Old-time photography

Back before everyone had a camera it was common to have one’s photograph taken in a studio and printed onto sturdy cardboard. Several copies were printed and people then gave them to friends and family as mementoes. My late grandmother had a considerable collection of such photographs. Some she had been given or had inherited from her parents, but some she had accumulated through her postcard collecting. I don’t know where this particular photograph came from, and she did not know who the subject was, but what struck me was that when you turned the photo over there was, on the back, not blank cardboard or a postcard backing, but a photo of the gentleman taken from the back: