"No more in sight, eh?"
"Not yet. This one is heading west."
"Guess we had better get up that way, then," said Frank.
Jack assented.
A moment later the hydroplane was skimming swiftly over the water. For perhaps three hundred yards Frank kept the craft on the water; then sent it soaring into the air above.
There was not a word between the two boys until the hydroplane was a quarter of a mile in the air. Then Jack said:
"Make your elevation half a mile and then head west, slowly. The chances are there will be more of them. In the darkness we can let them overtake us and mingle with them in safety."
Frank gave his endorsement to this plan and the machine continued to rise. At the proper elevation, Frank turned the hydroplane's head westward and reduced the speed to less than thirty miles an hour. So slow was its gait, in fact, that it had the appearance of almost standing still.
Jack scanned the eastern horizon with his glass.
"See anything?" asked Frank.