h them," laughed
Tom. "He wouldn't like it."

"I should say not!"

Ned well remembered Mary's uncle, who had been associated with Tom in
recovering the treasure in the undersea search.

"Well, if she can't be here, she can't," said Tom, as philosophically
as possible. "I'd better run over and bid her goodbye."

This Tom did, though Ned noticed that his chum acted as though lonesome
on his return.

"But when he gets to work testing his new chemical he'll be all right,"
decided Ned.

CHAPTER XIII

A SUCCESSFUL TEST

"It took you long enough," Ned remarked as Tom entered the main office
of the plant, having been to see Mary off on her trip to Newmarket.
This was following his call of the night before to learn more
particulars of her unexpected visit.

"Yes, I didn't plan to be gone so long," apologized Tom. "But I thought
while I was there I might as well go all the way with her."

"And did you?"

"Yes. In the electric runabout. I wanted to come back and get the
airship, but she said she wanted to look nice when she met her
relatives, and as yet airship travel is a bit mussy. Though when I get
my cabined cruiser of the clouds I'll guarantee not to ruffle a curl of
the daintiest girl!"

"Getting poetical in your old age!" laughed Ned. "Well, here is that
statement you said you wanted me to get ready. Want to go over it now?"

"No, I guess not, as long as you know it's all right. I'm going to
start right in and get ready for a bang-up test."

"Of what--your new aerial fire fighting apparatus?"

"Yes. Mr. Baxter and I are going to make up a lot of the chemical
compound that--we discovered through using it on the blazing tree--will
best do the trick. Then I'm going to try it on a pit fire, and after
that on a big blaze with an airship."

"Let me know when you do," begged Ned. "I want to see you do it."

"I'll send you word," promised the young inventor.

Then he began several days and nights of hard work. And he was glad to
have the chance to occupy himself, for, though Tom professed not to be
much affected by the departure of Mary Nestor, he really was very
lonesome.

"How is her uncle, Barton Keith, by the way?" asked Ned, when he called
on his chum one day, to find him reading a letter which needed but half
an eye to tell was from Mary.

"About as usual," was the answer. "He sends word by Mary that he'll be
glad to see us any time we want to call. He has some nice offices in
the Landmark