In 1851, Antoine Claudet wrote to French magazine "La Lumière" in response to a patent given to the Mayer brothers for their "multiplicateur", which photographed multiple (identical) images onto a single plate (a technique that created the carte de visite format that was very popular in the 1860s). Claudet claimed to have invented something very similar in 1844, with results exhibited at the French Industrial Exposition of 1844, including a self portrait that showed 12 sides of his face. Before the end of 1851, Claudet claimed to have created a stereoscope that showed people in motion. The stereo viewer could show a motion of two phases repetitively. During the next two years, Claudet worked on a camera that would record stereoscopic pairs for four different poses (patented in 1853). Claudet found that the stereoscopic effect didn't work properly in this device, but believed the illusion of motion was successful.