She　felt　that　she　could　safely　owe　him　any　debt　of　gratitude；　however
  great；　while　he；　on　his　part；　took　what　I　fancied；　both　then　and
  afterward；　were　unnecessary　pains　to　assure　her　that；　in　the　event
  of　his　finding　the　assassin；　she　need　have　no　fear　of　his　making
  any　claim　whatsoever　upon　her。　　And　so　the　whole　affair　was　dropped
  for　the　time　being　and　the　rest　of　the　evening　devoted　to　listening
  to　Maitland's　account　of　his　experiences　while　abroad。
  The　next　morning　I　called　upon　our　detective　at　his　laboratory　and
  asked　him　what　he　intended　to　do　next。　　He　replied　that　he　had　no
  plans　as　yet；　but　that　he　wished　to　review　with　me　all　the　evidence
  at　hand。
  〃You　see；〃　he　said；　〃the　thing　that　renders　the　solution　of　this
  mystery　so　difficult　is　the　fact　that　all　our　clues；　while　they
  would　be　of　the　utmost　service　in　the　conviction　of　the　assassin
  had　we　found　him；　are　almost　destitute　of　any　value　until　he　has
  been　located。　　Add　to　this　that　we　are　now　unable　to　find　any
  motive　for　the　crime　and　you　can　see　how　slight　are　our　hopes　of
  success。　　If　ever　we　chance　to　find　the　man；　…　for　I　feel　that
  such　a　consummation　would　result　more　from　chance　than　from
  anything　else；　…　I　think　we　can　convict　him。
  〃Here；　for　example；〃　he　said；　taking　up　a　small　slip　of　glass
  which　he　had　cut　from　the　eastern　parlour　window　of　the　Darrow
  house；　〃is　something　I　have　never　shown　either　you　or　Miss　Darrow。
  It　is　utterly　worthless；　so　far　as　assisting　us　to　track　the
  assassin　is　concerned；　but；　if　ever　we　suspect　the　right　man；　the
  evidence　on　that　glass　would　probably　convict　him；　though　there
  were　ten　thousand　other　suspects。〃
  I　took　the　glass　from　him　and；　examining　it　with　the　utmost　care；
  I　detected　a　smutch　of　yellowish　paint　upon　it；　nothing　more。
  〃For　Heaven's　sake；　Maitland！〃　I　said　in　astonishment；　〃of　what
  possible　use　can　that　formless　daub　of　paint　be；　or　is　there
  something　else　on　the　glass　that　has　escaped　me？〃　　He　laughed　at
  my　excitement　as　he　replied：
  〃There　is　nothing　there　hut　the　paint　spot。　　Regarding　that；　however；
  you　have　come　to　a　very　natural　though　erroneous　conclusion。　　It　is
  not　formless〃；　and　he　passed　me　a　jeweller's　eye…glass　to　assist　me
  in　a　closer　examination。　　He　was　right。　　The　paint　lay　upon　the
  glass　in　little　irregular　furrows　which　arranged　themselves
  concentrically　about　a　central　oval　groove　somewhat　imperfect　in
  shape。　　〃Well；〃　continued。　　Maitland；　as　I　returned　him　the
  magnifying　glass；　〃what　do　you　make　of　it？〃　　〃If　you　hadn't　already
  attached　so　much　importance　to　the　thing；〃　I　said；　〃I　should
  pronounce　it　a　daub　of　paint　transferred　to　the　glass　by　somebody's
  thumb；　but；　as　such　a　thing　would　be　clearly　useless；　I　am　at　a　loss
  to　know　what　it　is。〃
  〃Well；〃　he　rejoined；　〃you've　hit　the　nail　on　the　head；　…　that's　just
  what　it　is；　but　you　are　entirely　wrong　in　your　assumption　that　the
  thumb…mark　can　have　no　value　as　evidence。　　Do　you　not　know　that
  there　are　no　two　thumbs　in　the　world　which　are　capable　of　making
  indistinguishable　marks？〃　　I　was　not　aware　of　this。　　〃How　do　you
  know；〃　I　asked；　〃that　this　mark　was　made　by　the　assassin？　　It　seems
  to　me　there　can　hardly　be　a　doubt　that　one　of　the　painters；　while
  priming　the　sill；　accidentally　pressed　his　thumb　against　the　glass。
  His　hands　would　naturally　have　been　painty；　and　this　impression
  would　as　naturally　have　resulted。〃
  〃What　you　say；〃　replied　Maitland；　〃is　very　good；　so　far　as　it　goes。
  My　reasons　for　believing　this　thumb…mark　was　made　by　the　assassin　are
  easily　understood。　　First：　there　was　another　impression　of　a　thumb
  in　the　moist　paint　of　the　sill　directly　under　that　upon　the　glass。
  Both　marks　were　made　by　the　same　thumb　and；　in　the　lower　one；　the
  microscope　revealed　minute　traces　of　gravel　dust；　not　elsewhere
  discernible　upon　the　sill。　　The　thumb　carried　the　dust　there；　and
  was　the　thumb　of　the　hand　pressed　into　the　gravel；　…　the　hand　of
  which　I　have　a　cast。　　You　see　how　this　shows　how　the　thumb　came　to
  have　paint　upon　it　when　pressed　upon　the　glass。　　Second：　the　two
  men　engaged　in　priming　the　house；　James　Cogan　and　Charles　Rice；　were
  the　only　persons　save　the　assassin　known　to　have　been　upon　that　side
  of　the　house　the　day　of　the　murder。　　〃Here；〃　he　said；　carefully
  removing　two　strips　of　glass　from　a　box；　〃are　the　thumb…marks　of
  Cogan　and　Rice　made　with　the　same　paint。　　You　see　that　neither　of
  these　men　could；　by　any　possibility；　have　made　the　mark　upon　the
  glass。　　So　there　you　are。　　But　we　are　missing　the　question　before
  us。　　What　line　of　procedure　can　you　suggest；　Doc？　　I'm　all　at　sea。〃
  〃We　must　find　someone；〃　I　said；　〃who　could　have　had　a　motive。　　This
  someone　ought　to　have　a　particularly　good　reason　for　concealing　his
  footprints；　and　is　evidently　lame　besides。　　I　can't　for　the　life　of
  me　see　anything　else　we　have　to　go　by；　unless　it　be　the　long　nail
  of　the　little　finger；　and　I　don't　see　how　that　is　going　to　help　us
  find　the　assassin　…　unless　we　can　find　out　why　it　was　worn　long。
  If　we　knew　that　it　might　assist　us。　　As　I　have　already　suggested；　a
  Chinaman　might　have　a　long　nail　on　the　little　finger；　but　he　would
  also　have　the　other　nails　long；　wouldn't　he？　　Furthermore；　he　might
  use　the　boards　to　conceal　the　prints　of　his　telltale　foot…gear；　but
  why　should　he　not　have　put　on　shoes　of　the　ordinary　type？　　If　he　had
  time　to　prepare　the　boards；　…　the　whole　affair　shows　premeditation；
  …　clearly　he　had　time　to　change　his　boots。　　The　Chinese　are　usually
  small；　and　this　might　easily　account　for　the　smallness　of　the　hand
  as　shown　by　your　cast。　　These　are　the　pros　and　cons　of　the　only　clue
  that　suggests　itself　to　me。　　By　the　way；　Maitland；　it's　a　shame　we
  did　not　try；　before　it　was　too　late；　to　track　this　fellow　down　with
  a　dog。〃
  〃Ah；〃　he　replied；　〃there　is　another　little　thing　I　have　not　told　you。
  After　you　had　left　the　house　with　Miss　Darrow　on　the　night　of　the
  murder；　and　all　the　servants　had　retired；　I　locked　the　parlour
  securely　and　quietly　slipped　out　to　look　about　a　bit。　　As　you　know；
  the　moon　was　very　bright　and　any　object　moderately　near　was　plainly
  visible。　　I　went　around　to　the　eastern　side　of　the　house　where　the
  prints　of　the　hand　and　boards　were　found；　and　examined　them　with
  extreme　care。　　What　I　particularly　wished　to　learn　was　the　direction
  taken　by　the　assassin　as　he　left　the　house　and　the　point　at　which
  he　had　removed　the　boards　from　his　feet。　　The　imprints　of　the　boards
  were　clearly　discernible　so　far　as　the　loose　gravel　extended；　but
  beyond　that　nothing　could　be　discovered。　　I　sat　down　and　pondered
  over　the　matter。　　I　had　about　concluded　to　drive　two　nails　into　the
  heels　of　my　boots　to　enable　me　to　distinguish　my　own　footprints　from
  any　other　trail　I　might　intersect；　and　then；　starting　with　the　house
  as　a　centre；　to　describe　an　involute　about　it　in　the　hope　of　being
  able　to　detect　some　one　or　more　points　where　my　course　crossed　that
  of　the　assassin；　when　I　remembered　that　my　friend　Burwell；　whose
  Uncle　Tom's　Cabin　Combination　recently　stranded　at　Brockton　was　at
  home。　　As　you　are　perhaps　aware　an　Uncle　Tom　Company　consists　of
  a　'Legree；'　one　or　two　'Markses；'　one　or　two　'Topsies；'　'Uncle　Tom；'
  a　'Little　Eva；'　who　should　not　be　over　fifty　years　old；　…　or　at
  least　should　not　appear　to　be；　…　two　bloodhounds；　and　anybody　else
  that　happens　to　be　available。　　It　really　doesn't　make　the　least
  difference　how　many　or　how　few　people　are　in　the　cast。　　I　have
  heard　that　an　Uncle　Tom　manager　on　a　Western　circuit；　most　of　whose
  company　deserted　him　because　the　'ghost'　never　walked；　succeeded
  in　cutting　and　rewriting　the　piece　so　as　to　double　'George　Harris'
  and　'Legree；'　'　Marks'　and　'Topsy；'　'Uncle　Tom'　and　'Little　Eva。'
  As　for　the　rest　he　had　it　so　arranged　that　he　could　himself　'get
  off　the　door'　in　time　to　'do；'　with　the　aid　of　the　dogs；　all　the
  other　characters。　　You　see　the　dogs　held　the　stage　while　he　changed；
  say；　from　'Eliza'　to　Eva's　father。　　'George　Harris'　would　look　off
  left　second　entrance　and　say　that　'Legree'　was　after　him。　　　Then　he
  would　discharge　a　revolver；　rush　off　right　first　entrance；　where　he
  would　pass　his　weapon　to　'Eva'　and　'Uncle　Tom；'　and　this　bisexual
  individual　would　discharge　it　in　the　wings　at　the　imaginary　pursuer；
  while　'Harris　'　would　put　on　a　wire　beard；　slouch　hat；　black
  melodramatic　cape；　and；=20rushing　behind　the　flat；　enter　left　as
  'Legree。'
  〃The　hardest　thing　to　manage　was　the　death　of　'Little　Eva'　with
  'Uncle　Tom'　by　the　bedside；　but　managerial　genius　overcame　the
  difficulty　after　the　style　of　Mantell's　'Corsican　Brothers。'　　You
  see　it　is　all　easy　enough　when　you　know　how。　　'Little　Eva'　is
  discovered；　sitting　up　in　bed　with　the　curtains　drawn　back。　　She
  says　what　she　has　to　say　to　her　father　and　the　rest。　　Then　her
  father　has　a　line　in　which　he　informs　'Eva'　that　she　is　tired　and
  had　better　try　to　sleep。　　She　says　she　will　try；　just　to　please　him；
  and　he　gently　lowers　her　back　upon　the　pillows　and　draws　the
  curtains　in　front　of　the　bed。　　But　instead　of　utilising　this
  seclusion　for　a　refreshing　sleep　'Eva'　rolls　out　at　the　back　side
  of　the　bed。　　'Legree'　snatches　off　'Eva's'　wig　and　'Topsy'　deftly
  removes　the　white　nightdress　concealing　his　…　'Eva's'　…　'Un