New Zealand's own self-described mad professor, Boris van Galvin, has a working collection of more than 30 electric-shock machines. Once used as a kind of cure-all for common household ailments, their manuals list instructions for fixing everything from muscle aches to constipation, cataracts, hysteria and parasites.
"One of the units has a manual that says it cures death apparent," Boris says, unpacking a car boot-full of leather and wooden cases. "So you're laying on the ground apparently dead and someone shocks you back to life. Not sure if that was an early version of a defibrillator or someone who slipped into a coma."
He came across his first electrotherapy device by chance, when he was gifted what a friend thought was a crystal radio. "I looked it up and it turned out it was an original home electrotherapy unit, dating back to 1902. So rather than pull it apart and repurpose it, I decided to rebuild it. Rebuilt it, got it working. That was kind of my first."
Boris began collecting them, and started doing shows almost accidentally, after taking a kit to a costume party. "I decided to go as the Mad Professor. I went along with one of the electrotherapy units, and everyone kind of went, 'ooh can I have a go? So I started shocking people."
With the oldest dating back to the early 1800s, most of these devices are still in working order, and he's always happy to demonstrate. Take a probe in your hand, and it prickles. Turn up the voltage up a little and you can see the pulse of electricity moving under your skin on a metronome beat, watch your muscles contract and release. It's not painful, exactly, but it's not comfortable.
Lined up on a table, some devices also provide their own pocket history of repression. If you belonged to a historically marginal group—LGBTQ, mentally ill, or female—there's a strong chance that at some point, someone suggested using electricity to rewire your brain.
In one case, there's a large black device was once used for gay conversion therapy. The voltage of this one, he says, is much higher than on the traditional home medical kits.
"It's sort of awful to think it was used on someone," he says.
Many of the units were once used for varying forms of 'mental ailment'.
"Things like schizophrenia, behavioural issues, things we might now know as ADHD," Boris says. "Back then would've been treated with electrotherapy: like, 'Hey, calm down, here's an extreme shock to put you in a better mindset'.
One machine's manual suggests the appropriate usages for hysteria, a psychiatric condition once thought to exclusively affect women—especially those who didn't respond well to the strictures of social convention.
"Be careful and do not give the patient any sudden shocks," it reads. "Give the patient general treatment with secondary current. In most cases the sedative influence of this tonic treatment will be sufficient."
As well as a good old-fashioned electric current, hysteria was also treated by doctors with 'massage devices', including the first prototype vibrators.
While electricity is still used in the medical profession today—including with some success in the treatment of symptoms for Parkinson's disease, it was once a blunt instrument.
"The original concept was, let's hook some electrodes up to someone's temple and turn the power up. Science is beginning to show maybe there was some credence in the general ideas. But it was too broad. Just hitting someone with a hammer doesn't work."
"One of the machines I have was used for or designed to be used for conversion therapy, and it's a horrible thing to hear that someone's actually had to go through that. Trying to fix something that isn't broken."
Perhaps ironically, the same electrotherapy devices that were once used to try and erase social and sexual difference have now been enthusiastically adopted by the kink community.
"A friend of mine said, you should really go to one of the fetish balls. I'd never heard of a fetish ball, but I thought OK."
He attended with a machine, and soon a line of eager shock-ees started forming.
"It's an environment where everybody is accepted and an inclusive environment. I really just fell into the kink scene, and I was surprised by how open and understanding people were. You're not considered weird. It's really nice to see that level of acceptance and understanding that in the real world people just don't get."
Follow Tess on Twitter.