come. By thetime he vanished over the rise he had settled into the long, easy trotthat would carry him a good fifteen miles an hour all the way to thehealing spring.
Behind him the glistening square slab rested, oblivious of hisdeparture. The two halves of the wrecked bridge still reached yearning,torn arms toward one another; and across the gap the ruins of the hugecity squatted in silence, coldly aloof.
A wind born leaf dipped down in coy flight to investigate the slab--andslipped past the veil. The fresh cut end of the stick Jan had cut formeda white dot on the green carpet of stunted grass. Bright red stained alarge spot on the green and formed a ribbon that led to the edge of thesquare of cold luminescence;--the red trail of blood left by the strangevisitor from out of the square. And in the clean blue sky a bright sunbeamed benignly over all, ignoring--
* * * * *
"My leader!" Carl Grinch clicked his heels softly, and bowed stifflyfrom the waist. His high, intellectual forehead, clear blue eyes andfinely cut features, together with his civilian garb, indicated that hewas a scientist. He was, in fact, much more than a scientist. He was THEscientist of Aleme.
"At ease." The leader waved a gloved hand carelessly, a cruel smiletwisting the harsh face of the dictator of Aleme and avowed leader ofdowntrodden masses in every country on Amba.
His eyes held a gleam of satisfaction as he watched the uneasy tensenessof the scientist. He gloried in a sadistic satisfaction at his power tosnuff out the life of one so great,--or let him live to serve hisLeader.
"I told you not to come to me until you had succeeded in the task I setyou," Generalissimo Hute Hitle said coldly. "Your presence means thatyou have, no doubt?"
"Yes, my Leader," Carl Grinch smiled. "Everything is in readiness."
"Good," Hitle said. He rubbed his chin slowly, a smile of triumphcreasing his face into unaccustomed wrinkles. "Now we can't lose. Wewill let loose the destruction and let it take its course. After it isover we will return to rule an unresisting planet. Explain again to methe theory of the device."
"The theory of operation of the devise is, of course, understandableonly by a highly trained specialist," Carl Grinch said placatingly.
"You know what I mean," Hute Hitle snarled. "I'm not interested in whatmakes it work. Only in what it does."
"To begin with," Carl Grinch said. "Space has three dimensions. We livein those three dimensions of length, breadth, and thickness. This iscalled 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 pointin the time continuum, which moves along a single time line.
"Since there are only three dimensions of space, all things must be inour space. It is the time co-ordinates that determine whether we areaware of something or not. At this very moment there is an infinity ofuniverses all occupying the same space, but each in a different positionin time. They are existing now, but separated from us in a direction atright angles to the universal time stream.
"Mathematically, these other universes are expressed in co-ordinatesthat have the square root of a minus one as a coefficient. Alsomathematically, these universes are imaginary, but not in thenon-mathematical, mythical sense. They are just as real as ours, butrelatively imaginary or relatively non-existent.
"All this has been known by others. They have also known that to make animaginary value real it is only necessary to multiply it by the squareroot of a minus one. Then it becomes real. This fact became the enteringwedge into the principal that enabled me to succeed in bridging theabyss of right angle time travel.
"As you know, many years ago the secret of single dimension time travelwas solved. However, it would not answer our problem. Though it is truetime travel, it amounts to nothing more than perfect stasis forcontrolled periods, and if destruction hits the space the time travelleris in, he is as vulnerable as he would be if not travelling. In order toescape that it is necessary to step over, so to speak, into one of theimaginary universes at right angles to us in the time continuum andtravel forward there.
"So, all I had to do was discover some principal for multiplying asector of space by the square root of a minus one. As you know, I didthat. Then I discovered that there are gaps, so that it was impossibleto discover another universe co-existent in space, without determiningthe basic equation of the time curve.
"As everyone knows, both time and space are curved, due to thedistortion of mass on surrounding space and time. The exact equation forthis curvature had to be determined.
"We knew beforehand that it had to be a cubic equation. Each cubicequation 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, itexists in three forms, the positive, the negative and the neutral. Theseunits are the positron, the negatron, and the neutron. Those three arethe three solutions in space to the co-ordinates of the existentialprimal point.
"But also there must be two other universes co-existent with ours inspace, but separated sideways in time. They would be impossible to findwith the machine without solving the cubic equation of the curvature ofour 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. Thebow was lower than usual to hide the gleam of triumph that rose unbiddenin the scientist's eyes.
* * * * *
The Leader stood with military stiffness, looking curiously at thesquare of glowing force. It was set flush with the wooden floor of theroom, 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 tothe edge of the space above the square place and seemed to end there,--atube with no lens in the end.
"The telescope is pointed into one of the other two worlds," Carl wasexplaining. "Without a physical solid connecting the two there is nocontact."
"What is the nature of that?" Hute asked, pointing at the glowing squaresurface.
"It's difficult to explain it," Carl answered, "I'll put it this way.Two attracting bodies that are close enough together will revolve aroundeach other, like the sun and our planet, Amba. The material of this slabis what I have named tri-matter. It consists of matter from all threeuniverses of our time equation, blended into one solid. Before I wasable to contact these other two universes it was necessary to use themachine, which took incredible power to operate for a few brief moments,and had to be so delicately controlled that the slightest vibrationunbalanced its adjustment. Once the materials were gathered and blendedso they could not separated, I had a permanent bridge into the otherworlds. The machine and its incredible power were no longer needed.
"You must remember that the three universes occupy the same space, sothat spatially they are not separated at all. Their separation wastemporal, and at right angles to the path from the past into the future.The attracting forces of the atoms had to be directed across this planeof time by the machine. When that took place the materials had to bebrought together so that the three substances blended would cohere. Oncethey were brought into that state the bridge was established. The bridgeis anchored at this end in the matter of our universe and at the othertwo ends in the matter of those universes, just as the bridge above thisbuilding is anchored on this side to the matter of the bank of this sideof the river, and on the other to the matter there."
"And you just have to walk across?" Hute asked.
"That's all there is to it," Carl replied casually.
"And,"
Hute's eyes took on a crafty gleam. "A time machine in one ofthese other universes could carry me to any point in the future withoutdanger it might have encountered in this one, such as an atom bombdropped on the space it would have been in here?"
"That's correct," Carl agreed. "If you will look through the telescopeyou will see my aides already nearing completion on the time machine."
Hute placed his eyes to the telescope. The scene that appeared was quitea normal one. The landscaping was different in many ways. The vegetationwas prolific and of strange forms. But for a considerable area theground was flat, meeting the surface of the ordinary world only at theone spot where the tri-matter block was anchored.
A dozen workmen were busy on the conventional time machine. Hute