I took a couple pictures of an antique viewing rig on my vacation - unfortunately, there was very little info on this rig (age, heritage, etc.) and my kids weren't that interested in waiting to talk to a museum curator - it seemed worth sharing nonetheless. A little internet searching later suggests that this rig is likely from somewhere in the time period of 1850-1900.

It's very interesting that millions of these stereo pictures were created in the latter half of the 1800's; their popularity waned somewhat with other forms of media but they have never gone away. One of the things I noticed was that as the public was not paying a lot of attention, the military was still using stereo technology for aerial photography and th related strategizing.