But not a sound had broken the stillness since the strangers had arrived, except that of their own voices.  They began to wonder if there were no people to inhabit this magnificent city of the inner world.

Suddenly a man appeared through a hole in the roof next to the one they were on and stepped into plain view.  He was not a very large man, but was well formed and had a beautiful face—­calm and serene as the face of a fine portrait.  His clothing fitted his form snugly and was gorgeously colored in brilliant shades of green, which varied as the sunbeams touched them but was not wholly influenced by the solar rays.

The man had taken a step or two across the glass roof before he noticed the presence of the strangers; but then he stopped abruptly.  There was no expression of either fear or surprise upon his tranquil face, yet he must have been both astonished and afraid; for after his eyes had rested upon the ungainly form of the horse for a moment he walked rapidly to the furthest edge of the roof, his head turned back over his shoulder to gaze at the strange animal.

“Look out!” cried Dorothy, who noticed that the beautiful man did not look where he was going; “be careful, or you’ll fall off!”

But he paid no attention to her warning.  He reached the edge of the tall roof, stepped one foot out into the air, and walked into space as calmly as if he were on firm ground.

The girl, greatly astonished, ran to lean over the edge of the roof, and saw the man walking rapidly through the air toward the ground.  Soon he reached the street and disappeared through a glass doorway into one of the glass buildings.

“How strange!” she exclaimed, drawing a long breath.

“Yes; but it’s lots of fun, if it is strange,” remarked the small voice of the kitten, and Dorothy turned to find her pet walking in the air a foot or so away from the edge of the roof.

“Come back, Eureka!” she called, in distress, “you’ll certainly be killed.”

“I have nine lives,” said the kitten, purring softly as it walked around in a circle and then came back to the roof; “but I can’t lose even one of them by falling in this country, because I really couldn’t manage to fall if I wanted to.”

“Does the air bear up your weight?” asked the girl.

“Of course; can’t you see?” and again the kitten wandered into the air and back to the edge of the roof.

“It’s wonderful!” said Dorothy.

“Suppose we let Eureka go down to the street and get some one to help us,” suggested Zeb, who had been even more amazed than Dorothy at these strange happenings.

“Perhaps we can walk on the air ourselves,” replied the girl.

Zeb drew back with a shiver.

“I wouldn’t dare try,” he said.

“Maybe Jim will go,” continued Dorothy, looking at the horse.

“And maybe he won’t!” answered Jim.  “I’ve tumbled through the air long enough to make me contented on this roof.”