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".
John Jabez Edwin Mayall
In the 1840s, the daguerreotype portrait had virtually supplanted the hand-painted portrait miniature. Some critics complained that the daguerreotype portrait on a metal plate was cold and harsh and lacked the finesse and charm of the small-scale painted portrait. In March 1842, Richard Beard had patented a method of colouring daguerreotype pictures. The following month a newspaper reported that "Mr Beard has now discovered the means of colouring the plates after the photographic drawing is completed, thus giving the warmth and truth of a miniature painting." It is known that Mayall used a similar method of hand-colouring daguerreotype portraits while based in Philadelphia. When two journalists visited Mayall's new premises in London's Regent Street in 1853, they observed the work of the "colouring room" in which "two damsels were busily at work" adding colour to Mayall's daguerreotype portraits.