Mad as a Hatter is a term used to describe insanity A popular explanation of the phrase suggests that it was connected to mercury poisoning or something called Korsakoff’s syndrome which was experienced by hat-makers as a result of the long-term use of mercury products in the hat-making trade. In 18th and 19th century England mercury was used in the production of felt, which was used in the manufacturing of hats common of the time.This got into the blood stream and caused trembling in some people, a little like the symptoms of Parkinson’s Disease, and those who suffered the effects in this way were assumed to be mad.
There were tales of a man called Robert Crab, an eccentric who lived in Chesham, who was easily identified because of his distinctive hat and was known to locals as ‘the mad hatter’. He apparently gave away all his wealth to the poor and lived his life eating anything he could find in the countryside, such as grass, berries and dock leaves. The phrase passed over into the English language in the 19th century, thanks to Lewis Carroll and his novel Alice In Wonderland. In the story Carroll invented a mad hatter but he may have been inspired by a real-life figure.
Which brings me to Abraham Lincoln as every one knows was shot by John Wilkes Booth, but then Booth was shot by a fellow called Boston Corbett. Corbett spent his early life as a hat maker, and it is believed that the effects of his early life job affected his decision-making for his future. He was considered “mad as a hatter” for going against orders when he had Booth cornered in a barn in Virginia, and shooting Booth instead of taking him alive. After investigation, Corbett was forgiven for his disobedience, but left the army and went back to hat making. After a few years, Corbett was even more mad than people had once thought, and he was thrown into an insane asylum. Corbett managed to escape, and he was never seen again.