- Museum number
EIGHT-DAY LONGCASE CLOCK.
Ebonised pearwood-veneered? longcase of architectural design with rising hood, the top with pediment; three-panel door, plain plinth with bun feet. :
Gilt-brass dial with winged cherub's head spandrels. Silvered brass chapter ring with hours I-XII, minutes 5-60 and trefoil half-hour marks surrounding a quarters circle. The central area with matted finish. Blued-steel hour and minute hands.
Weight-driven eight-day movement. Rectangular plates with six baluster pillars secured at the front by latches. Anchor escapement with seconds beating pendulum. Striking train for hours only controlled by a count wheel mounted on the great-wheel arbor.
Great wheel 96
Centre wheel 70 pinion 8
3rd wheel 48 pinion 7
Escape wheel 30 pinion 8
Canon pinion 36
Minute wheel 36
Minute pinion 6
Hour wheel 72
Great wheel 78 count wheel mounted on arbor
Pin wheel 48 pinion 8 (with 8 hammer lifting pins)
Hoop wheel 48 pinion 6
Warning wheel 45 pinion 6
Fly pinion 5
- Production date
- 1675 (circa)
Thickness: 1.50 - 2.30 millimetres (Dial plate)
Diameter: 200 millimetres (Chapter ring, outer)
Height: 215 millimetres (Dial plate)
Height: 195 centimetres
Thickness: 24.70 millimetres (Chapter ring)
Width: 215 millimetres (Dial plate)
Width: 36.50 centimetres
Depth: 21 centimetres
- Curator's comments
- Text from 'Clocks', by David Thompson, London, 2004, p. 76.
London, c. 1675
Height 195 cm, width 36.5 cm, depth 21 cm
This clock by Joseph Knibb displays the next stage in the development of the longcase clock. Although its outward appearance is very similar to the Fromanteel clock described earlier (registration no. 1958,1006.2099), it is deceptive because this clock has an anchor escapement and a seconds-beating pendulum about one metre long, unlike the short bob pendulum on the Fromanteel clock. However, like the Fromanteel, this clock has bolt-and-shutter maintaining power and count-wheel striking.
The new anchor escapement appears in longcase clocks soon after 1670. Over the years there has been some debate concerning its inventor. It has been attributed to William Clement on the basis of a turret clock which he made for King's College, Cambridge, in 1671. Robert Hooke has also been credited with the invention of the escapement, based on a reference in William Dereham's 'The Artificial Clockmaker' of 1696. Here Dereham states that to his knowledge Hooke had denied that Knibb had anything to do with it. Hooke, however, was not a clockmaker and there is no evidence to suggest that he ever worked on such an idea and, indeed, he never claimed it as his own.
The maker with the strongest claim to the invention of the new escapement has to be Joseph Knibb. Early in 1670 a clock with an anchor escapement was supplied to order to Wadham College, Oxford, a college which incidentally was close to the Knibb workshops in Holywell Street. Also in that same year, Joseph Knibb was charged with the job of converting the clock of St Mary the Virgin in Oxford to the new anchor escapement. While neither of these clocks provides proof that Knibb was the actual inventor of the escapement, the evidence seems to point strongly in his favour.
The escapement itself provided one significant advantage over its predecessor; the verge. The operating angle through which the pendulum needed to swing was reduced to an arc where the path of the circle and the cycloid are almost the same, thus reducing circular error to a minimum. An incidental advantage of the new escapement with its greatly-reduced operating arc was that it allowed for the introduction of the seconds-beating pendulum. This may seem on the surface to be a fairly trivial matter but it enabled the clockmaker to put seconds indication on the clock dial very simply - and seconds were by this time becoming a significant division of time, one in which those interested in accurate timekeeping had a serious interest.
- On display (G39/od)
- 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.2100 (Ilbert Collection)
Previous owner/ex-collection number: Q294 (Ilbert Ledger)