impson by
searchlight," agreed the young inventor. "As to what he wanted, I
suppose he came to spy out some of my secret inventions--dad's and
mine. He's probably been hiding and sneaking around the works ever
since we arrested Schwen. Some of my men have reported seeing
strangers about, but I have kept Shop Thirteen well guarded.

"However, this fellow may have been waiting outside, and he may have
followed the tank when we started off a little while ago for the night
test. Then, when he saw our mishap and noticed that we were stalled, he
came in, boldly enough, thinking, I suppose, that, as I had never seen
him, he would take a chance on getting as much information as he could
in a hurry."

"But he didn't count on Ned's being here!" chuckled Mr. Damon.

"No; that's where he slipped a cog," remarked Mr. Nestor. "Well, Tom,
I like your tank, what I've seen of her, but it's getting late and I
think Mary and I had better be getting back home."

"We'll be ready to start in a little while," Tom said, after a brief
consultation with one of his men. "Still, perhaps it would be just as
well if you didn't ride back with me. She may go all right, and then,
again, she may not. And as it's dark, and we're in a rough part of the
field, you might be a bit shaken up. Not that the tank minds it!" the
young inventor hastened to add "She's got to do her bit over worse
places than this--much worse--but I want to get her in a little better
working shape first. So if you don't mind, Mary, I'll postpone your
initial trip."

"Oh, I don't mind, Tom! I'm so glad you've made this! I want to see the
war ended, and I think machines like this will help."

"I'll ride back with you, Tom, if you don't mind," put in Ned. "I guess
a little shaking up won't hurt me."

"All right--stick. We're going to start very soon."

"Well, I'm coming over to-morrow to have a look at it by daylight,"
said Mr. Damon, as he started toward his car.

"So am I," added Mary. "Please call for me, Mr. Damon."

"I will," he promised.

Mr. Nestor, his daughter, and Mr. Damon went back to the automobile,
while Ned remained with Tom. In a little while those in the car heard
once more the rumbling and roaring sound and felt the earth tremble.
Then, with a flashing of lights, the big, ungainly shape of the tank
lifted herself out of the little ditch in which she had come to a halt,
and began to climb back to the road.

Ned Newton stood beside Tom in the control t