Professor of Art History at Victoria University, Wellington, NZ and author of 'Photography Degree Zero' Geoffrey Batchen writes about the secret history of secret cameras.
Card (detail): Horace Engle, Untitled (Interior of a street car) 1888. Gelatin silver print, printed 1972, diameter 21.7 cms. Gift of Edward Leos. © 2011 Edward Leos. Courtesy of Museum of Modern Art, New York.