oth　about　the　rags　and　the　furtiveness　in　a　person　coming　out　of　those　rooms　lined　with　gold。　　She　took　cautiously　the　curved　garden　path　which　brought　her　within　half　a　hundred　yards　of　me；　then　she　stood　up　for　an　instant　on　the　terrace　of　turf　that　looks　towards　the　slimy　lake；　and　holding　her　flaming　lantern　above　her　head　she　deliberately　swung　it　three　times　to　and　fro　as　for　a　signal。　　As　she　swung　it　the　second　time　a　flicker　of　its　light　fell　for　a　moment　on　her　own　face；　a　face　that　I　knew。　　She　was　unnaturally　pale；　and　her　head　was　bundled　in　her　borrowed　plebeian　shawl；　but　I　am　certain　it　was　Etta　Todd；　the　millionaire's　daughter。
  〃She　retraced　her　steps　in　equal　secrecy　and　the　door　closed　behind　her　again。　　I　was　about　to　climb　the　fence　and　follow；　when　I　realized　that　the　detective　fever　that　had　lured　me　into　the　adventure　was　rather　undignified；　and　that　in　a　more　authoritative　capacity　I　already　held　all　the　cards　in　my　hand。　　I　was　just　turning　away　when　a　new　noise　broke　on　the　night。　　A　window　was　thrown　up　in　one　of　the　upper　floors；　but　just　round　the　corner　of　the　house　so　that　I　could　not　see　it；　and　a　voice　of　terrible　distinctness　was　heard　shouting　across　the　dark　garden　to　know　where　Lord　Falconroy　was；　for　he　was　missing　from　every　room　in　the　house。　　There　was　no　mistaking　that　voice。　　I　have　heard　it　on　many　a　political　platform　or　meeting　of　directors；　it　was　Ireton　Todd　himself。　　Some　of　the　others　seemed　to　have　gone　to　the　lower　windows　or　on　to　the　steps；　and　were　calling　up　to　him　that　Falconroy　had　gone　for　a　stroll　down　to　the　Pilgrim's　Pond　an　hour　before；　and　could　not　be　traced　since。　　Then　Todd　cried　‘Mighty　Murder！'　and　shut　down　the　window　violently；　and　I　could　hear　him　plunging　down　the　stairs　inside。　　Repossessing　myself　of　my　former　and　wiser　purpose；　I　whipped　out　of　the　way　of　the　general　search　that　must　follow；　and　returned　here　not　later　than　eight　o'clock。
  〃I　now　ask　you　to　recall　that　little　Society　paragraph　which　seemed　to　you　so　painfully　lacking　in　interest。　　If　the　convict　was　not　keeping　the　shot　for　Todd；　as　he　evidently　wasn't；　it　is　most　likely　that　he　was　keeping　it　for　Lord　Falconroy；　and　it　looks　as　if　he　had　delivered　the　goods。　　No　more　handy　place　to　shoot　a　man　than　in　the　curious　geological　surroundings　of　that　pool；　where　a　body　thrown　down　would　sink　through　thick　slime　to　a　depth　practically　unknown。　　Let　us　suppose；　then；　that　our　friend　with　the　cropped　hair　came　to　kill　Falconroy　and　not　Todd。　　But；　as　I　have　pointed　out；　there　are　many　reasons　why　people　in　America　might　want　to　kill　Todd。　　There　is　no　reason　why　anybody　in　America　should　want　to　kill　an　English　lord　newly　landed；　except　for　the　one　reason　mentioned　in　the　pink　paperthat　the　lord　is　paying　his　attentions　to　the　millionaire's　daughter。　　Our　crop…haired　friend；　despite　his　ill…fitting　clothes；　must　be　an　aspiring　lover。
  〃I　know　the　notion　will　seem　to　you　jarring　and　even　comic；　but　that's　because　you　are　English。　　It　sounds　to　you　like　saying　the　Archbishop　of　Canterbury's　daughter　will　be　married　in　St　George's；　Hanover　Square；　to　a　crossing…sweeper　on　ticket…of…leave。　　You　don't　do　justice　to　the　climbing　and　aspiring　power　of　our　more　remarkable　citizens。　　You　see　a　good…looking　grey…haired　man　in　evening…dress　with　a　sort　of　authority　about　him；　you　know　he　is　a　pillar　of　the　State；　and　you　fancy　he　had　a　father。　　You　are　in　error。　　You　do　not　realize　that　a　comparatively　few　years　ago　he　may　have　been　in　a　tenement　or　（quite　likely）　in　a　jail。　　You　don't　allow　for　our　national　buoyancy　and　uplift。　　Many　of　our　most　influential　citizens　have　not　only　risen　recently；　but　risen　comparatively　late　in　life。　　Todd's　daughter　was　fully　eighteen　when　her　father　first　made　his　pile；　so　there　isn't　really　anything　impossible　in　her　having　a　hanger…on　in　low　life；　or　even　in　her　hanging　on　to　him；　as　I　think　she　must　be　doing；　to　judge　by　the　lantern　business。　　If　so；　the　hand　that　held　the　lantern　may　not　be　unconnected　with　the　hand　that　held　the　gun。　　This　case；　sir；　will　make　a　noise。〃
  〃Well；〃　said　the　priest　patiently；　〃and　what　did　you　do　next？〃
  〃I　reckon　you'll　be　shocked；〃　replied　Greywood　Usher；　〃as　I　know　you　don't　cotton　to　the　march　of　science　in　these　matters。　　I　am　given　a　good　deal　of　discretion　here；　and　perhaps　take　a　little　more　than　I'm　given；　and　I　thought　it　was　an　excellent　opportunity　to　test　that　Psychometric　Machine　I　told　you　about。　　Now；　in　my　opinion；　that　machine　can't　lie。〃
  〃No　machine　can　be；〃　said　Father　Brown；　〃nor　can　it　tell　the　truth。〃
  〃It　did　in　this　case；　as　I'll　show　you；〃　went　on　Usher　positively。　　〃I　sat　the　man　in　the　ill…fitting　clothes　in　a　comfortable　chair；　and　simply　wrote　words　on　a　blackboard；　and　the　machine　simply　recorded　the　variations　of　his　pulse；　and　I　simply　observed　his　manner。　　The　trick　is　to　introduce　some　word　connected　with　the　supposed　crime　in　a　list　of　words　connected　with　something　quite　different；　yet　a　list　in　which　it　occurs　quite　naturally。　　Thus　I　wrote　‘heron'　and　‘eagle'　and　‘owl'；　and　when　I　wrote　‘falcon'　he　was　tremendously　agitated；　and　when　I　began　to　make　an　‘r'　at　the　end　of　the　word；　that　machine　just　bounded。　　Who　else　in　this　republic　has　any　reason　to　jump　at　the　name　of　a　newly…arrived　Englishman　like　Falconroy　except　the　man　who's　shot　him？　　Isn't　that　better　evidence　than　a　lot　of　gabble　　from　　witnessesif　the　evidence　of　a　reliable　machine？〃
  〃You　always　forget；〃　observed　his　companion；　〃that　the　reliable　machine　always　has　to　be　worked　by　an　unreliable　machine。〃
  〃Why；　what　do　you　mean？〃　asked　the　detective。
  〃I　mean　Man；〃　said　Father　Brown；　〃the　most　unreliable　machine　I　know　of。　　I　don't　want　to　be　rude；　and　I　don't　think　you　will　consider　Man　to　be　an　offensive　or　inaccurate　description　of　yourself。　　You　say　you　observed　his　manner；　but　how　do　you　know　you　observed　it　right？　You　say　the　words　have　to　come　in　a　natural　way；　but　how　do　you　know　that　you　did　it　naturally？　　How　do　you　know；　if　you　come　to　that；　that　he　did　not　observe　your　manner？　　Who　is　to　prove　that　you　were　not　tremendously　agitated？　　There　was　no　machine　tied　on　to　your　pulse。〃
  〃I　tell　you；〃　cried　the　American　in　the　utmost　excitement；　〃I　was　as　cool　as　a　cucumber。〃
  〃Criminals　also　can　be　as　cool　as　cucumbers；〃　said　Brown　with　a　smile。　　〃And　almost　as　cool　as　you。〃
  〃Well；　this　one　wasn't；〃　said　Usher；　throwing　the　papers　about。　　〃Oh；　you　make　me　tired！〃
  〃I'm　sorry；〃　said　the　other。　　〃I　only　point　out　what　seems　a　reasonable　possibility。　　If　you　could　tell　by　his　manner　when　the　word　that　might　hang　him　had　come；　why　shouldn't　he　tell　from　your　manner　that　the　word　that　might　hang　him　was　coming？　　I　should　ask　for　more　than　words　myself　before　I　hanged　anybody。〃
  Usher　smote　the　table　and　rose　in　a　sort　of　angry　triumph。
  〃And　that；〃　he　cried；　〃is　just　what　I'm　going　to　give　you。　　I　tried　the　machine　first　just　in　order　to　test　the　thing　in　other　ways　afterwards　and　the　machine；　sir；　is　right。〃
  He　paused　a　moment　and　resumed　with　less　excitement。　　〃I　rather　want　to　insist；　if　it　comes　to　that；　that　so　far　I　had　very　little　to　go　on　except　the　scientific　experiment。　　There　was　really　nothing　against　the　man　at　all。　　His　clothes　were　ill…fitting；　as　I've　said；　but　they　were　rather　better；　if　anything；　than　those　of　the　submerged　class　to　which　he　evidently　belonged。　　Moreover；　under　all　the　stains　of　his　plunging　through　ploughed　fields　or　bursting　through　dusty　hedges；　the　man　was　comparatively　clean。　　This　might　mean；　of　course；　that　he　had　only　just　broken　prison；　but　it　reminded　me　more　of　the　desperate　decency　of　the　comparatively　respectable　poor。　　His　demeanour　was；　I　am　bound　to　confess；　quite　in　accordance　with　theirs。　　He　was　silent　and　dignified　as　they　are；　he　seemed　to　have　a　big；　but　buried；　grievance；　as　they　do。　　He　professed　total　ignorance　of　the　crime　and　the　whole　question；　and　showed　nothing　but　a　sullen　impatience　for　something　sensible　that　might　come　to　take　him　out　of　his　meaningless　scrape。　　He　asked　me　more　than　once　if　he　could　telephone　for　a　lawyer　who　had　helped　him　a　long　time　ago　in　a　trade　dispute；　and　in　every　sense　acted　as　you　would　expect　an　innocent　man　to　act。　　There　was　nothing　against　him　in　the　world　except　that　little　finger　on　the　dial　that　pointed　to　the　change　of　his　pulse。
  〃Then；　sir；　the　machine　was　on　its　trial；　and　the　machine　was　right。　　By　the　time　I　came　with　him　out　of　the　private　room　into　the　vestibule　where　all　sorts　of　other　people　were　awaiting　examination；　I　think　he　had　already　more　or　less　made　up　his　mind　to　clear　things　up　by　something　like　a　confession。　　He　turned　to　me　and　began　to　say　in　a　low　voice：　　‘Oh；　I　can't　stick　this　any　more。　　If　you　must　know　all　about　me'
  〃At　the　same　instant　one　of　the　poor　women　sitting　on　the　long　bench　stood　up；　screaming　aloud　and　pointing　at　him　with　her　finger。　　I　have　never　in　my　life　heard　anything　more　demoniacally　distinct。　　Her　lean　finger　seemed　to　pick　him　out　as　if　it　were　a　pea…shooter。　　Though　the　word　was　a　mere　howl；　every　syllable　was　as　clear　as　a　separate　stroke　on　the　clock。