In the time that vacuum would have been made-there were 32V DC appliances-My Moms Mother had a sewing machine that ran from 32V.And the summer cottage she used-and later I went there-it was wired for 32V.The place was on an island-in Lake Winnepesaukie,NH.When I was a child-we visted the place each summer-the 32V system no longer worked-but I explored the building the 32V generating equipment was in-the "Hit Miss" gas engine and generator were still there.the battery banks long gone.Wiring torn down.A collector would have loved the engine and generator.Can't remember their brands-corroded nameplates.32V lightbulbs act like flashbulbs when connected to 120V-the cottage was rewired during a summer we were there-We were all wiring outlets and running cable-so nice to have REAL lights and no more candles and gas,kerosene lamps.The gas and kerosene lamps did give off a strange but pleasent light.So-I guess its possible that vacuum shown could have run from 32V-also was a common farm voltage in days before rural electrification.A 32V "WinCharger" unit charged a battery bank in the home or barn.that powered the lights and appliances.So--windmills for generating power are not new.Original WinCharger units are VERY valueable!Many have been found and restored-put back to service.Their battery banks can power an invertor-for 120V.

Nice story, thanks. Those old gas motors were called 'poppers' in the Midwest. They fired only enough to keep the momentum going-barely. I used to take my kids to old-time farm shows and these engines were featured a lot....still running and wired to make lights works and other early appliances. We always got a kick out of listening to them 'pop'....usually there were at least a dozen of them working at once with various displays. I'm sure they were a 'wonder' back then, but no thanks for any part of it now-great historical significance though. You don't even need the concept now; solar panels up on a roof supply power to an inverter and the inverter with its own batteries supplies 120v or 220v...simplicity itself without any noise or pollution.

Kevin