like a riding light on some boat at anchor. Then the lost vessel would dare run in for an anchorage, too, and she'd be wrecked. Jack Crab's grandfather was hanged for it. So Phineas told me."
"How awful!" gasped Helen.
But Ruth suddenly seized her hand, exclaiming: "See there! what is it fluttering on the rock: Look, Tom!"
At the moment the boy could not do so, as he had his hands full with the tiller and sheet, and his eyes were engaged as well. When he turned to look again at the Thimble, what had startled Ruth had disappeared.
"There was something white fluttering against the rock. It was down there, either below highwater mark, or just above. I can't imagine what it was."
"A seabird, perhaps," suggested Helen.
"Then where did it go to so suddenly? I did not see it fly away," Ruth returned.
The catboat sailed slowly past the seaward side of the Thimble. There were fifty places in which a person might hide upon the rock—plenty of broken boulders and cracks in the base of the conical eminence that formed the peculiarly shaped island.
The three watched the rugged shore very sharply as the catboat beat up the wind—the
