〃Yes；　on　the　stones　outside；　but　blood　of　what？〃
  〃Ah！〃　said　Rouletabille；　〃there　are　footmarks　visible　on　the　path
  …　the　ground　was　very　moist。　　I　will　look　into　that　presently。〃
  〃Nonsense！〃　interrupted　Daddy　Jacques；　〃the　murderer　did　not　go
  that　way。〃
  〃Which　way　did　he　go；　then？〃
  〃How　do　I　know？〃
  Rouletabille　looked　at　everything；　smelled　everything。　　He　went　down
  on　his　knees　and　rapidly　examined　every　one　of　the　paving　tiles。
  Daddy　Jacques　went　on：
  〃Ah！　…　you　can't　find　anything；　monsieur。　　Nothing　has　been　found。
  And　now　it　is　all　dirty；　too　many　persons　have　tramped　over　it。
  They　wouldn't　let　me　wash　it；　but　on　the　day　of　the　crime　I　had
  washed　the　floor　thoroughly；　and　if　the　murderer　had　crossed　it　with
  his　hobnailed　boots；　I　should　not　have　failed　to　see　where　he　had
  been；　he　has　left　marks　enough　in　Mademoiselle's　chamber。〃
  Rouletabille　rose。
  〃When　was　the　last　time　you　washed　these　tiles？〃　he　asked；　and　he
  fixed　on　Daddy　Jacques　a　most　searching　look。
  〃Why　…　as　I　told　you　…　on　the　day　of　the　crime；　towards　half…past
  five　…　while　Mademoiselle　and　her　father　were　taking　a　little　walk
  before　dinner；　here　in　this　room：　they　had　dined　in　the　laboratory。
  The　next　day；　the　examining　magistrate　came　and　saw　all　the　marks
  there　were　on　the　floor　as　plainly　as　if　they　had　been　made　with
  ink　on　white　paper。　　Well；　neither　in　the　laboratory　nor　in　the
  vestibule；　which　were　both　as　clean　as　a　new　pin；　were　there　any
  traces　of　a　man's　footmarks。　　Since　they　have　been　found　near　this
  window　outside；　he　must　have　made　his　way　through　the　ceiling　of
  The　Yellow　Room　into　the　attic；　then　cut　his　way　through　the　roof
  and　dropped　to　the　ground　outside　the　vestibule　window。　　But
  …　there's　no　hole；　neither　in　the　ceiling　of　The　Yellow　Room　nor
  in　the　roof　of　my　attic　…　that's　absolutely　certain！　　So　you　see
  we　know　nothing　…　nothing！　　And　nothing　will　ever　be　known！　　It's
  a　mystery　of　the　Devil's　own　making。〃
  Rouletabille　went　down　upon　his　knees　again　almost　in　front　of　a
  small　lavatory　at　the　back　of　the　vestibule。　　In　that　position　he
  remained　for　about　a　minute。
  〃Well？〃　I　asked　him　when　he　got　up。
  〃Oh！　　nothing　very　important；　…　a　drop　of　blood；〃　he　replied；
  turning　towards　Daddy　Jacques　as　he　spoke。　　〃While　you　were　washing
  the　laboratory　and　this　vestibule；　was　the　vestibule　window　open？〃
  he　asked。
  〃No；　Monsieur；　it　was　closed；　but　after　I　had　done　washing　the　floor；
  I　lit　some　charcoal　for　Monsieur　in　the　laboratory　furnace；　and；　as
  I　lit　it　with　old　newspapers；　it　smoked；　so　I　opened　both　the　windows
  in　the　laboratory　and　this　one；　to　make　a　current　of　air；　then　I　shut
  those　in　the　laboratory　and　left　this　one　open　when　I　went　out。　　When
  I　returned　to　the　pavilion；　this　window　had　been　closed　and　Monsieur
  and　Mademoiselle　were　already　at　work　in　the　laboratory。〃
  〃Monsieur　or　Mademoiselle　Stangerson　had；　no　doubt；　shut　it？〃
  〃No　doubt。〃
  〃You　did　not　ask　them？〃
  After　a　close　scrutiny　of　the　little　lavatory　and　of　the　staircase
  leading　up　to　the　attic；　Rouletabille　…　to　whom　we　seemed　no　longer
  to　exist　…　entered　the　laboratory。　　I　followed　him。　　It　was；　I
  confess；　in　a　state　of　great　excitement。　　Robert　Darzac　lost　none
  of　my　friend's　movements。　　As　for　me；　my　eyes　were　drawn　at　once　to
  the　door　of　The　Yellow　Room。　　It　was　closed　and；　as　I　immediately
  saw；　partially　shattered　and　out　of　commission。
  My　friend；　who　went　about　his　work　methodically；　silently　studied
  the　room　in　which　we　were。　　It　was　large　and　well…lighted。　　Two
  big　windows　…　almost　bays　…　were　protected　by　strong　iron　bars　and
  looked　out　upon　a　wide　extent　of　country。　　Through　an　opening　in
  the　forest；　they　commanded　a　wonderful　view　through　the　length　of
  the　valley　and　across　the　plain　to　the　large　town　which　could　be
  clearly　seen　in　fair　weather。　　To…day；　however；　a　mist　hung　over
  the　ground　…　and　blood　in　that　room！
  The　whole　of　one　side　of　the　laboratory　was　taken　up　with　a　large
  chimney；　crucibles；　ovens；　and　such　implements　as　are　needed　for
  chemical　experiments；　tables；　loaded　with　phials；　papers；　reports；
  an　electrical　machine；　…　an　apparatus；　as　Monsieur　Darzac　informed
  me；　employed　by　Professor　Stangerson　to　demonstrate　the　Dissociation
  of　Matter　under　the　action　of　solar　light　…　and　other　scientific
  implements。
  Along　the　walls　were　cabinets；　plain　or　glass…fronted；　through　which
  were　visible　microscopes；　special　photographic　apparatus；　and　a　large
  quantity　of　crystals。
  Rouletabille；　who　was　ferreting　in　the　chimney；　put　his　fingers　into
  one　of　the　crucibles。　　Suddenly　he　drew　himself　up；　and　held　up　a
  piece　of　half…consumed　paper　in　his　hand。　　He　stepped　up　to　where
  we　were　talking　by　one　of　the　windows。
  〃Keep　that　for　us；　Monsieur　Darzac；〃　he　said。
  I　bent　over　the　piece　of　scorched　paper　which　Monsieur　Darzac　took
  from　the　hand　of　Rouletabille；　and　read　distinctly　the　only　words
  that　remained　legible：
  〃Presbytery　…　lost　nothing　…　charm；　nor　the　gar　…　its　brightness。〃
  Twice　since　the　morning　these　same　meaningless　words　had　struck
  me；　and；　for　the　second　time；　I　saw　that　they　produced　on　the
  Sorbonne　professor　the　same　paralysing　effect。　　Monsieur　Darzac's
  first　anxiety　showed　itself　when　he　turned　his　eyes　in　the　direction
  of　Daddy　Jacques。　　But；　occupied　as　he　was　at　another　window；　he
  had　seen　nothing。　　Then　tremblingly　opening　his　pocket…book　he　put
  the　piece　of　paper　into　it；　sighing：　〃My　God！〃
  During　this　time；　Rouletabille　had　mounted　into　the　opening　of　the
  fire…grate　…　that　is　to　say；　he　had　got　upon　the　bricks　of　a　furnace
  …　and　was　attentively　examining　the　chimney；　which　grew　narrower
  towards　the　top；　the　outlet　from　it　being　closed　with　sheets　of
  iron；　fastened　into　the　brickwork；　through　which　passed　three　small
  chimneys。
  〃Impossible　to　get　out　that　way；〃　he　said；　jumping　back　into　the
  laboratory。　　〃Besides；　even　if　he　had　tried　to　do　it；　he　would　have
  brought　all　that　ironwork　down　to　the　ground。　　No；　no；　it　is　not
  on　that　side　we　have　to　search。〃
  Rouletabille　next　examined　the　furniture　and　opened　the　doors　of　the
  cabinet。　　Then　he　came　to　the　windows；　through　which　he　declared　no
  one　could　possibly　have　passed。　　At　the　second　window　he　found　Daddy
  Jacques　in　contemplation。
  〃Well；　Daddy　Jacques；〃　he　said；　〃what　are　you　looking　at？〃
  〃That　policeman　who　is　always　going　round　and　round　the　lake。
  Another　of　those　fellows　who　think　they　can　see　better　than　anybody
  else！〃
  〃You　don't　know　Frederic　Larsan；　Daddy　Jacques；　or　you　wouldn't
  speak　of　him　in　that　way；〃　said　Rouletabille　in　a　melancholy　tone。
  〃If　there　is　anyone　who　will　find　the　murderer；　it　will　be　he。〃
  And　Rouletabille　heaved　a　deep　sigh。
  〃Before　they　find　him；　they　will　have　to　learn　how　they　lost　him；〃
  said　Daddy　Jacques；　stolidly。
  At　length　we　reached　the　door　of　The　Yellow　Room　itself。
  〃There　is　the　door　behind　which　some　terrible　scene　took　place；〃
  said　Rouletabille；　with　a　solemnity　which；　under　any　other
  circumstances；　would　have　been　comical。
  CHAPTER　VII
  In　Which　Rouletabille　Sets　Out　on　an　Expedition　Under　the　Bed
  Rouletabille　having　pushed　open　the　door　of　The　Yellow　Room　paused
  on　the　threshold　saying；　with　an　emotion　which　I　only　later
  understood；　〃Ah；　the　perfume　of　the　lady　in　black！〃
  The　chamber　was　dark。　　Daddy　Jacques　was　about　to　open　the　blinds
  when　Rouletabille　stopped　him。
  〃Did　not　the　tragedy　take　place　in　complete　darkness？〃　he　asked。
  〃No；　young　man；　I　don't　think　so。　　Mademoiselle　always　had　a
  nightlight　on　her　table；　and　I　lit　it　every　evening　before　she　went
  to　bed。　　I　was　a　sort　of　chambermaid；　you　must　understand；　when　the
  evening　came。　　The　real　chambermaid　did　not　come　here　much　before
  the　morning。　　Mademoiselle　worked　late　…　far　into　the　night。〃
  〃Where　did　the　table　with　the　night…light　stand；　…　far　from　the
  bed？〃
  〃Some　way　from　the　bed。〃
  〃Can　you　light　the　burner　now？〃
  〃The　lamp　is　broken　and　the　oil　that　was　in　it　was　spilled　when　the
  table　was　upset。　　All　the　rest　of　the　things　in　the　room　remain　just
  as　they　were。　　I　have　only　to　open　the　blinds　for　you　to　see。〃
  〃Wait。〃
  Rouletabille　went　back　into　the　laboratory；　closed　the　shutters　of
  the　two　windows　and　the　door　of　the　vestibule。
  When　we　were　in　complete　darkness；　he　lit　a　wax　vesta；　and　asked
  Daddy　Jacques　to　move　to　the　middle　of　the　chamber　with　it　to　the
  place　where　the　night…light　was　burning　that　night。
  Daddy　Jacques　who　was　in　his　stockings　…　he　usually　left　his　sabots
  in　the　vestibule　…　entered　The　Yellow　Room　with　his　bit　of　a　vesta。
  We　vaguely　distinguished　objects　overthrown　on　the　floor；　a　bed　in
  one　corner；　and；　in　front　of　us；　to　the　left；　the　gleam　of　a
  looking…glass　hanging　on　the　wall；　near　to　the　bed。
  〃That　will　do！　　…　you　may　now　open　the　blinds；〃　said　Rouletabille。
  〃Don't　come　any　further；〃　Daddy　Jacques　begged；　〃you　may　make　marks
  with　your　boots；　and　nothing　must　be　deranged；　it's　an　idea　of　the
  magistrate's　…　though　he　has　nothing　more　to　do　here。〃
  And　he　pushed　open　the　shutter。　　The　pale　daylight　entered　from
  without；　throwing　a　sinister　light　on　the　saffron…coloured　walls。
  The　floor　…　　　for　though　the　laboratory　and　the