orld-line," he said sharply, excited in
spite of himself. "Revolving in the time dimension means telescoping
in the world-line.... It would be a strain no matter could endure...."

* * * * *

The mirror in the dimensoscope was not pointing in a fourth dimension.
It did not need to. It was reflecting light at a right angle, and
hence needed to be only at half of a right angle to the two courses of
the beam it reflected. But to whirl the steel globe into a fifth
dimension, the solenoid's support had for one instant to revolve in
time! For the fraction of a second it would have literally to pass
through its own substance. It would be required to undergo precisely
the sort of strain involved in turning a hollow seamless metal globe,
inside out! No metal could stand such a strain. No form of matter
known to man could endure it.

"It would explode!" said Tommy excitedly to himself, alone in the
great bare laboratory. "Steel itself would vaporize! It would wreck
the place!"

And then he looked blank. Because the place had very obviously not
been wrecked. And yet a metal ring had vanished, leaving no trace....

Von Holtz came back. He looked frightened.

"A--a repairman, Herr Reames," he said, stammering, "is on the way.
And--Herr Reames...."

Tommy barely heard him. For a moment, Tommy was all scientist,
confronted with the inexplicable, yet groping with a blind certainty
toward a conclusion he very vaguely foresaw. He waved his hand
impatiently....

"The Herr Jacaro is on the way here," stammered Von Holtz.

* * * * *

Tommy blinked, remembering that Von Holtz had told him he could make a
certain metal, the only metal which could be moved in the fourth
dimension.

"Jacaro?" he said blankly.

"The--friend of the Herr Professor Denham. He advanced the money for
the Herr Professor's experiments."

Tommy heard him with only half his brain, though that half instantly
decided that Von Holtz was lying. The only Jacaro Tommy knew of was a
prominent gangster from Chicago, who had recently cemented his
position in Chicago's underworld by engineering the amalgamation of
two once-rival gangs. Tommy knew, in a vague fashion, that Von Holtz
was frightened. That he was terrified in some way. And that he was
inordinately suspicious of someone, and filled with a queer
desperation.

"Well?" said Tommy abstractedly. The thought he needed was coming. A
metal which