“They are heads of criminals,” explained Frank. “I have heard that it is the custom of this country to suspend the heads of criminals at the gates of the cities in this manner. They are placed there as a warning to others.”
“A warning to us,” said the professor, his voice shaking. “It tells us we had better get out of this wretched country without delay. It is a warning to be heeded.”
“Nonsense! Come on, professor; we are losing time.”
“Go on! I am going back.”
“Good-by, professor.”
At a signal from Frank the two lads rode onward.
The professor watched them a few moments, and then rode after them, calling:
“Hold on; I will go.”
Of this Frank had felt confident all the time.
Away to the south they rode, having been told to bear a little to the east. Frank had a compass, and he did not believe they would get lost in the desert so they could not find their way out.