"Steady with that light there, signalman," he commanded suddenly. "Back slowly to port with the beam."
Darrin forced himself to be calm.
"Steady," he called, again. "Hold the light on anything you see, signalman."
"Aye, aye, sir; I do see something," replied the man who was manipulating the searchlight.
That he did see the mysterious something was proved by the manner in which he kept the light upon it.
That on which Darrin now trained his night glass was a marked rippling on the water, half a mile away, and farther seaward. A landsman would have missed it altogether. Yet that rippling on the sea's surface was clearly different from the motion of the water near by.
"It might be a school of large fish," Dave mused aloud, in Runkle's hearing, "though at night they are likely to rest. Runkle, and you, men, keep your eyes peeled to see if you can make out fish leaping out of the water."
The ripple continued, unbroken at any point. Moreover, it moved at uniform speed, and in a line nearly parallel with the coast.
Gradually the launch gained on that ripple. Dave could not turn his fascinated gaze away from the sight.
"I think I know what that is, sir," broke in Seaman Runkle, after three minutes of watching.