No one has ever accused Arnold & Son of being a mass-market brand. It makes complicated watches in small numbers for true mechanical watch fans—and with this new beast, it's appealing to the nerdiest of the bunch.
The Constant Force Tourbillon is actually even more complicated than its name might suggest (considering it's already a mouthful to say). The watch starts with a pretty simple concept: to push precision to its logical conclusion. Then the watchmakers go deep into show-off territory, by revealing every little facet of the mechanics required to achieve that goal. Let's see what I mean by that, bit by bit.
First up, the tourbillon, which is somehow the simplest part of this watch.
A tourbillon is a rotating carriage mechanism that was originally designed to mitigate the negative effects that gravity would have on a pocket watch's accuracy, specifically how it'd weigh down the spring as it sat in your pocket, stretching it out of shape and ruining the amplitude. A tourbillon evened out that force—so for a wristwatch, it's an unnecessary complication given the spring moves into all sorts of positions throughout normal use. But it is considered a must-have for hyperprecise watches.
Like I said, we're getting real nerdy here.
As a tribute to the past—specifically marine chronometers created by brand namesake John Arnold and other British clockmakers—the balance beats at just 3 Hz, the traditional speed for a tourbillon pocket watch (most wristwatches function at 4 Hz).
But let's move on to where things really get interesting.
You'll notice the two large power barrels at the top of the dial—they power the watch through a constant force system. This means that as the first barrel winds down, the second makes up the difference and keeps the amount of torque even throughout the full power reserve. When torque drops off, a watch becomes less accurate, so a steady flow keeps the watch performing at its best.
To show off all the precision, Arnold & Son engineered a third and final nerdy flourish: a deadbeat-seconds mechanism at 7 o'clock.
Mechanically this isn't too different from what you'll see in A&S's DTSB, though aesthetically it's much more subtle. Most brands would have just thrown the seconds hand on top of the tourbillon cage, a perfectly acceptable, if simple, solution. The extra mechanism here is meant for the die-hards who appreciate the complexity and want to see each precisely measured second ticked out discretely.
Which is all to say, the mechanics on this watch are stellar. If you have a Ph.D. in mechanical engineering (yeah, I'm looking at you), this trifecta of complications is certainly impressive enough.
For the rest of us self-schooled watch nerds, the finishings are beautiful, too. The movement is housed in a 46mm red gold case; bridges are brushed on the surfaces and polished on the bevels; the back of the movement has a semi-industrial feel to it; and the signature Arnold & Son hands are present on the dial. I think that word you're looking for on the tip of your tongue is "squeee."
The Constant Force Tourbillon is limited to only 28 pieces, all in red gold, priced at 197,500 CHF ($255,550).