The German film pioneer, Max Skladanowsky, first exhibited his serial photographic images in flip book form in 1894, as he and his brother Emil did not develop their own film projector until the following year. In 1894, Herman Casler invented a mechanized form of flip book called the Mutoscope, which mounted the pages on a central rotating cylinder rather than binding them in a book. The mutoscope remained a popular attraction through the mid-twentieth century, appearing as coin-operated machines in penny arcades and amusement parks.