it!"

"Have what--a fit of seasickness?"

"No, but these empty seats--the persons we saw you know--they belong
there and they're afraid to come out and be seen."

"Why should they be--if they're not the Fogers. I guess you've got
another think coming."

"Well, I'm sure there's something mysterious about those two--the
way they hid their faces as they came on board--not appearing at
supper--I'm going to keep my eyes open."

"All right, go as far as you like and I'm with you. Just now you may
pass me the powdered sugar. I want some on this pie."

Tom laughed at Ned's matter-of-fact indifference, but when the young
inventor turned in to his berth that night he could not stop
thinking of the empty seats--the two mysterious passengers--and the
two Fogers. They got all jumbled in his head and made his sleep
restless.

Morning saw the Maderia well out to sea, and, as there was quite a
swell on, the vessel rolled and pitched to an uncomfortable degree.
This did not bother Tom and Ned, who were used to sudden changes of
equilibrium from their voyages in the air. Nor did Mr. Damon suffer.
In fact he was feeling fine and went about on deck like an old salt,
blessing so many new things that he had many of the passengers
amused.

Poor Eradicate did suffer though. He was very seasick, and kept to
his berth most of the time, while some of his new friends did what
they could for him.

Tom had in mind a plan whereby he might solve the identity of the
mysterious passengers. He was going to do it by a process of
elimination--that is he would carefully note all on board until he
had fixed on the two who had aroused his suspicions. And he had to
do this because so many of the passengers looked very different, now
that they had on their ship "togs," than when first coming on board.

But the rough weather of the first day prevented the lad from
carrying out his plan, as many of the travelers kept to their
staterooms, and there were a score of vacant places at the tables.

The next day, however, was fine, and with the sea like the
proverbial mill pond, it seemed that everyone was out on deck. Yet
when meal time came there were these same two vacant seats.

"What do you think of it, Ned?" asked Tom, with a puzzled air.

"I don't know what to think, Tom. It sure is queer that these
two--whoever they are--don't ever come to meals. They can't be seasick
on a day like this, and they certainly weren't the first night."

"That's r