ical left on board. I can't give the demonstration that I planned
for tomorrow."

"You've given a better demonstration here than you ever could have in
the other city," declared Mr. Baxter. "I fancy this will be all the
test needed, Tom Swift!"

"Perhaps. I hope so. But we may as well land and see from the ground
the effect of our work. I'd also like to inquire if any one was hurt.
Let's go down."

It was rather ticklish work, making a landing in the midst of a
populous city, and at night. But as it happened, there had been a
number of buildings razed in the vicinity of the Landmark structure,
and there was a large, vacant level space. Also several of the city's
fire department searchlights were focused around the burning structure,
and when it became evident that an airship was going to land--though as
yet none guessed whose it was--the searchlights were turned on the
vacant spot and Tom was able to make a good landing, his own powerful
searchlight giving effective aid.

"What did you do that put out the fire?" demanded the chief of the
Newmarket department, as he rushed up with a crowd of others when Tom
and his friends alighted.

"I dropped a few grenades down that chimney," modestly answered the
young inventor.

"A few grenades! Say, you must have turned a whole river of them
loose!" cried the delighted chief. "It doused the fire quicker than I
ever saw one put out in all my life!"

"I'm glad I was successful," said Tom. "But was any one in the
building?"

"Yes, a few," answered a policeman, who was trying to keep the crowd
back from the airship. "They're bringing them out now."

"Killed?" gasped Tom.

"No. But some of them are badly hurt," the officer answered. "There
was one young lady and a man named Barton Keith--"

"Barton Keith!" shouted Tom, springing forward. "Was he--Who was the
young lady? I--I--"

But at that moment there was a stir in the crowd about the building, in
which only a little fire flow remained, and through the throng came a
disheveled and smoke-blackened young lady and a man whose clothing was
also greatly disarrayed.

"Mary!" cried the young inventor.

"Tom!" gasped Mary Nestor. "How did you get here?"

"I came to put out the fire," was the answer, and Tom cooled down now
that he saw Mary was unharmed. "How did you happen to be in the
building?"

"I was in Uncle Barton's office when the fire broke out," answered
Mary, "and we were trapped. We had to stay there, with t