Stereograph

I have often seen "twin-pictures" like this in Antique shops or second hand shops. 

Some time ago my daughter bought this at a market.

And now I, too, have found one. It's a simple device for viewing photos

The picture is placed in front of the device, like you can see below. 

The device is a kind of "binocular". You put it close to your eyes ( there's also room for your nose....)

Then you adjust it so that the two pictures becomes one picture in 3D. Neat, or what?!
 

This must be some of the very first devices for pictures in 3D. But when was this? Anyone who knows?

Regards Jorun (Brudeblogg)