ower of the great tank as
she started on her homeward way.

"Isn't it wonderful!" murmured Mary, as she saw Tank A lumbering along
toward the road. "Oh, and to think that human beings made that. To think
that Tom should know how to build such a wonderful machine!"

"And run it, too, Mary! That's the point! Make it run!" cried her
father. "I tell you, that Tom Swift is a wonder!"

"Bless my dictionary, he sure is!" agreed Mr. Damon.

Along the road, back toward the shop whence it had emerged, rumbled the
tank. The noise brought to their doors inhabitants along the country
thoroughfare, and some of them were frightened when they saw Tom
Swift's latest war machine, the details of which they could only guess
at in the darkness.

"She'll butt over a house if it gets in her path, knock down trees,
chew up barbed-wire, and climb down into ravines and out again, and go
over a good-sized stream without a whimper," said Tom, as he steered
the great machine.

There was little chance then for Ned to see much of the inside
mechanism of the tank. He observed that Tom, standing in the forward
tower, steered it very easily by a small wheel or by a lever,
alternately, and that he communicated with the engine room by means of
electric signals.

"And she steers by electricity, too," Tom told his friend. "That was
one difficulty with the first tanks. They had to be steered by brute
force, so to speak, and it was a terrific strain on the man in the
tower. Now I can guide this in two ways: by the electric mechanism
which swings the trailer wheels to either side, or by varying the speed
of the two motors that work the caterpillar belts. So if one breaks
down, I have the other."

"Got any guns aboard her--I mean machine guns?" asked Ned.

"Not yet. But I'm going to install some. I wanted to get the tank in
proper working order first. The guns are only incidental, though of
course they're vitally necessary when she goes into action. I've got
'em all ready to put in. But first I'm going to try the grippers."

"Oh, you mean the gap-bridgers?" asked Ned.

"That's it," answered Tom. "Look out, we're going over a rough spot
now."

And they did. Ned was greatly shaken up, and fairly tossed from side to
side of the steering tower. For the tank contained no springs, except
such as were installed around the most delicate machinery, and it was
like riding in a dump cart over a very rough road.

"However, that's part of the game," Tom