“She couldn’t climb down, Jim,” said Dorothy. “To climb means to go up.”Soon afterward the horse tells another character, “You may go down, but you can only climb up.” But Jim does so “with a twinkle in his round eyes.” Evidently he still thinks this rule is silly.
“Who said so?” demanded the horse.
“My school-teacher said so; and she knows a lot, Jim.”
“To ‘climb down’ is sometimes used as a figure of speech,” remarked the Wizard.
“Well, this was a figure of a cat,” said Jim, “and she went down, anyhow, whether she climbed or crept.”
And did Baum himself accept the proscription against “climb down”? A search through his books shows that he definitely didn’t.
The Wonderful Wizard of Oz uses five variations on the phrase “climb down.” Baum’s other fantasy for 1900, The Magical Monarch of Mo, uses three. That was the same year that The Inland Printer, a Chicago trade magazine that Baum knew well, advised against the phrase.
In The Life and Adventures of Santa Claus (1902), the title character “climbs down” chimneys five times. Other Baum novels that contain the phrase include Ozma of Oz (once), Rinkitink in Oz (twice), Sky Island (twice), and The Magic of Oz (three times). Those titles nearly cover the breadth of Baum’s novel-writing career.
In having Dorothy correct Jim’s grammar, Baum was probably just setting up a joke. But that scene also showed Dorothy’s somewhat bossy side (evident in other conversations in other books), and added to illustrator John R. Neill’s gentrification of a plain Kansas farmgirl. Despite her elided words, she was becoming more snooty about language than her creator.