- Museum number
Wall clock in rectangular ebony-veneered and tortoise-shell case with hinged, glazed front door; back with two rings for hanging the clock; brass, velvet covered dial plate with applied silver chapter-ring; Roman hours I-XII within an outer circle calibrated 10-60 for each hour with transversal lines to enable minutes to be read using a single hand; below is applied silver apron; clock wound through dial above 6 o'clock; silver hand with engraved rosette at centre, steel tip now missing; spring-driven eight-day timepiece movement with rectangular brass plates and baluster pillars; pendulum suspended by thread with curved cheeks at each side; verge escapement.
- Production date
Height: 25 centimetres
Thickness: 10.30 centimetres
Width: 20.30 centimetres
- Curator's comments
- Text from 'Clocks', by David Thompson, London, 2004, p. 66.
J. Bernard van Stryp
Antwerp, c. 1660
Height 25 cm, width 20.3 cm, depth 10.3 cm
In 1657 Christiaan Huygens in The Hague introduced the pendulum as a new and effective device for improving the accuracy of clocks. Before this momentous innovation, clocks were controlled by either a wheel balance or a weighted foliot, neither of which had a natural period of oscillation and so could not provide a constant with which to control the rate. Clocks would vary by as much as half an hour per day and, perhaps more annoyingly, would be erratic in their performance.
The introduction of the pendulum as the controlling device changed matters overnight, and clocks were made which could keep time to within one minute per day. Huygens took out a patent in the Netherlands and employed the clockmaker Salomon Coster to make pendulum clocks. Coster, unfortunately, died soon afterwards in 1659. Huygens failed to obtain patents in either France or England for his new device, and soon all new clocks in these countries were fitted with it. Many older clocks were modernized by the addition of a pendulum.
Bernard van Stryp made this small spring-driven clock in Antwerp (Anvers) in about 1660. In keeping with Huygens' invention, it has a pendulum and cycloidal cheeks on the pendulum suspension. According to Huygens' calculations, the ideal pendulum should swing through a cycloidal path and not a circle. To this end, early pendulum clocks were fitted with cycloidal cheeks which were intended to force the pendulum, suspended from silk threads, into the correct path. So confident were the early makers of these clocks in their ability to keep good time that for a short period they abandoned the use of a fusee in favour of a simple going barrel. The time taken for the pendulum to swing is determined by its length and not the arc through which it swings, within certain limits. This led the makers of early pendulum clocks to believe that the huge differences in power delivered from the mainspring to the escapement between the spring being fully wound and almost unwound could be accommodated by the pendulum simply changing the arc through which it swung depending on the force imparted to it. In practice both this and the use of cycloidal cheeks were found wanting and caused more problems than they solved so that later spring-driven pendulum clocks went back to using a fusee and dispensed with the cycloidal cheeks. The clock is signed 'J Bernard Van Stryp fecit Anuers', on a small silver plaque.
Another interesting feature on this clock, which has a velvet-backed dial popular with Dutch makers, is the method of indicating the time in minutes and seconds. The chapter ring has an outer circle divided for minutes but each minute division has two diagonal lines, which enables the time to be read to probably about a minute using only a single hand.
Bequeathed by Mr E. H. Brooks in 1991.
- On display (G39/dc7)
- Acquisition date
- Britain, Europe and Prehistory
- Registration number