A FINE AND VERY RARE EBONY VENEERED GRANDE SONNERIE TABLE CLOCK, STRIKING THE RARE 'DOUBLE SIX' SYSTEMJoseph Knibb, London, circa 1685
The case
Surmounted by a gilt brass tied-bud handle on circular pommels over three pierced brass mounts, the flat-topped cornice with moulded underside over glazed rectangular side panels and a moulded base, the front door with pierced sound fret and mask and scroll escutcheons

The dial
Measuring 6.5 inches square and signed along the lower edge 'Joseph Knibb, Londini fecit' and cornered by winged cherubs head spandrels, the silvered chapter ring with an outer minute band marked in 5s enclosing the Roman hours with fleur de lis half-hour markers, the matted centre with chamfered date aperture and blued steel hands

The movement
The triple gut fusee movement with split front plates united by eight baluster-shaped latched pillars, the going train with knife-edge verge escapement, striking the quarters and every 15 minutes on a pair of graduated bells and the hours on a separate bell, activated via a pair of engraved countwheels mounted on the backplate. The backplate signed in a gentle arc across the centre, within shaded foliate scrolls terminating in flowerheads, enclosed by a single line border 33cms (13ins) high.
33cms (13ins) high.注脚Joseph Knibb's concern with the conservation of energy is evident throughout his working life. This extended particularly to his striking system. With his double six Grande Sonnerie system Knibb saves 188 blows each day, over a conventional Grande Sonnerie wheel train. With a conventional 24 hour striking system, a day is divided in just two 12 hour periods. Knibb's doubled six system takes this a stage further by dividing the striking day into four quarters. In the first quarter of the day, from midnight to six am, the clock strikes one to six as expected, at seven am, the clock strikes one up to six at midday. The third quarter, the clock strikes at 1pm as expected up to six pm and then reverts to one at seven pm up to six at midnight. As with the two period 12 hour strike period, where we always knew which period we are in, we should know which quarter of the day is passing as well. To assist the owners to familiarise themselves with the system, the first and third quarter of Knibb's ingenious movement will always be in step with any other conventional clock.

Provenance
Bobinet

A similar example was sold Christie's, July 2002, lot 188 for £107,850