- Museum number
Clock on inclined plane of type invented by William Congreve; ball rolling down zigzag grooves in open frame with columns at sides; surmounted by three silvered-metal rings indicating seconds, minutes and hours; original Sheraton satinwood case with stepped base and columns surmounted by domed glass hood.
Gt wheel 84 (Fusee with 14 turns)
2nd wheel 50/31
3rd wheel 96/50
4th wheel 100/8
5th wheel 96/10
6th wheel 2/10 ("wheel" has 2 locking pins)
- Production date
Height: 24 inches
Length: 17 inches (square)
- Curator's comments
- Text from 'Clocks', by David Thompson, London, 2004, p. 148.
Santiago James Moore French
Rolling Ball Clock
Royal Exchange, London, c. 1830
Height 61 cm, base width 43 cm, depth 43 cm
Sir William Congreve (1772-1828) was the second son of Lieutenant General Sir William Congreve. Like his father, he was a military man serving in the Royal Artillery. As Comptroller of the Woolwich Laboratory he developed rockets first used in naval attacks on the French fleet at Boulogne Harbour in 1805 and 1806. In later life he was Member of Parliament for Plymouth (1820-1828) but is perhaps best known for some ingenious inventions, including a colour printing system. In the horological world his name lives on in the form of a clock controlled by a steel ball rolling down a sloped track. He was granted a patent in 1808 for his 'extreme detached escapement' and his rolling ball clock. The original weight-driven clock can still be seen in the Rotunda building of the Royal Artillery Museum at the Woolwich Arsenal.
Although his clock was a serious attempt to improve timekeeping, it was anything but successful in that respect. On the other hand, the design found immediate popularity, and clocks incorporating it have been made by numerous makers from the early nineteenth century to this day. While many see these clocks as an attempt at perpetual motion, there is no mystery involved. The ball rolling down the track does not drive the clock, but simply determines the rate at which the clock runs. Each time the ball reaches the end of its run it hits a release lever which unlocks the grooved tray. The power of the mainspring is then transmitted through a train of gears which tilts the tray and locks it so that the ball then begins its journey back down the track until it reaches the bottom and triggers the release to repeat the process. The ball is timed to take just thirty seconds to make its journey, but all manner of influences such as temperature change, humidity change and dust on the track conspire to make these clocks bad timekeepers.
This particular clock, in a most elegant satinwood case, is glazed all round and with a large glass dome at the top. It was made in about 1830 by the firm of Santiago James Moore French, whose business was at 15 Sweetings Alley, Royal Exchange, London, and it is signed 'French Royal Exchange London 470'. The three dials indicate hours on the left, minutes in the middle and seconds on the right, although the seconds hand moves from 60 to 30 and so on as the table tilts and does not show actual seconds. A more detailed seconds indicator exists in the form of a slide above the table where the seconds are indicated through a series of small windows, 0, 5, 10, 15, 20, 25, 30 and, when the table tilts, the slide moves to show 30-60 in five-second intervals.
- On display (G39)
- Latest: 2 (2018)
- Acquisition date
- Acquisition notes
- The Ilbert Collection of clocks, prints and other related material was destined to be sold at Christie's auction house on 6th-7th November 1958. As a result of the generous donation of funds by Gilbert Edgar CBE the sale was cancelled and the material purchased privately from the beneficiaries of the Ilbert Estate.NL1Ilbert's watches were then acquired with further funds from Gilbert Edgar CBE, public donations and government funds. These were then registered in the series 1958,1201.
- Britain, Europe and Prehistory
- Registration number
- Additional IDs
Previous owner/ex-collection number: CAI.2137 (Ilbert Collection)
Previous owner/ex-collection number: P336 (Ilbert Ledger)
Previous owner/ex-collection number: Q304 (Ilbert Ledger)