Invertibles

From Classic Puzzles for the Classroom:

The invertible, a picture that depicts one thing when held right side up and another when held upside down, was one of the most popular features of the comics puzzle page. From a puzzle standpoint it is an odd beast, being perhaps closer to an optical illusion than a true puzzle for the reader (though arguably not for the creator).

Perhaps the most impressive use of the form was made by turn-of-the-century artist Gustave Verbeek who produced a weekly invertible comic strip. In Verbeek’s world, a fish attacking a canoe in panel 5…

Might become a giant Roc in panel 8.

Here is another sample of Verbeek’s work followed by some of the invertibles you would have seen in Golden Age comics.