There was no time to lose.
Suddenly, at that moment, Frank saw a narrow opening in the gallery wall.
He rushed into it and found that he was in one of the many passages which made a honeycomb of the hill.
All was darkness, but the young inventor did not care for this, so long as safety was assured.
Barney was close behind.
They were just in time to avoid being seen by the foe.
Fortunately not one of the Mexicans turned into this passage.
“Thank Heaven, we have given them the slip for a moment,” Frank breathed.
“Bejabers, I’ve an idea!” exclaimed Barney, with eagerness.
“Indeed!” said Frank. “What is it, Barney?”