too frequently. They glided along,
crossed the lake and were proceeding up the opposite shore when, as
they turned out from a little bay and rounded a point of land, Mr.
Sharp exclaimed:

"Look out, Tom, there's rowboat just ahead!"

"Oh, I'll pass well to one side of that," answered the young inventor,
looking at the craft. As he did so, noting that there were four men in
it, one of the occupants caught a glimpse of the ARROW. No sooner had
he done so than he spoke to his companions, and they all turned to
stare at Tom. At first the lad could scarcely believe his eyes, but as
he looked more intently he uttered a cry.

"There they are!"

"Who?" inquired Mr. Sharp.

"Those men--the thieves! We must catch them!"

Tom had spoken loudly, but even though the men in the rowboat did hear
what he said, they would have realized without that that they were
about to be pursued, for there was no mistaking the attitude of our
hero.

Two of the thieves were at the oars, and, with one accord, they at once
increased their speed. The boat swung about sharply and was headed for
the shore, which they seemed to have come from only a short time
previous, as the craft was not far out in the lake.

"No, you don't!" cried Tom. "I see your game! You want to get to the
woods, where you'll have a better chance to escape! If this isn't
great luck, coming upon them this way!"

It was the work of but a moment to speed up the engine and head the
ARROW for the rowboat. The men were pulling frantically, but they had
no chance.

"Get between them and the shore!" cried Mr. Sharp. "You can head them
off then." This was good advice and Tom followed it. The men, among
whom the lad could recognize Happy Harry and Anson Morse, were all
excited. Two of them stood up, as though to jump overboard, but their
companions called to them to stop.

"If we only had a gun now, not to shoot at them but to intimidate
them," murmured the balloonist, "maybe they'd stop."

"Here's one," answered Tom, pointing to the seat locker, where he kept
the shotgun Mr. Duncan had given him. In a moment Mr. Sharp had it out.

"Surrender!" he cried, pointing the weapon at the men in the small boat.

"Don't shoot! Don't fire on us! We'll give up!" cried Happy Harry,
and the two with the oars ceased pulling.

"Don't take any chances," urged Mr. Sharp in a low voice. "Keep
between them and the shore. I'll cover them." Tom was steering from
an auxiliary sid