Daguerreotype
It is said that Daguerre has found the means to collect, on a plate prepared by him, the image produced by the camera obscura, in such a way that a portrait, a landscape, or any view, projected upon this plate by the ordinary camera obscura, leaves an imprint in light and shade there, and thus presents the most perfect of all drawings ... a preparation put over this image preserves it for an indefinite time ... the physical sciences have perhaps never presented a marvel comparable to this one.
A further clue to fixing the date of invention of the process is that when the Paris correspondent of the London periodical "The Athenaeum" reported the public announcement of the daguerreotype in 1839, he mentioned that the daguerreotypes now being produced were of considerably better quality than the ones he had seen "four years earlier".
Robert Cornelius
With his own knowledge of chemistry and metallurgy, as well as the help of chemist Paul Beck Goddard, Cornelius attempted to perfect the daguerreotype. Around October 1839, at age thirty, Cornelius took a self-portrait outside of the family store. The daguerreotype produced is an off-center portrait of a man with crossed arms and tousled hair. While Daguerre's photograph of the Boulevard du Temple, taken one year earlier, has since been discovered to incidentally include two human figures on the sidewalk (they just happened to stay motionless long enough to imprint on the exposure), Cornelius' image – which required him to sit motionless for 10 to 15 minutes – is the oldest known intentional photographic portrait/self-portrait of a human.