RE: Interesting Lucas part for sale on Ebay ...

["Dave and Linda" <daveandlindab@comcast.net>]

The Lucas three position switch, off-on-smoke.

This goes on the smoke theory of electricity.  The smoke travels from the
battery through the wires and powers the accessory sort of like pneumatics.
When you inadvertantly let the smoke out, thre is no longer sufficient
pressure for things to run.

This is an update from the early Industrial Revolution, where coal or wood
was burned to produce the smoke to run things, such as trains and factories.
They were very inefficient, most of the smoke was wasted up the stack.