and to make arrangements for Mr. Baxter's use of
the main laboratory, he betook himself to his own private quarters.

The next week or so was a busy time for Tom; so busy, in fact, that he
had little chance to see Mr. Baxter. All he knew was that the
unfortunate man was also laboring in his own line, and Tom wished him
success. He knew that if the man made any discoveries that would help
with the fire-extinguishing fluid he would report, as he had promised.

"Well, Tom, how goes it?" asked Ned one day when he came over to call
on his chum. "Are you ready to accept contracts for putting out
skyscraper blazes in all big cities?"

"Not yet," was the answer. "But I'm going to make another attempt, Ned."

"You mean another experiment?"

"Yes, I have evolved a new combination of chemicals, using something of
the carbonate idea as a basis. I found that I couldn't get away from
that, much as I wanted to. But my application is entirely new, at least
I hope it will prove so."

"When are you going to try it?" asked Ned.

"Right away. All I have to do is to put the chemicals in the metal
tank."

"Then I'd better get my leather suit on," remarked Ned, starting to
take off his street coat. Tom kept for his chum a full outfit of flying
garments, one suit being electrically heated.

"Oh, we aren't going up in any airship," Tom said.

"Why, I thought you were going to test your aerial fire fighting
dingus!" exclaimed Ned.

"So I am. But I want to stay on the ground and watch the effect on the
blaze as the tank bursts and scatters the chemical fluid."

"Then you want me, and perhaps Mr. Damon to take the stuff up in the
machine? Excuse me. I don't believe I care to run an airship myself."

"No," went on Tom, "there isn't any question of an airship this time.
No one is going up. Come on out into the yard and I'll show you."

Ned Newton followed his chum out into the big yard near one of the
shops. Erected in it, and evidently a new structure, was a large wooden
scaffold in square tower shape with a long overhanging arm and a
platform on the extremity. Beneath it was a pit dug in the earth, and
in this pit, which was directly under the outstanding arm of the tower,
was a pile of wood and shavings, oil-soaked.

"Oh, I see the game," remarked Ned. "You're going to drop the stuff
from this height instead of doing it from an airship."

"Yes," Tom answered. "There will be time enough to go on with the
airship end of it after