w a roaring furnace of
flames.

"No skyscraper work needed here," observed Tom. "But it will give me a
chance to use the latest combination I worked out. I'll try that first.
Are you ready with it, Mr. Baxter?"

"Yes," was the answer.

The young inventor, not heeding the cries of wonder that arose from
below and paying no attention to the uplifted hands and arms pointing
to him, steered his craft to a corner of the yard where there was a
small isolated fire in a pile of boards. It was Tom's idea to try his
new chemical first on this spot to watch the effect. Then he would turn
loose all his other containers of the chemical mixture that had proved
so effective in other tests.

Attention of those who had gathered to look at the fire was about
evenly divided between the efforts of the regular department and the
pending action by Tom Swift. The latter was not long in turning loose
his latest sensation.

"Let it go!" he cried to Mr. Baxter, and down into the seething caldron
of flame dropped a thin sheet-iron container of powerful chemicals.
Leaning over the cockpit of the aircraft, the occupants watched the
effect. There was a slight explosion heard, even above the roar of the
flames, and the tongues of fire in the section where Tom's extinguisher
had fallen died down.

"Good work!" cried Ned.

"No!" answered Tom, shaking his head. "I was a little afraid of this.
Not enough carbon dioxide in this mixture. I'll stick to the one I
found most effective." For the flames, after momentarily dying down,
burst out again in the spot where he had dropped the bomb.

Tom wheeled the airship in a sharp, banking turn, and headed for the
heart of the fire in the lumberyard. It was clearly getting beyond the
control of the regular department.

"How about you, Ned?" called Tom, for he had given his chum charge of
dropping the regular bombs containing a large quantity of the
extinguisher Tom had practically adopted.

"All ready," was the answer.

"Let 'em go!" came the command, and down shot the dark, spherical
objects. They burst as they hit the ground or the piles of blazing
lumber, and at once the powerful gases generated by the mixture of
several different chemicals were released.

Again the three in the airship leaned eagerly over the side of the
cockpit to watch the effect. It was almost magical in its action.

The bombs had been dropped into the very fiercest heart of the fire,
and it was only an instant before their