Daguerreotype
Morse met the inventor of the daguerreotype, Louis-Jacques-Mande Daguerre, in Paris in January 1839 when Daguerre's invention was announced [2]. While the daguerreotype fascinated Morse, he was concerned about how the new invention would compete with his telegraph. However, Morse's viewing of the daguerreotype alleviated his fears when he saw how revolutionary its technology was. Morse wrote a letter to his brother Sidney describing Daguerre's invention, which Sidney then published in the New-York Observer on April 20, 1839. While this was not the first report of the daguerreotype to appear in America, it was the first in-person report to appear in the United States.
Photography in Denmark
A number of other techniques developed in parallel with the use of daguerreotypes. The ambrotype, using collodium to produce a positive image on glass, and the pannotype, also collodium-based, were both used in Denmark from around 1855. Negative-based paper prints, used from the beginning of the 1850s, were produced on salt paper until around 1857 when salt was replaced by albumen. Collodion emulsion chloride paper was used from 1865 and in 1880 gelatin emulsion paper was introduced.