In On the Banks of Plum Creek (Chapter 22, “Town Party”), Laura and the other girls “laughed until they cried” at Nellie’s jumping-jack toy.

He was cut out of thin, flat wood; striped paper trousers and jacket were pasted on him, and his face was painted white with red cheeks and circles around his eyes, and his tall cap was pointed. He hung between two thin red strips of wood, and when you squeezed them he danced. His hands held on to twisted strings. He would turn a somersault over the strings; he would stand on his head with his toe on his nose.

Later, in The Long Winter, Grace received a double jumping-jack toy for Christmas (Chapter 18, “Merry Christmas”).

Two little, flat wooden men stood on a platform between two flat red posts. Their hands held onto two strings twisted tightly together above their heads. They wore peaked red caps and blue coats with gold buttons. Their trousers were red-and-green stripes. Their boots were black with turned-up toes. / Ma gently pressed the bottoms of the posts inward. One of the men somersaulted up and the other swung into his place. Then the first came down while the second went up and they nodded their heads and jerked their arms and swung their legs, dancing and somersaulting.

The Plum Creek manuscript only says that they all played with Willie’s jumping-jack… In The Long Winter manuscript, Wilder wrote:

Two funny faced little men with peaked red caps on their heads stood on a platform between two painted posts. Their coats were blue with gold buttons. Their trousers were red and green stripes. Their boots were black with turned up toes. / Ma reached across and pulled a string that hung from the top of the posts. One of the men went up and the other swung around to his place. Then the first came down and the second went up and they nodded their heads and jerked their arms as they danced around and around. “Oh look! Oh look!” Grace shouted while everyone laughed. “A double jumping jack,” Laura said and Ma added, “The first I ever saw.”

The toy described is usually called an acrobat or squeeze toy, not a jumping-jack. Note that in one version Ma “pulled a string that hung from the top of the posts” to animate the toy. There were acrobat toys that operated by pulling on a string that hung at the top of a single post, but usually these were one-stick toys, in contrast to the two-stick toys that required you to push the sticks together in order to make the acrobat(s) move. A traditional jumping-jack featured moving arms and legs, strung so that a single pull of a string hanging from the bottom would cause the arms and legs to raise.

The acrobat toy pictured above is of painted wood and has an 1876 patent date.