Mirror View, Yosemite Valley, Mariposa County, Cal.

<p>Stereographs were made by taking two photographs of the same scene with lenses about two and a half inches apart to match the distance between human eyes. Viewed through a stereoscope, the two images combine to give the illusion of depth. Enormously popular as items for both entertainment and education, millions of stereographs were produced from 1850 to 1930, documenting disasters, expeditions, monuments, and exotic locations. Carleton Watkins first photographed Yosemite in 1861, and his views of the valley portrayed this newly seen American West as pristine and majestic. In addition to his “mammoth-plate” camera that produced 18 x 22–inch negatives, Watkins had made approximately 1,400 stereo negatives by the end of 1866, which were packaged in series and sold singly or by the dozen to tourists and casual customers. In this image, Watkins’s common use of mirroring as a pictorial device is enhanced by the startling three-dimensional effect of the stereo view.</p>