They've been a mainstay of sci-fi props for years but you'll be hard-pressed to find someone on the street that can tell you what they actually do. They're Mercury Arc Reactors and our friends at Oobject have collected nine of the best.
A three phase, six anode mercury arc rectifier, formerly used at a 600V DC traction substation of the Athens-Piraeus railway.
Household Mercury Arc Rectifier.
Mercury rectifier on display in Beromunster, Switzerland.
Mercury Vapour Arc Rectifier from University of Aberdeen Collection.
Rectifier at the Cengelhan Koc Museum in Turkey.
Rectifier from Type 80 Early Warning Radar System.
The two mercury arc rectifiers at Kempton Steam Museum, London.
Twin Mercury Arc Rectifiers from the Doncaster Odeon. movie theatre
Working Mercury Arc Rectifier.