More than the sum of its 684 components
This monument to timekeeping is the fifth masterpiece in A. Lange & Söhne’s “Pour le Mérite” series, whose most salient element is its constant force inside the movement. Among other factors, the precision of a mechanical timepiece depends on maintaining the most uniform flow of power from the energy reserve to the escapement possible. But even the best high-performance mainsprings in modern wristwatches cannot entirely overcome a fundamental physical disadvantage: they exert much stronger torque when fully wound than after they’ve slackened. Watchmakers have devised numerous tech- nical artifices to compensate for the fact that diminishing power in the mainspring leads to a decline in the balance’s amplitude. The engineers at A. Lange & Söhne in Glashütte opted for a very traditional but also highly elaborate way to compensate for the mainspring’s waning power. The functional principle is derived from physics: the longer a lever is, the less force is needed to perform a task. Conversely, more force is required to accomplish the same work with a shorter lever. The function served by the lever is performed here by a fusée with a slim chain. The initial and strongest spring power acts on the smallest circumference of the fusée. The fusée’s continually increasing diameter compensates for the gradual decline of torque exerted by the mainspring. A planetary gear inside the fusée ensures that the flow of energy from the barrel to the escapement remains uninterrupted when the mainspring is manually wound. The slender chain in the brand-new Tourbograph Perpetual “Pour le Mérite” contains a total of 636 tiny links. This is admittedly only one detail, but its importance shouldn’t be underestimated. This masterpiece’s full spectrum of technical elements includes a tourbillon, a split-second chrono-
graph, and a perpetual calendar that needs no manual resetting until 2100. A 43 mm platinum case houses complex hand-wound Caliber L133.1. If the chain is counted as one component, then the total number of parts is 684, of which 206 compose the calendar module with leap-year indication and moon-phase display, which won’t err by one full day until 122.6 years have passed.