Mats give us some wonderful clues as to a daguerreotype's (and ambrotype's) original date.
The Daguerreotype in America Once the daguerreotype process was published in Paris in 1839, it spread rapidly to America.
At its worst, it amounts to an invasion of the celebritys privacy; after all, famous people are still human beings entitled to pursue romantic relationships in their personal lives. Very often, such characters will be a musicians girlfriend whose antics or presence cause the band to break up; shes often a direct send-up of Trope Namer Yoko Ono.
A common twist is for her to be perfectly nice and sweet, but for the rest of the band to be so paranoid about this happening (or at least jealous of the attention shes getting from their bandmate) that the band breaks up anyway.
Most clues are evident by just looking at the image. This is not recommended for the amateur or skittish.
The image, case, or brass holder can be damaged easily.
At the height of daguerreotype popularity in 1853, there were reportedly 86 studios in New York City.