Daguerreotypes were exquisitely detailed, but the only way to make a copy was to take another daguerreotype of the daguerreotype.

In 1851, Frederick Scott Archer discovered a way to create negative images on glass plates. It was a wet, messy process using flammable materials, but once dried, the image was permanent. The negatives could then be used to make an infinite number of paper prints, which were almost as detailed as daguerreotypes.

At first, though, photographers took those glass plate negatives and placed them in the same kind of cases that had been used for daguerreotypes. A photograph in a case was what people were used to! These cased negatives were called Ambrotypes after their inventor.

Against a black background, the negatives look just like daguerreotypes… or do they? Cased photographs have tricked historians into thinking that a less valuable ambrotype is a rarer daguerreotype.