Back in the late 1800s, this device was considered to be “High Tech”. It is a stereoscope viewer that Abraham Lincoln purchased for his sons when they lived in Springfield, Illinois.
The photograph above shows the original stereoscope that now sits in the Lincoln Home. This device was used by the Lincoln children to view photographs, also newer technology at the time, in what they thought was 3D. They would take turns in the evening, looking at various photographs form around the world.
The earliest type of stereoscope was invented by Sir Charles Wheatstone in 1838. It used a pair of mirrors at 45 degree angles to the user's eyes, each reflecting a picture located off to the side. It demonstrated the importance of binocular depth perception by showing that when two pictures simulating left-eye and right-eye views of the same object are presented so that each eye sees only the image designed for it, but apparently in the same location, the brain will fuse the two and accept them as a view of one solid three-dimensional object. Wheatstone's stereoscope was introduced in the year before the first practical photographic process became available, so drawings were used. This type of stereoscope has the advantage that the two pictures can be very large if desired.