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.
Daguerreotype
In the Becquerel variation of the process, published in 1840 but very seldom used in the 19th century, the plate, sensitized by fuming with iodine alone, was developed by overall exposure to sunlight passing through yellow or red glass. The silver iodide in its unexposed condition was insensitive to the red end of the visible spectrum of light and was unaffected, but the latent image created in the camera by the blue, violet and ultraviolet rays color-sensitized each point on the plate proportionally, so that this color-filtered "sunbath" intensified it to full visibility, as if the plate had been exposed in the camera for hours or days to produce a visible image without development.