Albumen prints were the new photographic technology in the middle of the 19th century. This period was squarely within the European Industrial Revolution and about 25 years after the discovery of light sensitive materials by Niepce and Daguerre. Large scale use of albumenized paper began in 1850 and extended through 1890, although craftspersons (and hobbyist) still make excellent albumen prints today. In the Industrial Revolution, technologies and materials were being actively explored and developed at a blistering pace. This is analogous to our current digital revolution, allowing for today's massive increase in communications abilities.

Read the history, see the photos and video clips or make a search. And here is one of my favourites photographers. (via PLEP)

PS.: I choose that Atget photo because it looks like an Expressionist image.