In the year that photography was introduced to the world, 1839, a cartoon in a French broadside showed a gallows for the draftsmen and engravers who would be put out of work by the new medium. This was only the beginning of a long tradition of amused, and amusing, depictions of photography, a practice now reviewed in Heinz and Bridget Henisch's new book. Positive Pleasures explores the humorous commentary about photography that emerged...