A rare collection of 45 cartes-de-visite with 20+ different photography studios imprinted on backs. The cartes-de-visite was a type of small photograph which was patented in Paris, France by photographer André Adolphe-Eugène Disdéri in 1854. 

The new invention was so popular it was known as "cardomania" and it spread throughout Europe and then quickly to America and the rest of the world.  Each photograph was the size of a visiting card, and such photograph cards were traded among friends and visitors. Albums for the collection and display of cards became a common fixture in Victorian parlors. The immense popularity of these card photographs led to the publication and collection of photographs of prominent persons. (From Wikopedia)