Louis Jacques Mande Daguerre (1787 – 1851) was a French painter and an inventor who had earlier devised the well-known Diorama. Both he and Niepce sought to get fixed images by means of the camera obscura. At the end of 1829 the two men formed a partnership to improve the method of heliography. The joint efforts of the two inventors of photography were aimed at the perfection of the camera and at the search of a chemical way of treatment of light-sensitive material. But in 1833 Niepce died and Daguerre had to continue his experiments by himself.
It was only in 1837 that he achieved some results. The process consisted in sensitizing a polished silver plate with iodine vapors. As a result, on the mirror-polished surface there appeared a layer of photo-sensitive silver iodide. This plate was then put into the camera obscura and exposed. After that the latent image on the plate of silver iodide was "developed" and made visible by exposure to mercury vapor. To fix the image permanently Daguerre used a hot solution of table salt, later he started using a solution of hyposulphite, discovered by an English astronomer and physicist John Frederick William Herschel (1792 - 1871). Thus, it was a unique positive image allowing no reproduction of the picture. It was a mirror image and to better see it, it was necessary to hold it at a certain angle. Daguerre called the improved process after himself: daguerreotype (derived from his last name Daguerre and the Greek word typos – print, image).
On January 7,1839 the French Academy of Sciences announced the daguerreotype process. Secretary Dominique François Jean Arago (1786-1853) reported to the scientific meeting about Daguerre´s amazing invention saying that "from now on the sun´s ray became an obedient painter of the surroundings".
In August of the same year, Francois Arago on behalf of the Academy addressed the Chambre des Deputes of the French Parliament where it was decided to make photography the common property of the people, securing Daguerre and Niepce's heirs a lifetime pension for the discovery.
In the USA the first daguerreotypes were made soon after a new method of getting images in a mechanical way had been announced in France. Daguerreotype started spreading at an unbelievable speed. A lot of different people seeing the proper perspective of this technical innovation began to master the skill of photography.