rammed the ship, as had happened on the going voyage, and
several times they were surrounded by hordes of wild polar fish and
walrusses, but there were no accidents, and in a couple of weeks the
ship entered the temperate zone.

Then came lazy happy days of sailing through the tropical region. They
landed at several islands and renewed their supply of food.

"I'm coming back this way some day," observed Mr. Henderson one
afternoon as the ship was sailing along on top of the waves.

"What for?" asked Jack.

"To investigate that strange island with a big hole in the middle that
seems to lead to the centre of the earth," was the answer. "I have a
fancy we can explore that by means of a balloon. I'm going to try."

"Will you take us along?" asked the two boys.

"I'll see," replied the professor.

And later on he did take them on a trip, a thousand miles
underground,--but that is another story to tell.

It was about a week later that the voyagers came within sight of Key
West.

"Off there lies the United States," said Mr. Henderson.

"Hurrah for home!" cried Mark.

Three days later they landed at a small Florida town. The sight of the
_Porpoise_ attracted throngs of people to the dock where she tied up.
Among them was a newsboy.

"Get me all the papers for the past month," said Jack. "I want to see
what the news is."

"Same here," put in Mark, and the papers were soon brought.

"Hurrah!" exclaimed Jack, as soon as he had looked at several of the
sheets.

"What is it?" asked Mark, who was unfolding a paper.

"Anarchists Confess," read Jack. "Two Englishmen Admit They Blew Up
Hotel Where Lord Peckham Was Stopping. No Suspicion Attaches to Two
Youths Who So Mysteriously Disappeared!"

"Hurrah!" joined in Mark.

"Those are only the head lines," went on Jack. "There's a long story,
and I guess it lets us out."

The two boys were completely cleared of the slightest shade of suspicion
of the outrage, and there was even an interview with the English
detective in which he admitted that he was wrong.

A week later the _Porpoise_ tied up at her own dock, whence she was
launched.

"Back again," remarked the professor as he stepped ashore. "I've been to
the south pole, and to the north pole. I wonder where I shall go next?"

"To the big hole and underground," suggested Jack.

"We shall see," said Mr. Henderson with a twinkle in his eyes.

THE END

The Dave Dashaway Series

By ROY ROCKWOOD