He and Ned, with some of the crew and gunners, went outside the tank.

She was a sorry-looking sight, very different from the trim appearance she had presented when she first left the shop. Bricks, bits of stone, and piles of broken cement in chunks and dust lay thick on her broad back. But no real damage had been done, as a hasty examination showed.

"Well, are you satisfied, Tom?" asked his chum.

"Yes, and more," was the answer. "Of course this wasn't the hardest test to which she could have been submitted, but it will do to show what punishment she can stand. Being shot at from big guns is another matter. I'll have to wait until she gets to Flanders to see what effect that will have. But I know the kind of armor skin she has, and that doesn't worry me. There's one thing more I want to do while I have her out now."

"What's that?" asked Ned.

"Take her for a long trip cross country, and then shove her through some extra heavy barbed wire. I'm certain she'll chew that up, but I want to see it actually done. So now, if you want to come along, Ned, we'll go cross country."

"I'm with you!"

"Get inside then. We'll let the dust and masonry blow and rattle off as we go along."

The tank started off across the fields, which stretched for many miles on either side of the deserted factory, when suddenly Ned, who was again at his post in the observation tower, called:

"Look, Tom!"

"What at?"

"That corner of the factory which is still standing. Look at those men coming out and running away!"

Ned pointed, and his chum, leaning over from the steering wheel and controls, gave a start of surprise as he saw three figures clambering down over the broken debris and making their way out of what had once been a doorway.

"Did they come out of the factory, Ned?"

"They surely did! And unless I miss my guess they were in it, or around it, when we went through like a fellow carrying the football over the line for a touchdown."

"In there when the tank broke open things?"

"I think so. I didn't see them before, but they certainly ran out as we started away."

"This has got to be looked into!" decided Tom. "Come on, Ned! It may be more of that spy business!"

Tom Swift stopped the tank and prepared to get out.

Chapter XVI

The Old Barn

"There's no use chasing after 'em, Tom," observed Ned, as the two chums stood side by side outside the tank and gazed after the three men running off across the fields as fast as they could go. "They've got too much a start of us."

"I guess you're right, Ned," agreed Tom. "And we can't very well pursue them in the tank. She goes a bit faster than anything of her build, but a running man is more than a match for her in a short distance. If I had the Hawk here, there'd be a different story to tell."

"Well, seeing that you haven't," replied Ned, "suppose we let them go--which we'll have to, whether we want to or not--and see where they were hiding and if they left any traces behind."

"That's a good idea," returned Tom.

The place whence the men had emerged was a portion of the old factory farthest removed from the walls the tank had crunched its way through.

Consequently, that part was the least damaged.

Tom and Ned came to what seemed to have been the office of the building when the factory was in operation. A door, from which most of the gla.s.s had been broken, hung on one hinge, and, pushing this open, the two chums found themselves in a room that bore evidences of having been the bookkeeper's department. There were the remains of cabinet files, and a broken letter press, while in one corner stood a safe.

"Maybe they were cracking that," said Ned.

"They were wasting their time if they were," observed Tom, "for the combination is broken--any one can open it," and he demonstrated this by swinging back one of the heavy doors.

A quant.i.ty of papers fell out, or what had been papers, for they were now torn and the edges charred, as if by some recent fire.

"They were burning these!" cried Ned. "You can smell the smoke yet.

They came here to destroy some papers, and we surprised them!"

"I believe you're right," agreed Tom. "The ashes are still warm." And he tested them with his hand. "They wanted to destroy something, and when they found we were here they clapped the blazing stuff into the safe, thinking it would burn there.

"But the closing of the doors cut off the supply of air and the fire smouldered and went out. It burned enough so that it didn't leave us very much in the way of evidence, though," went on Tom ruefully, as he poked among the charred sc.r.a.ps.

"Maybe you can read some of 'em," suggested Ned.

"Part of the writing is in German," Tom said, as he looked over the ma.s.s. "I don't believe it would be worth while to try it. Still, I can save it. Here, I'll sweep the stuff into a box, and if we get a chance we can try to patch it together," and finding a broken box in what had been the factory office the young inventor managed to get into it the charred remains of the papers.

A further search failed to reveal anything that would be useful in the way of evidence to determine what object the three men could have had in hiding in the ruins, and Tom and Ned returned to the tank.

"What do you think about them, Tom?" asked Ned, as they were about to start off once more for the cross-country test.

"Well, it seems like a silly thing to say--as if I imagined my tank was all there was in this part of the country to make trouble--but I believe those men had some connection with Simpson and with that spy Schwen!"

"I agree with you!" exclaimed Ned. "And I think if we could get head or tail of those burned papers we'd find that there was some correspondence there between the man I saw up the tree and the workman you had arrested."

"Too bad we weren't a bit quicker," commented Tom. "They must have been in the factory when we charged it--probably came there to be in seclusion while they talked, plotted and planned. They must have been afraid to go out when the tank was walking through the walls."

"I guess that's it," agreed Ned. "Did you recognize any of the men, Tom?"

"No, I didn't see 'em as soon as you did, and when they were running they had their backs toward me. Was Simpson one?"

"I can't be sure. If one was, I guess he'll think we are keeping pretty closely after him, and he may give this part of the country a wide berth."

"I hope he does," returned Tom. "Do you know, Ned, I have an idea that these fellows--Schwen Simpson, and those back of them, including Blakeson--are trying to get hold of the secret of my tank for the Germans."

"I shouldn't be surprised. But you've got it finished now, haven't you?

They can't get your patents away from you."

"No, it isn't that," said Tom. "There are certain secrets about the mechanism of the tank--the way I've increased the speed and power, the use of the spanners, and things like that--which would be useful for the Germans to know. I wouldn't want them to find out these secrets, and they could do that if they were in the tank a while, or had her in their possession."

"They couldn't do that, Tom--get possession of her--could they?"