made　in　a　simple　embankment　of　stones；　but　in　a　mass　of　schist；　which　had　perated　to　this　depth　in　the　coal　stratum。　Had　the　object　of　the　explosion　been　to　discover　a　new　vein？　Or　had　someone　wished　simply　to　destroy　this　portion　of　the　mine？　Thus　he　questioned；　and　when　he　made　known　this　occurrence　to　his　father；　neither　could　the　old　overman　nor　he　himself　answer　the　question　in　a　satisfactory　way。

〃It　is　very　queer；〃　Harry　often　repeated。 〃The　presence　of　an　unknown　being　in　the　mine　seems　impossible；　and　yet　there　can　be　no　doubt　about　it。 Does　someone　besides　ourselves　wish　to　find　out　if　a　seam　yet　exists？ Or；　rather；　has　he　attempted　to　destroy　what　remains　of　the　Aberfoyle　mines？ But　for　what　reason？　I　will　find　that　out；　if　it　should　cost　me　my　life！〃

A　fortnight　before　the　day　on　which　Harry　Ford　guided　the　engineer　through　the　labyrinth　of　the　Dochart　pit；　he　had　been　on　the　point　of　attaining　the　object　of　his　search。　He　was　going　over　the　southwest　end　of　the　mine；　with　a　large　lantern　in　his　hand。 All　at　once；　it　seemed　to　him　that　a　light　was　suddenly　extinguished；　some　hundred　feet　before　him；　at　the　end　of　a　narrow　passage　cut　obliquely　through　the　rock。　He　darted　forward。

His　search　was　in　vain。 As　Harry　would　not　admit　a　supernatural　explanation　for　a　physical　occurrence；　he　concluded　that　certainly　some　strange　being　prowled　about　in　the　pit。　But　whatever　he　could　do；　searching　with　the　greatest　care；　scrutinizing　every　crevice　in　the　gallery；　he　found　nothing　for　his　trouble。

If　Jack　Ryan　and　the　other　superstitious　fellows　in　the　mine　had　seen　these　lights；　they　would；　without　fail；　have　called　them　supernatural；　but　Harry　did　not　dream　of　doing　so；　nor　did　his　father。　And　when　they　talked　over　these　phenomena；　e