Schwinn Dealer Derailleur Demonstrator

 The derailleur gear system has been around since 1912, invented in France. I can picture the conversation. 
"The worst thing about chain and sprockets is that sometimes, the chain comes off the sprockets, how can we turn that into a feature?...... " 
"Voila! Here's a system where we make the chain come off the sprockets purposely and look, now you have have different speeds!" 
"Bet ya can't do that with both sprockets!"
"Oh yeah? Watch this. Now you have a lot of different gears!"

I think it was the sixties before they were introduced on this side of the Atlantic and potential buyers had to be skeptical of the system. Schwinn made these chrome plated displays for their dealers to demonstrate the concept. 

 Incidentally, both these devices are available for sale, located in Europe, contact me for details.

thanks, Rolf!