"You must not stop!" cries John; "urge your horses on--fly while you
have time. I hear them coming!"

He tries to start Lady Ruth's nag, but she pulls on the lines.

"I decline to run and leave you here, Doctor Chicago," she says,
resolutely.

"But you must go," he declares.

"Nonsense!" breaks in Philander. "Here's room for you, John. Jump up."

The young man sees that the quickest way to get them started is to obey,
so he manages to reach the saddle in front of the professor, who clasps
his arms about him and holds on.

This done, they clatter on again.

It soon becomes evident that their pursuers gain upon them rapidly,
despite their best efforts. There can be but one end to the race, and
this is in plain view.

John keeps his wits about him. If caught upon the open by the rushing
column of fierce desert warriors, a desperate engagement must ensue,
which will doubtless end in their complete annihilation, for it can
hardly be expected that Sir Lionel will be able to play his great game
twice on the same night.

The Englishman has maintained a stolid silence all this while. Perhaps
he is out of humor at the change in the arrangements, and fears lest,