First of all I feel like I have to say, here and now, that I have no formal training in the horological world. Everything I know comes from reading books and learning stuff about watches simply because it's something I'm passionate about. This means that if you're reading this and you see something that you think is incorrect or could have been said differently, you're more than welcome to post a comment and say what you think. Actually, I encourage you do that because I want to learn more. Anyway, today I want to talk about the 𝘛𝘰𝘶𝘳𝘣𝘪𝘭𝘭𝘰𝘯.
The tourbillon is, yes, a fancy French word for 'whirlwind', but it is also an important addition to the watch escapement. The escapement of a watch is basically what makes the hands of a mechanical watch move, thus keeping time.
It was developed in the late 1700s and first introduced and patented by French-Swiss watchmaker Abraham-Louis Breguet in 1801. Breguet began working on it because in the past, before somebody thought of adding a bracelet/strap, people would keep their watches in their pockets and this would directly impact the ability of watch to keep time because of gravity.
A pocket watch will inevitably end up positioned vertically in your pocket and this means that the whole mechanism is going to be affected by gravity. The tourbillon is continuously rotating the wheel to balance out positional errors. This means that gravity is going to affect different parts of the mechanism instead of constantly affecting the same section.
Think about a car that's been left unattended and parked for an extended period of time. At some point, gravity is going to ruin the wheels because certain parts of the wheel surface, the bits that are perpendicular to the road, are being pushed down harder by the weight of the car. If you move the car around on a regular basis, the weight of the car is going to be averaged out and distributed across the entire wheel surface. Completely dumb analogy, I know, but I feel like it kinda works.
Modern watches are worn on your wrist meaning the tourbillon is basically overkill. In fact, watchmakers usually utilize it to showcase mechanical and engineering prowess and that's why tourbillon watches are often very expensive.
There are several types of tourbillon. Double or triple axis, the latter of which was only recently invented (2004), and then there's the "flying" tourbillon, which is so called because the tourbillon itself is only supported on one side and connected to the rest of watch movement with one piece of material.
The little gear on the left side of the tourbillon is the only connection to the rest of the movement
One of the most astounding tourbillon watches I've ever seen in person, at the 2017 Top Marques Watches, is the Greubel Forsey GMT Quadruple Tourbillon. It is a limited edition watch, only 66 units ever built, with a three-dimensional rotating terrestrial globe incorporated in the dial. It rotates following the time zone you're in. It is a truly spectacular piece. And atrociously expensive, too. Dammit. I'm broke.