Instead of the power from the mainspring flowing directly into the escapement, it has to first pass through Arnold & Son’s continuous force mechanism. The already regulated power supply costs a little hairspring, which releases a constant amount of force to the tourbillon once a second. With this mechanism, there will nevertheless come a stage when the energy released by the twin barrels along with the continuous force mechanism falls below a point that is enough to maintain a regular output. When this occurs, the watch stops rather than letting an isochronal error to creep in the timekeeping.In accession to this intriguing solution, the Arnold & Son Continuous Force Tourbillon features a deadbeat seconds complication, which causes the seconds hand to “tick” instead of sweep as you may expect in a mechanical timepiece. Outstanding consistency is achieved thanks to the symmetry of the movement’s construction, as well as the fact that the constant pressure escapement remains stationary throughout performance, while the tourbillon cage moves once a minute. That is in an attempt to decrease the effect of gravity to the escapement’s functioning. Assuming, however, that this watch is not likely to be worn in the presence of powerful magnetic fields (it is barely acceptable for use on a construction site or while flying a helicopter, for instance), the complication perfectly matches the intended application.The Arnold & Son Constant Force Tourbillon watch is a limited edition of that only 28 will be made. The A&S5119 movement has 39 jewels, a depth of 6mm, a 90-hour energy book, and operates in 21,600vph. The movement is almost perfectly symmetrical, and each of the specialized components are observable on the dial-side. The three-dimensional motion architecture is designed to replicate the English tradition of marine chronometer construction.
Arnold & Son, which was acquired by Citizen of Japan last year, has just announced the Time Pyramid at Baselworld 2013. A skeleton watch with the movement laid out in a triangular form, the Pyramid is inspired by the standing English skeleton clocks of the nineteenth century which had a similar movement shape.
Sandwiched between two sapphire crystals is the open-worked A&S 1615 movement, developed by La Joux-Perret, the sister company of Arnold & Son (and also now owned by Citizen). The movement runs from 12 to 6 o’clock with the balance wheel at the top, followed by the linear gear train, and the twin barrels at six o’clock, each with its own power reserve indicator. Together both barrels give a power reserve of 80 hours.
The Pyramid is in rose gold with a large, 44.6 mm case, which should allow for a panoramic view of the usual movement. The retail price is CHF39,960 which is equivalent to about USD42,100. – SJX