Per the conservator, Peter Mustardo, who resealed the daguerreotype in 1990, the plate has hallmark #20a in Floyd and Marion Rinhart, The American Daguerreotype (Athens, GA: The University of Georgia Press, 1981), p. 424.
See plate 163 for reproduction of case design, "Maiden with Cornucopia" dated ca. 1851 in Floyd and Marion Rinhart, American Miniature Case Art (South Brunswick and New York: A. S. Barnes and Company, 1969), p. 141.
Text on image per Stanley B. Burns in Sleeping Beauty: "In this dramatic photograph there is no attempt to portray the child as sleeping. This is a dead child. In the nineteenth century, aside from the usual childhood diseases of diptheria, scarlet fever, and measles, water loss by diarrheas killed tens of thousands of children. Epidemics of cholera, typhoid fever, and dysentery were caused by infected milk and water. Even the "ordinary" summer diarrheas were often fatal, because fluid replacement was unknown. One of the prevailing medical thoughts of the time was to treat the patient by producing in them symptoms similar to the disease symptoms from which they were suffering. This often killed them."