The Wizard of Oz by Lynam Frank Baum Chapter 2 Page 13

At once the cap changed to a slate, on which was written in big, white chalk marks:

“LET DOROTHY GO TO THE CITY OF EMERALDS”

The little old woman took the slate from her nose, and having read the words on it, asked, “Is your name Dorothy, my dear?”

“Yes,” answered the child, looking up and drying her tears.

“Then you must go to the City of Emeralds. Perhaps Oz will help you.”

“Where is this city?” asked Dorothy.

“It is exactly in the center of the country, and is ruled by Oz, the Great Wizard I told you of.”

“Is he a good man?” inquired the girl anxiously.