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".
Hand-colouring of photographs
Parallel efforts to produce coloured photographic images affected the popularity of hand-colouring. In 1842 Daniel Davis Jr. patented a method for colouring daguerreotypes through electroplating, and his work was refined by Warren Thompson the following year. The results of the work of Davis and Thompson were only partially successful in creating colour photographs and the electroplating method was soon abandoned. In 1850 Levi L. Hill announced his invention of a process of daguerreotyping in natural colours in his "Treatise on Daguerreotype". Sales of conventional uncoloured and hand-coloured daguerreotypes fell in anticipation of this new technology. Hill delayed publication of the details of his process for several years, however, and his claims soon came to be considered fraudulent. When he finally did publish his treatise in 1856, the process – whether bona fide or not – was certainly impractical and dangerous.