A tourbillon is a small piece of equipment which can be included in the casing of a watch to house the balance wheel and escapement. At one time, tourbillons were viewed as critical for timekeeping accuracy, in addition to being a very fine example of a watchmaker's art. Modern watches do not require this piece of horological equipment, although luxury watches are sometimes made with tourbillons to make them seem more precise and valuable.
The idea behind the tourbillon was that the effects of gravity on personal watches had to be offset by something in the mechanics of the watch. Watchmakers believed that personal watches grew inaccurate over time because of the fact that the watch was kept constantly in motion, with innumerable tiny shifts over the course of the day which would slowly pull the workings of the watch out of sync. As evidence to support their claim, they pointed to fixed city clocks and standing clocks which managed to keep time very well, suggesting that the key different between fixed clocks and personal watches was the constant movement on the part of personal watch owners.
In 1895, watchmaker Abraham-Louis Breguet came up with the idea of a tourbillon, a rotating cage which was used to keep the workings of the watch balanced so that gravity would not pull a watch out of time. The word “tourbillon” means “whirlwind,” and it is a reference to the motion of the device inside the watch. Watchmakers quickly caught on to the introduction, and tourbillons became a must-have for anyone who wanted an accurate watch.
In actuality, research would seem to suggest that the tourbillon actually has a minimal effect on the function of a watch. In fact, early personal watches were simply unreliable because of the nature of their construction, and as watchmakers refined their art, they were able to develop more accurate timepieces. The inclusion or exclusion of the tourbillon appears to have made minimal difference when it came to accuracy.
The precise and detailed machining of the tourbillon, on the other hand, is a testimony to the skills of the watchmaker. Even after watchmakers generally accepted that the device did not serve a function, they continued to include it in their watches to indicate high quality and to assure their customers that they were purchasing the very best. Luxury watch companies have maintained the fad for the tourbillon, listing it as a notable feature in their high-end products to appeal to consumers.