Horloge Marine à deux Barillets | A brass and mahogany boxed two-day marine chronometer with original tipsy key

Abraham-Louis Breguet’s marine chronometers represent a landmark in horological precision and innovation and were a genre to which he devoted particular attention after his appointment in 1815 as Horloger de la Marine. His earliest examples, such as Nos. 104, 105 and 106, drew on elements from John Arnold’s work, including the three-armed compensation balance and helical balance spring. Yet even these early chronometers displayed striking originality: Breguet introduced a detachable escapement platform, allowing rapid adjustment and repair, and adopted gimbal-mounted boxes to keep the chronometer as level as possible on board ship. While his first marine chronometers employed twin barrels to drive a single fusee, he later turned away from the fusee in favour of a new twin-barrel “motor” that he argued provided a more uniform and reliable source of power.

A distinctive feature of Breguet’s chronometers, retained throughout his later production, was the systematic division of the movement into four functional systems—motor, wheelwork, escapement and regulator. This modular approach meant that each part could be examined, adjusted or substituted independently. The escapement and balance, carried on a detachable platform secured by just three screws, could be removed for regulation or replaced entirely without dismantling the whole movement. Daniels emphasised that this arrangement not only simplified servicing but also allowed Breguet’s workshops to produce chronometers in greater quantity by streamlining the work of his craftsmen.¹

Interestingly Breguet et Fils marine chronometer no. 3194 (circa 1821), which is held by the National Maritime Museum in Greenwich, is accompanied by a highly detailed description of its attributes.² In these “Observations for marine timekeeper No. 3194 of Messrs. Breguet et Fils”, Breguet describes a “motor” formed by two separate barrels with very long, flexible mainsprings (each giving 15–20 turns), of which only the middle four turns are used in practice. This yields about 50 hours’ run, during which the coils remain nearly parallel—neither bearing on the arbor nor on the barrel wall—so that the delivery of torque is steady and uniform. The two barrels do not increase power; rather, their opposed action on a common arbor balances the load on the pivots and smooths transmission. Designed to be wound daily, Breguet noted that over the initial 24-hour running period the driving force diminishes by less than 1/40 (around 2.5%) of its initial value, a gradual and regular decrease that the balance spring’s isochronism can readily accommodate. By dispensing with the fusee—and with it the chain, guard, and the auxiliary maintaining-power spring with its clickwork—Breguet et Fils avoided sources of irregularity and breakage and removed the need for separate maintaining power. Breguet also emphasised that the escapement and regulator are mounted on a detachable platform for convenient examination, exchange and service.

Breguet was acutely aware of the detrimental effects of sea air, both in corroding the movement’s parts and in degrading the lubricating oils.³ With this in mind, Maison Breguet aimed to produce a marine chronometer better protected against such conditions. The brass casement of this example would have provided robust protection: the bowl is solid and without apertures, and the glazed front bezel screws down firmly to seal it. Access for winding is through a small opening in the glass, itself covered by a tightly fitting brass cap, ensuring that the aperture is securely closed when not in use.

As a presentation piece, this marine chronometer was an exceptionally fitting gift. For a ship’s captain it combined dual symbolism: a luxury object of prestige and refinement, and at the same time a precision instrument of direct practical use at sea. Breguet’s marine chronometers of this period were often housed in finely finished mahogany cases, fitted with numerous hand-made brass components of the highest quality. The development of such aesthetic and technically refined chronometers was made possible by the substantial prices paid by the French Marine Department, and their excellence would have been well known to those presenting the instrument to Captain Bilard. Indeed, it is evident that Bilard himself treasured his marine chronometer – the Breguet Archives noting that he returned the chronometer three times for service, the last entry, dated 7 December 1859. 

The union of mechanical excellence with elegant construction ensure Breguet’s marine chronometers continue to be highly sought after by today’s collectors.

¹ Daniels, George, The Art of Breguet, London & New York: Sotheby Parke, Bernet, 1975, p.84.

² Betts, Jonathan, Marine Chronometers at Greenwich, Oxford: OUP & National Maritime Museum Greenwich, 2017, pp. 296-297.

³ See op. cit. p. 298 where a letter from Louis Antoine Breguet discussing the detrimental effect of sea air on marine chronometers is reproduced in translation.