Interconnected

In the UK, a public performance of hypnotism requires a government permit, as set out in the Hypnotism Act 1952. Which only makes you think: what public fear or media frenzy occurred in 1951 that the then-government leapt in to control mesmerism?

Update

Phil points out the history of hypnotism in the '50s and '60s: As far as the 1950's and 60's went there was only one interest in hypnosis by the general public. That was the practise of hypnosis for entertainment purposes, stage hypnotism. In 1952, the practise of stage hypnosis came under parliamentary scrutiny, in the form of a court case Rains-Bath v Slater. (Waxman 1989)

Ralph Slater was an American Hypnotist who performed in Brighton in 1948. During this performance, a lady accused Slater of assault and professional negligence. The case allowed for the professional negligence but did not find that an assault occurred. (Singleton, Lord Justice 1952). This incident led to a private member's bill to be passed in parliament. In August 1952, the Hypnotism Act was placed on the statute book. The Act conferred power to any local authority which granted licenses for the regulation of places used for public entertainment, to attach conditions to that license in relation to the demonstration or performance of hypnosis. (HMSO 1952).

And here's a very pertinent question to the Secretary of State, in Parliament in 1951! (Thanks Chris!)

It's weird to think that hypnotism was so serious and feared - a real power, a potential terrorism - that it had to be regulated. Which (of course) reminds me of the UN Weather Weapon Treaty (1976) which bans military use of 'environmental modification techniques' ... the deliberate manipulation of natural processes--the dynamics, composition or structure of the Earth, including its biota, lithosphere, hydrosphere and atmosphere, or of outer space -- ie, artificial rain, hurricanes and earthquakes. Imagine attacking New York with an artificial earthquake. Or a hyper-thunderstorm. Shiiiit.

Geoengineering was quite a topic in the 1970s (Kurt Vonnegut's brother invented the modern process of cloud seeding, dropping silver iodide into the sky to produce rain), and there was a fear that there would be an arms-race as there had been with atomic weapons. So: a treaty to ban military geoengineering. And, I'm guessing, given no military investment, that's why we didn't get the spin-off benefits in farming and domestic use. Who knows what 35 years of investment in geoengineering would have got us! Tabletop volcanos! Genetically modified tomatoes that create their own microclimate! Super-local sunny days to always have blue sky for picnics! Pocket clouds! And instead, we got the internet. If I sound disappointed it's because I am.