The layout of the movement is not just for aesthetic reasons,” says watchmaker Stephen Forsey, holding one of his latest pieces. “It is actually quite strategic.” Forsey’s new watch, the Double Balancier 35°, looks strange with its two inclined timekeeping elements beating steadily underneath the crystal. But by the standards of Greubel Forsey, the boutique watch brand that Forsey started in 2004 with partner Robert Greubel, the watch might actually appear even stranger. Unlike virtually every timepiece for which the brand is known, the Double Balancier 35° contains no tourbillon.
“When we started, we made it our mission to improve the performance of the wristwatch,” continues Forsey. “The fundamental research we performed in the beginning led to the idea of the double tourbillon for which we have become known. But we also knew even at the early stage that we wanted to explore other avenues, and fixed inclined escapements quickly became important.”
In many ways Greubel Forsey’s latest creation is intended to alleviate the same problem as the brand’s other watches, namely the effect of gravity as the watch sits in different positions—the same problem that inspired the invention of the tourbillon at the end of the 18th century. As gravity pulls at the crucial hairspring as well as the balance wheel and its pivots, it can have marked effects on the rate of the watch. But the effects can differ dramatically depending on whether the watch is lying flat or sitting upright. Greubel Forsey’s remedy has always been to mechanically produce an average of the different positional rate errors for better overall performance. Its first invention, the Double Tourbillon 30°, moves the balance constantly in three dimensions so that its rate reflects an average of the different positions as it moves through space. Its more complex Quadruple Tourbillon employs two such mechanisms and combines their rates through differential gears, creating a further and more accurate average.
The Double Balancier 35° essentially borrows a little from both concepts. The two balance systems are averaged with a differential to produce a single, more accurate rate. And while they do not rotate independently like tourbillons, the two balances are precisely located to avoid the extremes of position error. “In real life, wristwatches can lie in one position [when not being worn] for six to 12 hours at a stretch,” explains Forsey. “This can affect them considerably.” The piece is designed for this eventuality through the placement of the balances. If one balance is lying flat, the other is positioned so it will not be on a vertical plane. The rates will remain closer to one another, thus making the average rate more accurate.
Greubel Forsey’s first experiment placed two inclined escapements on top of one another with an incline of 20 degrees from the plane of the movement. The company displayed a large-scale model of the escapement in 2009—that configuration was refined and placed into a special “Experimental Watch Technology” edition of six pieces in 2011. The current model with the 35-degree inclination and the separated balances is now part of the brand’s regular collection.
The new system brings additional benefits besides accuracy. At 14.35 mm thick the new watch is hardly ultrathin, but it is nonetheless the thinnest timepiece in the Greubel Forsey collection. “This escapement has afforded us an interesting reduction in volume,” says Forsey, “one we imagine we might use with different complications in the future.”
Greubel Forsey, 212.221.8041, www.greubelforsey.com