Patented in 1894. was essentially a flip-book which could only be viewed by peering through an eyepiece, and cranking a handle to simulation motion. It wasn't long before the technology was adapted to provide naughty peep show-type experiences.
Here are ten such devices, which are kindly provided with an interactive reveal-o-function, so that you too may enjoy some saucy peeking. Brace yourself for some seriously hot vintage action!