Can someone explain what this double chain mechanism does?

[decotriumph]

I photographed this at the Bicycle Museum of America in Ohio and can't remember what the purpose is. Thanks

 

[bikejunk]

looks like it would give you a mechanical advantage like a block and tackle Id love to see more photos could also be a 2 speed but hard to tell from this angle

 

[Major Taylor Archive]

Retro direct drive. Forward = low gear, backward = high gear.

Here's how to build one - https://snapguide.com/guides/build-a-retro-direct-bicycle/

 

[decotriumph]

Retro direct drive. Forward = low gear, backward = high gear.

Here's how to build one - https://snapguide.com/guides/build-a-retro-direct-bicycle/

Thanks!