Following up on such horological milestones as 2014’s flying tourbillon model, and last year’s pocketwatch with five-minute repeater, Baume & Mercier adds another notable timepiece to its vintage-inspired Clifton collection. The Clifton Manual 1830 appears simple on the outside, but inside is an all-new proprietary movement, the first to be equipped with an exclusive, accuracy-improving system called TwinSpir.
Inside the watch’s 42-mm polished and satin-finished rose-gold case is the new manual-winding Caliber BM12-1975M, designed by Baume & Mercier in collaboration with the movement specialists at Manufacture Horlogerie Valfleurier. The movement, which has 18 jewels and a 28,800 vph frequency and boasts a power reserve of 90 hours, is equipped with the exclusive TwinSpir technology, which incorporates a number of technical innovations developed by the Research & Innovation department at Richemont, parent company of Baume & Mercier and a number of other luxury watch brands.
The TwinSpir technology is centered around a newly developed hairspring with a composite structure combining two layers of silicon, alternatively oriented and bound through an extra layer of silicon dioxide, which also acts as a thermo-compensating element. Combined with the movement’s other noteworthy technical element — a newly designed, inertia-type balance wheel— the technology has several benefits, according to Baume & Mercier. These include enhancing the precision of the movement in various positions and over time; limiting the movement’s sensitivity to surrounding magnetism; and ensuring a greater resistance to small shocks and repeated vibrations.
To get into a bit more technical detail, the monocrystalline silicon used in hairsprings is a non-magnetic, light, corrosion-resistant material that exhibits different elastic and thermo-elastic properties for different crystalline orientations — a variation of response known as the material’s “elastic anisotropy.” As a watch’s hairspring expands and contracts during its oscillations, the elastic anisotropy tends to affect the evenness of those oscillations and, consequently, the watch’s chronometric performance. The TwinSpir system overcomes these limitations through its combination of two layers of silicon, with different crystalline orientations, so that the variations are balanced, thus making the oscillations more even and the timekeeping, as a result, more precise. Moreover, an additional outer layer of silicon dioxide works in concert with the inner, thermo-compensating layer of the same substance to ensure a stable performance by the hairspring across a range of temperatures.
Finally, Caliber BM12-1975M’s newly designed balance wheel is an inertia adjustment type, as opposed to the more traditional type that uses an index-pin assembly. With the latter type of assembly, the balance’s rate can be adjusted only through correcting the active length of the hairspring. Inertia-adjustment types, by contrast, offer the key advantage of a more vibrations-resistant rate setting, as the inertia-adjusting weights — which ensure the precise adjustment of the watch rate — are securely held on the balance wheel between its arms and dedicated supports.
The Baume & Mercier Clifton Manual 1830 shows an elegant, understated face, with its opaline silvered dial enhanced with 18k rose gold hour numerals and indices and gilt hour and minute hands. On the other side, the movement’s haute horlogerie decorations — including côtes de Genève on the bridges, circular graining on the mainplate, blued screws, and engraved text — are on display through a screw-down sapphire caseback. The black alligator strap is secured by a rose-gold pin buckle. Baume & Mercier says that this watch will be produced in very limited quantities; priced at 12,000 Swiss francs (approximately $12,045), it is available at retail as of April 2017.