pproached　unseen　and　called　to　him　from　a　little　distance。　〃He　turned　round　and　saw　me。　　What　he　imagined　I　was　I　do　not　know；　but　a　finer　picture　of　fear　and　astonishment　I　never　saw。　He　stood　incapable　of　moving　a　limb；　riveted　to　the　spot；　mouth　open　and　eyes　staring。　。　。　。　He　remained　motionless　until　our　black　got　within　a　few　yards　of　him；　when　suddenly　throwing　down　his　waddies；　he　jumped　into　a　mulga　bush　as　high　as　he　could　get。〃　He　could　not　speak；　and　answered　not　a　word　to　the　inquiries　made　by　the　black；　but；　trembling　from　head　to　foot；　〃waved　with　his　hand　for　us　to　be　off。〃
  That　the　eyebrows　are　raised　by　an　innate　or　instinctive　impulse　may　be　inferred　from　the　fact　that　Laura　Bridgman　invariably　acts　thus　when　astonished；　as　I　have　been　assured　by　the　lady　who　has　lately　had　charge　of　her。　　As　surprise　is　excited　by　something　unexpected　or　unknown；　we　naturally　desire；　when　startled；　to　perceive　the　cause　as　quickly　as　possible；　and　we　consequently　open　our　eyes　fully；　so　that　the　field　of　vision　may　be　increased；　and　the　eyeballs　moved　easily　in　any　direction。　But　this　hardly　accounts　for　the　eyebrows　being　so　greatly　raised　as　is　the　case；　and　for　the　wild　staring　of　the　open　eyes。　The　explanation　lies；　I　believe；　in　the　impossibility　of　opening　the　eyes　with　great　rapidity　by　merely　raising　the　upper　lids。　To　effect　this　the　eyebrows　must　be　lifted　energetically。　Any　one　who　will　try　to　open　his　eyes　as　quickly　as　possible　before　a　mirror　will　find　that　he　acts　thus；　and　the　energetic　lifting　up　of　the　eyebrows　opens　the　eyes　so　widely　that　they　stare；　the　white　being　exposed　all　round　the　iris。　　Moreover；　the　elevation　of　the　eyebrows　is　an　advantage　in　looking　upwards；　for　as　long　as　they　are　lowered　they　impede　our　vision　in　this　direction。　Sir　C。　Bell　gives＇3＇　a　curious　little　proof　of　the　part　which　the　eyebrows　play　in　opening　the　eyelids。　　In　a　stupidly　drunken　man　all　the　muscles　are　relaxed；　and　the　eyelids　consequently　droop；　in　the　same　manner　as　when　we　are　falling　asleep。　To　counteract　this　tendency　the　drunkard　raises　his　eyebrows；　and　this　gives　to　him　a　puzzled；　foolish　look；　as　is　well　represented　in　one　of　Hogarth's　drawings。　　The　habit　of　raising　the　eyebrows　having　once　been　gained　in　order　to　see　as　quickly　as　possible　all　around　us；　the　movement　would　follow　from　the　force　of　association　whenever　astonishment　was　felt　from　any　cause；　even　from　a　sudden　sound　or　an　idea。
  ＇2＇　‘The　Polyglot　News　Letter；'　Melbourne；　Dec。　1858；　p。　　2。
  With　adult　persons；　when　the　eyebrows　are　raised；　the　whole　forehead　becomes　much　wrinkled　in　transverse　lines；　but　with　children　this　occurs　only　to　a　slight　degree。　The　wrinkles　run　in　lines　concentric　with　each　eyebrow；　and　are　partially　confluent　in　the　middle。　　They　are　highly　characteristic　of　the　expression　of　surprise　or　astonishment。　Each　eyebrow；　when　raised；　becomes　also；　as　Duchenne　remarks；＇4＇　more　arched　than　it　was　before。
  ＇3＇　‘The　Anatomy　of　Expression；'　p。　　106。
  The　cause　of　the　mouth　being　opened　when　astonishment　is　felt；　is　a　much　more　complex　affair；　and　several　causes　apparently　concur　in　leading　to　this　movement。　　It　has　often　been　supposed＇5＇　that　the　sense　of　hearing　is　thus　rendered　more　acute；　but　I　have　watched　persons　listening　intently　to　a　slight　noise；　the　nature　and　source　of　which　they　knew　perfectly；　and　they　did　not　open　their　mouths。　Therefore　I　at　one　time　imagined　that　the　open　mouth　might　aid　in　distinguishing　the　direction　whence　a　sound　proceeded；　by　giving　another　channel　for　its　entrance　into　the　ear　through　the　eustachian　tube；　But　Dr。　W。　Ogle＇6＇　has　been　so　kind　as　to　search　the　best　recent　authorities　on　the　functions　of　the　eustachian　tube；　and　he　informs　me　that　it　is　almost　conclusively　proved　that　it　remains　closed　except　during　the　act　of　deglutition；　and　that　in　persons　in　whom　the　tube　remains　abnormally　open；　the　sense　of　hearing；　as　far　as　external　sounds　are　concerned；　is　by　no　means　improved；　on　the　contrary；　it　is　impaired　by　the　respiratory　sounds　being　rendered　more　distinct。　　If　a　watch　be　placed　within　the　mouth；　but　not　allowed　to　touch　the　sides；　the　ticking　is　heard　much　less　plainly　than　when　held　outside。　　In　persons　in　whom　from　disease　or　a　cold　the　eustachian　tube　is　permanently　or　temporarily　closed；　the　sense　of　hearing　is　injured；　but　this　may　be　accounted　for　by　mucus　accumulating　within　the　tube；　and　the　consequent　exclusion　of　air。　We　may　therefore　infer　that　the　mouth　is　not　kept　open　under　the　sense　of　astonishment　for　the　sake　of　hearing　sounds　more　distinctly；　notwithstanding　that　most　deaf　people　keep　their　mouths　open。
  ＇4＇　Mecanisme　de　la　Physionomie；'　Album；　p。　　6。
  ＇5＇　See；　for　instance；　Dr。　Piderit　（‘Mimik　und　Physiognomik；'　s。　88）；　who　has　a　good　discussion　on　the　expression　of　surprise。
  ＇6＇　Dr。　Murie　has　also　given　me　information　leading　to　the　same　conclusion；　derived　in　part　from　comparative　anatomy。
  Every　sudden　emotion；　including　astonishment；　quickens　the　action　of　the　heart；　and　with　it　the　respiration。　　Now　we　can　breathe；　as　Gratiolet　remarks＇7＇　and　as　appears　to　me　to　be　the　case；　much　more　quietly　through　the　open　mouth　than　through　the　nostrils。　Therefore；　when　we　wish　to　listen　intently　to　any　sound；　we　either　stop　breathing；　or　breathe　as　quietly　as　possible；　by　opening　our　mouths；　at　the　same　time　keeping　our　bodies　motionless。　One　of　my　sons　was　awakened　in　the　night　by　a　noise　under　circumstances　which　naturally　led　to　great　care；　and　after　a　few　minutes　he　perceived　that　his　mouth　was　widely　open。　He　then　became　conscious　that　he　had　opened　it　for　the　sake　of　breathing　as　quietly　as　possible。　　This　view　receives　support　from　the　reversed　case　which　occurs　with　dogs。　A　dog　when　panting　after　exercise；　or　on　a　hot　day；　breathes　loudly；　but　if　his　attention　be　suddenly　aroused；　he　instantly　pricks　his　ears　to　listen；　shuts　his　mouth；　and　breathes　quietly；　as　he　is　enabled　to　do；　through　his　nostrils。
  When　the　attention　is　concentrated　for　a　length　of　time　with　fixed　earnestness　on　any　object　or　subject；　all　the　organs　of　the　body　are　forgotten　and　neglected；＇8＇　and　as　the　nervous　energy　of　each　individual　is　limited　in　amount；　little　is　transmitted　to　any　part　of　the　system；　excepting　that　which　is　at　the　time　brought　into　energetic　action。　　Therefore　many　of　the　muscles　tend　to　become　relaxed；　and　the　jaw　drops　from　its　own　weight。　This　will　account　for　the　dropping　of　the　jaw　and　open　mouth　of　a　man　stupefied　with　amazement；　and　perhaps　when　less　strongly　affected。　I　have　noticed　this　appearance；　as　I　find　recorded　in　my　notes；　in　very　young　children　when　they　were　only　moderately　surprised。
  ＇7＇　‘De　la　Physionomie；'　1865；　p。　　234。
  ＇8＇　See；　on　this　subject；　Gratiolet；　ibid。　　p。　　254。
  There　is　still　another　and　highly　effective　cause；　leading　to　the　mouth　being　opened；　when　we　are　astonished；　and　more　especially　when　we　are　suddenly　startled。　　We　can　draw　a　full　and　deep　inspiration　much　more　easily　through　the　widely　open　mouth　than　through　the　nostrils。　Now　when　we　start　at　any　sudden　sound　or　sight；　almost　all　the　muscles　of　the　body　are　involuntarily　and　momentarily　thrown　into　strong　action；　for　the　sake　of　guarding　ourselves　against　or　jumping　away　from　the　danger；　which　we　habitually　associate　with　anything　unexpected。　But　we　always　unconsciously　prepare　ourselves　for　any　great　exertion；　as　formerly　explained；　by　first　taking　a　deep　and　full　inspiration；　and　we　consequently　open　our　mouths。　　If　no　exertion　follows；　and　we　still　remain　astonished；　we　cease　for　a　time　to　breathe；　or　breathe　as　quietly　as　possible；　in　order　that　every　sound　may　be　distinctly　heard。　Or　again；　if　our　attention　continues　long　and　earnestly　absorbed；　all　our　muscles　become　relaxed；　and　the　jaw；　which　was　at　first　suddenly　opened；　remains　dropped。　　Thus　several　causes　concur　towards　this　same　movement；　whenever　surprise；　astonishment；　or　amazement　is　felt。
  Although　when　thus　affected；　our　mouths　are　generally　opened；　yet　the　lips　are　often　a　little　protruded。　　This　fact　reminds　us　of　the　same　movement；　though　in　a　much　more　strongly　marked　degree；　in　the　chimpanzee　and　orang　when　astonished。　As　a　strong　expiration　naturally　follows　the　deep　inspiration　which　accompanies　the　first　sense　of　startled　surprise；　and　as　the　lips　are　often　protruded；　the　various　sounds　which　are　then　commonly　uttered　can　apparently　be　accounted　for。　But　sometimes　a　strong　expiration　alone　is　heard；　thus　Laura　Bridgman；　when　amazed；　rounds　and　protrudes　her　lips；　opens　them；　and　breathes　strongly。＇9＇　One　of　the　commonest　sounds　is　a　deep　_Oh_；　and　this　would　naturally　follow；　as　explained　by　Helmholtz；　from　the　mouth　being　moderately　opened　and　the　lips　protruded。　On　a　quiet　night　some　rockets　were　fired　from　the　‘Beagle；'　in　a　little　creek　at　Tahiti；　to　amuse　the　natives；　and　as　each　rocket；　was　let　off　there　was　absolute　silence；　but　this　was　invariably　followed　by　a　deep　groaning　_Oh_；　resounding　all　round　the　bay。　Mr。　Washington　Matthews　says　that　the　North　American　Indians　express　astonishment　by　a　groan；　and　the　negroes　on　the　West　Coast　of　Africa；　according　to　Mr。　Winwood　Reade；　protrude　their　lips；　and　make　a　sound　like　_heigh；　heigh_。　　If　the　mouth　is　not