d before. But I cannot move
other mirrors into the positions they have in this instrument. I do
not know how."

* * * * *

Tommy shook his head impatiently, staring at the so-simple, yet
incredible device whose theory had been mathematically proven
numberless times, but never put into practice before.

"Having made this device," said Von Holtz, "the Herr Professor
constructed what he termed a catapult. It was a coil of wire, like the
large machine there. It jerked a steel ball first vertically, then
horizontally, then laterally, then in a fourth-dimensional direction,
and finally projected it violently off in a fifth-dimensional path. He
made small hollow steel balls and sent a butterfly, a small sparrow,
and finally a cat into that other world. The steel balls opened of
themselves and freed those creatures. They seemed to suffer no
distress. Therefore he concluded that it would be safe for him to go,
himself. His daughter refused to permit him to go alone, and he was so
sure of his safety that he allowed her to enter the globe with him.
She did. I worked the catapult which flung the globe in the fifth
dimension, and his device for returning failed to operate. Hence he is
marooned."

"But the big catapult--"

"Can you not see that the big catapult is broken?" demanded Von Holtz
bitterly. "A special metal is required for the missing parts. That, I
know how to make. Yes. I can supply that. But I cannot shape it! I
cannot design the gears which will move it as it should be moved! I
cannot make another dimensoscope. I cannot, Herr Reames, calculate any
method of causing four right angles to be all at right angles to each
other. It is my impossibility! It is for that that I have appealed to
you. You see it has been done. I see that it is done. I can make the
metal which alone can be moved in the necessary direction. But I
cannot calculate any method of moving it in that direction! If you can
do so, Herr Reames, we can perhaps save the Herr Professor Denham. If
you cannot--Gott! The death he will die is horrible to think of!"

"And his daughter," said Tommy grimly. "His daughter, also."

* * * * *

He paced up and down the laboratory again. Von Holtz moved to the
work-bench from which he had taken Denham's note. There was a pile of
such memoranda, thumbed over and over. And there were papers in the
angular, precise handwriting which was Von Holtz's own, a