age about him. A strong
escort brought Evelyn. Aten was grinning proudly, as though he had in
person defeated the enemy. And as Evelyn shakingly put out her hand to
touch Tommy's arm--it was only later that he realized he had been
wounded in half a dozen minor ways--a shadow roared over their heads.
The crackle of firearms came from it.

"Jacaro!" snarled Tommy. He leaped instinctively to pursue. But the
flying thing was bound for a landing in an open square, the same one
which not long since had seen the heaviest fighting. It alighted there
and toppled askew on contact. Figures tumbled out of it, in torn and
ragged garments fashioned in the style of the very best tailors of the
Earth's underworld.

Men of Yugna raced to intercept them. Firearms spat and bellowed
luridly. In a close-knit, flame-spitting group, the knot of men raced
over fallen bodies and hurtled areas where the pavement had cooled to
no more than a dull-red heat where a thermit shell had struck. One
man, two, three men fell under the small-arms fire. The gangsters went
racing on, firing desperately. They dived into a tunnel and
disappeared.

* * * * *

"The Tube!" roared Smithers. "They' goin' for the Tube!"

He plunged forward, and Tommy seized his arm.

"They'll go through your Tube," he said curtly. "It looks like the one
they came through. They'll think it is. Let 'em!"

Smithers tried to tear free.

"But they'll get back to Earth!" he raged. "They'll get off clear!"

The sharp, cracking sound of a gun-cotton explosion came out of the
doorway into which Jacaro and his men had dived. Tommy smiled very
grimly indeed.

"They've gone through," he said drily, "and they've blown up the Tube
behind them. But--I didn't tell you--I took a look at your castings.
Your pupils were putting them together, ready for the steam to go in,
in place of the coils I used. But--er--Smithers! You'd discarded one
pair of castings. They didn't satisfy you. Your pupils forgot that.
They hooked them all together."

Smithers gulped.

"Instead of four right-angled bends," said Tommy grimly, "you have six
connected together. You turned on the steam in a hurry, not noticing.
And I don't know how many series of dimensions there are in this
universe of ours. We know of two. There may be any number. But Jacaro
and his men didn't go back to Earth. God only knows where they landed,
or what it's like. Maybe somewhere a million miles in spac