"Too heavy to float," was the answer of Mollie, as she again lifted it.

"But it could work up in a heavy wind or sea; that is, if it didn't go
down too far from shore," Grace remarked. "But can't we get it open some
way?"

"We might break it," Mollie observed. "Otherwise, I don't see how we
can. It is a complicated lock, if I am any judge," and she looked at the
front of the box. "Let me take that stake, Amy."

"Oh, no! Don't break it open!" expostulated Betty. "We must try and see
if we can't slip the lock, after we get it home. Papa has a lot of odd
keys."

"But I don't see any lock!" exclaimed Grace.

"There it is," and Betty pushed to one side a round disk of metal that
fitted over the keyhole.

Whether this was to keep out sand or water, the girls could not
determine. It might even have been designed to hide the keyhole, but
former use, or the battering which the box had received, had loosened
and disclosed the metal slide, and Betty's quick eyes had discerned the
object of it.

"It would take a peculiar key to open that," decided Mollie. "Mamma has
a historic French jewel case home, and it has a lock something like
that."

"Oh, suppose this contains--jewels!" cried Grace. "Wouldn't it be
just--"

"Nonsense!" broke in Betty. "If the box contains anything at all it is
probably papers of no value. My own opinion is that there's nothing in
it, for it's too light. However, we'll take it home, and see what the
boys say."

"You seem to have a great deal of faith in their opinion," laughed
Mollie. "Ah, my dear!" and she put a finger on Betty's blushing cheek.
"Methinks it is the opinion of _one_ certain boy you want."

"Silly!" murmured Betty.

"Oh, don't mind us. A legal opinion would be most excellent to have,"
mocked Grace. "Now who is eating the chocolates?" she wanted to know.

Betty did not answer. She bent over the black box, with its indefinable
air of mystery, and the three queer letters on the top. She was,
seemingly, trying to find a way to open it.

Finally she straightened up, looked once more across the bay and said:

"Well, let's take it to Edgemere."

"And let's hurry, too!" urged Amy.

"Hurry? Why?" asked Grace. "There's no more danger from the storm."

"No, but those men might come back, and, finding their treasure
gone--oh, well, let's hurry," she finished.

"Don't make me nervous," begged Grace, with a glance over her shoulder.
"Come along, Betty. I'm just dying to see what