Dante’s Dentist

http://www.google.com/patents/US353403

In 1886 Levi Deckard of Pennsylvania patented an electrified dental chair to provide “electricity as an anaesthetic” to people undergoing tooth extractions and other painful operations.

The dentist operates a foot-driven generator, the patient grips the electrodes, “and the desired shock is produced.” Deckard doesn’t explain why he thinks this will stop pain — but it certainly must be distracting.