Clockmakers were continually searching for new ways of making their clocks more accurate. In 1-15 George Graham (c.1673-1751) invented the deadbeat anchor escapement, which eliminated all elements of recoil when the pallets engaged the escape %% heel, and in 1726 he created a pendulum with a glass, mercury-filled bob that compensated for temperature changes. Such mechanisms were used in precision clocks that in turn were used to regulate other timekeepers and became known as regulators. John Harrison (1693-1776) invented the marine chronometer, which enabled mariners to establish exact longitude at sea.
BRITISH, FRENCH, AND AMERICAN REGULATORS
Regulators were made in Britain and France in the
18th and 19th centuries and in the USA from the end
of the 18th century. British longcase and wall regulators had plain mahogany cases and silvered-brass dials. Minutes were indicated on the chapter ring, hours and
seconds on subsidiary dials. Early longcase regulators
had solid trunk doors and pediment tops; from c.1750 dazed doors and rounded tops were usual. French regulators were elaborate, with ornate finials, a square Top, and ormolu mounts. Dials were usually in enamel
ith a brass bezel. Most regulators were timepieces, so the vibrations of a striking mechanism did not affect accuracy; many had a system of springs for maintaining power to ensure that time was not lost during winding. Graham’s mercurial pendulum was used in some regulators; others had gridiron or wood-rod pendulums.
VIENNA REGULATORS
Vienna regulators of exceptional quality were produced during the first quarter of the 19th century. These weight-driven clocks, usually wall-hung, are of two main types: the Laterndlubr (”lantern clock”) and the more common Dachlubr (”rooftop clock”). A few longcase designs were also produced. Cases were relatively plain but well made, with a pediment top. Dials were enamelled or of silvered brass, with hours around the chapter ring. Some cases also have a beat scale – a small plaque with equal divisions – to indicate whether the pendulum is swinging equally. From the 1840s cases were more ornate, often with decorative carving. Imitations of varying quality were made in the late 19th and the early 20th century in Silesia and the Black Forest (and also in the USA), with striking mechanisms and enamel dials. The movements of later examples arc often of poorer quality.
CHRONOMETERS
Mariners relied on accurate, spring-driven chronometers to calculate longitude so as to work out their position at sea. Chronometers were made from the late 18th century, but most common today are 19th-century examples. The best were made in Britain and France. Most feature a spring detent escapement – more accurate than an ordinary regulator’s escapement. Most chronometers were mounted in brass gimbals (pivoted rings) to offset motion at sea, and held in a glazed wooden box with a lid. The case was often mahogany with brass side handles. Most examples arc of one-, two-, or eight-day duration, with an engraved, silvered dial. A subsidiary up/down dial shows how long the clock has left to run before rewinding. Dials were usually signed by the maker or retailer and have a serial number.
British, French, and American regulators
• CASES most British cases are of mahogany and very plain; French cases are more ornate, typically with ormolu mounts
• DIALS British dials have minutes around the chapter
ring, with subsidiary dials for seconds and hours
• MOVEMENTS most have a precision deadbeat escapement, often ten with jewelled anchor pallets to reduce friction; wooden rod, mercurial, or gridiron pendulums were used to balance temperature changes
Vienna regulators
• CASES these are usually in a very fine Classical style,
with a pediment top and six or nine glazed sections
• DIALS most are of enamel or silvered brass, with hours around the chapter ring
• MOVEMENTS these are very similar to those on other European regulators and extremely finely made
Chronometers
• CASES most are mahogany, but those made for private yachts may have more expensive veneers such as rosewood; lids are often missing or replaced
• DIALS subsidiary up/down dials showing time left
before rewinding were typical; Arabic numerals were common on American 1940s chronometers
• MOVEMENTS escapements are sophisticated and need regular overhauling to keep accurate time

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