Alexander S. Spiegel patented an advertising device in 1906 that used a transparent material with black, opaque vertical stripes and a sliding black and white image made up of thin black stripes that were alternately revealed and obscured by the striped overlay. As the lower image was slowly slid beneath the transparent grid, the image would appear to move. These soon appeared in postcards like this one of a cowboy on a horse. The effect could be finicky if the sliding part was not aligned perfectly. However, this method of creating moving images is still used to make novelty products today.Date: Country (if not USA): State: City: Provenance: Ken Prag Collection