Charles Fort was keenly interested in the phenomena of collective action and the behaviour of crowds, and he recorded many episodes of ‘mass hysteria’, from contagious fainting fits triggered by ‘strange smells’ to mystery assailants who stab with pins and epidemics of lights in the sky or ghosts.

In the sixth chapter of Wild Talents (1931), Fort, at the end of a discussion of puzzling outbreaks of hair-snipping in western cities, spends a couple of pages describing a panic in China in 1876 1. Beginning in Nanjing in May 1876, invisible and uncatchable culprits were cutting off people’s pigtails, generally instantaneously and without the owner’s knowledge.