"If we weren't cautious, it wouldn't do us any good if we did find him,"
argued Jack. "First thing you know we would be at the bottom."

Frank considered this point a moment.

"Guess you're right," he said at last.

"Swish!" went something at this moment, and, turning quickly, Frank saw
a dark shape speeding away up the river.

"Hey! There went one the other way," he cried to Jack.

"That so?" replied Jack anxiously. "There is something up here, and I'm
going to find out what it is."

He slowed down even more, and, striking a match, lighted the
searchlight, which, until this moment, he had not deemed advisable.

As the light flashed over the water, the lad made out another small
motorboat dead ahead, upon which signs of life became apparent. Jack saw
figures gesticulating violently; then the boat headed directly for the
one occupied by the two boys.

"Guns, Frank!" said Jack quietly. "They are coming at us."

"Leave it to me," replied Frank. "You run the boat. I'll do the rest."

"Don't shoot unless you have to," warned Jack.

Frank made no reply.