Louis Jacques Mandé Daguerre first introduced the daguerreotype in 1839 in 1839, and it was the first publicly announced photographic process. Daguerreotypes are produced by treating a silver-coated copper plate with light-sensitive chemicals, exposing it in a camera, and developing it with a mercury vapor. Harvard University has collected these unique documents for over 150 years, and this digital collection provides interested parties with access to some of these items. Visitors can look at class photos of Harvard students, along with portraits of Henry James, Jenny Lind, and James McNeill Whistler. These portraits can be found in the "Portrait Sitters" area, along with those of Martin Van Buren and Horatio Alger. The site also contains links to a complete directory of photographs at Harvard and a detailed research guide.