"My God! what have I done?" gasped the American in alarm.

"Settled our fate, I have no doubt," muttered the Alphian from the darkness.

Johnston had recoiled from the whirling wheel, and now cautiously groped back to it, and attempted to turn it. It would not move.

"It has caught some way," he groaned under his breath.

"And we have no light to find the cause of the trouble," added the Alphian, who had knelt down and was feeling about the wheel.

Presently he rose.

"I give it up," he sighed, "I cannot understand it. The machinery is somewhere inside.""It has grown colder," shuddered Johnston.

"We were warmed by the light, of course," remarked Branasko, "and now we feel the dampness more. We are going at a frightful speed."Just then there was a jar, and the sun swung so violently from side to side that the two men were prostrated on the floor. The speed seemed to slacken.

"I wonder if we are going to stop," groaned the American, and he sat up and held to Branasko. "Perhaps they will draw us back to rectify the mistake, and then----""It cannot be done," interrupted the Alphian. "The machinery runs only one way. We shall simply have to finish our journey in darkness.""They may catch us on the other side before the sun starts back through the tunnel," suggested the American.

"Not unlikely," returned Branasko. "There, we are going ahead again. One thing in our favor is that we can more easily escape capture in darkness than if the sun were shining.""Does the sun stop before entering the tunnel?""I do not know," replied Branasko; "perhaps somebody will be there to see what is wrong with the light. We must have our wits about us when we land."Johnston was looking over the edge of the platform. "If the king's display is taking place down there I can see no sign of it.""How stupid of us!" ejaculated Branasko. "Of course, clouds sufficiently dense to hide the sun from Alpha would also prevent us from seeing the display below. I ought to----"He was interrupted by a grand outburst of harmony. The whole earth seemed to vibrate with sublime melody. "Our blunder has not been discovered yet," finished Branasko, after a pause, "else the fete down below would have been over. I am cold; shall we go inside?"Johnston's answer was taken out of his mouth by a loud rattling beneath the floor, near the wheel he had just turned; the sun shook spasmodically for an instant, and its entire surface was faintly illuminated, but the light failed signally.

"It must have been an extra current of electricity sent to relight the lamps," remarked Johnston; and, as he concluded, the sun trembled again, and another flash and failure occurred. "Look,"cried the American, "the clouds are thinning; see the lights below! They have discovered the accident!"They both leaned over the railing and looked below. As far as the eye could reach, within the arc of their vision, they could see fitful lights flashing up, here and there, and going out again.

And then they heard faint sounds of crashing masonry and the condensed roar of human voices, which seemed to come from above rather than from below. The Alphian turned. "I cannot stand the cold," he said.

Johnston followed him. The rapid motion of the swinging sphere made him dizzy, and he caught Branasko's arm to keep from falling.

"How can we tell when we go over the wall?" he asked anxiously.

"We shall have to guess at it," was the answer. "At any rate we must be near the lower door so as to get out quickly if it is necessary to do so to escape detection."In the darkness they slowly made their way down the stairs to the great room.

"There ought to be some way of making a light," said the Alphian, and his voice sounded loud and hollow in the empty chamber. After several failures to find the stairs they descended to the door they had entered. Branasko opened it a little, and a breeze came in. They sat down on the stone, and after a while, in sheer fatigue, they fell asleep. Hours passed. Branasko rose with a start, and shook Johnston.

"Our speed is lessening," he exclaimed. "We must be going down. Be ready to jump out the instant we stop. There, let me open the door wider."