"I am sure that I do, Runkle," Dave Darrin returned. "It's a submarine, for some reason just barely submerged. That line of ripple is the wake left by her periscope."
As if to confirm the young naval officer's words, the ripple parted. As the line on the water broke, the periscope came fully into view, and the turret showed above water, continuing to rise until the deck was awash.
"There's the pest of the seas!" cried an excited voice.
Every man on the launch was now straining his eyes for a better look at the submarine, barely a quarter of a mile away.
CHAPTER XXIII
THE PUZZLE OF THE DEEP
"Coxswain!" shouted Dave.
"Aye, aye, sir."
"Send up three blue rockets!"