A stereograph is made of two pictures mounted next to each other, viewed with a set of lenses known as a stereoscope. Taken around 7 cm apart (this roughly corresponds to the spacing of the eyes), the left picture represents what the left eye would see, and likewise for the right. Typically, stereographs were viewed on a hand-held stereoscope, a device that was developed by Oliver Wendell Holmes in 1861. When observing the pictures through a stereoscope, the pair of photographs converge into a single three-dimensional image.
Widely popular from the mid-nineteenth century to the early decades of the twentieth century, stereoscopy was first described in 1832 by English physicist Sir Charles Wheatstone. In 1849, Sir David Brewster further developed the process. Stereoscopes gained international recognition at the Crystal Palace Exhibition of 1851.
By the Exposition of Turin 1911 this precurson to the moving image had lost some of its novelty, as film was making itd debut in Turin, but stereographs continued to be popular items and collections of views were sold in a range of prices. A colllection of stereographic views of the 1911 pavilions was created by the firm of Ubertalli & Morsolin.