"Let's take after him," suggested Jack, and, nothing loath, Mark
assented. The two lads broke into a run, but, as they leaped forward,
the man also increased his pace, and they could hear his feet pounding
out a tattoo on the hard road.

The two youths reached the bridge, and sped across it. They glanced
hastily on either side, thinking possibly the man might have had some
companions, but no one was in sight, and the stranger himself was now
out of view around a bend in the highway.

"No use going any farther," suggested Jack, pulling up at the far side
of the bridge. "There are two roads around the bend, and we couldn't
tell which one he'd take. Besides, it might not be altogether safe to
risk it."

Mark and Jack, on their return, told Professor Henderson and the German
scientist something of their little excursion.

"But who could he have been?" asked Mr. Roumann. "Perhaps if you ask
the boy who brought the note he can tell you."

"We'll do it in the morning," decided Mark.

"It's peculiar that he wanted Mark to meet him," spoke Amos Henderson.
"Have you any enemies that you know of, Mark?"

"Not a one. But what makes you think this man was an enemy, Professor?"

"From the fact that he ran when he saw you and Jack together. Evidently
he expected to get Mark out alone."