e opposite side of the street
where the girl and Mr. Nestor could be seen in the light of a street
lamp.

"They're going out to see Tom's secret," said Mr. Damon. "There's
plenty of room in my car. Let's ask them to go with us."

"Surely," agreed Ned, and a moment later he and Mary were in the rear
seat while Mr. Damon and Mr. Nestor were in the front, Mr. Damon at the
wheel, and they were soon speeding down the road.

"I do hope everything will go all right," observed Mary.

"What do you mean?" asked Ned.

"I mean Tom is a little bit anxious about this test."

"Did he tell you what it was to be?"

"No; but when he called to invite father and me to be present he seemed
worried. I guess it's a big thing, for he never has acted this way
before--not talking about his work."

"That's right," assented Ned. "But the secret will soon be disclosed, I
fancy. But how is it you aren't going to the dance with Lieutenant
Martin? He told me you had half accepted for to-night."

"I had." And if it had been light enough Ned would have seen Mary
blushing. "I was going with him. It's a dance for the benefit of the
Red Cross to get money for comfort kits for the soldiers. But when Tom
sent word that he'd like to have me present to-night, why--"

"Oh, I see!" broke in Ned, with a little laugh. "'Nough said!"

Mary's blushes were deeper, but the kindly night hid them.

Then they conversed on matters connected with the big war--the selling
of Liberty Bonds, the Red Cross work and the Surgical Dressings
Committee, in which Mary was the head of a junior league.

"Everybody in Shopton seems to be doing something to help win the war,"
said Mary, and as there was just then a lull in the talk between her
father and Mr. Damon her words sounded clearly.

"Yes, everybody--that is, all but a few," said Mr. Nestor, "and they
ought to get busy. There are some young fellows in this town that ought
to be wearing khaki, and I don't mean you, Ned Newton. You're doing
your bit, all right."

"And so is Tom Swift!" exclaimed Mr. Damon, as if there had been an
implied accusation against the young inventor. "I heard, only to-day,
that one of his inventions--a gas helmet that he planned--is in use on
the Western front in Europe. Tom gave his patents to the government,
and even made a lot of the helmets free to show other factories how to
turn them out to advantage."

"He did?" cried Mr. Nestor.

"That's what he did. Talk about doing your b