Ned returned with a short iron bar, sharp and flat at one end. With this, and an axe, they attacked the secret door. As the professor had said, having gained his knowledge from overhearing the thieves talk while he was a captive, the portal was really but a shell. It was quickly forced open, the secret lock on the inside being broken.
Though they worked quickly they made as little noise as possible, for they feared, from what Professor Snodgrass had said about the two entrances being guarded, that someone would be stationed near the secret door.
But no alarm was raised, for while it was true that a guard was usually kept at the farther end of the tunnel, where it opened into the valley, on this occasion the man had been called away to help in re-branding the cattle.
So, thus favored by fortune, the Motor Boys and the professor were able, undetected by those whom they sought to capture, to force open the door. As it swung back on iron hinges set in the inner face of the rock, a dark tunnel was revealed. Hesitating a moment, to make sure none of the rustlers was there, they stepped in.
“Look! here’s the stone-boat and the ropes and pulleys they used to haul the cattle over a space so all trace of them would be lost,” exclaimed Bob, pointing to the contrivance that was at the opening of the tunnel, which, in reality was a large cave.
“Yes, that’s what I had my midnight ride on,” laughed Professor Snodgrass, who seemed to take huge delight in leading a raid on his former captors. “This is a new one they had just finished making in the woods when, unexpectedly, they caught me.”
“Hadn’t we better wait for the cowboys?” asked Bob, as Jerry and Ned seemed inclined to lead the way farther along the tunnel. “Besides, it’s so dark we can’t see more than a few feet,” and he pointed to the black void beyond.
“Yes, it is dark, and we’ll need lanterns,” said the scientist. “But we have time to go along a little way and explore. The raiding party won’t be here for some time yet.”
“We have plenty of electric flashes on the airship,” Jerry said. “We’ll get them and have a look.”