A. Lange & Söhne’s Richard Lange Jumping Seconds was the belle of the ball at SIHH 2016. A watch nerd’s dream timepiece, its name was a reference to the dead-beat second complication. In addition to this mechanism, it also featured a constant force device or remontoire d’égalité. First unveiled as a limited edition of 100 pieces in platinum, this timepiece is now available in pink gold with a limited run of 100 pieces.

The platinum version was unveiled at SIHH 2016

The Richard Lange line, named after the founder’s son, has over the years seen many innovations like the first fusée-and-chain transmission in a wristwatch (in the Richard Lange Pour le Mérite released in 1994), a patented stop-seconds mechanism for the tourbillon (Richard Lange Tourbillon Pour le Mérite released in 2011) and the use of a constant force escapement (on the Richard Lange Perpetual Calendar Terraluna, 2014).

A dead-beat second complication or jumping seconds is among the classic complications in precision horology. Pocket watches used dead-beat seconds to determine sidereal time as well as geographical longitude, doctors used it to measure short-time intervals when taking a pulse.

It fell out of favor sometime in the late 20th century because unlike the sweeping movement of the seconds hand in a mechanical watch, a watch with a dead-beat seconds complication mimicked the movement of the seconds hand in quartz watches and was hence not favored by watch snobs.

The rose gold version is limited to 100 pieces as well

However, in recent times, brands like Arnold & Son and Jaeger-LeCoultre have introduced new models featuring this complication. The difference in Lange's Jumping Seconds is in the way the Saxon brand executes the quartz-like movement of the seconds hand. And to appreciate this execution, one has to first understand the functioning of a constant force device (or remontoire d’égalité).

The remontoire d’égalité is a spiral spring placed on one of the gear train wheels to ensure that the escapement gets a constant supply of power as long as there’s juice in the barrel. This helps keep the amplitude of the balance spring constant for precision timekeeping. 

The mainspring periodically rewinds the remontoire spring. While in the Richard Lange Perpetual Calendar Terraluna, it was rewound in 10-second intervals; the boffins at Glashütte chose one-second increments to rewind this spiral spring, which is placed on the fourth wheel of the new Caliber L094.1 in-house movement. This causes the seconds hand to move in one-second increments across the dial.

A close-up of the remontoire spring of the constant-force escapement

The party trick here is actually a clever arrangement that distributes constant-force generation and the seconds jump to two wheel trains. The first gear train extends from the mainspring barrel to the balance and, in one-second intervals, uniformly delivers energy to the escapement via remontoire d’égalité. It does this with the help of a five-point star attached to the escape-wheel pivot.

Every second, one point of the star releases a long lever (called a ‘flirt’), which makes one full rotation before being blocked by the next tooth on the star. This rotation moves the seconds hand forward to the next full-second marker. This motion also rewinds the remontoire spring of the constant-force escapement.

A dead-beat seconds with a constant-force escapement has been done before, notably in the F.P. Journe Tourbillon Souverain.

To underline its scientific observation watch credentials and further improve accuracy, Lange added a zero reset mechanism to this delicate system. Pull out the crown and the seconds hand returns to the 12 o’ clock position and moves again in one-second increments once the time is set and the crown is pushed in.

The fabulous Caliber L094.1 is made up of 390 parts

And since a constant-force escapement delivers even torque during the power-reserve range, Lange felt that it wasn’t necessary to show a classical power-reserve indicator on the dial. Instead, the user is now alerted that the watch needs to be wound when there are 10 hours left in the watch. A small red triangle appears on the dial to indicate the ‘End of Power’.

But what makes this watch truly special, and a watch nerd’s dream, is that Lange has managed to combine a constant-force escapement that powers a jumping seconds hand, a zero-reset mechanism and a novel end of power-reserve indication in a watch case that is just 39.9 mm wide and is only 10.6 mm thick.

Despite the horological heft, this is an understated timepiece

Despite the fact that this is an incredibly complex and a high-complication watch, it has a very understated look. The classic Regulator-style solid silver dial of the Richard Lange family returns, however this time it’s the seconds hand that gets the center stage. The hours and minutes hand sit next to each other just below the seconds dial and the end of power reserve indicator sits inside a triangular aperture in the dial where the hour and minute circles intersect.

The hand-wound movement Caliber L094.1 consists of 390-parts and has the kind of finishing that you would expect from Lange. The bridges are made of untreated German silver and decorated with Glashütte ribbing, the balance cock is hand-engraved, there are eight screwed gold chatons, as well as decorated and polished surfaces. Encased in pink gold, this is limited to 100 pieces and is priced $78,100.