This lightweight, inexpensive chair is known as a Vienna café chair. More precisely, it was chair design number 18 by Thonet, a German furniture maker. It is identifiable by its curved legs and back and embossed seat. Thonet experimented with industrial technologies and processes for decades in the 19th century, and his 18th try at making a cheap, durable chair was a smash success. Chairs like this one became nearly ubiquitous in public buildings. They appear in Capitol images from 1890 well into the 1940s.
