Von Holtz began to unscrew two wing-nuts which kept the top of the aluminum casting in place.
“It is the first piece of apparatus which Professor Denham made,” he said precisely. “I know the theory, but I cannot duplicate it. Every dimension is at right angles to all other dimensions, of course. The Herr Professor has a note, here—”
He stopped his unscrewing to run over a heap of papers on the work-bench—papers over which he seemed to have been poring desperately at the time of Tommy’s arrival. He handed a sheet to Tommy, who read:
“If a creature who was aware of only two dimensions made two right-angled objects and so placed them that all the angles formed by the combination were right angles, he would contrive a figure represented by the corner of a box; he would discover a third dimension. Similarly, if a three-dimensioned man took three right angles and placed them so that all the angles formed were right angles, he would discover a fourth dimension. This, however, would probably be the time dimension, and to travel in time would instantly be fatal. But with four right angles he could discover a fifth dimension, and with five right angles he could discover a sixth….”
Tommy Reames put down the paper impatiently.
“Of course” he said brusquely. “I know all that stuff. But up to the present time nobody has been able to put together even three right angles, in practise.”
Von Holtz had returned to the unscrewing of the wing-nuts. He lifted off the cover of the dimensoscope.
“It is the thing the Herr Professor did not confide to me,” he said bitterly. “The secret. The one secret! Look in here.”
Tommy looked. The objective-glass at the end of the telescope faced a mirror, which was inclined to its face at an angle of forty-five degrees. A beam of light from the objective would be reflected to a second mirror, twisted in a fashion curiously askew. Then the light would go to a third mirror….