Longcase astronomical regulator

Maker: Clockmaker: Ferdinand Berthoud (French, 1727–1807)

Maker: Case maker: Balthazar Lieutaud (French, ca. 1720–1780)

Modeler: Mounts probably cast from models by Philippe II Caffieri (French, 1714–1774)

Date: ca. 1768–70

Culture: French, Paris

Medium: Case: oak veneered with ebony and brass, with gilt-bronze mounts; Dial: white enamel; Movement: gilded brass and steel

Dimensions: Overall: 90 1/2 × 21 × 12 3/4 in. (229.9 × 53.3 × 32.4 cm)

Classification: Horology

Credit Line: The Jack and Belle Linsky Collection, 1982

Accession Number: 1982.60.50


The case, designed in a severe Neoclassical style with added Chinese ornamental motifs, was made by one of the leading cabinetmakers, or ébénistes, of mid-eighteenth-century Paris. It is fitted with a tall glass panel in the trunk for the prominent display of the characteristically heavy French version of the gridiron pendulum that regulates the escapement of the movement. The dial displays hours, minutes, and seconds indicated by a spray of concentrically mounted hands. The minute hand, ornamented with a sunburst, was originally intended to show true solar time. (The hand for mean solar time is now missing.) Berthoud made a specialty of equation timepieces: clocks and watches that show both true solar time, which varies slightly according to the season of the year, and mean solar time, which does not. His first equation clock was approved by the French Académie des Sciences in 1752.