A nice discovery if I say so myself, I have printed the photo inside a magic lantern slide which I have recently bought on eBay. The photo shows in my eyes a unique scene.
It is an early 1900's magic lantern glass slide with a photo of a man standing in front of a pneumatic tube station. The photo must be taken somewhere in Berlin, Germany.
I think it is a unique one, because it shows *three* types of transportation in one shot.
The man on the photo is sending a carrier in a pneumatic tube station manufactured by the Mix & Genest company, which is probably connected to the Berlin pneumatic tube mail system (Stadtrohrpost). I conclude this from the title of the slide "Rohrpost für fernbetrieb", translated: long distance pneumatic tube system.
At the left and right side of photo you see a pneumatic tube station for internal building transportation (Hausrohrpost).