I got lucky and found this link:
http://www.panoramicphoto.com/ which explains:
The panoramic camera is a unique invention in that it has the capability of "panning" both camera and film resulting in an image that can display up to a full 360 degree view.
The most popular camera, at that time, was the Circuit camera, a large, box-like machine that was mounted on a sturdy tripod and featured a clock-like mechanism that would transport the film in one direction while the camera panned in the opposite direction - exposing the film (quite slowly) as it traveled past the lens.
I noticed that some of the pictures from that site had the same two vertical lines - I first thought that bathing photo had been folded.