They did not discuss the matter of the light. It did not appear again and Nicky and Cliff dropped off to sleep. Tom, lying awake, battling with himself mentally, trying to make his common sense defeat his instinctive apprehension, started and almost thrust Cliff over the low rail with the violence of his motion.
From somewhere about the hull of their sloop came three distinct taps! Rap! Rap! Rap!
“What was that?” whispered Tom.
Mr. Neale, seated near the tiller, half dozing, answered, as Cliff and Nicky stirred and came awake.
“Probably drifting wood or possibly we are almost on a coral reef—or the anchor cable may have rubbed and made the noise. There is not a thing!——”
“Look!” gasped Nicky—“Look! In the water! Light—bluish light, moving away.”
Everyone was fully awake and staring in every direction. Cliff located Nicky’s indicating finger, followed the direction, saw a swirl of phosphorescence in the water.
“Maybe a shark!” he declared, “a shark came up to investigate us, looking for food, I’ll bet!”
“That was it!” declared Mr. Neale. “Go back to sleep.”
“There’s the light again!” Tom quavered. Even Cliff and Nicky felt chilling prickles run up and down their spines at Tom’s tone. Sam looked and slumped down, hiding his face in the cockpit.