In announcing the daguerreotype process to the public in August 1839, even so eager a promoter as François Arago felt compelled to admit that the process was unlikely ever to serve for portraiture, owing to the length of exposure, which in bright summer sun lasted four-and-a-half to eleven minutes and in subdued winter light an hour or more. The free use of Daguerre's process, however, invited optical and chemical improvements that made portraiture feasible and widespread within a mere two years. Among those who enhanced the sensitivity of daguerreotype plates by new chemical means was Louis-Auguste Bisson, whose label on the verso of this work advertises "Daguerreotype portraits in shade, indoors, and in a few seconds, perfected." Even more than a standard portrait, this daguerreotype is a tour de force of instantaneity, for the panting dog, its tongue hanging out of its mouth, could neither be instructed to sit still nor be physically held in a metal neck brace, a common studio prop for immobilizing human sitters. This unassuming portrait of a pet, humorously presented as if in his doghouse, was made by Bisson for his childhood neighbor and surrogate sister Rosa Bonheur (1822-1899). After the death of her mother, eleven-year-old Rosa had been welcomed into the home of Mme Bisson, the mother of Louis-Auguste and his two brothers, and there she earned her first wages as an artist coloring the heraldic engravings of M. Bisson. By the time she was in her twenties Bonheur was a highly acclaimed painter of animal scenes. No doubt part of the vast menagerie that she kept at her house, this dog is presented by Bisson in a familiar--even familial--way rather than as a photographic study intended to aid the artist's work.