Have you ever wondered where the colloquial English phrase “Mad as a Hatter” came from? It is used to lightheartedly suggest that someone is crazy, suffering from insanity, not playing with a full deck, etc.
It seems to have came from Denton, Greater Manchester, England where men predominantly worked in the hattery business. In this process of making hats mercury was used. After an accumulation in the body it is known to give symptoms of madness.
The first known mention of “Mad as a Hatter” was in an 1829 issue of Blackwood’s Edinburgh Magazine. In 18th and 19th century England, mercury was used in the making of felt which was common in the period hats. This prolonged exposure would cause slurred speech, tremors, stumbling, and, in extreme cases, hallucinations. John Wilkes Booth, Abraham Lincoln’s killer, was shot by Boston Corbett, a hat maker. He went against the orders “to take him alive” and was considered at the time “Mad as a Hatter”. He was not charged with a crime but left the army and went back to his hat making career. A few years later he ended up in an insane asylum, from which he escaped and was never seen again.