The tourbillon (the word means 'whirlwind' in French) was invented to increase the accuracy of chronometers, in a period when their precision was essential in ensuring accurate navigation at sea. It is an enormously complex mechanism, and one that today has become a virtuoso hallmark of the very finest mechanical watches. Tourbillons are also spectacularly beautiful, a pulsating heart, a miniature mechanism revolving as it beats.
At the time that it was invented, one of the problems of mechanical watches was that the balance spring's rate of oscillation was affected by the watch's position, because of differences in the force of gravity. The tourbillon, developed by French-Swiss watchmaker Abraham-Louis Breguet, possibly in cooperation with English chronometer-builder John Arnold, was designed to even out the effects of gravity by rotating the escapement and balance wheel.
The start of the tourbillon's history can be seen in Room 38-39 of the British Museum in London, in the form of a silver-cased chronometer. Abraham-Louis Breguet visited London in the 1780s, and he met John Arnold, who at that time was one of the leading chronometer makers. They evidently got on very well, probably because each recognized the other's skills – they were in fact the two most inventive watchmakers of their times. As a result of this meeting, John Arnold sent his son John Roger to work with him from 1792 to 1794, at his workshop at Quai l'Horloge in Paris.
On his journey to Paris, John Roger took this chronometer with him as a gift to Breguet, or perhaps the two great watchmakers had already discussed a cooperation on a new and more accurate timepiece. Whatever, between 1792 and 1794, Breguet modified the piece, adding the new revolving assembly that he named the tourbillon.
In a touching ending to the story, Breguet later returned the modified timepiece to John Roger Arnold, in 1808, nine years after John Arnold's death in 1799. Breguet added an engraved plate that reads: 'The first tourbillon regulator by Breguet incorporated in one of the first works by Arnold. Breguet's tribute to the honoured memory of Arnold. Presented to his son in 1808.'
In the photo below, a portrait of Breguet.
Below, watch a Breguet video about the tourbillon: