d in the open air.

As they had expected, there was no explosion, but, what was more
serious, there was not even the slight crackling which indicates the
presence of a small quantity of firedamp. Simon took the stick which
Harry was holding, fixed his lamp to the end of it, and raised it high
above his head, up to where the gas, by reason of its buoyancy, would
naturally accumulate. The flame of the lamp, burning straight and clear,
revealed no trace of the carburetted hydrogen.

"Close to the wall," said the engineer.

"Yes," responded Ford, carrying the lamp to that part of the wall at
which he and his son had, the evening before, proved the escape of gas.

The old miner's arm trembled whilst he tried to hoist the lamp up. "Take
my place, Harry," said he.

Harry took the stick, and successively presented the lamp to the
different fissures in the rock; but he shook his head, for of that
slight crackling peculiar to escaping fire-damp he heard nothing. There
was no flame. Evidently not a particle of gas was escaping through the
rock.

"Nothing!" cried Ford, clenching his fist with a gesture rather of anger
than disappointment.

A cry escaped Harry.

"What's the matter?" asked Starr quickly.

"Someone has stopped up the cracks in the schist!"

"Is that true?" exclaimed the old miner.

"Look, father!" Harry was not mistaken. The obstruction of the fissures
was clearly visible by the light of the lamp. It had been recently done
with lime, leaving on the rock a long whitish mark, badly concealed with
coal dust.

"It's he!" exclaimed Harry. "It can only be he!"

"He?" repeated James Starr in amazement.

"Yes!" returned the young man, "that mysterious being who haunts our
domain, for whom I have watched a hundred times without being able to
get at him--the author, we may now be certain, of that letter which was
intended to hinder you from coming to see my father, Mr. Starr, and who
finally threw that stone at us in the gallery of the Yarrow shaft! Ah!
there's no doubt about it; there is a man's hand in all that!"

Harry spoke with such energy that conviction came instantly and fully
to the engineer's mind. As to the old overman, he was already convinced.
Besides, there they were in the presence of an undeniable fact--the
stopping-up of cracks through which gas had escaped freely the night
before.

"Take your pick, Harry," cried Ford; "mount on my shoulders, my lad!
I am still strong enough to bear you!"