called the space continuum.

"There is also a three dimensional time continuum. This also has length, which is past-present-future. In addition it has width and breadth, which are approximated by the idea of simultaneity to a certain extent. This is not, however, the simultaneity of events co-existent in our one, three-dimensional space. All events we can be aware of are in one point in the time continuum, which moves along a single time line.

"Since there are only three dimensions of space, all things must be in our space. It is the time co-ordinates that determine whether we are aware of something or not. At this very moment there is an infinity of universes all occupying the same space, but each in a different position in time. They are existing now, but separated from us in a direction at right angles to the universal time stream.

"Mathematically, these other universes are expressed in co-ordinates that have the square root of a minus one as a coefficient. Also mathematically, these universes are imaginary, but not in the non-mathematical, mythical sense. They are just as real as ours, but relatively imaginary or relatively non-existent.

"All this has been known by others. They have also known that to make an imaginary value real it is only necessary to multiply it by the square root of a minus one. Then it becomes real. This fact became the entering wedge into the principal that enabled me to succeed in bridging the abyss of right angle time travel.

"As you know, many years ago the secret of single dimension time travel was solved. However, it would not answer our problem. Though it is true time travel, it amounts to nothing more than perfect stasis for controlled periods, and if destruction hits the space the time traveller is in, he is as vulnerable as he would be if not travelling. In order to escape that it is necessary to step over, so to speak, into one of the imaginary universes at right angles to us in the time continuum and travel forward there.

"So, all I had to do was discover some principal for multiplying a sector of space by the square root of a minus one. As you know, I did that. Then I discovered that there are gaps, so that it was impossible to discover another universe co-existent in space, without determining the basic equation of the time curve.

"As everyone knows, both time and space are curved, due to the distortion of mass on surrounding space and time. The exact equation for this curvature had to be determined.

"We knew beforehand that it had to be a cubic equation. Each cubic equation has three roots for every value of the independent variable, which is in space. It also has three roots for every value of the time. Basically, that means that if any primal unit exists in our space, it exists in three forms, the positive, the negative and the neutral. These units are the positron, the negatron, and the neutron. Those three are the three solutions in space to the co-ordinates of the existential primal point.

"But also there must be two other universes co-existent with ours in space, but separated sideways in time. They would be impossible to find with the machine without solving the cubic equation of the curvature of our time line."

"So you have solved that and contacted one of the other two universes," Hute Hitle broke in impatiently.

"Exactly," Carl Grinch said.

"Take me to it," Hute ordered. "I want to see for myself."

"Yes, my Leader," Carl said, clicking his heels again and bowing. The bow was lower than usual to hide the gleam of triumph that rose unbidden in the scientist's eyes.

The Leader stood with military stiffness, looking curiously at the square of glowing force. It was set flush with the wooden floor of the room, and seemed to be nothing more than a square carpet of luminosity.

Near it was a tripod with a telescope attached. The telescope went up to the edge of the space above the square place and seemed to end there,—a tube with no lens in the end.