As the beautiful Witch kissed the little girl goodbye, she slipped upon
her finger a curious ring. At once, Button-Bright exclaimed, "Why,
where has she gone?"

"I'm right here," said Trot's voice by his side. "Can't you see me?"

"No," replied the boy, mystified.

Rosalie laughed. "It's a magic ring I've loaned you, my dear," said
she, "and as long as you wear it, you will be invisible to all eyes,
those of Blueskins and Pinkies alike. I'm going to let you wear this
wonderful ring, for it will save you from being discovered by your
enemies. If at any time you wish to be seen, take the ring from your
finger; but as long as you wear it, no one can see you, not even Earth
people."

"Oh, thank you!" cried Trot. "That will be fine."

"I see you have another ring on your hand," said Rosalie, "and I
perceive it is enchanted in some way. Where did you get it?"

"The Queen of the Mermaids gave it to me," answered Trot. "But Sky
Island is so far away from the sea that the ring won't do me any good
while I'm here. It's only to call the mermaids to me if I need them,
and they can't swim in the sky, you see."

Rosalie smiled and kissed her again. "Be brave, my dear," she said,
"and I am sure you will be able to find Cap'n Bill without getting in
danger yourself. But be careful not to let any Blueskin touch you, for
while you are in contact with any person you will become visible. Keep
out of their way, and you will be perfectly safe. Don't lose the ring,
for you must give it back to me when you return. It is one of my
witchcraft treasures, and I need it in my business."

The Trot climbed the ladder, although neither Button-Bright nor Rosalie
could see her do so, and when she was on top the broad wall she pulled
up the knotted ropes and began to search for a place to let it down on
the other side. A little way off she found a bluestone seat near to the
inner edge, and attaching the ladder to this, she easily descended it
and found herself in the Blue City. A guard was pacing up and down near
her, but as he could not see the girl, he of course paid no attention
to her. So after marking the place where the ladder hung that she might
know how to reach it again, Trot hurried away through the streets of
the city.

TROT'S INVISIBLE ADVENTURE

CHAPTER 22

All the Blueskins except a few soldiers had gone to bed and were sound
asleep. A blue gloom hung over the city, which was scarcely relieved by
a few bluish, wavering