For some time she sat there hugging her knees and thinking long, long
thoughts, and it was not until the sound of little waves lapping
against the rocks roused her that she woke from her day dream and
realized with terror that the tide had turned. The channels and lower
levels of the bay were already brimming over, and the water was deep
about the rocks on which she perched. At almost the same moment Dan
had been surprised by a cold wave which washed over his bare feet,
and, turning about, was dismayed to find a sheet of blue water
covering the bay and to see Nancy standing on the topmost rock
shouting "Dan! Dan!" at the top of her lungs. For one astonished
instant he looked at her, then, throwing down his shovel, he plunged
unhesitatingly into the icy bath. And now Nancy, realizing that there
was not a moment to lose if she hoped to reach the shore in safety,
let herself slowly down off the rocks, leaving the basket behind her,
and started toward her brother.

The water was already so deep in the channels that their progress
toward each other was slow, but they ploughed bravely on, feeling the
bottom carefully at each step lest they sink in some sand-pocket or
hollow washed out by the tide. Some distance away toward Charlestown
a fishing schooner rocked on the deeper water of the bay, and a
fisherman in a small boat, attracted by the shouting, looked up, and,
seeing the two struggling figures, instantly bent to his oars and
started toward them. Though he rowed rapidly, it was some minutes
before he could reach the children, who were now floundering about in
water nearly up to their necks.

[Illustration]