ABSTRACT
During the first three decades of the nineteenth century, in different places, several researchers had been trying to attain an old goal: to make permanent the images of external objects formed inside the camera obscura. Some precursors had focused their research toward that direction. Thomas Wedgwood was probably the first one to undertake experiments with the purpose of “retaining” the outline of objects on photosensitive surfaces in 1799 and 1800. By the mid-1810s, Niépce, a retired military Frenchman who—although he could not be called a scientist, was certainly passionate about the sciences—had already used silver salts (silver chloride), to obtain paper negatives. His goal was to prevent the paper from getting dark after being exposed to light, thus, he performed several essays using nitric acid. The diorama was introduced in Paris around 1822 by Daguerre himself and by Charles Marie Bouton and became a much appreciated spectacle in that city.
