 ,cassiopeia is also "o ( ! con/ellations t nev] set to ,briti% obs]v]s2 b n[ we h to speak ( gr\ps :i* d set1 & :i*1 !re=e1 c only be obs]v$ :5 ! prop] season comes r\nd4 ,! fir/ ( ^! is 8! ,great ,squ>e ( ,pegasus02 y _c see ?is gr\p conv5i5tly 9 ! spr+ or summ]1 b dur+ ! autumn & w9t] x is well plac$ aft] nightfall4 ,!re are f\r conspicu\s />s =m+ ! corn]s ( ! squ>e1 & !n ?ree o!rs m>k$ 1 1 & 7,fig4 #ic71 :i* =m a sort ( h&le to ! squ>e4 ,9 fact1 if y once recognize ?is gr\p1 y w p]haps see 9 x a resemblance to a great saucepan ) a some:at b5t h&le1 & !n y w be acqua9t$ ) a l>ge tract ( ,/>-l& ne> ! ,squ>e ( ,pegasus4 ,f ! figure y w see t a l9e imag9$ to be drawn f ! ,pole ,/> ov] ! end ( ,cassiopeia1 & !n produc$ z f> aga91 w j lead to ! ,great ,squ>e4 ,i h also m>k$ on ?is figure two objects t are ( great telescopic int]e/2 "o ( !m is ! ,nebula 9 ,&rom$a1 ( :i* we _h an acc\nt 9 ! la/ lecture4 ,y see x lies halfway betwe5 ! corn] ( ! squ>e & ! gr\p ( ,cassiopeia4 ,ano!r int]e/+ object is ! /> m>k$ ,&rom$4 ,! telescope %[s x to consi/ ( a pair ( />s1 ! colors ( :i* are beautifully contra/$4 ,at ! end ( ?is h&le to ! ,great ,squ>e ( ,pegasus is ! /> 1 9 ! con/ellation ( ,p]seus4 ,x lies betwe5 two o!r />s & 4 ,we ref] to ,fig4 #hd1 9 :i* ^! />s are %[n4 ,we !re employ$ ! figure to indicate ! position ( ,algol1 ! rem>kable v>iable />4 ,y\r map w also po9t out "s o!r important /ell> features4 ,if we curve r\nd ! ?ree m>k$ 1 1 & ( ,p]seus1 ! eye is conduct$ to ,capella1 a gem ( ! fir/ magnitude 9 ! con/ellation ( ,auriga4 ,close to ,capella is a long triangle1 ! corn]s ( :i* are ! 8,hdi10 ! ?ree kids--:i* ,capella is suppos$ to nurture4 ,if we c>ry a curve ?r\gh 1 1 1 ( ,p]seus1 & n[ b5d x 9 ! opposite way1 ! eye is l$ ?r\gh & 9 ! same con/ellation1 & !n on to ! ,pleiades1 ( :i* we h already spok54 ,illu/ration3 ,,fig4 #id4--,orion & ,sirius4 ,p]seus lies 9 "o ( ! ri*e/ p>ts ( ! heav5s4 ,! ,milky ,way /ret*es across ! gr\p1 & ! sky is /rewn ) />s beyond numb]4 ,ev5 an op]a-glass direct$ to ?is teem+ con/ellation _c fail to af=d ! obs]v] a delightful glimpse ( cele/ial sc5]y4 ,we may1 h[ev]1 specially rem9d ! beg9n] t ! objects on ?is map are n always to be se51 & z an illu/ration ( ! way 9 :i* ! situation & ! visibility ( ! con/ellations are affect$ by ! "t ( ye>1 ,i %all take ! case ( ! ,pleiades & foll[ !m ?r\gh a season4 ,let u suppose t we make a se>* = ?is gr\p at #aa ,p4,m4 e night4 ,on ! #a/ ( ,janu>y1 ! ,pleiades w be f\nd high up 9 ! sky 9 ! s\?we/4 ,on ! #a/ ( ,m>*1 !y w be sett+ 9 ! we/ at ! same h\r4 ,on ! #a/ ( ,may1 ! ,pleiades are n visible1 nei!r are !y on ! #a/ ( ,july4 ,on ! #a/ ( ,septemb]1 !y w be se5 l[ d[n 9 ! ea/4 ,on ! #a/ ( ,novemb]1 !y w be high 9 ! heav5s 9 ! s\!a/4 ,on ! ensu+ #a/ ( ,janu>y1 ! ,pleiades w be f\nd back 9 ! same place :i* !y occupi$ on ! same date 9 ! prec$+ ye>1 & s on ?r\gh\t ! cycle4 ,( c\rse1 y w n suppose t _! *anges are due to actual motions 9 ! gr\p ( />s !mselves4 ,!y are m]ely app>5t1 & are to be expla9$ by ! motion ( ! e>? r\nd its axis1 & ! revolution ar\nd ! sun4 ,next we are to become acqua9t$ ) ! glory ( our w9t] skies1 ! con/ellation ( ,orion1 ,fig4 #id4 ,i d>e say _m ( my read]s are already famili> ) ! well-kn[n tw9 />s :i* =m ! belt ( ,orion1 b if n1 !y w be able to recognize x by ! help ( ! gr\ps already le>n$4 ,imag9e a l9e drawn f ! ,pole ,/> ?r\gh ,capella1 & !n produc$ z mu* fur!r aga91 & we %all be conduct$ into ! prec9cts ( ,orion4 ,?is gr\p lies on ! equator1 &1 consequ5tly1 x is equally famili> to s\!rn a/ronom]s & to ^? ( ! nor?4 ,x c be be/ se5 by ^? :o obs]ve x f or ne> ! equator4 ,! brighte/ /> 9 ,orion is kn[n ei!r z ,orionis or z ,betelgeuze1 by :i* "n x is repres5t$ 9 ! figure4 ,?is /> is ( ! fir/ magnitude1 & s is ,rigel on ! opposite side ( ! belt4 ,! ?ree />s ( ! belt & ! two o!rs1 & 1 at :i* !y po9t above & bel[1 are ( second magnitude4 ,! own] ( a telescope f9ds especial attractions 9 ?is con/ellation4 ,notably among ! subjects :i* w int]e/ him is ! ,great ,nebula1 ! position ( :i* is indicat$ 9 our figure4 ,"u ! middle ( ! belt are a few />s1 ar\nd :i* is a hazy light t is p]ceptible ) ! smalle/ telescopic aid4 ,view$ by in/rum5ts ( adequate proportions1 ^! h develop$ into a m>vell\s nebula ( gl[+ gas1 atta9+ to dim5sions s va/ t no "o has yet ev] attempt$ to e/imate !m4 ,! vic9ity ( ,orion is also enri*$ ) "s ( ! mo/ int]e/+ /ell> objects4 ,foll[ ! l9e ( ! belt upw>ds to ! "r1 & y\r eye is conduct$ to a ruddy fir/ magnitude /> nam$ ,aldeb>an1 9 ! con/ellation ( ! ,bull4 ,?is is a pleas+ object1 :i* ! beg9n] w sometimes be apt to confuse ) ! planet ,m>s1 to :i*1 "u c]ta9 circum/ances1 x c]ta9ly be>s a resemblance4 ,ano!r v pleas+ little gr\p1 kn[n z ! ,hyades1 w be f\nd ne> ,aldeb>an4 ,if ! l9e ( ! belt ( ,orion be c>ri$ d[n to ! left1 x w be f\nd to po9t to ,sirius1 or ! ,dog ,/>4 ,y w f9d x an int]e/+ occupation to make = y\rself maps ( small p>ts ( ! heav5s4 ,fir/ copy out ! *ief />s 9 _! prop] places f ! /> atlas1 & !n fill 9 ! small] />s ) y\r own obs]vations4 ,try fir/ on "s limit$ region ( ! heav5s2 take ! figure ( ,cassiopeia1 = in/ance1 or ! ,squ>e ( ,pegasus1 & see if y c produce a fair repres5tation ( ^? gr\ps by m>k+ 9 ! />s t y\r in/rum5t w %[ y2 or take ! ,pleiades & make a trac+ ( ! pr9cipal />s ( ! gr\p f ! sket* t we h giv5 7,fig4 #hi71 !n take an op]a-glass & fill 9 z c>efully z y c all t x w %[4 ,i c assure y t y w f9d a little def9ite "w ( ?is k9d full ( int]e/ & in/ruction4 ,b ,i hope y w desire to advance fur!r 9 ! /udy ( ! heav5s4 ,x is to be rememb]$ t ) ev5 ! mo/ mod]ate in/rum5ts !re is mu* to be done4 ,_m comets h be5 detect$1 & _m planets h be5 discov]$1 by ! use ( telescopes s small t !y c\ld be easily c>ri$ out f ! h\se = ! ev5+'s "w & br\ght back aga9 aft] ! obs]vations 7 ov]4 ,x rema9s = me to add a few words :i* w help y 9 f9d+ ! planets4 ,x is1 ( c\rse1 impossible to repres5t su* objects z ,jupit]1 ,saturn1 ,v5us1 ,m>s1 & ,m]cury on maps ( ! heav5s1 because ^! bodies are con/antly mov+ ab\t1 & if _! places 7 "r to-day !y w\ld be wrong to-morr[4 ,! almanac w be necess>y = y "h4 ,y mu/ f9d out by its help :at planets are visible & 9 :at "p ( ! sky !y are plac$4 ,!n y w h to comp>e y\r maps ) ! heav5s1 & :5 y f9d a bright />-l body t is n %[n on y\r maps y may conclude at once t x is ! planet4 ,al?\gh ^! objects are s />-l to ! unaid$ eye1 yet ! resemblance is at once dispell$ :5 we use a telescope4 ,! /> is only a bright po9t ( light & :ite1 ! planet %[s a visible %ape4 ,?is is1 at lea/1 ! case ) ! five planets ,i h nam$2 = !re are o!rs1 su* z ,uranus & ,neptune1 :i* are too f> to be mu* m ?an />-l po9ts 9 ord9>y telescopes4 ,! m9or planets w\ld n int]e/ y4 ,i hope t ! read+ ( ,,/>-,,l& w1 at all ev5ts1 induce y to make a beg9n+ ( ! /udy ( ! heav5s1 if y h n already done s4 ,if y h ! advantage ( a telescope1 s mu* ! bett]2 b1 if ?is is impossible1 make ! be/ use ( y\r own eyes4 ,d n put x (f or wait till y get "s "o to tea* y4 ,if x be cle> ?is v night1 g out & f9d ! ,great ,be> & ! ,pole ,/>1 & z _m ( ! o!r con/ellations z y c1 & at once comm5ce y\r c>e] z an a/ronom]4 ,,table ,,( ,,useful ,,a/ronomical ,,facts4 ,! sun's mean di/ance f ! e>? is #ib1gjj1jjj miles2 8 diamet] is #hfe1jjj miles1 & he rotates 9 a p]iod betwe5 #be & #bf days4 ,! moon's mean di/ance f ! e>? is #bch1jjj miles2 ! diamet] ( ! moon is #bafj miles1 & ! "t ( revolution r\nd ! e>? is #bg4cbb days4 ,,! ,,planets4 ---------------------------------------- -------------------------- ,mean ,di/ance ,p]iodic ,"t ,diamet] f ! ,sun ( ,revolution ( ,planet ,axial ,rotation4 9 ,millions 9 ,days4 9 ,miles4 ( ,miles4 ---------------------------------------- -------------------------- ,hrs4 ,m9s4 ,secs4 ,m]cury #ce4i #hg4ifi #b1iib ,unc]ta94 ,v5us #fg4j #bbd4gj #g1ffj ,unc]ta94 ,e>? #ib4g #cfe4bf #g1iah #bc #ef #d4ji ,m>s #ada #fhf4ih #d1bjj #bd #cg #bb4g ,jupit] #dhb #d1ccb4f #he1jjj #i #ee -- ,saturn #hhd #aj1gei #ga1jjj #aj #ad #bc4h ,uranus #a1ghj #cj1fhg #ca1gjj ,unkn[n4 ,neptune #b1ghj #fj1abg #cd1ejj ,unkn[n4 ---------------------------------------- -------------------------- ,,! ,,satellites ,,( ,,m>s4 ---------------------------------------- --------- ,"n4 ,mean ,di/ance f ,p]iodic ,"t4 ,c5tre ( ,m>s4 ---------------------------------------- --------- ,hrs4 ,m9s4 ,secs4 ,phobos #e1hjj miles4 #g #ci #ad ,deimos #ad1ejj 0 #cj #ag #ed ---------------------------------------- --------- ,,! ,,satellites ,,( ,,jupit]4 ---------------------------------------- --------------- ,"n4 ,mean ,di/ance f ,p]iodic ,"t4 ,c5tre ( ,jupit]4 ---------------------------------------- --------------- ,days ,hrs4 ,m9s4 ,secs4 ,i #bfb1jjj miles4 #a #ah #bg #cd ,,ii #dag1jjj 0 #c #ac #ac #db ,,iii #ffd1jjj 0 #g #c #db #cc ,,iv #a1agj1jjj 0 #af #af #cb #aa ,v #aab1djj 0 -- #aa #eg 787 ---------------------------------------- ---------------- ,,! ,,satellites ,,( ,,saturn4 ---------------------------------------- --------------- ,"n4 ,mean ,di/ance f ,p]iodic ,"t4 ,c5tre ( ,saturn4 ---------------------------------------- --------------- ,days ,hrs4 ,m9s4 ,secs4 ,mimas #aah1jjj miles4 #j #bb #cg #bg4i ,enceladus #aeb1jjj 0 #a #h #ec #f4g ,te?ys #ahh1jjj 0 #a #ba #ah #be4g ,dione #bda1jjj 0 #b #ag #da #h4i ,rhea #ccg1jjj 0 #d #ab #be #aj4h ,titan #gha1jjj 0 #ae #bb #da #be4b ,hyp]ion #idf1jjj 0 #ba #g #g #dj4h ,iapetus #b1bhj1jjj 0 #gi #g #ed #dj4d ---------------------------------------- --------------- ,a n9? satellite 0 discov]$ 9 ,augu/1 #ahih1 by ,pr(4 ,w4 ,h4 ,pick]+1 b its mean di/ance & p]iodic "t h n yet be5 det]m9$ ) precision4 ,,! ,,satellites ,,( ,,uranus4 ---------------------------------------- ----- ,"n4 ,mean ,di/ance f ,p]iodic ,"t4 ,c5tre ( ,uranus4 ,days4 ---------------------------------------- ----- ,ariel #aai1jjj miles4 #b4ebjchc ,umbriel #aff1jjj 0 #d4addaba ,titania #bgb1jjj 0 #h4gjehig ,ob]on #cfc1jjj 0 #ac4dfcbfi ---------------------------------------- ----- ,,! ,,satellite ,,( ,,neptune4 ---------------------------------------- ----- ,"n4 ,mean ,di/ance f ,p]iodic ,"t4 ,c5tre ( ,neptune4 ,days4 ---------------------------------------- ----- ,anonym\s #bbj1jjj miles4 #e4hgfij ---------------------------------------- ----- ,,index4 ,a4 ,active ,volcanoes1 ,numb] (1 #aab4 ,adams1 ( ,cambridge1 & ,lev]ri]1 ( ,p>is1 #bdi4 ,address ( ,mr4 ,john ,smi?1 #ccj4 ,africa w\ld be bett] kn[n if on ,moon1 #aje4 ,air z ,blanket to keep ,e>? ,w>m1 #h4 ,air n ,transp>5t1 #abe4 0 ,pump1 #ahc4 0 ,resi/ance (1 #ahb4 ,alcor1 #cdc4 ,aldeb>an1 #chi4 ,algol1 #cdb1 #che4 ,alpha ,c5tauri1 #cai2 ,railway to1 #cch4 ,anci5t ,!ory to acc\nt = ,ris+ & ,sett+ ( ,sun1 #dh4 ,&rom$a1 #che4 ,&rom$a1 ,nebula 91 photograph$ by ,mr4 ,rob]ts1 #cfd4 ,&rom$es1 #caj4 ,annual ,motion ( ,e>? r\nd ,sun1 #ef4 ,annul> ,eclipses1 #hh4 ,app>5t ,smallness ( ,di/ant ,objects1 #be4 ,appe>ance ( ! ,sun1 #ce4 ,appe>ance ( ! ,sun dur+ a ,total ,eclipse1 #dj4 ,arctic ,sun1 #ff4 ,area ( ,moon's ,surface1 #hb4 ,ariel1 #bdc4 0 ,di/ance & ,p]iod (1 #cib4 ,ar?ur's ,seat1 ,volcano1 #aad4 ,asaph ,hall1 ,pr(essor1 #aie4 ,a/]oids or ,small ,planets1 #bjc4 ,a/ronom] & ,ma!matician1 #add4 ,a/ronom]s1 ,h[ !y measure ! ,di/ances ( ! ,heav5ly ,bodies1 #ai4 ,a/ronomical ,facts1 ,table (1 #cia4 ,a/ronomie1 l'1 ,a ,fr5* ,j\rnal1 #cj4 ,a?lete on ,moon1 #aca4 ,atlantic1 ,sun dropp$ into1 #dh4 ,atmosph]e ( ,moon1 #abe4 ,attraction ( ,gravitation1 #aai1 #ahf4 ,augu/ ,meteors1 #cji4 ,auriga1 #che4 ,auv]gne1 ,anci5t ,volcanoes 91 #aad4 ,awful ,vi/a ( ,lessons1 #cga4 ,axis ( ,e>? ,con/ant 9 ,direction1 #fi4 ,b4 ,babies on ! ,moon1 #acj4 ,balloon1 ,h[ support$1 #abd4 ,b&s on ,saturn1 #bbd4 ,be>1 ,great1 #cha2 ,little1 #chc4 ,belts on ,jupit]1 #bae4 ,b5efits t we receive f ! ,sun1 #aj4 ,betelgeuze1 #chh4 ,biela's ,comet1 #caa4 ,blanket to keep ,e>? ,w>m1 #h4 ,books1 ,numb] (1 ,necess>y to describe ,univ]se1 #cgb4 ,brahe1 ,ty*o1 #agj4 ,brightness ( ,saturn1 #bbc4 0 0 ! ,/>s1 #cdj4 0 0 0 ,sun1 #a4 ,brighton ,coa*1 #ach4 ,briti% ,museum ,collection ( ,meteorites1 #cac4 ,briti% ,natural ,hi/ory ,museum1 #cgj4 8,br[n ,bess10 #fh4 ,brussels1 #cbh4 ,bull1 ,con/ellation ( !1 #chh4 ,burn+-glass1 ,exp]im5t )1 #c4 ,button illum9at$1 #aeb4 ,c4 ,cambridge ,obs]vations ( ,neptune1 #bea4 ,capella1 #che4 ,c>ig\1 ,m\nt1 9 ,pyr5ees1 #ca4 ,c>ol9e ,isl&1 #db4 ,c>t-:eel1 ,measurem5ts )1 #agc4 ,cassiopeia1 #chd4 ,ca/or & ,pollux1 #cde4 ,cele/ial ,libr>y1 #cgb4 0 0 ,size (1 #cgc4 ,*anges ( ! ,seasons1 #ff4 ,*anges ( ! ,sun ) ! ,seasons1 #eg4 ,*>les ,i41 #ai4 ,*ri/mas ,"t1 ,:at ! ,sun does = u at1 #aj4 ,cl]k-,maxwell's ,top1 #ahb4 ,clock to c\nt ,sun's ,di/ance1 #ah4 ,cl\ds a ,=m ( ,/eam1 #ae4 0 fill our ,riv]s1 etc41 #ae4 0 on ,jupit]1 #baf4 0 0 ,m>s1 #aia4 0 0 ,neptune1 #bec4 0 0 ,saturn1 #bbd4 0 0 ,uranus1 #bdc4 ,clu/] 9 ! ,c5taur1 #cbh4 ,clu/]s ( ,/>s1 #cbg4 ,coal1 ,mode ( ,production (1 #aa4 0 ,:5ce came x81 #aa4 ,coal-pit1 #bja4 ,cock & ! ,sun1 #ff4 ,codde1 ,m>cus1 ,picture ( ,sunset1 #cj4 ,coldness ( ,m\nta9 ,tops1 #h4 ,colli]1 ,eye ( a1 #bja4 ,color ( ,/>s1 #cdj4 ,columbiad ,!ory ( ,meteorites1 #cad4 ,comet attract$ by ,sun1 #bgd4 0 collid+ ) ,e>?1 #bha4 0 ,encke's1 #adc1 #bei4 ,comet1 ,great1 ( ,septemb]1 #ahhb1 #bgg4 ,comet1 ,halley's1 #bfc4 0 ,id5tification ( a1 #beh4 0 ,mat]ials ( a1 #bgf4 0 ,movem5ts ( a1 #bee4 0 ( ,biela1 #caa4 0 ( #ahfa1 #bha4 0 se5 at ,sun's ,edge1 #bgh4 0 ,spe$ ( a1 #bef4 0 ,weigh+ ,scales = a1 #bgf4 ,comets & ,%oot+ ,/>s1 #bee4 0 ,disposition ( ,tails (1 #beg4 0 ,extravagance (1 #bhc4 0 ,tails (1 #bha4 ,common1 ,mr41 #bgh4 ,comp>ative ,sizes ( ,planets1 #aci4 ,comp>ison ( ,sol> ,sy/em & ,nebula1 #cfg4 ,cool+ ( ,e>? & ,moon1 ,illu/ration (1 #aaf4 ,cop5hag51 ,resid5ce ( ,ty*o1 #agj4 ,corona ( ! ,sun1 #dd4 ,cotton ,y>n1 #ccd4 ,crape ,r+ ( ,saturn1 #bbe4 ,crat]s on ! ,moon1 #ajh4 ,crat]s1 ,t]re/rial & ,lun>1 comp>$1 #aac4 ,cricket on ! ,moon1 #aca4 ,cun>d]'s ,lights at ,sea1 #cbf4 ,d4 ,dani% ,h\nds ( ,ty*o ,brahe1 #agb4 ,day & ,night1 #df1 #ea4 ,daylight1 ,/>s se5 91 #ei4 ,deimos & ,phobos1 ,satellites ( ,m>s1 #bjj4 ,deimos1 ,di/ance & ,p]iod (1 #cia4 ,des]tion1 ,h]s*el's1 #bca4 ,dew>1 ,pr(essor1 #ec1 #ee1 #ahg4 ,diction>y1 ,worce/]'s1 ,use (1 #bfi4 ,dione1 ,di/ance & ,p]iod (1 #cib4 ,direction ( ,e>?'s ,axis ,con/ant1 #fi4 ,discov]ies ( ,kepl]1 #agd4 0 0 ,newton1 #agh4 ,disguis$ ,/>s1 #bje4 ,disposition ( ,comets' ,tails1 #beg4 ,di/ance ( ! ,sun1 #ag1 #baj1 #cia4 ,di/ances ( ,heav5ly ,bodies1 ,h[ measur$1 #ai4 ,di/ances ( ,nebul1 #cfe4 0 0 ! ,/>s1 #ccb4 ,di/ant ,objects1 ,app>5t ,smallness (1 #be4 ,d\ble ,/>s1 #cdb2 ,motion (1 #cdd4 ,d4 ,q41 #baj4 ,draw+ ( ! ,sol> ,sy/em1 #ace4 ,duff]91 ,"l1 #fe4 ,duns9k ,obs]vatory1 ,telescope (1 #ie4 ,du/ f ,meteors1 #bib4 ,e4 ,eagle 9 ,we/ ( ,irel&1 #bg4 ,e>?1 ,annual ,motion (1 #ef4 0 collid+ ) ,comet1 #bha4 0 ,diamet] (1 #cia4 0 ,di/ance (1 f ,sun1 #cia4 ,e>?1 ,hi/ory (1 z se5 f ,/>s1 #ccg4 ,e>?1 ,int]nal ,heat (1 #aae4 0 ,moon-view (1 #gh4 ,e>?1 ,p]iod (1 #cia4 0 ,rank (1 9 ,space1 #cbi4 0 ,rotation (1 #di1 #cia4 0 view$ f ,sun1 #bh4 0 ,visibility (1 #cfi4 ,eclipse1 ,total1 ,appe>ances se5 dur+1 #dj4 ,eclipses1 ,h[ produc$1 #hd4 0 ,annul>1 #hh4 0 ( ,jupit]'s ,satellites1 #bai4 0 0 ,moon1 #hi4 ,ed9burgh ,ca/le1 #aad4 ,effect ( ,moon's ,di/ance on its ,appe>ance1 #hi4 ,electric ,lamp1 ,heat+ ,effect (1 #f4 ,ellipse1 #afg2 ,importance (1 #afi4 0 & ,p>abola1 #afi1 #bge4 ,elliptic ,pa?s ( ,planets1 #afi4 ,enceladus1 ,di/ance & ,p]iod (1 #cib4 ,encke's ,comet1 #adc1 #bei2 ,p]iodicity (1 #bfj4 ,eros1 #baj4 ,et]nal ,sn[ on ,m\nta9 ,summits1 #i4 ,euclid1 #bb4 ,ev5+ ,/>1 #aea4 ,exam9+ ,moon1 ,qu>t] ! ,be/ ,"t =1 #ajg4 ,exp]im5t ) ,burn+-glass1 #c4 ,explosion ( ,krakatoa1 #aac4 ,express ,tra9 to ! ,sun1 #ai4 ,ext9ct ,crat]s on ! ,e>?1 #aad2 on ! ,moon1 #aad4 ,eye ( a ,colli]1 #bja4 ,eyes1 ,use ( ,two1 #ai4 ,f4 ,facts1 ,table ( ,useful ,a/ronomical1 #cia4 ,five o',clock ,tea1 ,sun's ,%>e 91 #aj4 ,f9lay1 ,mr41 #bgh4 ,flag/aff1 ,height (1 #aaj4 ,flora1 ,lawn-t5nis on1 #bji4 ,fly-boats on ,royal ,canal1 ,smoo? ,motion (1 #eb4 ,fly+ ,ma*9es1 #bjh4 ,focus1 #e2 ( ,ellipse1 #agj4 ,football on ,moon1 #aca4 ,fossil ,trees1 #aa4 ,france1 ,ext9ct ,crat]s 91 #aad4 ,friday1 #ace4 ,g4 ,galle ( ,b]l9 f9ds ,neptune1 #bea4 ,geissl]'s ,tubes1 #cfa4 ,geography ( ,m>s1 #ahh4 0 0 ! ,moon1 #aje4 ,george ,,iii4 & ,h]s*el1 #bch4 ,georgium ,sidus1 #bdj4 ,giant ,planets1 #bab2 ,orbits (1 #bac4 ,globe1 ,%ad[ (1 #agj4 ,gr& ,meteors1 #bie4 ,gravitation1 #abj1 #ahf4 0 on ,moon1 #abh4 0 0 ,small ,planets1 #bji4 0 0 ! ,sun1 #acb4 ,great ,be>1 #afa2 ,numb] ( ,/>s 91 #cbc2 ,h[ to f9d1 #cha4 ,gre51 ,mr41 #aic4 ,gre5wi*1 #ach4 ,gr9d+ ,specula1 #bce4 8,gu>ds10 #chc4 ,h4 ,habitability ( ,moon1 #abc4 0 0 ,o!r ,worlds1 #acc4 ,hall1 ,pr(essor ,asaph1 #aie4 ,halley's ,comet1 #bfc2 ,reappe>ance (1 #bff4 ,heat1 ,int]nal1 ( ,e>?1 #aae4 0 ( ! 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,pyr5ees1 #ca4 ,m\nta9s on ! ,moon1 ,h[ measur$1 #ajh4 ,m\nta9 ,tops1 ,coldness (1 #h4 ,n4 ,nam+ ! ,/>s1 #cha4 ,nasmy?1 #ce4 ,national ,debt1 #cci4 ,nature ( ,saturn's ,r+s1 #bbe4 ,nebula 9 ,orion1 #chh4 0 ,r+1 9 ,lyra1 #ced4 ,nebul1 #cec4 ,nebul & ,sol> ,sy/em comp>$1 #cfg4 ,nebul1 ,di/ances (1 #cff4 0 ,photographs (1 #cfb4 ,nebul1 ,/>s 91 #cff4 0 ,:at made (1 #cei4 ,neptune1 ,discov]y (1 #bdd4 ,neptune1 ,=m] ,obs]vations (1 #beb4 ,neptune's ,brightness1 #beb4 0 ,cl\ds1 #bec4 ,neptune's ,diamet]1 ,di/ance1 ,p]iod1 & ,rotation1 #cia4 ,neptune's ,size1 #bec4 0 ,satellite1 #bec4 ,neptune's ,satellite1 ,di/ance & ,p]iod (1 #cic4 ,neptune's ,"t ( ,revolution1 #bac4 ,newton's ,discov]ies1 #agh4 ,night & ,day1 #df1 #ea4 ,noonday ,gun1 #e4 ,nor? ,pole1 #ec2 ,cont9ual ,day at1 #gj2 ,sun%9e at1 #ga4 ,novemb] ,%[]s ( ,meteors1 #bii4 ,numb] ( ,books ,necess>y to describe ,univ]se1 #cgb4 ,numb] ( ,m9or ,planets1 #bjg4 0 0 ,/>s1 #cba4 ,o4 ,ob]on1 #bdc2 ,di/ance & ,p]iod (1 #cib4 ,objects1 ,di/ant1 ,app>5t ,smallness (1 #be4 ,obs]v+ ,robes1 #agb4 ,occultation ( ,/> by ,moon1 #abf4 ,octagon ,*apel1 ,ba?1 ,organi/ (1 #bca4 ,old ,moon 9 ,new ,moon's ,arms1 #gg4 ,orbit ( ,leonids1 #cjb4 ,orbits ( ,giant ,planets1 #bac4 0 0 ,uranus & ,neptune1 #bej4 ,orion1 #chg4 ,oxyg5 ,necess>y to ,life1 #abd4 ,p4 ,pacific ,ocean1 ,track ( ,eclipse across1 #db4 ,p>abola1 #afi1 #bfi4 0 & ,ellipse1 #afi1 #bge4 ,p>abolic ,reflectors1 #bgb4 ,pegasus1 ,squ>e (1 #chd4 ,p5dulum1 #ed4 ,p]iodicity ( ,comets1 #bfc4 ,p]seids1 #cji4 ,p]seus1 #cbg1 #che4 ,p]turbation ( ,encke's ,comet1 #adf4 ,phases ( ,m]cury1 #adb4 0 0 ! 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,moon1 #ajc4 ,s&wi* ,isles1 ,crat] 9 !1 #aab4 ,satellites1 #aie4 0 ( ,jupit]1 #bah4 0 0 ,m>s1 #aid4 0 0 ,saturn1 #bbi4 ,satellites ( ,uranus1 ,revolution (1 #bdc4 ,saturday1 #ace4 ,saturn1 #bbb4 0 & ,e>?1 #bbc4 ,saturn's ,b&s & ,cl\ds1 #bbd4 0 ,brightness1 #bbc4 ,saturn's ,diamet] & ,di/ance1 #cia4 ,saturn's ,int]nal ,heat1 #bbd4 0 ,p]iod1 #cia4 0 ,r+s1 #bbd4 0 ,rotation1 #cia4 0 ,satellites1 #bbi4 ,saturn's ,satellites1 ,di/ances & ,p]iods (1 #cib4 ,saturn's ,"t ( ,revolution1 #bab4 ,scale ( ,univ]se1 #cai4 ,se>* = ,small ,planets1 #bje4 ,seas on ,m>s1 #aic4 0 0 ! ,moon1 #ajh4 ,seasons1 ,*anges ( !1 #ff4 ,seasons1 ,*anges ( ! ,sun ) !1 #eg4 ,se5 & ,unse5 ,univ]se1 #cgg4 ,%ad[ ( ,globe1 #agj4 ,%ape & ,size ( ! ,sun1 #bi4 ,%oot+ ,/>s & ,comets1 #bee4 ,%oot+ ,/>s1 ,:at becomes ( !m1 #bij4 ,sidus1 ,georgium1 #bdj4 ,sirius1 #cah4 0 ,h[ to f9d1 #chi4 ,sirius1 ,position (1 on ,map ( ,univ]se1 #cai4 ,size ( ,cele/ial ,libr>y1 #cgc4 0 ,m9or ,planets1 #bjg4 0 ,moon1 #gi1 #aja4 0 ! ,sun1 #bi4 ,sizes1 ,comp>ative1 ( ,planets1 #aci4 ,sizes1 ,comp>ative1 ( ,e>? & ,sun1 #ca4 ,smi?1 ,mr4 ,john1 8 ,address1 #ccj4 ,smoke ,r+s1 #ceg4 ,sn[ on ,m\nta9 ,tops1 #i4 ,sn[ball1 #bid4 ,sodium1 #cej4 ,sol> ,gravitation1 #acb4 0 ,prom95ces1 #dd4 ,sol> ,sy/em & ,nebula comp>$1 #cfg4 ,sol> ,sy/em1 ,draw+ ( !1 #ace4 ,spectroscope1 #ceb4 ,speculum ,gr9d+1 #bce4 0 ,metal1 #bce4 ,spe$ ( ,planets1 #ach4 ,spl5dor ( ,v5us1 #aea4 ,spots on ! 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