e　popular　appreciation。　　But　enthusiasm　was　by　no　means　the　universal　attitude　with　which　the　world　regarded　aerial　enterprise。　　A　remarkable　and　instructive　instance　is　given　to　the　contrary　by　M。　W。　de　Fonvielle　himself。
  He　records　an　original　ballooning　exploit；　organised　at　Algiers；　which　one　might　have　supposed　would　have　caused　a　great　sensation；　and　to　which　he　himself　had　called　public　attention　in　the　local　journals。　　The　brothers　Braguet　were　to　make　an　ascent　from　the　Mustapha　Plain　in　a　small　fire　balloon　heated　with　burning　straw；　and　this　risky　performance　was　successfully　carried　out　by　the　enterprising　aeronauts。　　But；　to　the　onlooker；　the　most　striking　feature　of　the　proceeding　was　the　fact　that　while　the　Europeans　present　regarded　the　spectacle　with　curiosity　and　pleasure；　the　native　Mussulmans　did　not　appear　to　take　the　slightest　interest　in　it；　〃And　this；〃　remarked　de　Fonvielle；　〃was　not　the　first　time　that　ignorant　and　fanatic　people　have　been　noted　as　manifesting　complete　indifference　to　balloon　ascents。　　After　the　taking　of　Cairo；　when　General　Buonaparte　wished　to　produce　an　effect　upon　the　inhabitants；　he　not　only　made　them　a　speech；　but　supplemented　it　with　the　ascent　of　a　fire　balloon。　　The　attempt　was　a　complete　failure；　for　the　French　alone　looked　up　to　the　clouds　to　see　what　became　of　the　balloon。〃
  In　the　summer　of　1867　an　attempt　was　made　to　revive　the　long　extinct　Aeronautic　Company　of　France；　established　by　De　Guyton。　　The　undertaking　was　worked　with　considerable　energy。　　Some　forty　or　fifty　active　recruits　were　pressed　into　the　service；　a　suitable　captive　balloon　was　obtained；　thousands　of　spectators　came　to　watch　the　evolutions；　and　many　were　found　to　pay　the　handsome　fee　of　100　francs　for　a　short　excursion　in　the　air。　For　all　this；　the　effort　was　entirely　abortive；　and　the　ballooning　corps；　as　such；　dropped　out　of　existence。
  A　little　while　after　this　de　Fonvielle；　on　a　visit　to　England；　had　a　most　pathetic　interview　with　the　veteran　Charles　Green；　who　was　living　in　comfortable　retirement　at　Upper　Holloway。　　The　grand　old　man　pointed　to　a　well…filled　portfolio　in　the　corner　of　his　room；　in　which；　he　said；　were　accounts　of　all　his　travels；　that　would　require　a　lifetime　to　peruse　and　put　in　order。　　Green　then　took　his　visitor　to　the　end　of　the　narrow　court；　and；　opening　the　door　of　an　outhouse；　showed　him　the　old　Nassau　balloon。　　〃Here　is　my　car；〃　he　said；　touching　it　with　a　kind　of　solemn　respect；　〃which；　like　its　old　pilot；　now　reposes　quietly　after　a　long　and　active　career。　　Here　is　the　guide　rope　which　I　imagined　in　former　years；　and　which　has　been　found　very　useful　to　aeronauts。。。。　Now　my　life　has　past　and　my　time　has　gone　by。。。。　Though　my　hair　is　white　and　my　body　too　weak　to　help　you；　I　can　still　give　you　my　advice；　and　you　have　my　hearty　wishes　for　your　future。〃
  It　was　but　shortly　after　this；　on　March　26；　1870；　that　Charles　Green　passed　away　in　the　85th　year　of　his　age。
  De　Fonvielle's　colleague；　M。　Gaston　Tissandier；　was　on　one　occasion　accidentally　brought　to　visit　the　resting　place　of　the　earliest　among　aeronauts；　whose　tragic　death　occurred　while　Charles　Green　himself　was　yet　a　boy。　　In　a　stormy　and　hazardous　descent　Tissandier；　under　the　guidance　of　M。　Duruof；　landed　with　difficulty　on　the　sea　coast　of　France；　when　one　of　the　first　to　render　help　was　a　lightkeeper　of　the　Griz…nez　lighthouse；　who　gave　the　information　that　on　the　other　side　of　the　hills；　a　few　hundred　yards　from　the　spot　where　they　had　landed；　was　the　tomb　of　Pilatre　de　Rozier；　whose　tragical　death　has　been　recorded　in　an　early　chapter。　　A　visit　to　the　actual　locality　the　next　day　revealed　the　fact　that　a　humble　stone　still　marked　the　spot。
  Certain　scientific　facts　and　memoranda　collected　by　the　talented　French　aeronaut　whom　we　are　following　are　too　interesting　to　be　omitted。　　In　the　same　journey　to　which　we　have　just　referred　the　voyagers；　when　nearly　over　Calais；　were　witnesses　from　their　commanding　standpoint　of　a　very　striking　phenomenon　of　mirage。　　Looking　in　the　direction　of　England；　the　far　coast　line　was　hidden　by　an　immense　veil　of　leaden…coloured　cloud；　and；　following　this　cloud　wall　upward　to　detect　where　it　terminated；　the　travellers　saw　above　it　a　greenish　layer　like　that　of　the　surface　of　the　sea；　on　which　was　detected　a　little　black　point　suggesting　a　walnut　shell。　　Fixing　their　eyes　on　this　black　spot；　they　presently　discerned　it　to　be　a　ship　sailing　upside　down　upon　an　aerial　ocean。　　Soon　after；　a　steamer　blowing　smoke；　and　then　other　vessels；　added　themselves　to　the　illusory　spectacle。
  Another　wonder　detected；　equally　striking　though　less　uncommon；　was　of　an　acoustical　nature；　the　locality　this　time　being　over　Paris。　　The　height　of　the　balloon　at　this　moment　was　not　great；　and；　moreover；　was　diminishing　as　it　settled　down。　　Suddenly　there　broke　in　upon　the　voyagers　a　sound　as　of　a　confused　kind　of　murmur。　　It　was　not　unlike　the　distant　breaking　of　waves　against　a　sandy　coast；　and　scarcely　less　monotonous。　　It　was　the　noise　of　Paris　that　reached　them；　as　soon　as　they　sank　to　within　2；600　feet　of　the　ground；　but　it　disappeared　at　once　when　they　threw　out　just　sufficient　ballast　to　rise　above　that　altitude。
  It　might　appear　to　many　that　so　strange　and　sudden　a　shutting　out　of　a　vast　sound　occurring　abruptly　in　the　free　upper　air　must　have　been　more　imaginary　than　real；　yet　the　phenomenon　is　almost　precisely　similar　to　one　coming　within　the　experience　the　writer；　and　vouched　for　by　his　son　and　daughter；　as　also　by　Mr。　Percival　Spencer；　all　of　whom　were　joint　observers　at　the　time；　the　main　point　of　difference　in　the　two　cases　being　the　fact　that　the　〃region　of　silence〃　was　recorded　by　the　French　observers　as　occurring　at　a　somewhat　lower　level。　　In　both　cases　there　is　little　doubt　that　the　phenomenon　can　be　referred　to　a　stratum　of　disturbed　or　non…homogeneous　air；　which　may　have　been　very　far　spread；　and　which　is　capable　of　acting　as　a　most　opaque　sound　barrier。
  Attention　has　often　been　called　in　these　pages　to　the　fact　that　the　action　of　the　sun　on　an　inflated　balloon；　even　when　the　solar　rays　may　be　partially　obscured　and　only　operative　for　a　few　passing　moments；　is　to　give　sudden　and　great　buoyancy　to　the　balloon。　　An　admirable　opportunity　for　fairly　estimating　the　dynamic　effect　of　the　sun's　rays　on　a　silk　globe；　whose　fabric　was　half　translucent；　was　offered　to　the　French　aeronauts　when　their　balloon　was　spread　on　the　grass　under　repair；　and　for　this　purpose　inflated　with　the　circumambient　air　by　means　of　a　simple　rotatory　fan。　　The　sun　coming　out；　the　interior　of　the　globe　quickly　became　suffocating；　and　it　was　found　that；　while　the　external　temperature　recorded　77　degrees；　that　of　the　interior　was　in　excess　of　91　degrees。
  CHAPTER　XVII。　ADVENTURE　AND　ENTERPRISE。
  A　balloon　which　has　become　famous　in　history　was　frequently
  used　in　the　researches　of　the　French　aeronauts　mentioned　in　our　last　chapter。　　This　was　known　as　〃The　Giant；〃　the　creation　of　M。　Nadar；　a　progressive　and　practical　aeronaut；　who　had　always　entertained　ambitious　ideas　about　aerial　travel。
  M。　Nadar　had　been　editor　of　L'Aeronaut；　a　French　journal　devoted　to　the　advancement　of　aerostation　generally。　　He　had　also　strongly　expressed　his　own　views　respecting　the　possibility　of　constructing　air　ships　that　should　be　subject　to　control　and　guidance　when　winds　were　blowing。　　His　great　contention　was　that　the　dirigible　air　ship　would；　like　a　bird；　have　to　be　made　heavier　than　the　medium　in　which　it　was　to　fly。　　As　he　put　it；　a　balloon　could　never　properly　become　a　vessel。　　It　would　only　be　a　buoy。　　In　spite　of　any　number　of　accessories；　paddles；　wings；　fans；　sails；　it　could　not　possibly　prevent　the　wind　from　bodily　carrying　away　the　whole　concern。
  After　this　strong　expression　of　opinion；　it　may　appear　somewhat　strange　that　such　a　bold　theoriser　should　at　once　have　set　himself　to　construct　the　largest　gas　balloon　on　record。　　Such；　however；　was　the　case　and　the　reason　urged　was　not　otherwise　than　plausible。　　For；　seeing　that　a　vast　sum　of　money　would　be　needed　to　put　his　theories　into　practice；　M。　Nadar　conceived　the　idea　of　first　constructing　a　balloon　so　unique　and　unrivalled　that　it　should　compel　public　attention　in　a　way　that　no　other　balloon　had　done　before；　and　so　by　popular　exhibitions　bring　to　his　hand　such　sums　as　he　required。　　A　proper　idea　of　the　scale　of　this　huge　machine　can　be　easily　gathered。　　The　largest　balloons　at　present　exhibited　in　this　country　are　seldom　much　in　excess　of　50；000　cubic　feet　capacity。　　Compared　with　these　the　〃Great　Nassau　Balloon；〃　built　by　Charles　Green；　which　has　been　already　sufficiently　described；　was　a　true　leviathan；　while　Coxwell's　〃Mammoth〃　was　larger　yet；　possessing　a　content；　when　fully　inflated；　of　no　less　than　93；000　cubic　feet；　and　measuring　over　55　feet　in　diameter。　　This；　however；　as　will　be　seen；　was　but　a　mere　pigmy　when　compared　with　〃The　Giant；〃　which；　measuring　some　74　feet　in　diameter；　possessed　the　prodigious　capacity　of　215；000　cubic　feet。
  But　the　huge　craft　possessed　another　novelty　besides　that　of　exceptional　size。　　It　was　provided　with　a　subsidiary　balloon；　called　the　〃Compensator；〃　and　properly　the　idea　of　M。　L。　Godard；　the　function　of　which　wa