e　carefully　followed　the　principal　gallery；　without　ever　turning　aside　into　the　narrow　tunnels　which　radiated　to　the　right　and　left。　It　seemed　as　if　the　returning　was　to　be　acplished　as　easily　as　the　going；　when　an　unexpected　accident　occurred　which　rendered　the　situation　of　the　explorers　very　serious。

Just　at　a　moment　when　Harry　was　raising　his　lamp　there　came　a　rush　of　air；　as　if　caused　by　the　flapping　of　invisible　wings。　The　lamp　escaped　from　his　hands；　fell　on　the　rocky　ground；　and　was　broken　to　pieces。

James　Starr　and　his　panions　were　suddenly　plunged　in　absolute　darkness。 All　the　oil　of　the　lamp　was　spilt；　and　it　was　of　no　further　use。 〃Well；　Harry；〃　cried　his　father；

〃do　you　want　us　all　to　break　our　necks　on　the　way　back　to　the　cottage？〃

Harry　did　not　answer。 He　wondered　if　he　ought　to　suspect　the　hand　of　a　mysterious　being　in　this　last　accident？　Could　there　possibly　exist　in　these　depths　an　enemy　whose　unaccountable　antagonism　would　one　day　create　serious　difficulties？　Had　someone　an　interest　in　defending　the　new　coal　field　against　any　attempt　at　working　it？ In　truth　that　seemed　absurd；　yet　the　facts　spoke　for　themselves；　and　they　accumulated　in　such　a　way　as　to　change　simple　presumptions　into　certainties。

In　the　meantime　the　explorers'　situation　was　bad　enough。　They　had　now；　in　the　midst　of　black　darkness；　to　follow　the　passage　leading　to　the　Dochart　pit　for　nearly　five　miles。　There　they　would　still　have　an　hour's　walk　before　reaching　the　cottage。

〃e　along；〃　said　Simon　Ford。 〃We　have　no　time　to　lose。　We　must　grope　our　way　along；　like　blind　men。 There's　no　fear　of　losing　our　way。 The　tunnels　which　open　off　our　road　are　only　just　like　those　in　a　molehill；　and　by　following　the　chief　gallery　we　shall　of　course　reach