1832, but did not really publicize his invention until June 1838. He recognized the possibility of a combination with photography soon after Daguerre and Talbot announced their inventions and got Henry Fox Talbot to produce some calotype pairs for the stereoscope. He received the first results in October 1840, but was not fully satisfied as the angle between the shots was very big. Between 1841 and 1842 Henry Collen made calotypes of statues, buildings and portraits, including a portrait of Charles Babbage shot in August 1841. Wheatstone also obtained daguerreotype stereograms from Mr. Beard in 1841 and from Hippolyte Fizeau and Antoine Claudet in 1842. None of these have yet been located. David Brewster developed a stereoscope with lenses and a binocular camera in 1844. He presented two stereoscopic self portraits made by John Adamson in March 1849. A stereoscopic portrait of Adamson in the University of St Andrews Library Photographic Archive, dated "circa 1845', may be one of these sets. A stereoscopic daguerreotype portrait of Michael Faraday in Kingston College's Wheatstone collection and on loan to Bradford National Media Museum, dated "circa 1848", may be older. Color process A practical means of color photography was sought from the very beginning. Results were demonstrated by Edmond Becquerel as early as the year of 1848, but exposures lasting for hours or days were required and the captured colors were so light-sensitive they would only bear very brief inspection in dim light. The first durable color photograph was a set of three black-and-white photographs taken through red, green, and blue color filters and shown superimposed by using three projectors with similar filters. It was taken by Thomas Sutton in 1861 for use in a lecture by the Scottish physicist James Clerk Maxwell, who had proposed the method in 1855. The photographic emulsions then in use were insensitive to most of the spectrum, so the result was very imperfect and the demonstration was soon forgotten. Maxwell's method is now most widely known through the early 20th century work of Sergei Prokudin-Gorskii. It was made practical by Hermann Wilhelm Vogel's 1873 discovery of a way to make emulsions sensitive to the rest of the spectrum, gradually introduced into commercial use beginning in the mid-1880s. Two French inventors, Louis Ducos du Hauron and Charles Cros, working unknown to each other during the 1860s, famously unveiled their nearly identical ideas on the same day in 1869.