"There was the small catapult," said Von Holtz bitterly, "but it was dismantled. The Herr Professor saw me examining it, and he dismantled it. So that I did not learn how to calculate the way of changing the position--"

Tommy's eyes rested queerly on Von Holtz for a moment.

"You know how to make the metal required," he said suddenly. "You'd better get busy making it. Plenty of it. We'll need it."

Von Holtz stared at him, his weak eyes almost frightened.

"You _know_? You know how to combine the right angles?"

"I think so," said Tommy. "I've got to find out if I'm right. Will you make the metal?"

Von Holtz bit at his too-red lips.

"But Herr Reames!" he said stridently, "I wish to know the equation!

Tell me the method of pointing a body in a fourth or a fifth direction. It is only fair--"

"Denham didn't tell you," said Tommy.

Von Holtz's arms jerked wildly.

"But I will not make the metal! I insist upon being told the equation!

I insist upon it! I will not make the metal if you do not tell me!"

Smithers was in the laboratory, of course. He had been surveying the big solenoid-catapult and scratching his chin reflectively. Now he turned.

But Tommy took Von Holtz by the shoulders. And Tommy's hands were the firm and sinewy hands of a sportsman, if his brain did happen to be the brain of a scientist. Von Holtz writhed in his grip.

"There is only one substance which could be the metal I need, Von Holtz,"

he said gently. "Only one substance is nearly three-dimensional.

Metallic ammonium! It's known to exist, because it makes a mercury amalgam, but n.o.body has been able to isolate it because n.o.body has been able to give it a fourth dimension--duration in time. Denham did it. You can do it. And I need it, and you'd better set to work at the job. You'll be very sorry if you don't, Von Holtz!"

Smithers said with a vast calmness.

"I got me a hunch. So if y'want his neck broke...."

Tommy released Von Holtz and the lean young man gasped and sputtered and gesticulated wildly in a frenzy of rage.

"He'll make it," said Tommy coldly. "Because he doesn't dare not to!"

Von Holtz went out of the laboratory, his weak-looking eyes staring and wild, and his mouth working.

"He'll be back," said Tommy briefly. "You've got to make a small model of that big catapult, Smithers. Can you do it?"

"Sure," said Smithers. "The ring'll be copper tubing, with pin-bearings. Wind a coil on the lathe. It'll be kinda rough, but it'll do. But gears, now...."

"I'll attend to them. You know how to work that metallic ammonium?"

"If that's what it was," agreed Smithers. "I worked it for the Professor."

Tommy leaned close and whispered:

"You never made any gears of that. But did you make some springs?"

"Uh-huh!"

Tommy grinned joyously.

"Then we're set and I'm right! Von Holtz wants a mathematical formula, and no one on earth could write one, but we don't need it!"

Smithers rummaged around the laboratory with a casual air, acquired this and that and the other thing, and set to work with an astounding absence of waste motions. From time to time he inspected the great catapult thoughtfully, verified some impression, and went about the construction of another part.

And when Von Holtz did not return, Tommy hunted for him. He suddenly remembered hearing his car motor start. He found his car missing. He swore, then, and grimly began to hunt for a telephone in the house.

But before he had raised central he heard the deep-toned purring of the motor again. His car was coming swiftly back to the house. And he saw, through a window, that Von Holtz was driving it.

The lean young man got out of it, his face white with pa.s.sion. He started for the laboratory. Tommy intercepted him.

"I--went to get materials for making the metal," said Von Holtz hoa.r.s.ely, repressing his rage with a great effort. "I shall begin at once, Herr Reames."

Tommy said nothing whatever. Von Holtz was lying. Of course. He carried nothing in the way of materials. But he had gone away from the house, and Tommy knew as definitely as if Von Holtz had told him, that Von Holtz had gone off to communicate in safety with someone who signed his correspondence with a J.

Von Holtz went into the laboratory. The four-cylinder motor began to throb at once. The whine of the dynamo arose almost immediately after.

Von Holtz came out of the laboratory and dived into a shed that adjoined the brick building. He remained in there.

Tommy looked at the trip register on his speedometer. Like most people with methodical minds, he had noted the reading on arriving at a new destination. Now he knew how far Von Holtz had gone. He had been to the village and back.

"Meaning," said Tommy grimly to himself, "that the J who wants plans and calculations is either in the village or at the end of a long-distance wire. And Von Holtz said he was on the way. He'll probably turn up and try to bribe me."

He went back into the laboratory and put his eye to the eyepiece of the dimensoscope. Smithers had his blow-torch going and was busily acc.u.mulating an apparently unrelated series of discordant bits of queerly-shaped metal. Tommy looked through at the strange mad world he could see through the eyepiece.

The tree-fern forest was still. The encampment of the Ragged Men was nearly quiet. Sunset seemed to be approaching in this other world, though it was still bright outside the laboratory. The hours of day and night were obviously not the same in the two worlds, so close together that a man could be flung from one to the other by a mechanical contrivance.

The sun seemed larger, too, than the orb which lights our normal earth. When Tommy swung the vision instrument about to search for it, he found a great red ball quite four times the diameter of our own sun, neatly bisected by the horizon. Tommy watched, waiting for it to sink. But it did not sink straight downward as the sun seems to do in all temperate lat.i.tudes. It descended, yes, but it moved along the horizon as it sank. Instead of a direct and forthright dip downward, the sun seemed to progress along the horizon, dipping more deeply as it swam. And Tommy watched it blankly.

"It's not our sun.... But it's not our world. Yet it revolves, and there are men on it. And a sun that size would bake the earth.... And it's sinking at an angle that would only come at a lat.i.tude of--"

That was the clue. He understood at once. The instrument through which he regarded the strange world looked out upon the polar regions of that world. Here, where the sun descended slantwise, were the high lat.i.tudes, the coldest s.p.a.ces upon all the whole planet. And if here there were the gigantic growths of a carboniferous era, the tropic regions of this planet must be literal infernos.

And then he saw in its gradual descent the monster sun was going along behind the golden city, and the outlines of its buildings, the magnificence of its spires, were limned clearly for him against the dully glowing disk.

Nowhere upon earth had such a city ever been dreamed of. No man had ever envisioned such a place, where far-flung arches interconnected soaring, towering columns, where curves of perfect grace were united in forms of utterly perfect proportion....