topped more than once, and, loitering along, it was dark when they neared their destination.
As they would have drawn up to the wharf there was a sudden flash of light--gone in a moment--followed by a dark body that swished by them like a flash.
Frank uttered an exclamation of astonishment.
"See that?" he demanded.
"Yes. What could it have been?"
"You've got me, but it's heading toward the open sea. Great Scott! Maybe it's an enemy."
"Yes; you know how anxious the Germans are over this submarine business. Maybe this fellow has been spying about. May be going to report to a German submarine out there some place."
"Think we had better follow and have a look?" asked Jack.
"Believe it would be a good idea. Let's go."
Without another word, Jack brought the boat about and headed after the one that had so recently dashed by them. In the darkness ahead there was nothing to be seen.
"Like looking for a needle in a haystack," Jack