For those of you not familiar with daguerreotypes, here is a brief explanation.
Daguerreotypes are our first real form of photography.
Dags were first made in 1839 in France by M. Daguerre. They became immediately popular and by the mid 1840's, were in wide-spread use throughout the world. In the United States their popularity peeked between 1840 and 1860, with almost all antique examples coming from that period. The process of making daguerreotypes was complicated and dangerous and involved the use of hazardous chemicals including mercury. Each dag is actually the plate that was in the photographer's camera when the picture was taken.