little power. For a hundred years now we have been losing ground. Our fuel is rapidly becoming exhausted. Soon the Doom will sweep onward unchecked, and man will go for ever.
"I have told you this because it is in your power to save mankind," Nak went on, his voice tense. "For you can move in time, and that"
A warning throbbing went through the great room. A hidden bell was clanging out a muffled warning. Abruptly Nak swung about, raced to a machine. His slender fingers flickered swiftly over a switchboard.
"Look!" he commanded.
On the oval another picture grew–a great tower, monolithic and huge, set on a plain of empty snow. In the distance a black wall marched. The Doom, sweeping inexorably onward to claim earth for its own.
"The tower–it is the one in which we stand," Nak said.
From the tower's summit a pale finger of light reached out. It swept down, bathing the black ramp. Little flaming sparks flashed and glittered. And suddenly the jet wall was gone.
It had vanished, disappeared into thin air. In its place was a deep gorge, from which boiling vapors seethed up.
"It is annihilated," Nak said quietly. "But it will come again, as it has always come. And eventually the power of the ray will be gone. Then"
He did not finish. He touched the switchboard, and the picture faded. Again he faced Blake.
"Don't you understand? I have told you this–shown you the Doom–because you can help us."
"Help you?" Blake said hoarsely. "God–if I could! But we had no science compared to yours"
"You can move in time. If we had known the secret of the annihilating ray when the Doom first came to earth–when the meteor first struck in Australia–we could have destroyed the seed before the infection had a chance to spread."
"And I can take you back in time," Blake interrupted. "That's what you mean, isn't it? I can take you back to the day when the meteor struck, and you can destroy it with your ray! But can I transport the ray"
Nak brought out a gleaming metal cylinder from his mesh garment. "This projector has sufficient power. The meteor was a small one. You will do it, then?"
"Of course! Get what you need, and we can go–now."
The dwarf smiled. "I need nothing but this projector," he said as he came to the platform. Awkwardly he clambered through the railing.
Blake, his finger on the bakelite lever, hesitated. Nak glanced at him inquiringly. "Is something wrong?"
Blake had remembered the plunge into the other dimension, where physical laws were so strangely altered or suspended. He was not sure, now, that he could find his way back to his own time. He explained the problem to Nak.
The dwarf chuckled. "Can you open this platform–show me the machinery?" he asked.
Blake nodded. He lifted a panel in the metal flooring, and Nak peered down. After a moment he nodded, thrust an arm through the gap, and made a hasty adjustment.
"That will do it," he said. "Simply
