Gravity (effect on the regulating organ)

Gravity is the silent enemy of any mechanical watch, and understanding it well changes the way you look at a movement. The problem isn't the force itself, but its constant direction: when the balance wheel remains still in a vertical position — as happened with pocket watches carried in a waistcoat pocket — the hairspring works asymmetrically, and the rate shifts. The extent of the shift depends on position, the shape of the hairspring, and the quality of the balance wheel's own balancing.

Abraham-Louis Breguet patented the tourbillon in 1801 precisely for this reason. The idea is brutally logical: if gravity alters the rate because it always acts from the same side, place the regulating organ in a cage that rotates on itself — normally one rotation per minute — and the disturbance is distributed across all angles, canceling itself out over time. It doesn't disappear: it gets averaged. The difference is substantial.

The classic tourbillon rotates on a single axis. It works well for pocket watches, almost always held in a vertical position with the 6 pointing downward. On the wrist the problem is different: the wrist moves, continuously changes orientation, and gravity strikes from varying directions. This is where multi-axis variants are born. The bi-axial tourbillon rotates on two axes at different speeds — in the Fam al Hut Möbius Mk1 prototype one completes a rotation in 60 seconds, the other in 150 — and covers more geometric planes. The tri-axial tourbillon adds a third axis, multiplying coverage but also constructive complexity and the weight of the cage itself, which becomes a drain on the power reserve.

The flying tourbillon is a constructive variant, not a compensation one: the cage is supported from a single point rather than two, which makes it visually lighter and allows its rotation to be appreciated from both sides, but doesn't necessarily improve gravitational compensation.

It must be said clearly: on a modern wristwatch, regulated in six positions and with a well-balanced balance wheel, gravity's effect is already largely contained during construction. The tourbillon solves with mechanical elegance a problem that quality manufacture today addresses through other tools as well: silicon hairsprings, compensated balance wheels, fine regulation by position. From the bench, I've seen pieces with tourbillons that perform worse than a well-regulated ETA 2824. The mechanism is real, the physics is correct, but final precision depends on the overall execution of the caliber, not the tourbillon in isolation.