In one of the walls was an opening about four feet high. Entering this, the two men groped their way along a straight tunnel just wide enough for them to pass in single file.
"This must have been made by the Greeks when they held the tower," the old man continued.
"For what purpose? There's nothing in it."
"But there is the dynamite in the cellar behind. I think the tunnel must have been intended for a mine."
"To blow up something outside? Let us see in what direction it goes."
A glance at his compass showed him that the tunnel ran towards the north-east.
"It is plain," said Marco. "Here at the end we may be standing beneath the track. The Greeks intended to blow it up. I suppose the necessity passed when the Turks retreated, and the dynamite was left here and forgotten. Perhaps the Greeks who made the tunnel were killed in the fighting afterwards."
"Well, this may be a lucky find for us. We must see if it does end beneath the track."
Measuring his paces as they returned to the cellar, he went up, and counted an equal number from the doorway of the tower, following the direction of the tunnel as nearly as he could judge it. The thirty-second pace brought him to the wall; there were still nine more to take. At the forty-first he arrived at the centre of the track.
"You were right," he said; "the intention was clearly to have a means of blowing up the track. As you say, an explosion just there would make it impassable. This may be a lucky find for us, my friend. We must remove the dynamite to the end of the tunnel, and make some sort of fuse."