Photographs had previously served as calling cards, but Disdéri's invention of the paper "carte de visite" (i.e. "visiting card") photograph second enabled the mass production of photographs. On 27 November 1854 he patented the system of printing ten photographs on a single sheet (although there is no evidence that a system printing more than eight actually materialized). This was the first patent ever for a "carte de visite." Disdéri's's "cartes de visite" were 6×9 cm, about the size of conventional (nonphotographic) visiting cards of the time, and were made by a camera with four lenses and a sliding plate holder; a design inspired by the stereoscopic cameras.