"Aeroplane shed," answered the lad. "But don't worry dad. It's only a
small blaze. We'll get it out. You stay here. We'll attend to it--Mr.
Jackson and Eradicate and I."

"No--I'm going to help!" exclaimed Mr. Swift, sturdily. "I'll be with
you, Tom. Go on!"

The lad rushed down to the yard, closely followed by the engineer, who
had caught up another extinguisher. Eradicate was rushing about, not
knowing what to do, but still keeping up his shouting.

"It's on de roof! De roof am all blazin'!" he yelled.

"Quit your noise, and get to work!" cried Tom. "Get out a ladder, Rad,
and raise it to the side of the shed. Then play this extinguisher on
the blaze. Mr. Jackson, you help me run the Humming-Bird out. After
she's safe we'll tackle the fire."

Tom cast a hurried look at the burning shed. The flames were shooting
high up from the roof, now, and eating their way down. As he rushed
toward the big doors, which he intended to open to enable him to run
out his sky racer, he was wondering how the fire came to start so high
up as the roof. He wondered if a meteor could have fallen and caused it.

As the doors, which were quickly unlocked by Tom, swung back, and as he
and the engineer started to go in, they were met by choking fumes as if
of some gas. They recoiled for the moment.

"What--what's that?" gasped Tom, coughing and sneezing.

"Some chemical--I--I don't know what kind," spluttered Mr. Jackson.
"Have you any carboys of acid in there Tom, that might have exploded by
the heat?"

"No; not a thing. Let's try again."

Once more they tried to go in, but were again driven back by the
distressing fumes. The fire was eating down, now. There was a hole
burned in the roof, and by the leaping tongues of flame Tom could see
his aeroplane. It was almost in the path of the blaze.

"We must get her out!" he shouted. "I'm going in!"

But it was impossible, and the daring young inventor nearly succumbed
to the choking odors. Mr. Jackson dragged him back.

"We can't go in!" he cried. "There has been some mysterious work here!
Those fumes were put here to keep us from saving the machine. This fire
has been set by some enemy! We can't go in!"

"But I am going!" declared Tom. "We'll try the back door."

They rushed to that, but again were driven out by the gases and vapors,
which were mingled with the smoke. Disheartened, yet with a wild desire
to do something to save his precious craft, Tom Swift drew back for a
momen