vy steel, some shelves of the same and a seat which folded up
against the wall made of like powerful material.

"This is supposed to be the captain's room, where he stays when he
directs matters." Tom explained. "The machinery is below and beyond
here."

"How'd you come to evolve this?" asked Ned. "I haven't seen half enough
of the outside, to say nothing of the inside."

"You'll have time enough," Tom said. "This is my first completed tank.
There are some improvements to be made before we send it to the other
side to be copied.

"Then they'll make them in England as well as here, and from here we'll
ship them in sections."

"I don't see how you ever thought of it!" exclaimed the girl, in wonder.

"Well, I didn't all at once," Tom answered, with a laugh. "It came by
degrees. I first got the idea when I heard of the British tanks.

"When I had read how they went into action and what they accomplished
against the barbed wire entanglements, and how they crossed the
trenches, I concluded that a bigger tank, one capable of more speed,
say ten or twelve miles an hour, and one that could cross bigger
excavations--the English tanks up to this time can cross a ditch of
twelve feet--I thought that, with one made on such specifications, more
effective work could be done against the Germans."

"And will yours do that?" asked Ned. "I mean will it do ten miles an
hour, and straddle over a wider ditch than twelve feet?"

"It'll do both," promptly answered Tom. "We did a little better than
eleven miles an hour a while ago when I yelled to you to get out of the
way just now. It's true we weren't under good control, but the speed
had nothing to do with that. And as for going over a big ditch, I think
we straddled one about fourteen feet across back there, and we can do
better when I get my grippers to working."

"Grippers!" exclaimed Mary.

"What kind of trench slang is that, Tom Swift?" asked Mr. Damon.

"Well, that's a new idea I'm going to try out It's something like
this," and while from a distant part of the interior of Tank A came the
sound of hammering, the young inventor rapidly drew a rough pencil
sketch.

It showed the tank in outline, much as appear the pictures of tanks
already in service--the former simile of two wedge-shaped pieces of
metal put together broad end to broad end, still holding good. From one
end of the tank, as Tom drew it, there extended two long arms of
latticed steel construction.

"The i