time, by any means, that he had gone aloft with Tom. "I happened
to be coming over in my auto," he went on to explain, "when I
happened to see the fire down in the meadow. I was afraid you
didn't know about it."

"Oh, yes," replied Tom. "I had Rad and Koku light a big pile of
packing boxes, to represent, as nearly as possible, on a small
scale, a burning building. I plan now to sail over it and drop
the tins of chemicals. They are arranged to burst as they fall
into the blaze, and I hope the carbon dioxide set loose will
blanket out the fire."

"Sounds interesting," commented Mr. Damon. "I'll go along."

The airship was wheeled out of the hangar and was soon ready
for the flight. A big cloud of black vapor down in the meadow
told Tom and Ned that Koku and Eradicate had done their work
well. The giant and the colored man had poured oil over the wood
to make a fierce blaze that would give Tom's new chemical
combination a severe test.

A mechanic turned the propeller of the airship until there was
an accumulation of gas in the different cylinders. Then he
stepped back while Tom threw on the switch. This was not one of
the self-starting types, of which Tom possessed one or two.

"Contact!" cried Tom sharply, and the man stepped forward to
give the big blades a final turn that would start the motor.
There was a muffled roar and then a steady staccato blending of
explosions. Tom raced the motor while his men held the machine in