This one is the woman’s doing.
If somebody is ‘as mad as a hatter’ we say that they are completely insane; a fully fledged lunatic. The phrase is thought to have originated from the use of mercury in the making of hats in the 19th century. This was known to have affected the nervous systems of hatters, causing them to tremble and appear insane. In my mind I see them snuffling about their little shops dribbling and barking at shadows. The use of mercury compounds and the resulting effects are well-established – mercury poisoning is still known today as ‘Mad Hatter’s disease’. However, although it is clear that hatters often suffered trembling fits as a result of mercury poisoning, I can find little historical evidence to link hat making to the actual coining of the phrase ‘as mad as a hatter’.
Incidentally, for the Mad Hatter in Alice’s Adventures in Wonderland Lewis Carroll may have taken his inspiration from Theophilus Carter, who was an Oxford cabinet maker and furniture dealer with a reputation for eccentric behaviour. The cap, or in Carter’s case the top hat, certainly fits. He was something of a ‘mad inventor’ and came up with the alarm-clock bed, which woke people by tipping the bed over. Carroll would have been familiar with the sight of Carter, in full top hat, outside his shop at 48 High Street, Oxford, where he lived in the 1850s – during the time that Carroll was an Oxford don.