t　smaller；　measuring　only　91　feet　by　30　feet；　and　operated　by　an　electric　motor　placed　in　circuit　with　a　powerful　battery　of　bichromate　cells。　　Two　trials　were　made　with　this　vessel　in　October；　1883；　and　again　in　the　following　September；　when　it　proved　itself　capable　of　holding　its　course　in　calm　air　and　of　being　readily　controlled　by　the　rudder。
  But；　ere　this；　a　number　of　somewhat　similar　experiments；　on　behalf　of　the　French　Government；　had　been　entered　upon　by　Captains　Renard　and　Krebs　at　Chalais…Meudon。　　Their　balloon　may　be　described　as　fish…shaped；　165　feet　long；　and　27。5　feet　in　principal　diameter。　It　was　operated　by　an　electric　motor；　which　was　capable　of　driving　a　screw　of　large　dimensions　at　forty…eight　revolutions　per　minute。　　At　its　first　trial；　in　August；　1884；　in　dead　calm；　it　attained　a　velocity　of　over　twelve　miles　per　hour；　travelling　some　two　and　a　half　miles　in　a　forward　direction；　when；　by　application　of　the　rudder　and　judicious　management；　it　was　manoeuvred　homewards；　and　practically　brought　to　earth　at　the　point　of　departure。
  A　more　important　trial　was　made　on　the　12th　of　the　following　month；　and　was　witnessed　by　M。　Tissandier；　according　to　whom　the　aerostat　conveying　the　inventors　ascended　gently　and　steadily；　drifting　with　an　appreciable　breeze　until　the　screw　was　set　in　motion　and　the　helm　put　down；　when　the　vessel　was　brought　round　to　the　wind　and　held　its　own　until　the　motor；　by　an　accident；　ceased　working。　　A　little　later　the　same　air　ship　met　with　more　signal　success。　　On　one　occasion；　starting　from　ChalaisMeudon；　it　took　a　direct　course　to　the　N。E。；　crossing　the　railway　and　the　Seine；　where　the　aeronauts；　stopping　the　screw；　ascertained　the　velocity　of　the　wind　to　be　approximately　five　miles　an　hour。　　The　screw　being　again　put　in　motion；　the　balloon　was　steered　to　the　right；　and；　following　a　path　parallel　to　its　first；　returned　to　its　point　of　departure。　Starting　again　the　same　afternoon；　it　was　caused　to　perform　a　variety　of　aerial　evolutions；　and　after　thirty…five　minutes　returned　once　more　to　its　starting　place。
  A　tabular　comparison　of　the　four　navigable　balloons　which　we　have　now　described　has　been　given　as　follows：
  Date。　　　　Name。　　　　　　　　　　　　　Motor。　　　　　　　　　　　Vel。　p。　Sec。　1852　　M。　Henri　Giffard　　　　Steam　engine　　　　　13。12　ft。　1872　　M。　Dupuy　de　Lome　　　　Muscular　force　　　　9。18　ft。　1883　　MM。　Tissandier　　　　　　Electric　motor　　　　9。84　ft。　1884　　MM。　Renard　&　Krebs　　Electric　motor　　　18。04　ft。
  About　this　period；　that　is　in　1883；　and　really　prior　to　the　Meudon　experiments；　there　were　other　attempts　at　aerial　locomotion　not　to　be　altogether　passed　over；　which　were　made　also　in　France；　but　financed　by　English　money。　　The　experiments　were　performed　by　Mr。　F。　A。　Gower；　who；　writing　to　Professor　Tyndall；　claims　to　have　succeeded　in　〃driving　a　large　balloon　fairly　against　the　wind　by　steam　power。〃　　A　melancholy　interest　will　always　belong　to　these　trials　from　the　fact　that　Mr。　Gower　was　subsequently　blown　out　to　sea　with　his　balloon；　leaving　no　trace　behind。
  At　this　stage　it　will　be　well　to　glance　at　some　of　the　more　important　theories　which　were　being　mooted　as　to　the　possibility　of　aerial　locomotion　properly　so　called。　　Broadly；　there　were　two　rival　schools　at　this　time。　　We　will　call　them　the　〃lighter…than…air…ites〃　and　the　〃heavier…than…air…ites；〃　respectively。　　The　former　were　the　advocates　of　the　air　vessel　of　which　the　balloon　is　a　type。　　The　latter　school　maintained　that；　as　birds　are　heavier　than　air；　so　the　air　locomotive　of　the　future　would　be　a　machine　itself　heavier　than　air；　but　capable　of　being　navigated　by　a　motor　yet　to　be　discovered；　which　would　develop　proportionate　power。　　Sir　H。　Maxim's　words　may　be　aptly　quoted　here。　　〃In　all　Nature；〃　he　says；　〃we　do　not　find　a　single　balloon。　　All　Nature's　flying　machines　are　heavier　than　the　air；　and　depend　altogether　upon　the　development　of　dynamic　energy。〃
  The　faculty　of　soaring；　possessed　by　many　birds；　of　which　the　albatross　may　be　considered　a　type；　led　to　numerous　speculations　as　to　what　would　constitute　the　ideal　principle　of　the　air　motor。　　Sir　G。　Cayley；　as　far　back　as　1809；　wrote　a　classical　article　on　this　subject；　without；　however；　adding　much　to　its　elucidation。　　Others　after　his　time　conceived　that　the　bird；　by　sheer　habit　and　practice；　could　perform；　as　it　were；　a　trick　in　balancing　by　making　use　of　the　complex　air　streams　varying　in　speed　and　direction　that　were　supposed　to　intermingle　above。
  Mr。　R。　A。　Proctor　discusses　the　matter　with　his　usual　clear…sightedness。　　He　premises　that　the　bird　may；　in　actual　fact；　only　poise　itself　for　some　ten　minutesan　interval　which　many　will　consider　far　too　smallwithout　flap　of　the　wings；　and；　while　contending　that　the　problem　must　be　simply　a　mechanical　one；　is　ready　to　admit　that　〃the　sustaining　power　of　the　air　on　bodies　of　a　particular　form　travelling　swiftly　through　it　may　be　much　greater　or　very　different　in　character　from　what　is　supposed。〃　　In　his　opinion；　it　is　a　fact　that　a　flat　body　travelling　swiftly　and　horizontally　will　sink　towards　the　ground　much　more　slowly　than　a　similar　body　moving　similarly　but　with　less　speed。　　In　proof　of　this　he　gives　the　homely　illustration　of　a　flat　stone　caused　to　make　〃　ducks　and　drakes。〃　　Thus　he　contends　that　the　bird　accomplishes　its　floating　feat　simply　by　occasional　powerful　propulsive　efforts；　combined　with　perfect　balance。　　From　which　he　deduces　the　corollary　that　〃if　ever　the　art　of　flying；　or　rather　of　making　flying　machines；　is　attained　by　man；　it　will　be　by　combining　rapid　motion　with　the　power　of　perfect　balancing。〃
  It　will　now　appear　as　a　natural　and　certain　consequence　that　a　feature　to　be　introduced　by　experimentalists　into　flying　machines　should　be　the　〃Aeroplane；〃　or；　in　other　words；　a　plane　which；　at　a　desired　angle；　should　be　driven　at　speed　through　the　air。　　Most　notable　attempts　with　this　expedient　were　now　shortly　made　by　Hiram　Maxim；　Langley；　and　others。
  But；　contemporaneously　with　these　attempts；　certain　feats　with　the　rival　aerostatthe　balloonwere　accomplished；　which　will　be　most　fittingly　told　in　this　place。
  CHAPTER　XX。　　A　CHAPTER　OF　ACCIDENTS。
  It　will　have　been　gathered　from　what　has　been　already　stated　that　the　balloonist　is　commonly　in　much　uncertainty　as　to　his　precise　course　when　he　is　above　the　clouds；　or　when　unable　from　darkness　to　see　the　earth　beneath　him。　　With　a　view　of　overcoming　this　disadvantage　some　original　experiments　were　suggested　by　a　distinguished　officer；　who　during　the　seventies　had　begun　to　interest　himself　in　aeronautics。
  This　was　Captain　Burnaby。　His　method　was　to　employ　two　small　silk　parachutes；　which；　if　required；　might　carry　burning　magnesium　wires；　and　which　were　to　be　attached　to　each　other　by　a　length　of　silk　thread。　　On　dropping　one　parachute；　it　would　first　partake　of　the　motion　of　the　balloon；　but　would　presently　drop　below；　when　the　second　parachute　would　be　dismissed；　and　then　an　imaginary　line　drawn　between　the　two　bodies　was　supposed　to　betray　the　balloon's　course。　　It　should　be　mentioned；　however；　that　if　a　careful　study　is　made　of　the　course　of　many　descending　parachutes　it　will　be　found　that　their　behaviour　is　too　uncertain　to　be　relied　upon　for　such　a　purpose　as　the　above。　　They　will　often　float　behind　the　balloon's　wake；　but　sometimes　again　will　be　found　in　front；　and　sometimes　striking　off　in　some　side　direction；　so　wayward　and　complex　are　the　currents　which　control　such　small　bodies。　　Mr。　Glaisher　has　stated　that　a　balloon's　course　above　the　clouds　may　be　detected　by　observing　the　grapnel；　supposed　to　be　hanging　below　the　car；　as　this　would　be　seen　to　be　out　of　the　vertical　as　the　balloon　drifted；　and　thus　serve　to　indicate　the　course。　　However　this　may　be；　the　most　experienced　sky　sailors　will　be　found　to　be　in　perplexity　as　to　their　direction；　as　also　their　speed；　when　view　of　the　earth　is　obscured。
  But　Captain　Burnaby　is　associated　notably　with　the　adventurous　side　of　ballooning；　the　most　famous　of　his　aerial　exploits　being；　perhaps；　that　of　crossing　the　English　Channel　alone　from　Dover　on　March　23rd；　1882。　　Outwardly；　he　made　presence　of　sailing　to　Paris　by　sky　to　dine　there　that　evening；　inwardly；　he　had　determined　to　start　simply　with　a　wind　which　bid　fair　for　a　cross…Channel　trip；　and　to　take　whatever　chances　it　might　bring　him。
  Thus；　at　10。30　a。m。；　just　as　the　mail　packet　left　the　pier；　he　cast　off　with　a　lifting　power　which　rapidly　carried　him　to　a　height　of　2；000　feet；　when　he　found　his　course　to　be　towards　Folkestone。　　But　by　shortly　after　11　o'clock　he　had　decided　that　he　was　changing　his　direction；　and　when；　as　he　judged；　some　seven　miles　from　Boulogne；　the　wind　was　carrying　him　not　across；　but　down　the　Channel。　　Then；　for　nearly　four　hours；　the　balloon　shifted　about　with　no　improvement　in　the　outlook；　after　which　the　wind　fell　calm；　and　the　balloon　remained　motionless　at　2；000　feet　above　the　sea。　　This　state　of　things　continuing　for　an　hour；　the　Captain　resolved　on　the　heroic　expedient　of　casting　out　all　his　ballast　and　philosophically　abiding　the　issue。　　The　manoeuvre　turned　out　a　happy　one；　for　the　balloon；　shooting　up　to　11；000　feet；　caught　a　current；　on　which　it　was　rapidly　carried　towards　and　over　the　main　land；　and；　when　twelve　miles