Louis Daguerre
Daguerre was perhaps the most famous of several people who invented photography. The partnership was a short one, Niépce dying in 1833, but Daguerre continued to experiment. He made an important discovery by accident. In 1835, so the story goes, he put an exposed plate in his chemical cupboard, and some days later found, to his surprise, that the latent image had developed. Daguerre eventually concluded that this was due to the presence of mercury vapour from a broken thermometer. This important discovery that a latent image could be developed made it possible to reduce the exposure time from some eight hours to thirty minutes.