“Good!” cried Trot.  “Now I can climb up.”

“Don’t you want me to go with you?” asked Button-Bright a little wistfully.

“No,” said the girl.  “You must stay to lead the army.  And if you can think of a way, you must try to rescue us.  Perhaps I’ll be able to save Cap’n Bill by myself; but if I don’t, it’s all up to you, Button-Bright.”

“I’ll do my best,” he promised.

“And here, keep my polly till I come back,” added Trot, giving him the bird.  “I can’t take it with me, for it would be a bother, an’ if it tried to spout po’try, I’d be discovered in a jiffy.”

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