Photography in the United States
In spring 1839, the daguerreotype was introduced into the United States by an Englishman named D.W. Seager, who took the first photograph of a view of St. Paul’s Church and a corner of the Astor House in Lower Manhattan in New York City. Painter and inventor Samuel Finley Breese Morse had met Louis Daguerre in Paris in the spring of 1839, becoming the first American to see his photographic process and becoming enamored with it as a result. When he returned to the United States later that year, he enthusiastically promoted the daguerreotype while hailing Seager's prototypical image. Morse had painted "The Gallery of the Louvre" in 1833, and the appeal of the medium of the daguerreotype was an obvious one to him: it was a means of making faithful copies of artworks, in addition to anything else that would be still in front of the slow eye of the camera.
Louis Désiré Blanquart-Evrard
He was born and raised in Lille where he studied chemistry with Charles Frédéric Kuhlmann and miniature painting on porcelain. After Louis Daguerre solved the problem of long exposure time and introduced daguerreotypy, a practical photographic process, to the general public in 1839, Blanquart-Evrard developed interest in photography. He studied the "calotype", salt-print negative process, and in 1847 became the first person to publish on negative/positive paper photo process in France. He developed a method of bathing the paper in solutions of potassium iodide and silver nitrate rather than brushing these chemical baths on the surface. In January 1847, he presented his research on stabilizing the photo prints by floating them in the silver solution to the French Academy of Sciences.