The tourbillon was invented to neutralise the effects of gravity on a pocket watch’s movement. As it asserts a downward force on the movement, the balance spring becomes skewed and is thus unable to “breathe” concentrically.
(Related: The Watch Expert's Guide: B for Barrel)
Here’s where the tourbillon comes in. It keeps the balance wheel and balance spring constantly rotating, so that it is never in the same position all the time. Gravity’s effect on the balance spring is thus averaged out across the multiple positions.
Fittingly, one of Franck Muller’s latest creations within the Vanguard line is named the Gravity and it comes with an extra-large tourbillon to drive the point home—the largest in the industry, as a matter of fact. Needless to say, the results are spectacular, where an enormous aperture on this not-small timepiece gives pride of place to the complex device.
With its massive 21.2mm diameter, the bridge of the tourbillon is guaranteed to turn heads. It resembles the crossbars of a suspension bridge and is curved at the ends, giving the entire structure a palpable three-dimensional effect. Underneath, the tourbillon rotates at a leisurely 18,000 vph within an elliptical cage made of aluminium for optimal lightness, and the possibility to create different colours through anodisation.