This is the Violet ray Machine. It was originally made in the 1920's and this one comes with two probe. A standard mushroom probe, and a probe to comb through your hair.
I have no idea if this works, right now it definitely doesn't because the wires going in and out of the box are badly frayed. However one that has been corrected, and I'm brave enough to connect it to the mains current; it still may not work. Insulation may have broken down, internal cables may have corroded, capacitors which are made with waxed paper may have shorted. Or of course, the probes may have leaked.
The thing is basically a high voltage generator - like a car ignition - with a spark gap to excite it. In this case the spark gap works (I assume) at mains frequency. The probes are probably just partial vacuums - but there may be some gas like argon or neon in there to glow.
Overall I would expect the effect to be similar to a plasma ball, and despite the huge medical and spirital claims made for these things over the years, just as about useless.
But pretty.