hypnovoyeur: Marie Antoinette’s gold Breguet pocket watch, ca. 1827. It took 44 years to complete after it was first commissioned in 1793. Marie Antoinette never saw the watch through to its completion, as she was sent to the guillotine 10 years before its completion. It is referred to as the Queen/Mona Lisa of watches.
Tourbillon is an addition to the mechanics of a watch escapement. Developed around 1795 by the French-Swiss watchmaker Abraham-Louis Breguet from an earlier idea by the English chronometer maker John Arnold, a tourbillon aims to counter the effects of gravity by mounting the escapement and balance wheel in a rotating cage, to negate the effect of gravity when the timepiece (thus the escapement) is stuck in a certain position.