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The dataset generation failed
Error code:   DatasetGenerationError
Exception:    ArrowInvalid
Message:      JSON parse error: Invalid value. in row 0
Traceback:    Traceback (most recent call last):
                File "/usr/local/lib/python3.14/site-packages/datasets/packaged_modules/json/json.py", line 324, in _generate_tables
                  df = pandas_read_json(f)
                File "/usr/local/lib/python3.14/site-packages/datasets/packaged_modules/json/json.py", line 38, in pandas_read_json
                  return pd.read_json(path_or_buf, **kwargs)
                         ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
                File "/usr/local/lib/python3.14/site-packages/pandas/io/json/_json.py", line 815, in read_json
                  return json_reader.read()
                         ~~~~~~~~~~~~~~~~^^
                File "/usr/local/lib/python3.14/site-packages/pandas/io/json/_json.py", line 1014, in read
                  obj = self._get_object_parser(self.data)
                File "/usr/local/lib/python3.14/site-packages/pandas/io/json/_json.py", line 1040, in _get_object_parser
                  obj = FrameParser(json, **kwargs).parse()
                File "/usr/local/lib/python3.14/site-packages/pandas/io/json/_json.py", line 1176, in parse
                  self._parse()
                  ~~~~~~~~~~~^^
                File "/usr/local/lib/python3.14/site-packages/pandas/io/json/_json.py", line 1392, in _parse
                  ujson_loads(json, precise_float=self.precise_float), dtype=None
                  ~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
              ValueError: Expected object or value
              
              During handling of the above exception, another exception occurred:
              
              Traceback (most recent call last):
                File "/usr/local/lib/python3.14/site-packages/datasets/builder.py", line 1827, in _prepare_split_single
                  for key, table in generator:
                                    ^^^^^^^^^
                File "/src/services/worker/src/worker/job_runners/config/parquet_and_info.py", line 613, in wrapped
                  for item in generator(*args, **kwargs):
                              ~~~~~~~~~^^^^^^^^^^^^^^^^^
                File "/usr/local/lib/python3.14/site-packages/datasets/packaged_modules/json/json.py", line 327, in _generate_tables
                  raise e
                File "/usr/local/lib/python3.14/site-packages/datasets/packaged_modules/json/json.py", line 290, in _generate_tables
                  pa_table = paj.read_json(
                      io.BytesIO(batch), read_options=paj.ReadOptions(block_size=block_size)
                  )
                File "pyarrow/_json.pyx", line 342, in pyarrow._json.read_json
                File "pyarrow/error.pxi", line 155, in pyarrow.lib.pyarrow_internal_check_status
                  return check_status(status)
                File "pyarrow/error.pxi", line 92, in pyarrow.lib.check_status
                  raise convert_status(status)
              pyarrow.lib.ArrowInvalid: JSON parse error: Invalid value. in row 0
              
              The above exception was the direct cause of the following exception:
              
              Traceback (most recent call last):
                File "/src/services/worker/src/worker/job_runners/config/parquet_and_info.py", line 1369, in compute_config_parquet_and_info_response
                  parquet_operations, partial, estimated_dataset_info = stream_convert_to_parquet(
                                                                        ~~~~~~~~~~~~~~~~~~~~~~~~~^
                      builder, max_dataset_size_bytes=max_dataset_size_bytes
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                  )
                  ^
                File "/src/services/worker/src/worker/job_runners/config/parquet_and_info.py", line 948, in stream_convert_to_parquet
                  builder._prepare_split(split_generator=splits_generators[split], file_format="parquet")
                  ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                File "/usr/local/lib/python3.14/site-packages/datasets/builder.py", line 1694, in _prepare_split
                  for job_id, done, content in self._prepare_split_single(
                                               ~~~~~~~~~~~~~~~~~~~~~~~~~~^
                      gen_kwargs=gen_kwargs, job_id=job_id, **_prepare_split_args
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                  ):
                  ^
                File "/usr/local/lib/python3.14/site-packages/datasets/builder.py", line 1880, in _prepare_split_single
                  raise DatasetGenerationError("An error occurred while generating the dataset") from e
              datasets.exceptions.DatasetGenerationError: An error occurred while generating the dataset

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history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
THELIBRARYOFTHEUNIVERSITYOFCALIFORNIAPRESENTEDBYPROF.CHARLESA.KOFOIDANDMRS.PRUDENCEW.KOFOID HISTORYOFASTRONOMY APOPULARHISTORYOFASTRONOMYDURINGTHENINETEENTHCENTUEYBYAGNESM. JUPITER1879 SATURN1885 THIRDEDITIONLONDON:ADAM&CHARLESBLACK1893 CU PREFACETOTHETHIRDEDITION.THEintervalofsixyearssincethepublicationoftheSecondEdit...
1
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
anceofMr.Kanyard,especiallyfortheThird.TheiravailabilityisduetothecourtesyoftheCounciloftheEoyalAstronomicalSociety,ofProfessorGeorgeE.Hale,ofProfessor M368106 viPREFACETOTHETHIRDEDITION.Barnard,andofDr.andMrs.Huggins,toallofwhomthewriteroffersgratefulacknowledgments.Sheventurestohopethattheremodelledworkwillenjoynoles...
2
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
ularinitsneeds,sinceitsprogressnowprimarilydependsupontheinterestin,andconsequenteffortstowardsitsadvancementofthegeneralpublic;morepopularinitsnature,becausethekindofknowledgeitnowchieflytendstoaccumulateismoreeasilyintelligiblelessremotefromordi- viiiPREFACETOTHEFIRSTEDITION.naryexperiencethanthatevolvedbytheaidofthe...
3
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
erbeignored.But,astheoutcomeoftheenormousdevelopmentgiventothepowersofthetelescopeinrecenttimes,togetherwiththeswiftadvanceofphysicalscience,andtheinclusion,bymeansofthespectroscope,oftheheavenlybodieswithinthedomainofitsinquiries,muchknowledgehasbeenacquiredregardingthenatureandconditionofthosebodies,forming,itmightbe...
4
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
ddleofthepresentcentury.Herschel'sinquiriesintotheconstructionoftheheavensstrikethekeynoteofthefirstpart;thediscoveryofsun-spotandmagneticperiodicityandofspectrumanalysisdeterminethecharacterofthesecond.Wherethenatureofthesubjectrequiredit,however,thisarrangementhasbeendisregarded.Clearnessandconsist-encyshouldobviousl...
5
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
kindandmodeofthesurrenderineachseparatecasemustalwayspossessastronginterestwhetherforstudyorforexample.TheacknowledgmentsofthewriterareduetoProfessorEdwardS.Holden,directoroftheWashburnObservatory,Wisconsin,andtoDr.Copeland,chiefastronomerofLordCrawford'sObservatoryatDunecht,formanyvaluablecom-munications.LONDON,Septem...
6
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
ningsHerschel'sTheory,ftheSolarConstitutionSirJohnHerschel'sTrade-WindHypothesisBaily'sBeadsTotalSolarEclipseof1842CoronaandProminencesEclipseof1851Page62CHAPTERIV.PLANETAEYDISCOVEEIES.Bode'sLawSearchforaMissingPlanetItsDiscoverybyPiazziFurtherDiscoveriesofMinorPlanetsUnexplainedDisturbanceofUranusDiscoveryofNeptuneIts...
7
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
CONTENTS.xiii CHAPTERII.SOLAROBSERVATIONSANDTHEORIES.BlackOpeningsinSpotsCarrington'sObservationsRotationoftheSunKirchhofE'sTheoryoftheSolarConstitutionFaye'sViewsSolarPhotographyKewObservationsSpectroscopicMethodCyclonicTheoryofSun-SpotsVolcanicHypothesisASolarOut-burstSun-SpotPeriodicityPlanetaryInfluenceNasmyth'sWi...
8
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
orp-tionbyourAirTheSunBlueTheSolarConstant. .Page268 xiv CONTENTS.CHAPTEEVI.THESUN'SDISTANCE.DifficultyoftheProblemOppositionsofMarsTransitsofVenusLunarDisturbanceVelocityofLightTransitof1874InconclusiveResultOppositionofMarsin1877MeasurementsofMinorPlanetsTransitof1882Newcomb'sDeterminationoftheVelocityofLightCombined...
9
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
OEIESOPPLANETAEYEVOLUTION.OriginoftheWorldaccordingtoKantLaplace'sNebularHypothesis-MaintenanceoftheSun'sHeatMeteoricHypothesisRadiationtheResultofContractionRegenerativeTheoryFaye'sSchemeofPlanetaryDevelopmentOriginoftheMoonEffectsofTidalFriction.'' . .pa(je374 CONTENTS.xvCHAPTERX.RECENTCOMETS.Donati'sCometTheEarthaga...
10
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
eiadesPhotographicStar-ChartingStellarParallaxDoubleStarsStellarPhotometryStatusofNebulasPhotographsandDrawingsoftheMilkyWayStarDrift Page450CHAPTERXIII.METHODSOFBESEAECH.DevelopmentofTelescopicPowerSilveredGlassReflectorsGiantRefractorsComparisonwithReflectorsTheLickTelescopeAtmo-sphericDisturbanceMechanicalDifficulti...
11
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
monioussystem,withoutasyetanyideaofacompellingcause.Theplanetsrevolvedincirclesbecauseitwastheirnaturetodoso,justaslaudanumsetstosleepbecauseitpossessesavirtusdormittta.Thisfirstandoldestbranchisknownas"observa-tional.^or"practicalastronomy."Itsbusinessistonotefactsasaccuratelyaspossible;anditisessentiallyunconcernedwi...
12
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
progressofscienceduringthenineteenthcenturyhasservedtoconfirmandrendermoreexclusive.Inquisitionsbegunwiththetelescopehavebeenextendedandmadeeffectiveinunhoped-fordirectionsbytheaidofthespectroscopeandphotographiccamera;andalargepartofourattentioninthepresentvolumewillbeoccupiedwiththebrilliantresultsthusachieved.Theune...
13
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
lainedtotheFrenchAcademy,November19,1787,thecauseofthemoon'sacceleratedmotion.Asameremachine,thesolarsystem,sofar INTRODUCTION.3asitwasthenknown,wasfoundtobecompleteandintelligibleinallitsparts;andintheMtfcaniqueCelesteitsmechanicalper-fectionsweredisplayedunderaformofmajesticunitywhichfitlycommemoratedthesuccessivetri...
14
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
indbeendestroyed,theGreenwichrecordsalonewouldsufficefortherestorationofastronomy;1andtheestablishmentwasindeedabsolutelywithoutarival.Systematicobservationsofsun,moon,stars,andplanetswereduringthewholeoftheeighteenthcenturymadeonlyatGreenwich.Herematerialswereaccumulatedforthesecurecorrectionoftheory,andhererefinement...
15
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
lpositionattheendofayear.Bradley'ssecondgreatdiscoverywasfinallyascertainedin1748.Nutationisareal"nodding"oftheterrestrialaxispro-ducedbythedraggingofthemoonattheterrestrialequatorialprotuberance.Fromitresultsanapparentdisplacementofthestars,eachofthemdescribingalittleellipseaboutitstrueor"mean"position,inaperiodofeigh...
16
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
tarivalintheconstructionofreflectors;thesectors,quadrants,andcirclesofGraham,Bird, INTRODUCTION.5Kamsden,andGarywereinimitablebyContinentalworkman-ship.ThuspracticalandtheoreticalastronomyadvancedonparallellinesinEnglandandFrancerespectively,theimprovementoftheirseveraltoolsthetelescopeandthequadrantontheoneside,andthe...
17
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
roftheirporten-touscharacter;itrankedthemasdenizensofthesolarsystem.Again,thetransitsofVenusin1761and1769werethefirstoccurrencesofthekindsincetheawakeningofsciencetotheirconsequence.Imposingpreparations,journeystoremoteandhardlyaccessibleregions,officialexpeditions,internationalcommunications,allforthepurposeofobservin...
18
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
implelanguageinwhichtheywereconveyedformedacombinationpowerfullyeffectivetothoseleastsuscep-tibleofnewimpressions.NorwastheevokedenthusiasmlimitedtotheBritishIsles.InGermany,SchroterfollowedlongointervalloinHerschel'strack.VonZachsetonfootfromGothathatgeneralcommunicationofideaswhichgiveslifetoaforwardmovement.Bodewrot...
19
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
totheshareofignorantorill-providedassiduity. INTRODUCTION.7Observers,accordingly,havemultiplied;observatorieshavebeenfoundedinallpartsoftheworld;associationshavebeenconstitutedformutualhelpandcounsel.Aformalastronomicalcongressmetin1789atGothathen,underDukeErnestII.andVonZach,thefocusofGermanastronomyandinstitutedacomb...
20
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
imatedbythesingleaimofcollecting"particulars"intheirspecialbranchforwhatBacontermedaHistoryofNature,eventuallytobeinterpretedaccordingtothesagaciousinsightofsomeoneamongthemgiftedabovehisfellows.ThefirstreallyeffectiveastronomicalperiodicalwastheMonatliclieCorrespondent,startedbyVonZachintheyear1800.Itwasfollowedin1822...
21
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
irredanimpressionableaudiencetothepitchofprovidinghimwiththemeansoferectingatCincinnatithefirstastronomicalestablish-mentworthythenameinthatgreatcountry.Onthe1stofJanuary1882nolessthanonehundredandforty-fourwereactivewithinitsboundaries.Theapparitionofthegreatcometof1843gaveanadditionalfilliptothemovement.Totheexciteme...
22
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
utureconquest.Theirgradualappropriationhasabsorbed, INTRODUCTION.9andwilllongcontinuetoabsorb,thepowerswliicliithasservedtodevelop.Butthisisnottheonlydirectioninwhichastronomyhasenlarged,orratherhaslevelled,itsboundaries.Theunificationofthephysicalsciencesisperhapsthegreatestintellectualfeatofrecenttimes.Theprocesshasi...
23
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
hemutualrevolutionsofthestellarmultitudeduringtractsoftimewhichseemtolengthenouttoeternityasthemindattemptstotraversethem,shedoesnotadmittobebeyondherken;norissheindifferenttothecon-stitutionoftheminutestatomofmatterthatthrillstheetherintolight.Howsheentereduponthisvastlyexpandedinherit-ance,andhow,sofar,shehasdealtwit...
24
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
dwithimprovedappliancestheenumerationwasrenderedmoreandmoreaccurateandcomplete;butthesecretsofthestellarsphereremainedinviolate.Inaqualified,thoughveryrealsense,SirWilliamHerschelmaybecalledtheFounderofSiderealAstronomy.Beforehistimesomecuriousfactshadbeennoted,andsomeingenious CHAP.i. SIDEREALASTRONOMY.uspeculationsha...
25
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
fthesun,"3toaccountforcertainsuspectedchangesinstellarpositions;Bradleyin1748,andLambertin1761,pointedoutthatsuchapparentdisplacements(bythattimewellascertained)wereinallprobabilityacombinedeffectofmotionsbothofsunandstars;andMayeractuallyattemptedtheanalysis,butwithoutresult.Onthe13thofAugust1596,DavidFabricius,anunpr...
26
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
AlgolinPerseussharedthesamepeculiaritytoamarkeddegree.Altogethertheclassembracedin1782half-a-dozenmembers.Whenitisaddedthatafewstar-coupleshadbeennotedinsingu-larly,butitwassupposedaccidentally,closejuxtaposition,andthatthefailureofrepeatedattemptstofindanannualparallaxpointedtodistancesforthestarsatleast400,000timesth...
27
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
astrouscampaignof1757,hisparentsremovedhimfromtheregiment,thereisreasontobelieve,inasomewhatunceremoniousmanner.Technically,indeed,hein-curredthepenaltiesofdesertion,remittedaccordingtotheDukeofSussex'sstatementtoSirGeorgeAirybyaformalpardonhandedtohimpersonallybyGeorgeIII.onhispresenta-1BradleytoHalley,Phil.Trans.,vol...
28
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
mountingtothirty-fiveoreventhirty-eightlessonsaweek.Heinfactpersonifiedthemusicalactivityofaplacetheneminentlyandenergeticallymusical.Butthesemultifariousavocationsdidnottakeupthewholeofhisthoughts.Hiseducation,notwithstandingthepovertyofhisfamily,hadnotbeenneglected,andhehadalwaysgreedilyassimilatedeverykindofknowledg...
29
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
cametohisaid.HavingpurchasedtheapparatusofaQuakeroptician,hesetaboutthemanu-factureofspeculawithazeal^whichseemedtoanticipatethewonderstheyweretodisclosetohim.Itwasnotuntilfifteenyearslaterthathisgrindingandpolishingmachineswereinvented,sotheworkhadatthattimetobeentirelydonebyhand.Duringthistediousandlaboriousprocess(w...
30
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
."3Henowrapidlyincreasedthepowerandperfectionofhistelescopes.Mirrorsofseven,ten,eventwentyfeetfocallength,weresuccessivelycompleted,andunprecedentedmagnifyingpowersemployed.Hisenergywasunceasing,hisperseveranceindomitable.Inthecourseoftwenty-oneyearsnolessthan430parabolicspeculalefthis1CarolineLucretiaHerschel,bornatHa...
31
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
ecureaccuracyinhisobservations;yetinonenighthewouldexamine,singlyandattentively,upto400separateobjects.ThediscoveryofUranuswasamereincidentoftheschemehehadmarkedoutforhimselfafruit,gatheredasitwerebytheway.Itformed,nevertheless,theturning-pointinhiscareer.Fromastar-gazingmusicianhewasatoncetrans-formedintoaneminentastr...
32
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
erianGuelphicOrderin1816,andin1821hebecamethefirstPresidentoftheEoyalAstronomicalSociety,hissonbeingitsfirstForeignSecretary.Bjuthishealthhadnowforsomeyearsbeenfailing,andonAugust25,1822,hediedatSlough,intheeighty-fourthyearofhisage,andwasburiedinUptonchurchyard.Hisepitaphclaimsforhimtheloftypraiseofhaving"burstthebarr...
33
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
e,risingtothrongsofsunswithinthecircuitoftheMilkyWaythe"eclipticofthestars,"ashephraseditexpandingtoincludegroupsofmanyMilkyWays;theseagaincombiningtoformtheunitofahigherorderofassemblage,andsoonwardsandupwardsuntilthemindreelsandsinksbeforetheimmensityofthecontemplatedcreations.1AnOriginalTheoryorNewHypothesisoftheUni...
34
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
pbehindoftreesinaforesttotheeyeofanadvancingspectator;2buttheappearanceswhichhethuscorrectlydescribedhewasunabletodetect.Byamoresearchinganalysisofasmallercollectionofpropermotions,HerschelsucceededinrenderingapparenttheveryconsequencesforeseenbyMayer.Heshowed,forexample,thatArcturusandVegadid,infact,appeartorecedefrom...
35
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
ananalyticalinquiryin1789.4Phil.Trans.,vol.xcv.,p.233.5Ibid.,vol.xcvi.,p.205. i8 HISTORYOFASTRONOMY.PARTI.liemadeapreliminaryattempttoascertainthespeedofthesun'sjourney,whichhenodoubtgreatlyunder-estimatedinfixingitataboutthreemilesasecond.Yetthevalidityofhisgeneralconclusionastothelineofsolartravel,thoughlongdoubted,h...
36
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
selfmadetheattempt;butwithhis"Trique-trum,"ajointedwoodenrulewiththedivisionsmarkedinink,constructedbyhimself,hewashardlyabletomeasureanglesoftenminutes,farlessfractionsofasecond.Galileo,amoreimpassioneddefenderofthesystem,strainedhisears,asitwere,fromArcetri,inhisblindandsorrowfuloldage,fornewsofadiscoverywhichtwomore...
37
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
educedtooneofsimplemicrometricalmeasurement.The"double-starmethod"wasalsosuggestedbyJamesGregoryin1675,andagainbyWallisini693;2Huygensfirst,andafterwardsDr.LongofCambridge(about1750),madefutileexperimentswithit;anditeventuallyled,inthehandsofBessel,tothesuccessfuldeter-minationoftheparallaxof61Cygni.Itsadvantageswereno...
38
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
NOMY.PARTI.afterthreeyears,byanadditionallistof434.Inboththesecollectionsthedistancesseparatingtheindividualsofeachpairwerecarefullymeasured,and(withafewexceptions)thedirec-tionswithreferencetoacelestialmeridian,ofthelinesjoiningtheircentres(technicallycalled"anglesofposition")weredeterminedwiththeaidofa"revolving-wire...
39
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
ewyearsmayinformusthatsomeofthegreatnumberofdouble,triplestars,&c.,whichhavebeenobservedbyMr.Herschel,aresystemsofbodiesrevolvingabouteachother."ThisremarkablespeculativeanticipationhadapracticalcounterpartinGermany.FatherChristia.nMayer,aJesuitastronomeratMannheim,sethimself,inJanuary1776,tocol-lectexamplesofstellarpa...
40
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
eintheyearfollowing,3heremarkedthattheidentical,propermotionsofthetwostarsforming,tothenakedeye,thesinglebrightorbofCastorcouldonlybeexplainedasbothequallyduetothe"systematicparallax"causedbythesun'smovementinspace.Plainlyshowingthatthenotionofaphysicaltie,compellingthetwobodiestotraveltogether,hadnotasyetenteredintohi...
41
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
,p.162.3Ibid.,vol.Ixxiii.,p.272.4Phil.Trans.,vol.xciii.,p340. 22HISTORYOFASTRONOMY.PARTi. gBootis,1681years;cLyraewasnotedasa"double-double-star,"achangeofrelativesituationhavingbeendetectedineachofthetwopairscomposingthegroup;andtheoccultationofonestarbyanotherinthecourseoftheirmutualrevolutions,wasdescribedashavingbe...
42
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
MilkyWay,todelineateitsform,measureitsdimensions,andsearchouttheintricaciesofitsconstruction,wastheprimarytaskofhislife,whichheneverlostsightof,andtowhichallhisotherinvestigationsweresubordinate.Hewasabsolutelyaloneinthisboldendeavour.Unaided,hehadtodevisemethods,accumulatematerials,andsiftoutresults.Yetitmaysafelybeas...
43
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
oeveryreaderofanastronomicaltext-book.Widely-varyingevidencewas,asmighthavebeenexpected,derivedfromanexaminationofdifferentportionsofthesky.Somefieldsofviewwerealmostblank,whileothers,inorneartheMilkyWay,blazedwiththeradianceofmanyhundredstarscompressedintoanareaaboutone-fourththatofthefull-moon.Inthemostcrowdedparts11...
44
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
hil.Trans.,vol.Ixxv.,p.255. 24HISTORYOFASTRONOMY.PARTI.itsneighboursaswidelyasthesunfromSirius."Itappears."hewrotein1789,'''thattheheavensconsistofregionswheresunsaregatheredintoseparatesystems";andincertainassemblageshewasabletotrace"acourseortideofstarssettingtowardsacentre,"denoting,notdoubtfully,thepresenceofattrac...
45
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
ecannotbesurprisedthatmanythingsformerlytakenforgrantedshouldonexaminationprovetobedifferentfromwhattheyweregenerallybutincautiouslysupposedtobe.Forinstance,anequalscatteringofthestarsmaybeadmittedincertaincalculations;butwhenweexaminetheMilkyWay,orthecloselycompressedclustersofstarsofwhichmycatalogueshaverecordedsoman...
46
history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
ncy,inthesunsofourfirmament,conclusionsdrawnfromsuchacomparisonareentirelyworthless.Inanotherbranchofsiderealsciencebesidesthatofstellaraggregation,Herschelmayjustlybestyledapioneer.Hewasthefirsttobestowseriousstudyontheenigmaticalobjectsknownas"nebulae."Thehistoryoftheacquaintanceofourracewiththemiscomparativelyshort....
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history_of_astronomy_A_Popular_History_of_Astronomy_During_the_Nineteenth_Centur.txt
ebula,WashingtonObservations,vol.xxv.,1878(pub.1882).sMathemataAstronomica,p.75. 26HISTORYOFASTRONOMY.PARTI.aglimpseofamoreluminousregionbeyond."*Halleyin1716knewofsixnebulae,whichhebelievedtobecomposedofa"lucidmedium"diffusedthroughtheetherofspace.2Heappears,however,tohavebeenunacquaintedwithsomepreviouslynoticedbyHev...
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ostimperceptibledegreesfromevidentclusters,suchasthePleiades,tospotswithoutatraceofstellarformation,thegradationsbeingsowellconnectedastoleavenodoubtthatallthesephenomenawereequallystellar.Thesingularvarietyoftheirappearancewasthusdescribedbyhim:"Ihaveseen,"hesays"doubleandtreblenebulaevariouslyarranged;largeoneswithsm...
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itsorigintomanyremarkablylargeaswellasprettycloselyscatteredsmallstars,thatmayhavedrawntogethertherest."3Butthecontinuedactionofthissame"clusteringpower"would,hesupposed,eventuallyleadtothebreakingupoftheoriginalmajesticGalaxyintotwoorthreehundredseparategroups,alreadyvisiblygathering.Suchminornebulas,duetothe"decay"of...
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bid.,vol.Ixxix.,p.213.3Ibid.,vol.Ixxv.,p.254.*Ibid.,vol.Ixxix.,p.225. 28HISTORYOFASTRONOMY.PARTr.resemblealuxuriantgardenwhichcontainsthegreatestvarietyofproductionsindifferentnourishingbeds;andoneadvantagewemayatleastreapfromitis,thatwecan,asitwere,extendtherangeofourexperiencetoanimmenseduration.For,tocontinuethesimi...
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tvanishesbeforehim.Inthesamemannerwepassthroughgentlestepsfromacoarseclusterofstars,suchasthePleiades...tillwefindourselvesbroughttoanobjectsuchasthenebulainOrion,wherewearestillinclinedtoremainintheonceadoptedideaofstarsexceed-inglyremoteandinconceivablycrowded,asbeingtheoccasionofthatremarkableappearance.Itseems,ther...
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veahintofthedirectioninwhichhismindwasmov-ingbytheremarkthatthisself-luminousmatterseemed"morefittoproduceastarbyitscondensation,thantodependonthestarforitsexistence."2Thiswasnotanovelidea.TychoBrahehadtriedtoexplaintheblazeofthestarof1572asduetoasuddenconcentrationofnebulousmaterialintheMilkyWay,evenpointingoutthespac...
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277. 30HISTORYOFASTRONOMY.PARTI.phaseofcondensation.Thevalidityofhisreasoning,however,wasevidentlyimpairedbyhisconfessedinabilitytodistinguishbetweenthedimraysofremoteclustersandthemilkylightoftruegaseousnebulae.., Itmaybesaidthatsuchspeculationsarefutileinthemselves,andnecessarilybarrenofresults.Buttheygratifyaninhere...
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-dour,andsometimesbrilliantlycontrastedincolour,wereseentobeheldtogetherinsystems,consistingoftwo,three,four,evensixmembers,whoserevolutionsexhibitedawiderangeofvarietybothinperiodandinorbitalform.Anewdepartmentofphysicalastronomywasthuscreated,1andrigidcalculationforthefirsttimemadepossiblewithintheastralregion.Thevas...
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desandstreamsofsunstobesettingtowardspowerfulcentresofattraction;newsystemstobeinprocessofformation,whileeffeteoneshastenedtodecayorregenerationwhenthecourseappointedforthembyInfiniteWisdomwasrun.Andthus,toquotethewordsoftheobserverwho"hadlookedfartherintospacethaneverhumanbeingdidbeforehim,"1"thestateintowhichtheinces...
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encefindsitsadvantage,asinmanycasesithastakenitsorigin,incondescensiontopracticalclaims.Indeed,tobringsuchknowledgeasnearaspossibletoabsoluteprecisionhasbeendennedbynomeanauthority1asthetrueendofastronomy.Severalcausesconcurredaboutthebeginningofthepresentcenturytogiveafreshandpowerfulimpulsetoinvestigationshavingthise...
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ulandprolongedseriesofobservationsexecutedbyhimformedthebasisoftheimprovedtheories,andcorrectedtablesofthecelestialmovements,whichwererapidlybeingbroughttocompletionabroad.Hiscatalogueofthirty-six"fundamental"starswasbesidesexcellentinitsway,andmostserviceable.YethewasdevoidofBradley'sinstinctfordiviningtheneedsofthefu...
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rs,Schroter,andVonZach,justandelevatedideasonthesubjectwerepropagated,intelligencewasdiffused,andafirmgroundpreparedforcommonactioninmutualsympathyanddisinterestedzeal.Theywerepowerfullysecondedbythe1Fittedtotheoldtransitinstrument,July11,1772.3 34HISTORYOFASTRONOMY.PARTI.foundation,in1804,byayoungartilleryofficernamed...
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her'schoicetowardsamercantilecareer.Inhisfifteenthyear,accordingly,heenteredthehouseofKuhlenkamp&Sons,inBremen,asanapprenticedclerk.Hewasnowthrowncompletelyuponhisownresources.Fromhisfather,astrugglingGovernmentofficial,heavilyweightedwithalargefamily,hewaswellawarethathehadnothingtoexpect;hisdormantfacultieswereroused...
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observationwasmadewithasextant,rudelyconstructedunderhisowndirections,andacommonclock.ItsobjectwasthedeterminationofthelongitudeofBremen,anditssuccess,hetellsushimself,1filledhimwitharaptureofdelight,which,byconfirminghistastes,decidedhisdestiny.HenoweagerlystudiedBode'sJahrbuchandVonZach'sMonatliclieCorrespondents,ove...
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hoursdevotedtostudy.ThepaperwasimmediatelysenttoVonZachforpublication,withanotefromOlbersexplainingthecircumstancesofitsauthor,andthenameofBesselbecamethecommonpropertyoflearnedEurope.Hehad,however,asyetnointentionofadoptingastronomy1BrieficechselmitOlbers,p.xvi. 36HISTORYOFASTRONOMY.PARTi.ashisprofession.Fortwoyearsli...
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fthattimethePrussianGovernmentchosehimtosuperintendtheerectionofanewobservatoryatKonigsberg.whichaftermanyvexatiousdelayscausedbytheprostrateconditionofthecountry,wasfinishedtowardstheendof1813.KonigsbergwasthefirstreallyefficientGermanobservatory.Itbecame,moreover,acentreofimprovement,notforGermanyalone,butforthewhole...
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nderthemavailableforexactpurposes.Piazzisetanexampleofimprovedmethodsofobservation,resultinginthepublication,in1803and1814,oftwocataloguesofabout7600starsthesecondbeingarevisionandenlargementofthefirstwhichfortheirtimeweremodelsofwhatsuchworksshouldbe.StephenGroombridgeatBlackheathwassimilarlyandmostbeneficiallyactive....
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eearthinitsorbit,causesaminutedisplacementknownasaberration.Nowitiseasytoseethatanyuncertaintyintheapplicationofthesecorrectionssapstheveryfoundationsofexactastronomy.Extremelyminutequantities,itistrue,areconcerned;butthelifeandprogressofmoderncelestialsciencedependsuponthe ]Bessel,Pop.Vorl.,p.440. 38HISTORYOFASTRONOMY...
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errorsofeachofBradley'sinstruments,andadifficultanddelicateinquiryintothetruevalueofeachcorrectiontobeappliedbeforetheentriesintheGreenwichjournalscouldbedevelopedintoafinishedandauthenticcatalogue.Althoughcompletedin1813,itwasnotuntilfiveyearslaterthattheresultsappearedwiththeproud,butnotinappropriatetitleofFundamenta...
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tsdrawnfromtheBradleyandPiazzicatalogues,athirdtermofcomparisonwaswanted,andthisBesselundertooktosupply.Byacourseof75,011observations,executedduringtheyears182133,withtheutmostnicetyofcare,thenumberofaccuratelyknownstarswasbroughtuptoabove$0,000,andanamplestoreoftrust-worthyfactslaidupfortheuseoffutureastronomers.Inthi...
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assimilarlyde-luded.ThecelebratedcontroversybetweentheAstronomerRoyalandDr.Brinkley,directoroftheDublinCollegeObservatory,turnedonthesamesubject.Brinkley,whowasinpossessionofafirst-ratemeridiancircle,believedhimselftohavediscoveredrela-tivelylargeparallaxesforfourofthebrighteststars;Pond,rely-1Durege,HesseVsLebenundWir...
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nJosephwaswitnessofthescene,becameinterestedinthesurvivor,andconsoledhismisfortunewithapresentofeighteenducats.Seldomwasmoneybetterbestowed.Partofitwenttobuybooksandaglass-polishingmachine,withthehelpofwhichyoungFraunhoferstudiedmathematicsandoptics,andsecretlyexercisedhimselfintheshapingandfinishingoflenses;theremaind...
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tstilloccupies.Byingeniousimprovementsinmountingandfitting,itwasadaptedtothefinestmicrometricalwork,andthusofferedunprecedentedfacilitiesbothfortlieexaminationofdoublestars(inwhichStruvechieflyemployedit),andforsuchsubtlemeasurementsasmightservetorevealordisprovetheexistenceofasensiblestellarparallax.Fraunhofer,moreove...
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ditatedimprove-mentsinreflectorsasimportantasthosehehadalreadyeffectedinrefractors;andwasbesideseagerlyoccupiedwithinvestiga-tionsintothenatureoflight,themomentouscharacterof 1Theheadsofthescrewsappliedtomovethehalvesoftheobject-glassintheKonigsbergheliometerareofsoconsiderableasizethatathousandthpartofarevolution,equi...
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adifferentcriterionofdistance.Itisimpossibletoescapefromtheconclusionthattheapparentlyswiftest-movingstarsare,onthewhole,alsothenearesttous,howevernumeroustheindividualexceptionstotherule.Now,asearlyasI792,1Piazzihadnoted,asanindicationofrelativevicinitytotheearth,theunusuallylargepropermotion(5.2"annually)ofadoublesta...
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ru-mentsandthevicinitytotheirselectedstarsofminute,physi-callydetachedcompanionsofferedspecialfacilities.Inthelastmonthof1838Besselmadeknowntheresultofoneyear'sobservations,showingfor61Cygniaparallaxofaboutathirdofasecond(O.3I36").1Hethenhadhisheliometertakendownandrepaired,afterwhichheresumedtheinquiry,andfinallytermi...
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inhisnativetownofDundee,hadbecomeknownforhisastronomicalattainments,andwasappointedin1831todirect 1AstronomischeNachricJiten,Nos.365-366.Itshouldbeexplainedthatwhichiscalledthe"annualparallax"ofastarisonlyhalfitsapparentdis-placement.Inotherwords,itistheanglesubtendedatthedistanceofthatparticularstarbytheradiusoftheear...
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rom1834untilhisprematuredeathin1844.Theresultjustifiedhisexpectations.FromthedeclinationmeasurementsmadeattheCapeanddulyreduced,aparallaxofaboutonesecondofarcclearlyemerged(diminishedbyGill'sandElkin'sobservations,1882-1883,to0.75"),but,byperhapsanexcessofcaution,waswithheldfrompublicationuntilfullercertaintywasafforde...
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vol.xi.,p.61. CHAP.ii.SIDEREALASTRONOMY.45GreatBear;lyetthevicinityofthisminuteobjectissomuchgreaterthanthatofthebrilliantVega,thatthelattertrans-portedtoitsplacewouldincreaseinlustrethirtytimes.Moreover,manyofthebrighteststarsarefoundtohavenosensibleparallax,whilethemajorityofthoseascertainedtobenearesttotheearthareof...
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fspecialarrangementsinthemselveshighlyimprobable,and,wemayconfidentlysay,non-existent.Thedistancesevenofthefewstarsfoundtohavemeasurableparallaxesareonascaleentirelybeyondthepowersofthehumanmindtoconceive.Intheattemptbothtorealisethemdistinctly,andtoexpressthemconveniently,anewunitoflength,itselfofbewilderingmagnitude,...
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iodtoenableus,byaneasysuminproportion,tofindtheircombinedmassintermsofthatofthesun.Thus,sinceaccordingtoDr.Doberck'selementsthetwostarsformingaCentaurirevolveroundtheircommoncentreofgravityatameandistancenearly25timestheradiusoftheearth'sorbit,inaperiodof88years,theattractiveforceofthetwotogethermustbejusttwicethesolar...
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RONOMY.47entiresiderealsystemtocontrol;andToucangepossesses,accordingtoDr.Gill,nearlyhalfthatamazingvelocitybesideswhatevermovementeachmayhavetowardsorfromtheearth,ofwhichthespectroscopemayeventuallygiveanaccount.Herschel'sconclusionastothemovementofthesunamongthestarswasnotadmittedasvalidbythemosteminentofhissuccessor...
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terminedbyMr.Main,reachedconclusionscloselysimilartothatindicatednearlyeightyyearspreviouslybythefirstgreatsiderealastronomer;whichMr.Plummer'sreinvesti-gationofthesubjectini8835servedbutslightlytomodify.Yetastronomerswerenotsatisfied.Dr.AuwersofBerlinfinishedin1886asplendidpieceofwork,6forwhichhereceivedin1888theGoldM...
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whichthemoreeasterlypositionofthesolarapexwasfullyconfirmed.ThebrilliantVegamayindeedbesaidtomarkacentreroundwhichnewlydeterminedapexestendlooselytogroupthemselves.4Thegeneraldirec-tionofthesolarmovementmayneverthelessberegardedasfairlywellknown;butastoitsrate,thegroundsofinferencelongremainedunsatisfactory.OttoStruve'...
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tices+vol.li.,p.243;Nature,vol.xliv.,p.572. CHAP.ii.SIDEREALASTRONOMY.49HerschelthrewoutthehintthatthegreatclusterinHercules(estimatedtoinclude14,000stars)mightprovetobethesupremeseatofattractiveforce-1ArgelanderplacedhiscentralbodyintheconstellationPerseus;2Fomalhaut,thebrilliantoftheSouthernFish,wassetinthepostofhono...
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ointwas,byanavowedlyconjecturalmethod,fixedat18,200,000years,implying,ontheextremelyhazardoussuppositionthatthedistanceofAlcyoneisthirty-fourmilliontimesthatoftheearthfromthesun,avelocityforoursystemofaboutthirtymilesasecond.TheschemeofsiderealgovernmentframedbytheDorpatastronomerwas,itmaybeobserved,ofthemostapprovedco...
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rdingtheplanetNeptunedoesnotbelongtothepresentdivisionofoursubject;astrictlyanalogousdiscoveryinthesiderealsystemwas,however,alsoveryclearlyforeshadowedbyhim.Hisearliestsuspicionsofnon-uniformityinthepropermotionofSiriusdatedfrom1834;theyextendedtoProcyonin1840;andafteraseriesofrefinedmeasurementswiththenewRepsoldcircl...
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inWestmnann'sJahrbuch,1867,p.615.~LetterfromBesseltoSirJ.Herschel,Month.Xot.,vol.vi.,p.139.3Wolf,Gesch.d,Astr.p.743,note.4Astr.Nach.,Nos.745-748. -CHAP.ii.SIDEREALASTRONOMY.51companionintheprecisepositionrequiredbytheory.Ithasnowbeenwatchedthroughthree-fifthsofarevolution(period49.4years),andprovestobeveryslightlylumin...
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hichheleftvacantwasnotoneeasytofill.Hislife'sworkmightbetrulydescribedas''epoch-making."Rarelyindeedshallwefindonewhoreconciledwiththesamesuccesstheclaimsoftheoreticalandpracticalastronomy,orsurveyedthesciencewhichhehadmadehisownwithaglanceequallycomprehensive,practical,andprofound.ThecareerofFriedrichGeorgWilhelmStruv...
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ationaffordedbytheFraun-hoferachromaticencouragedhimtoundertake,February11,1825,areviewoftheentireheavensdownto15southofthecelestialequator,whichoccupiedmorethantwoyears,andyielded,fromanexaminationofaboveI2O.OOOstars,aharvestofabout2200previouslyunnoticedcompositeobjects.Theensuingtenyearsweredevotedtodelicateandpatie...
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hastodemonstratetheirphysicalconnection,evenifnootherproofwereforthcoming.Manystarspreviouslybelievedtobesingledividedunderthe1UeberdieDoppelsterne,Bericftt.1827,p.22. CHAP.ii.SIDEREALASTRONOMY.53scrutinyoftheDorpatrefractor;whileinsomecases,onememberofa(supposed)binarysystemrevealeditselfasdouble,thusplacingthesurpris...
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onclusionthatsingledonotoutnumberconjoinedstarsmorethantwiceorthrice.5In1835StruvewassummonedbytheEmperorNicholastosuperintendtheerectionofanewobservatoryatPulkowa,nearSt.Petersburg,destinedforthespecialcultivationofsiderealastronomy.Boundlessresourceswereplacedathisdisposal,andtheinstitutioncreatedbyhimwasacknowledged...
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maintheinferencesarrivedatbyHerschelastotheconstructionoftheheavens.Accordingtohisview,theappearanceknownastheMilkyWayisproducedbyacollectionof(forthemostpart)irregularlycondensedstar-clusters,withinwhichthesunissomewhateccentricallyplaced.Thenebulousringwhichthusintegratesthelightofcountlessworldswassupposedbyhimtobem...
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otthustobefulfilled.TheacquaintanceofDr.Wollastondecidedhisscientificvocation-Already,in1816,wefindhimreviewingsomeofhisfather's1Etudesd"AstronomicStellaire,1847,p.82.-Ibid.,p.86.sSeeEncke's-criticisminAstr.Nach.,No.622. CHAP.ii.SIDEREALASTRONOMY.55doublestars;andhecompletedin1820the18-inchspeculumwhichwastobethechiefi...
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onalprincipleswithaperiodof58Jyears.EiickefollowedatBerlinwithastillmoreelegantmethod;andSirJohnHerschel,pointingouttheuselessnessofanalyticalrefinementswherethedatawerenecessarilysoimperfect,describedin1831agraphicalprocessbywhich"theaidoftheeyeandhand"wasbroughtin"toguidethejudgmentinacasewherejudgmentonly,andnotcalc...
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,landedatCapeTownonthei6thofJanuary1834.ChoosingasthesceneofhisobservationsaruralspotundertheshelterofTableMountain,hebeganregular"sweeping"onthe5thofMarch.Thesiteofhisgreatreflectorisnowmarkedwithanobelisk,andthenameofFeldhausenhasbecomememorableinthehistoryofscience;forthefouryears'workdonetheremaytrulybesaidtoopenth...
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dvarietyoftheircontentsbeingsuchthatalifetimemightwithgreatprofitbedevotedtotheirstudy.IntheGreaterNubecula,withinacompassofforty-twosquaredegrees,1Phil.Trans.,vol.cxxiii.,andResults,(Oc.,Introd.-.ResultsofAstro-nomicalObservationsmadeduringtheyears1834-8attfieCapeofGoodHope. CHAP.ii.SIDEREALASTRONOMY.57Herschelreckone...
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atreflectorsacrowdoftheseobjectsintostars.Hisformersomewhathesitatingbeliefintheexistenceofphos-phorescentmatter,"disseminatedthroughextensiveregionsofspaceinthemannerofacloudorfog,"3waschangedintoaconvictionthatnovaliddistinctioncouldbeestablishedbetweenthefaintestwispofcosmicalvapourjustdiscerniblewithapowerfultelesc...
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herexamplesofalikeimportmightbequoted.Theremarkablyfrequentoccurrenceofoneormoreminutestarsintheclosevicinityof"planetary"nebulgeledhimtoinfertheirdependentcondition;andheadvisedthemaintenanceofastrictwatchforevidencesofcirculatorymovements,notonlyoverthesesupposedstellarsatellites,butalsooverthenumerous"doublenebulae,...
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ominatedrjArgus.WhenHalleyvisitedSt.Helenain1677.itseemedofthefourthmagnitude;butLacailleinthemiddleofthefollowingcentury,andothersafterhim,classeditasofthesecond.In1827thetravellerBurchell,beingthenatSt.Paul,nearRioJaneiro,remarked1Phil.Trans.,vol.cxxiii.,p.503.-Itesults,&c.,p.136. CHAP.ii.SIDEREALASTRONOMY.59thatitha...
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butwasnotcarriedveryfar;andthestarnowshinessteadilyasoftheseventhmagnitude,itsreddishlightcontrastingeffectivelywiththesilveryraysofthesurroundingnebula.Anattempttoincludeitsfluctuationswithinacycleofseventyyearslhassignallyfailed;theextentandcharacterofthevicissitudestowhichitissubjectstampingitratherasaspeciesofconne...
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000),itbecamepossibletocomparestellarwithsolarradiance.Hencewasderived,inthecaseofthefewstarsatascertaineddistances,aknowledgeofreallustre.AlphaCentauri,forexample,emitsaboutfourtimes,Capella250timesasmuchlightasoursun;whileArcturus,judgingfromitsindefinitedistance,mustdisplaythesplendourofacoupleofthousandsuchluminari...
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ials.3HediedatCollingwoodinKent,MayII,1871,in1Phil.Trans.,vol.cxix..p.27.2Dr.Dreyer'sNewGeneralCatalogue,publishedin1888asvol.xlix.oftheRoyalAstronomicalSociety'sMemoirs,isanenlargementofHerschel'swork.Itincludes7,840entries.3Alistof10.320compositestarswasdrawnoutbyhiminorderofrightascension,andhasbeenpublishedinvol.xl...
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