"Yes," chorused both boys, gazing without hesitation into the black square which the swinging back of the rail had revealed. From the mouth of the dark pit a fetid, foul-smelling air rushed upward. It was the breath of the dead centuries.
"One moment," said the professor, staying Ralph as he was about to plunge forward undismayed into the abyss; "let some of that deadly gas out."
In apprehension of momentary discovery, the adventurers waited, starting at every sound. Outside the disturbance still went on. Feet could be heard rushing hither and thither. What could be happening?
"Now!" said the professor, after a few breathless minutes had passed.
Led by Ralph, they plunged downward, their feet encountering a flight of steps.
As they vanished into the unknown, the trap-door, actuated by some hidden machinery, which must have acted as their weight came on the long disused steps, swung silently back into place.
At the same instant there were several loud shouts from without, followed by a fusillade of rifles.
The escape of Jack and Pete from the tower had just been discovered, and while the ranch boy and the cow-puncher were surrounded by the perils through which we have followed them, the other members of the beleaguered party made their way forward into a blackness so utter as to feel almost solid.