Anotherresultofthisabruptdeparturewasaveryrapidrise，whichtooktheballoonaheightof3，000feetinthreeminutes’
space，andanother4，000feethigherinsixminutesmore。
Seventhousandfeetverticallyinnineminutesisfastpace;
butthevoyagersweretoknowhigherspeedyetthatdaywhentheverticalmotionwastobeinthereverseandwrongdirection。Attheheightnowreachedtheywereincloud，andwhilethusenvelopedthetemperature，asoftenhappens，remainedpracticallystationaryatabout32degrees，whilethatofthedewpointincreasedseveraldegrees。But，onpassingoutofthecloud，thetwotemperatureswereverysuddenlyseparated，thelatterdecreasingrapidlyunderadeepblueupperskythatwasnowwithoutacloud。Shortlyafterthisthetemperaturedroppedsuddenlysome8degrees，andthen，duringthenext12，000feet，creptslowlydownbysmallstages。
Presentlytheballoon，reachingmorethantwentythousandfeet，or，roughly，fourmiles，andstillascending，thethermometerwastakenwithsmallfitsofrisingandfallingalternatelytillanaltitudeof24，000feetwasrecorded，atwhichpointotherandmoreseriousmattersintrudedthemselves。
Theearthhadbeenforaconsiderabletimelosttoview，andtherateanddirectionofrecentprogresshadbecomemerelyconjectural。Whatmightbetakingplaceintheseobscuredandloftyregions？Itwouldbeaswelltodiscover。Sothevalvewasopenedratherfreely，withtheresultthattheballoondroppedamileinthreeminutes。Thenanothermileslower，byashade。Thenat12，000feetacloudlayerwasreached，andshortlyafterthevoyagersbrokethroughintotheclearbelow。
AtthatmomentMr。Glaisher，whowasbusywithhisinstruments，heardMr。Coxwellmakeanexclamationwhichcausedhimtolookoverthecar，andhewrites，"Theseaseemedtobeunderus。
Mr。Coxwellagainexclaimed，’There’snotamomenttospare:wemustsavethelandatallrisks。Leavetheinstruments。’Mr。
Coxwellalmosthungtothevalveline，andtoldmetodothesame，andnottominditscuttingmyhand。Itwasabolddecisionopeningthevalveinthisway，anditwasboldlycarriedout。"Asmaybesupposed，thebolddecisionendedwithacrash。Thewholetimeofdescendingthefourandaquartermileswasaquarterofanhour，thelasttwomilestakingfourminutesonly。Forallthat，therewasnopenaltybeyondafewbruisesandthewreckingoftheinstruments，andwhenlandwasreachedtherewasnorebound;theballoonsimplylayinerthardbythemarginofthesea。ThisterrificexperienceinitssalientdetailsisstrangelysimilartothatalreadyrecordedbyAlbertSmith。
Infurtherexperimentallaboursconductedduringthesummerofthisyear，manyinterestingfactsstandoutprominentlyamongavoluminousmassofobservations。InanascentinaneastwindfromtheCrystalPalaceinearlyJulyitwasfoundthattheupperlimitofthatwindwasreachedat2，400feet，atwhichlevelanair—streamfromthenorthwasencountered;butat3，000feethigherthewindagainchangedtoacurrentfromtheN。N。W。Attheheight，then，oflittlemorethanhalfamile，theseuppercurrentsweretravellingleisurely;butwhatwasmorenoteworthywastheirhumidity，whichgreatlyincreasedwithaltitude，andafactwhichmayoftenbenotedhereobtrudeditself，namely，whentheaeronautswereattheupperlimitsoftheeastwind，flat—bottomedcumuluscloudswerefloatingattheirlevel。Thesecloudswereentirelywithintheinfluenceoftheupperornorthwind，sothattheirundersideswereincontactwiththeeastwind，i。e。withamuchdrierair，whichatoncedissipatedallvapourincontactwithit，andthuspresentedtheappearanceofflat—bottomedclouds。Itisacommonexperiencetofindthelowersurfaceofacloudmowedoffflatbyaneastwindblowingbeneathit。
AttheendofJuneavoyagefromWolvertonwasaccomplished，whichyieldedremarkableresultsofmuchrealvalueandinterest。Thepreviousnighthadbeenperfectlycalm，andthroughnearlythewholemorningthesunshoneinaclearbluesky，withoutasymptomofwindorcomingchange。Shortlybeforenoon，however，cloudsappearedaloft，andtheskyassumedanalteredaspect。Thenthestateofthingsquicklychanged。Windcurrentsreachedtheearthblowingstrongly，andthehalf—filledballoonbegantolurchtosuchanextentthattheinflationcouldonlywithdifficultybeproceededwith。
Fiftymenwereunabletoholditinsufficientrestrainttopreventrudebumpingofthecarontheground，andwhen，atlength，arrangementswerecompleteandreleaseeffected，rapiddischargeofballastalonesavedcollisionwithneighbouringbuildings。
Itwasnowthatthedisturbanceoverheadcameunderinvestigation;and，consideringtheshortperiodithadbeeninprogress，provedmostremarkable，themoresothefurtheritwasexplored。At4，000feettheyplungedintothecloudcanopy，throughwhichasitwaspainfullycold，they，soughttopenetrateintotheclearabove，feelingconfidentoffindingthemselves，accordingtotheirusualexperience，inbrightbluesky，withthesunbrilliantlyshining。Onthecontrary，however，theregiontheynowenteredwasfurtherobscuredwithanothercanopyofcloudfarup。Itwaswhiletheyweretraversingthisclearintervalthatasoundunwontedinballoontravelassailedtheirears。Thiswasthe"sighing，orrathermoaning，ofthewindasprecedingastorm。"Rustlingofthesilkwithinthecordageisoftenheardaloft，beingduetoexpansionofgasorsimilarcause;buttheaeronautssoonconvincedthemselvesthatwhattheyheardwasattributabletonothingelsethantheactualconflictofaircurrentsbeneath。
Thentheyreachedfog——adryfog——and，passingthroughit，enteredafurtherfog，butwettingthistime，andwithinthenext1，000feettheywereonceagaininfogthatwasdry;andthen，reachingthreemileshighandseeingstrugglingsunbeams，theylookedaroundandsawcloudeverywhere，below，above，andfarcloudsontheirownlevel。Thewholeskyhadfilledinmostcompletelysincethehoursbutrecentlypassed，whentheyhadbeenexpatiatingontheperfectserenityoftheemptyheavens。
Stilltheyclimbedupwards，andinthenext2，000feethadenteredfurtherfog，dryatfirst，butturningwetterastheyrose。Atfourmileshightheyfoundthemselvesonalevelwithclouds，whosedarkmassesandfringededgesprovedthemtobeveritablerainclouds;and，whilestillobservingthem，thefogsurgedupagainandshutouttheview，andbythetimetheyhadsurmountedittheywerenolessthan23，000feetup，orhigherthantheloftiestoftheAndes。Evenhere，withcloudmassesstillpilinghighoverhead，theeagerobserver，bentonfurtherquests，wasforpursuingthevoyage;butMr。Coxwellinterposedwithanemphatic，"Tooshortofsand！"andthedownwardjourneyhadtobecommenced。Thenphenomenasimilartothosealreadydescribedwereexperiencedagain——fogbanks（sometimeswet，sometimesdry），rainshowers，andcloudstrataofpiercingcold。Presently，too，anewwonderforamidsummerafternoon——asnowsceneallaround，andspiculesoficesettlingandremainingfrozenonthecoatsleeve。Finallydroppingtoearthhelplesslythroughthelast5，000feet，withallballastspent，ElyCathedralwaspassedatclosequarters;
yeteventhatvastpilewashiddeninthegloomthatnowlayoveralltheland。
Itwasjustamonthlater，anddaybrokewiththoroughlydirtyweather，aheavysky，andfallingshowers。ThiswasthedayofallothersthatMr。Glaisherwaswaitingfor，havingdeterminedonmakingspecialinvestigationsconcerningtheformationofraininthecloudsthemselves。Ithadlongbeennoticedthat，inanordinaryway，iftherebetworaingaugesplaced，onenearthesurfaceoftheground，andanotheratasomewhathigherelevation，thenthelowergaugewillcollectmostwater。
Does，then，raincondenseinsomeappreciablequantityoutofthelowestlevel？Again，duringrain，istheairsaturatedcompletely，andwhatregulatesthequalityofrainfall，forrainsometimesfallsinlargedropsandsometimesinminuteparticles？ThesewerequestionswhichMr。Glaishersoughttosolve，andtherewasanother。
CharlesGreenhadstatedashisconvictionthatwheneverrainwasfallingfromanovercastskytherewouldalwaysbefoundahighercanopyofcloudover—hangingthelowerstratum。Ontheday，then，whichwearenowdescribing，Mr。Glaisherwishedtoputthishistheorytothetest;and，ifcorrect，thenhedesiredtomeasurethespacebetweenthecloudlayers，togaugetheirthickness，andtoseeifabovethesecondstratumthesunwasshining。Themaindetailsoftheascentreadthus:——
Intensecondstheywereinmist，andintensecondsmorewerelevelwiththecloud。At1，200feettheywereoutoftherain，thoughnotyetoutofthecloud。Emergingfromthelowercloudat2，300feet，theysaw，whatGreenwouldhaveforetold，anupperstratumofdarkcloudabove。Thentheymadeexcursionsupanddown，tryinghighandlowtoverifytheseconditions，andpassingthroughfogsbothwetanddry，atlastdriftingearthward，throughsquallsofwindandrainwithdropsaslargeasfourpennypieces，tofindthatonthegroundheavywethadbeenceaselesslyfalling。
AdaytripovertheeasternsuburbsofLondoninthesameyearseemsgreatlytohaveimpressedMr。Glaisher。ThenoiseofLondonstreetsasheardfromabovehasmuchdiminishedduringthelastfifteenyears’probablyowingtotheintroductionofwoodpaving。But，fortyyearsago，Mr。GlaisherdescribesthedeepsoundofLondonasresemblingtheroarofthesea，whenatamilehigh;whileatgreaterelevationsitwasheardatamurmuringnoise。Buttheviewmusthavebeenyetmorestrikingthanthehearing，forinonedirectionthewhitecliffsfromMargatetoDoverwerevisible，whileBrightonandtheseabeyondweresighted，andagainallthecoastlineuptoYarmouthyettheatmospherethatday，onemighthavethought，shouldhavebeeninturmoil，byreasonofaconflictofaircurrents;for，withintwomilesoftheearth，thewindwasfromtheeast;betweentwoandthreemileshighitwasexactlyopposite，beingfromthewest;butatthreemilesitwasN。E。;
while，higher，itwasagaindirectlyopposite，orS。W。
DuringhisresearchessofarMr。Glaisherhadfoundmuchthatwasanomalousinthewayofthewinds，andinotherelementsofweather。Hewasdestinedtofindmuchmore。Ithadbeencommonlyacceptedthatthetemperatureoftheairdecreasesattheaveragerateof10degreesforevery300feetofelevation，andvariouscomputations，as，forexample，thosewhichrelatetotheco—efficientofrefraction，havebeenfoundedonthisbasis;butMr。Glaishersoonestablishedthattheabovegeneralisationhadtobemuchmodified。Thefollowing，gatheredfromhisnotesisatypicalexampleofsuchsurprisesastheaeronautwithdueinstrumentalequipmentmaynotunfrequentlymeetwith。
Itwasthe12thofJanuary，1864，withanair—currentonthegroundfromtheS。E。，oftemperature41degrees，，whichveryslowlydecreasedupto1，600feetwhenawarmS。W。currentwasmetwith，andat3，000feetthetemperaturewas31/2degreeshigherthanontheearth。AbovetheS。W。streamtheairbecamedry，andherethetemperaturedecreasedreasonablyandconsistentlywithaltitude;whilefinesnowwasfoundfallingoutofthisupperspaceintothewarmerstreambelow。Mr。
Glaisherdiscussesthepeculiarityandformationofthisstreamintermswhichwillrepayconsideration。
"ThemeetingwiththisS。W。currentisofthehighestimportance，foritgoesfartoexplainwhyEnglandpossessesawintertemperaturesomuchhigherthanisduetohernorthernlatitude。OurhighwintertemperaturehashithertobeenmostlyreferredtotheinfluenceoftheGulfStream。Withoutdoubtingtheinfluenceofthisnaturalagent，itisnecessarytoaddtheeffectofaparallelatmosphericcurrenttotheoceaniccurrentcomingfromthesameregion——atrueaerialGulfStream。Thisgreatenergeticcurrentmeetswithnoobstructionincomingtous，ortoNorway，butpassesoverthelevelAtlanticwithoutinterruptionfrommountains。Itcannot，however，reachFrancewithoutcrossingSpainandtheloftyrangeofthePyrenees，andtheeffectofthesecoldmountainsinreducingitstemperatureissogreatthattheformercountryderivesbutlittlewarmthfromit。"
AnascentfromWoolwich，arrangedasneartheequinoxofthatyearascouldbemanaged，suppliedsomefurtherremarkableresults。Thetemperature，whichwas45degreestobeginwith，at4。7p。m。，creptdownfairlysteadilytill4，000feetaltitudewasregistered，when，inaregionofwarmfog，itcommencedrisingabruptly，andat7，500feet，inbluesky，stoodatthesamereadingaswhentheballoonhadrisenonly1，500feet。Then，amidmanyanomalousvicissitudes，themostcurious，perhaps，wasthatrecordedlateintheafternoon，when，at10，000feet，theairwasactuallywarmerthanwhentheascentbegan。
Thatthetemperatureoftheupperaircommonlycommencestoriseafternightfallasthewarmthradiatedthroughdayhoursofftheearthcollectsaloft，isafactwellknowntotheballoonist，andMr。Glaishercarriedoutwithconsiderablesuccessawell—arrangedprogrammeforinvestigatingthefactsofthecase。StartingfromWindsoronanafternoonoflateMay，hesoarrangedmattersthathisdeparturefromearthtookplaceaboutanhourandthreequartersbeforesunset，hisintentionbeingtorisetoadefiniteheight，andwithasuniformaspeedaspossibletotimehisdescentsoastoreachearthatthemomentofsundown;andthentore—ascendanddescendagainmapreciselysimilarmannerduringanhourandthree—quartersaftersunset，takingobservationsalltheway。
Ascendingforthefirstflight，heleftatemperatureof58
degreesontheearth，andfoundit55degreesat1，200feet，then43degreesat3，600feet，and291/2degreesattheculminatingpointof6，200feet。Then，duringthedescent，thetemperatureincreased，thoughnotuniformly，tillhewasnearlybrushingthetopsofthetrees，whereitwassome3degreescolderthanatstarting。
Itwasnowthattheballoon，showingalittlewaywardness，slightlyupsetaportionoftheexperiment，for，insteadofgettingtotheneighbourhoodofearthjustatthemomentofsunset，thetravellersfoundthemselvesatthatepoch600feetabovetheground，andovertheridgeofahill，onpassingwhichtheballoonbecamesuckeddownwithadowndraught，necessitatingaliberaldischargeofsandtopreventcontactwiththeground。Thiscircumstance，slightinitself，causedthelowestpointofthedescenttobereachedsomeminuteslate，and，stillmoreunfortunate，occasionedtheascentwhichimmediatelyfollowedtobearapidone，toorapid，doubtless，togivetheregisteringinstrumentsafairchance;butoneprincipalrecordaimedatwasobtainedatleastwithsufficienttruth，namely，thatattheculminatingpoint，whichagainwas6，200feet，thetemperatureread35degrees，orabout6degreeswarmerthanwhentheballoonwasatthesamealtitudealittlemorethananhourbefore。Thiscomparativelywarmtemperaturewaspracticallymaintainedforaconsiderableportionofthedescent。
WemaysummarisetheprincipalofMr。Glaisher’sgeneralisationsthus，usingasnearlyaspossiblehisownwords:——
"Thedecreaseoftemperature，withincreaseofelevation，hasadiurnalrange，anddependsuponthehouroftheday，thechangesbeingthegreatestatmid—dayandtheearlypartoftheafternoon，anddecreasingtoaboutsunset，when，withaclearsky，thereislittleornochangeoftemperatureforseveralhundredfeetfromtheearth;whilst，withacloudysky，thechangedecreasesfromthemid—dayhoursatalessrapidratetoaboutsunset，whenthedecreaseisnearlyuniformandattherateof1degreein2，000feet。
"Aircurrentsdifferingindirectionarealmostalwaystobemetwith。Thethicknessesofthesewerefoundtovarygreatly。
Thedirectionofthewindontheearthwassometimesthatofthewholemassofairupto20，000feetnearly，whilstatothertimesthedirectionchangedwithin500feetoftheearthSometimesdirectlyoppositecurrentsweremetwith。"
Withregardtothevelocityofuppercurrents，asshownbythetravelofballoons，whenthedistancesbetweentheplacesofascentanddescentaremeasured，itwasalwaysfoundthatthesedistanceswereverymuchgreaterthanthehorizontalmovementoftheair，asmeasuredbyanemometersneartheground。
CHAPTERXVI。SOMEFAMOUSFRENCHAERONAUTS。
Bythisperiodarevivalofaeronauticsinthelandofitsbirthhadfairlysetin。SincethelastascentsofGayLussac，in1804，alreadyrecorded，therehadbeenalullinballooningenterpriseinFrance，andnoseriousscientificexpeditionsarerecordeduntiltheyear1850，whenMM。BaralandBixioundertooksomeinvestigationsrespectingtheupperair，whichweretodealwithitslawsoftemperatureandhumidity，withtheproportionofcarbonicacidpresentinit，withsolarheatatdifferentaltitudes，withradiationandthepolarisationoflight，andcertainotherinterestingenquiries。
Thefirstascent，madeinJunefromtheParisObservatory，thoughaloftyone，wasattendedwithsomuchdangerandconfusionastobebarrenofresults。Thedeparture，owingtostormyweather，washurriedandillordered，sothatthevelocityinrisingwasexcessive，thenetconstrictedtherapidly—swellingglobe，andthevolumesofout—rushinggashalf—suffocatedthevoyagers。Thenalargerentoccurred，whichcausedanalarminglyrapidfall，andthetwophilosopherswerereducedtothenecessityofflingingawayalltheypossessed，theirinstrumentsonlyexcepted。Thelanding，inavineyard，washappilynotattendedwithdisaster，andwithinamonththesametwocolleaguesattemptedasecondaerialexcursion，againinwetweather。
Itwouldseemasifonthisoccasion，asontheformerone，therewassomelackofduemanagement，forthecar，suspendedatalongdistancefromtheballoonproper，acquiredviolentoscillationsonleavingtheground，anddashingfirstagainstatree，andthenagainstamast，brokesomeoftheinstruments。
Alittlelaterthereoccurredarepetitiononaminorscaleoftheaeronauts’previousmishap，forarentappearedinthesilk，though，luckily，solowdownintheballoonastobeofsmallconsequence，andeventuallyanaltitudeofsome19，000
feetwasattained。Atonetimeneedlesoficewereencounteredsettlingabundantlywithacracklingsoundupontheirnotebooks。Butthemostremarkableobservationmadeduringthisvoyagerelatedtoanextraordinaryfalloftemperaturewhich，asrecorded，iswithoutparallel。Ittookplaceinacloudmass，15，000feetthick，andamountedtoadropoffrom15
degreesto—39degrees。
In1867M。C。Flammarionmadeafewballoonascents，ostensiblyforscientificresearch。Hisaccountofthese，translatedbyDr。T。L。Phipson，iseditedbyMr。Glaisher，andmanyoftheexperiencesherelateswillbefoundtocontrastwiththoseofothers。Hisphysicalsymptomsalonewereremarkable，forononeoccasion，atanaltitudeofapparentlylittleover10，000
feet，hebecameunwellbeingaffectedwithasensationofdrowsiness，palpitation，shortnessofbreath，andsingingintheears，which，afterlandinggaveplacetoa"fitofincessantgaping"whilehestatesthatinlatervoyages，atbutslightlygreateraltitudes，histhroatandlungsbecameaffected，andhewastroubledwithpresenceofblooduponthelips。ThisdrawsforthafootnotefromMr。Glaisher，whichshouldbecommendedtoallwould—beskyvoyagers。Itrunsthus:——"IhaveneverexperiencedanyoftheseeffectstillI
hadlongpassedtheheightsreachedbyM。Flammarion，andatnoelevationwastherethepresenceofblood。"However，M。
Flammarionadduces，atleast，onereassuringfact，whichwillbereadwithinterest。Once，having，againsttheentreatiesofhisfriends，ascendedwithanattackofinfluenzauponhim，hecamedowntoearthagainanhourortwoafterwardswiththistroublesomecomplaintcompletelycured。
ItwouldseemasifthesoilofFrancesuppliedtheaeronautwithcertainphenomenanotknowninEngland，oneoftheseapparentlybeingtheoccasionalpresenceofbutterflieshoveringroundthecarwhenatconsiderableheights。M。
Flammarionmentionsmorethanoneoccasionwhenhethussawthem，andfoundthemtobewithoutsenseofalarmattheballoonoritspassengers。Again，theFrenchobserverseemsseldomtohavedetectedthoseoppositeairstreamswhichEnglishballoonistsmayfrequentlyobserve，andhavesuchcausetobewaryof。Hiswords，astranslated，are:——"tappearstomethattwoormorecurrents，flowingindifferentdirections，areveryrarelymetwithasweriseintheair，andwhentwolayersofcloudappeartotravelinoppositedirectionstheeffectisgenerallycausedbythemotionofonelayerbeingmorerapidthantheother，whenthelatterappearstobemovinginacontrarydirection。"Incontinuationoftheseexperiences，hespeaksofanoccasionwhen，speedingthroughtheairattherateofanordinaryexpresstrain，hewasdrawntowardsatempestbyaspeciesofattraction。
TheFrenchaeronaut’sestimateofwhatconstitutesaterrificrateoffalldifferssomewhatfromthatofotherswhosetestimonywehavebeenrecording。Inonedescent，falling（withoutreachingearth，however）adistanceof2，130feetintwominutes，hedescribestheearthrisingupwithfrightfulrapidity，though，aswillbeobserved，thisisnotnearlyhalfthespeedatwhicheitherMr。GlaisherorAlbertSmithandhiscompanionswereprecipitatedontobareground。Verymanycaseswhichwehavecitedgotoshowthattheknowledgeofthegreatelasticityofawell—madewickercarmayrobafallotherwisealarmingofitsterrors，whilethepracticalcertaintythataballoondescendingheadlongwillformitselfintoanaturalparachute，ifproperlymanaged，reducesenormouslytheriskattendinganymereimpactwithearth。Itwillbeallowedbyallexperiencedaeronautsthatfarworsechanceslieinsomeawkwardalightingground，orinthedraggingagainstdangerousobstaclesaftertheballoonhasfallen。
ManyofM。Flammarion’sexperimentsareremarkablefortheirsimplicity。Indeed，insomecaseshewouldseemtohaveappliedhimselftomakingtrialstheresultofwhichcouldnothavebeenseriouslyquestioned。Thefollowing，quotingfromDr。Phipson’stranslation，willserveasanexample:——
"Anothermechanicalexperimentwasmadeintheevening，andrenewednextday。IwishedtoverifyGalileo’sprincipleoftheindependenceofsimultaneousmotions。Accordingtothisprinciple，abodywhichisallowedtofallfromanotherbodyinmotionparticipatesinthemotionofthelatter;thus，ifwedropamarblefromthemastheadofaship，itpreservesduringitsfalltherateofmotionofthevessel，andfallsatthefootofthemastasiftheshipwerestill。Now，ifabodyfallsfromaballoon，doesitalsofollowthemotionofthelatter，ordoesitfalldirectlytotheearthinalinewhichisperpendiculartothepointatwhichweletitfall？Inthefirstcaseitsfallwouldbedescribedbyanobliqueline。Thelatterwasfoundtobethefact，asweprovedbylettingabottlefall。Duringitsdescentitpartakesoftheballoon’smotion，anduntilitreachestheearthisalwaysseenperpendicularlybelowthecar。"
Aninterestingphenomenon，relatingtotheformationoffogwaswitnessedbyM。Flammarioninoneofhisvoyages。Hewasflyinglowwithafastwind，andwhiletraversingaforesthenoticedhereandtherepatchesoflightclouds，which，remainingmotionlessindefianceofthestrongwind，continuedtohangabovethesummitsofthetrees。Theexplanationofthiscanhardlybedoubtful，beinganalogoustotheformationofanight—caponamountainpeakwherewarmmoistair—currentsbecomechilledagainstthecoldrocksurface，forming，momentarily，apatchofcloudwhich，thoughconstantlybeingblownaway，isasconstantlyre—formed，andthusismadetoappearasifstationary。
Theaboveinstructivephenomenoncouldhardlyhavebeennoticedsavebyanaeronaut，andthesamemaybesaidofthefollowing。PassinginaclearskyoverthespotwheretheMarneflowsintotheSeine，M。FlammarionnotesthatthewateroftheMarne，which，ashesays，isasyellownowasitwasinthetimeofJuliusCaesar，doesnotmixwiththegreenwateroftheSeine，whichflowstotheleftofthecurrent，norwiththebluewaterofthecanal，whichflowstotheright。Thus，ayellowriverwasseenflowingbetweentwodistinctbrooks，greenandbluerespectively。
Herewasopticalevidenceofthewayinwhichstreamsofwaterwhichactuallyunitemaycontinuetomaintainindependentcourses。Wehaveseenthatthesameistrueofstreamsofair，and，wherethesetraverseoneanotherinacopiousandcomplexmanner，wefind，aswillbeshown，conditionsproducedthatcauseagreatdeadeningofsound;thus，greatdifferencesinthetravelofsoundinthesilentupperaircanbenoticedondifferentdays，and，indeed，indifferentperiodsofthesameaerialvoyage。M。Flammarionbearsundeniabletestimonytothemannerinwhichtheequableconditionoftheatmosphereattendingfogenhances，totheaeronaut，thehearingofsoundsfrombelow。Butwhenhegivesdefiniteheightsastherangelimitsofdefinitesoundsitmustbeunderstoodthattheserangeswillbefoundtovarygreatlyaccordingtocircumstances。Thus，whereitisstatedthataman’svoicemaymakeitselfheardat3，255feet，itmightbeaddedthatsometimesitcannotbeheardataconsiderablylessaltitude;
and，again，thestatementthatthewhistleofalocomotiverisestonear10，000feet，andthenoiseofarailwaytrainto8，200feet，shouldbequalifiedanadditionalnotetotheeffectthatbothmaybeoccasionallyheardatdistancesvastlygreater。ButperhapsthemostcuriousobservationofM。
Flammarionrespectingsoundsaloftrelatestothatofecho。Tohisfancy，thishadavaguedepth，appearingalsotorisefromthehorizonwithacurioustone，asifitcamefromanotherworld。Tothewriter，onthecontrary，andtomanyfellowobserverswhohavespeciallyexperimentedwiththistestofsound，theechohasalwaysappearedtocomeverymuchfromtherightplace——thespotnearlyimmediatelybelow——andifthissuggesteditscomingfromanotherworldthenthesamewouldhavetobesaidofallechoesgenerally。
AboutthesameperiodwhenM。Flammarionwasconductinghisearlyascents，MM。deFonvielleandTissandierembarkedonexperimentalvoyages，whichdeservesomeparticularnotice。
InterestinthenewrevivaloftheartofaeronauticswasmanifestlybecomingreestablishedinFrance，andthoughwefindenthusiastsmorethanoncebitterlycomplainingofthelackoffinancialassistance，stillballooningexhibitions，whereveraccomplished，neverfailedtoarousepopularappreciation。Butenthusiasmwasbynomeanstheuniversalattitudewithwhichtheworldregardedaerialenterprise。A
remarkableandinstructiveinstanceisgiventothecontrarybyM。W。deFonviellehimself。