"No such luck," Tony remarked. "He'll be looking behind once in a while."
Frank found a pair of binoculars on one of the seats, and he raised them to his eyes, adjusting them so that Paul Blum and the speeding motorboat were brought within his line of vision. The distant Sleuth leaped closer as he looked through the glasses, and he could plainly see the face of the man at the wheel.
They had not been mistaken. The fugitive was Paul Blum.
Even as Frank looked, the man turned, and an expression of alarm crossed his face. He had seen the motorboat pursuing him.
Frank saw Blum lean forward, and the Sleuth began to increase its speed. The wing of water cleft by its bow became higher and the spray was flying. Swiftly, the motorboat began to draw away.
"He's seen us," said Frank, lowering the binoculars.
"We'll keep after him, anyway."
"We'll chase him clean across the Atlantic if the gas holds out," declared Tony.
Joe gave an exclamation of delight.
"The gas!" he exclaimed. "The gas! That's where we have him. I went down to the boathouse at noon just to see if there was enough gas in the tank, and it's pretty low. He hasn't enough to take him more than a few miles."