Starr having chosen the place where the holes were to be drilled； they were rapidly bored by Harry。 Some cartridges of dynamite were put into them。 As soon as the long； tarred safety match was laid； it was lighted on a level with the ground。 James Starr and his panions then went off to some distance。
〃Oh！ Mr。 Starr；〃 said Simon Ford； a prey to agitation； which he did not attempt to conceal； 〃never； no； never has my old heart beaten so quick before！ I am longing to get at the vein！〃
〃Patience； Simon！〃 responded the engineer。 〃You don't mean to say that you think you are going to find a passage all ready open behind that dyke？〃
〃Excuse me； sir；〃 answered the old overman； 〃but of course I think so！ If there was good luck in the way Harry and I discovered this place； why shouldn't the good luck go on？〃
As he spoke； came the explosion。 A sound as of thunder rolled through the labyrinth of subterranean galleries。 Starr； Madge； Harry； and Simon Ford hastened towards the spot。
〃Mr。 Starr！ Mr。 Starr！〃 shouted the overman。 〃Look！ the door is broken open！〃
Ford's parison was justified by the appearance of an excavation； the depth of which could not be calculated。 Harry was about to spring through the opening； but the engineer； though excessively surprised to find this cavity； held him back。 〃Allow time for the air in there to get pure；〃 said he。
〃Yes！ beware of the foul air！〃 said Simon。
A quarter of an hour was passed in anxious waiting。 The lantern was then fastened to the end of a stick； and introduced into the cave； where it continued to burn with unaltered brilliancy。 〃Now then； Harry； go；〃 said Starr； 〃and we will follow you。〃
The opening made by the dynamite was sufficiently large to allow a man to p