The purpose of a tourbillon in a watch is to counter the effects of gravity on the accuracy of timekeeping. A tourbillon is a mechanical device invented by Abraham-Louis Breguet in the late 18th century. It consists of a rotating cage that holds the escapement, balance wheel, and the hairspring of a mechanical watch. This rotating cage continuously revolves, typically completing one rotation per minute.
The constant rotation of the tourbillon averages out the gravitational forces that act on the balance wheel and the escapement, reducing errors that can occur due to variations in gravitational pull in different positions. This helps to improve the accuracy of the watch by compensating for the positional errors caused by gravity. Despite modern advancements in watchmaking and the use of materials, the tourbillon remains a highly regarded and complex complication preferred by enthusiasts and collectors for its technical prowess and aesthetic appeal.