Then, all at once, with a sudden movement, "Hand me your lamp, Harry," he said.

Ford took the lamp with a trembling hand. He drew off the wire gauze case which surrounded the wick, and the flame burned 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!" The young man understood in an instant. His father propped himself up against the rock. Harry got upon his shoulders, so that with his pick he could reach the line of the fissure. Then with quick sharp blows he attacked it. Almost directly afterwards a slight sound was heard, like champagne escaping from a bottle--a sound commonly expressed by the word "puff."

Harry again seized his lamp, and held it to the opening. There was a slight report; and a little red flame, rather blue at its outline, flickered over the rock like a Will-o'-the-Wisp.

Harry leaped to the ground, and the old overman, unable to contain his joy, grasped the engineer's hands, exclaiming, "Hurrah! hurrah! hurrah! Mr. Starr. The fire-damp burns! the vein is there!"

CHAPTER VII NEW ABERFOYLE

THE old overman's experiment had succeeded. Firedamp, it is well known, is only generated in coal seams; therefore the existence of a vein of precious combustible could no longer be doubted. As to its size and quality, that must be determined later.

"Yes," thought James Starr, "behind that wall lies a carboniferous bed, undiscovered by our soundings. It is vexatious that all the apparatus of the mine, deserted for ten years, must be set up anew. Never mind. We have found the vein which was thought to be exhausted, and this time it shall be worked to the end!"

"Well, Mr.