THE PROPERTY OF A PRIVATE COLLECTOR

A French seconds-beating two-day marine chronometer with special optic system for observing the amplitude of the balance

J. FOURNIER, NO. 46, CIRCA 1880

Details

A French seconds-beating two-day marine chronometer with special optic system for observing the amplitude of the balance
J. Fournier, No. 46, circa 1880
The frosted silver dial signed J. Fournier, Horlger de la Marine No. 46, Roman hour numerals, Breguet blued steel hour and minute hands, subsidiary seconds dial beating seconds (at IV) and sector up-and-down dial (at XI) both with blued steel hands, reversed fusee movement with both dial and back winding, Earnshaw escapement beating seconds, cut bimetallic balance (2.6 mm. diam.), with cylindrical heat compensation weight, immediately beneath the balance and mounted on the balance staff a thin brass disc (3.6 mm. diam.) which oscillates with the balance as it turns, and with stop/start mechanism consisting of a length of polished spring steel which by means of a key can be pressed against the brass disc thereby arresting the balance, palladium helical balance spring, flat strip steel detent with jewelled locking stone, mounted on the fourth wheel arbor an additional wheel having sixty teeth (one for each second), with associated detent with jewelled locking pallet operating an adjustable make/break gap switch, in vertically mounted brass bowl with circular spirit level (at XII), contained in square mahogany surround with removable wooden shutter to top, front and back, mounted on brass tripod assembly with three adjustable levelling screws
108 mm. dial diam., 155 mm. sq. wooden surround, 210 mm. high with brass base

Lot Essay

The construction of the optic/electrical system comprises an 8 mm. diam. hole in the dial (above VI) which goes right through to the underside surface of the back-plate in the central point of which is drilled a small hole (2.5 mm. diam.); in the brass disc mounted on the underside of the balance is a small hole (1.0 mm. diam.) which every half second traverses over the larger hole in the back-plate and allows a ray of light to pass right through the chronometer movement from the dial through to a small glazed port set in the back of the bowl, mounted on the side of the bow are two electric terminals (at I and XI) which, with certain components mounted on the top-plate complete the electric circuiting, the back of the bowl also carries a large glazed port through which the balance may be viewed and the stop/start mechanism controlled.

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