Clocks · Clock
The Late Regulator by John Harrison
- Maker / attribution
- John Harrison (maker)
- Date
- 1775–1776
- Historical period
- Precision & Scientific Horology (1750 – 1850)
- Country of origin
- England
- Object type
- Clock
- Dimensions
- Overall: 485 x 400 x 200 mm
- Holding institution
- Royal Museums Greenwich
- Accession / object no.
- ZAA0596
- Credit line
- National Maritime Museum, Greenwich, London. On loan from the Royal Astronomical Society.
- Catalogue title (original)
- The Late Regulator (English)
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Record summary
Held and catalogued by Royal Museums Greenwich (object number ZAA0596), this is a clock by John Harrison, made in England, dated 1775–1776. The Atlas places it in the Precision & Scientific Horology period (1750 – 1850) of its Clocks collection. Recorded dimensions: Overall: 485 x 400 x 200 mm. The record is illustrated with 2 photographs.
Assembled from the source record's structured fields. Dates and attributions are given as the source states them; where a field is missing the Atlas leaves it blank rather than estimating.
Catalogue description
Catalogue description — Royal Museums Greenwich
This regulator is known as the ‘RAS’ (Royal Astronomical Society) or ‘Late’ regulator, to distinguish it from the earlier wooden precision pendulum clocks made by Harrison in the 1720s. It was his last word in fixed, land-based, timekeeping design and Harrison himself suggested it might, if properly adjusted, be capable of keeping time to within one second in 100 days. Made at about the same time as H3 (1740-1759), it is the fixed, pendulum controlled ‘sister’ to that timekeeper and has much in common with it. The clock has a grasshopper escapement, a 30 second remontoir, and runs without any lubrication. As far as is known the RAS regulator was never finally adjusted by Harrison, though it may be the clock shown behind him in his portrait, in a wooden case with a gridiron pendulum. The pendulum was a restoration of Gould’s (made by James Agar-Baugh) in 1928.
Historical context
Precision & Scientific Horology (1750 – 1850)
Harrison solves longitude; Mudge invents the lever; Breguet's Paris workshop defines the modern watch.
The age of the deadbeat escapement, compensated pendulums and observatory regulators. Domestic clocks spread through the middle classes: English longcase and bracket clocks, French gilt-bronze mantel clocks, Viennese Biedermeier wall clocks, Black Forest painted-shield clocks, and the first American shelf clocks.
Read the period in the timelineMore clocks from this periodEarlier: Early Modern Horology
Atlas type guide
Regulators, wall and Vienna clocks
A regulator is a precision pendulum clock used as a time standard in observatories, workshops and railway offices. Typical features are a deadbeat or Graham escapement, a temperature-compensated pendulum (mercury jar, gridiron or later invar), maintaining power and a regulator dial that separates hours, minutes and seconds. George Graham's deadbeat escapement (c. 1715) and his mercury pendulum, together with Harrison's gridiron, set the pattern for two centuries.
Wall clocks span a much wider range: the elegant Viennese Laterndluhr and Dachluhr of the Biedermeier period, the Dutch stoelklok and staartklok, English 'dial' clocks used in schools, offices and railway stations, and mass-produced spring and weight wall clocks from Germany (Gustav Becker, Junghans, Kienzle) and America.
What to look for
- Deadbeat escapement and compensated pendulum (gridiron rods, mercury jar or wood rod).
- A regulator dial with a large central minute hand and separate hour and seconds dials.
- Vienna regulators: glazed cases, slender pendulum, small weights, enamel two-piece dials.
- German factory trademarks stamped on the backplate (e.g. Gustav Becker anchor and crown, Junghans star).
Dating clues
- Graham-type deadbeat regulators: from c. 1720.
- Viennese Laterndluhr: c. 1800–1850.
- German factory 'Vienna-style' regulators: c. 1870–1930; Gustav Becker serial numbers allow close dating.
General guidance written by the Atlas editors about this kind of object. It is not a statement about this particular piece; for that, rely on the source record above and on physical examination.
Read next:Deadbeat escapementAnchor (recoil) escapementGrasshopper escapement
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