"That will make it more difficult," one man answered. "But if the
invention is as valuable as--"

"Hush!" came a caution from another of the party. "This is too
public a place to discuss the matter. Wait until we get out. One of
us will have to see Swift, of course, and if he proves stubborn--"

"I guess you'd better hush yourself," retorted the man who had first
spoken, and then the voices subsided.

But Tom Swift had overheard something which made him vaguely afraid.
He started so at the sound of his father's name that he knocked a
fork from the table.

"What's the matter; getting nervous?" asked Ned with a laugh.

"I guess so," replied Tom, and when he stooped to pick the fork up,
not waiting for the girl who was serving at his table, he stole a
look at the strangers who had just entered. He was startled to note
that one of the men was the same he had seen in the post-office--the
man who answered the description of the one who had been inquiring
of Mr. Merton about the Swift shops.

"I'm going to keep my ears open," thought Tom as he went on eating
his dinner.