Moses Billings
With the development of the daguerreotype in the 1840s, the role of the portrait painter declined in general, because it was now much easier and much cheaper to have one's likeness presented in a visual format. While many portrait painters lost business in competition with the daguerreotype, Billings instead began to produce daguerreotype prints himself. It is not known exactly which prints were made by Moses Billings, as daguerreotypes were usually signed, when signed at all, along the side of the plate. Due to the traditional storing methods of daguerreotype plates, even this signature usually quickly became illegible. However, it has been generally noted, or at least hypothesized, that his daguerreotype prints showed a level of talent and artistry above that of amateur daguerreotypists. Though it is not known exactly which prints were his, it is known that he had largely abandoned the process by the 1850s. Even after he stopped making daguerreotypes, he did continue to paint people's portraits on canvas.
Daguerreotype
Daguerre met with Niépce and entered into correspondence with him. Niépce had invented an early internal combustion engine (the Pyréolophore) together with his brother Claude and made improvements to the velocipede, as well as experimenting with lithography and related processes. Their correspondence reveals that Niépce was at first reluctant to divulge any details of his work with photographic images. To guard against letting any secrets out before the invention had been improved, they used a numerical code for security. 15, for example, signified the tanning action of the sun on human skin ("action solaire sur les corps"); 34 – a camera obscura ("chambre noir"); 73 – sulphuric acid.