light　carburetted　hydrogen？〃

〃An　old　miner　could　not　be　deceived；〃　answered　Ford。 〃I　have　met　with　our　old　enemy；　the　fire…damp！〃

〃But　suppose　it　was　another　gas；〃　said　Starr。 〃Firedamp　is　almost　without　smell；　and　colorless。 It　only　really　betrays　its　presence　by　an　explosion。〃

〃Mr。　Starr；〃　said　Simon　Ford；　〃will　you　let　me　tell　you　what　I　have　done？ Harry　had　once　or　twice　observed　something　remarkable　in　his　excursions　to　the　west　end　of　the　mine。　Fire；　which　suddenly　went　out；　sometimes　appeared　along　the　face　of　the　rock　or　on　the　embankment　of　the　further　galleries。　How　those　flames　were　lighted；　I　could　not　and　cannot　say。　But　they　were　evidently　owing　to　the　presence　of　fire…damp；　and　to　me　fire…damp　means　a　vein　of　coal。〃

〃Did　not　these　fires　cause　any　explosion？〃　asked　the　engineer　quickly。

〃Yes；　little　partial　explosions；〃　replied　Ford；　〃such　as　I　used　to　cause　myself　when　I　wished　to　ascertain　the　presence　of　fire…damp。　Do　you　remember　how　formerly　it　was　the　custom　to　try　to　prevent　explosions　before　our　good　genius；　Humphry　Davy；　invented　his　safety…lamp？〃

〃Yes；〃　replied　James　Starr。 〃You　mean　what　the　'monk；'　as　the　men　called　him；　used　to　do。 But　I　have　never　seen　him　in　the　exercise　of　his　duty。〃

〃Indeed；　Mr。　Starr；　you　are　too　young；　in　spite　of　your　five…and…fifty　years；　to　have　seen　that。 But　I；　ten　years　older；　often　saw　the　last　'monk'　working　in　the　mine。　He　was　called　so　because　he　wore　a　long　robe　like　a　monk。　His　proper　name　was　the　'fireman。' At　that　time　there　was　no　other　means　of　destroying　the　bad　gas　but　by　dispersing　it　in　little　explosions；　before　its　buoyancy　had　collected　it　in　too　great　quantities　in　the　heights　of　the　galleries。　The　monk；　as　we　called　him；　with　his　face　maske