In celebration of the deep friendship and pioneering spirit shared by John Arnold and Abraham-Louis Breguet, Arnold & Son unveils the Constant Force Tourbillon 11—a fitting finale to the brand’s 260th anniversary tributes. Housed in a classic 41.5 mm case of 18-carat yellow gold, this limited edition of 11 pieces marries watchmaking heritage with contemporary mechanical mastery. The white grand feu enamel dial draws inspiration from naval chronometers once sold to British officers, and beneath it lies a constant force mechanism visible through the dial, while the tourbillon regulator reveals itself on the reverse—both nods to the marine chronometers that shaped watchmaking history. Entirely developed and assembled in La Chaux-de-Fonds, the hand-wound A&S5219 calibre offers a 100-hour power reserve through twin barrels and incorporates a patented constant force device. This mechanism ensures isochronous energy delivery to the tourbillon, preserving precision even as power wanes. Echoing John Arnold’s dedication to accessible chronometry and Breguet’s innovations in regulating systems, this movement distills their shared philosophy into a form both poetic and exacting. The flame-blued anchor that marks the dead-beat seconds is a subtle flourish—both functional and symbolic of the timekeeping science they advanced together. With enamel artistry, openworked gold bridges, and a recessed white opal subdial bearing Roman numerals, the dial of the Constant Force Tourbillon 11 is a canvas of elegance and clarity. Around the back, the sapphire crystal reveals a tourbillon carriage inspired by Breguet’s first regulator, itself built upon the base of Arnold’s marine chronometer No. 11. The inscription on the engraved silver plate echoes this union: “To the revered memory of John Arnold and Abraham-Louis Breguet. Friends in their time, legendary watchmakers always.” It’s a reminder that horology, at its finest, tells a story that transcends time.