oof, 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.

"May be Jim will go," continued Dorothy, looking at the horse.

"And may be he won't!" answered Jim. "I've tumbled through the air long
enough to make me contented on this roof."

"But we didn't tumble to the roof," said the girl; "by the time we
reached here we were floating very slowly, and I'm almost sure we could
float down to the street without getting hurt. Eureka walks on the air
all right."

"Eureka weighs only about half a pound," replied the horse, in a
scornful tone, "while I weigh about half a ton."

"You don't weigh as much as you ought to, Jim," remarked the girl,
shaking her head as she looked at the animal. "You're dreadfully
skinny."

"Oh, well; I'm old," said the horse, hanging his head despondently, "and
I've had lots of trouble in my day, little