where a
trolley line was built that ran to the town of Easton, where they were
to get the tools and parts of machinery.

They made the trip safely and without incident. When they gave the
machinist, to whom they had been directed by Mr. Henderson, the list of
the things needed, the man looked puzzled.

"I'll have to make one piece," he said. "You'll have to wait for it.
Can't promise it before to-morrow morning about eight o'clock."

"That will be all right," remarked Mark. "We'll call for it then."

So, bearing in mind Mr. Henderson's instructions, the boys engaged a
room at the hotel, which was quite a large one, for Easton was a
favorite summer resort and the town was filled with visitors. The lads
strolled about the town, had their dinner, and then went for a bath in
the surf. They retired early, for they were tired.

In the middle of the night Mark began to dream that he was on board the
_Porpoise_ and that the submarine blew up. There was a loud noise, he
saw a bright flash of flame, and saw rolling clouds of smoke. So vivid
was the vision that he thought he tried to leap out of the boat, and
awoke with a jump, to find Jack shaking him.

"What's the matter?" inquired Mark.

"The hotel's on fire!" shouted Jack.

Mark sprang out of bed and with Jack rushed to the window, for their
room was filled with thick smoke. They could see the dull glare of
flames, which every moment were becoming brighter.

The next instant a loud explosion shook the building. It swayed and
seemed likely to topple over. Outside the boys could hear excited shouts
and the puffing and whistling of fire engines.

"Quick! Run!" yelled Mark. He opened the door leading into the corridor,
but was driven back by a rush of flames and smoke that almost stifled
him.

"We must try the fire escape!" shouted Mark.

"Don't forget the valise with the tools;" exclaimed Jack, and Mark
hastened to where he had placed it under the bed.

Then the two boys rushed to the balcony on which their front windows
opened, and whence the fire escapes led down to the streets. The lads
had only time to slip on their coats, trousers, shoes and caps.

As they were preparing to clamber down the iron ladders they heard
someone on the balcony next to them shout:

"Here, you boys! Stop! I want you!"

CHAPTER V

A GRAVE ACCUSATION

"We haven't time now!" yelled back Mark, looking in the direction of the
voice, and seeing a short, stout man, who appear