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The Encyclopedia of Horology

Clock · Longcase astronomical regulator

Longcase astronomical regulator

Partially verified

This longcase astronomical regulator, created circa 1768–1770, is the work of horologist Ferdinand Berthoud, with its case attributed to master ébéniste Balthazar Lieutaud. The clock features a weight-driven going train with maintaining power, regulated by a Graham-type dead-beat escapement and a bimetallic gridiron pendulum. It is designed to track both mean time and solar time, utilizing an epicyclic system with a kidney-shaped cam mechanism mounted on the back of the calendar dial. The case is constructed of oak veneered with ebony and brass, finished with gilt-bronze mounts, including Chinese-inspired fret motifs on the base. The white enamel dial provides hour and minute indications, as well as a date aperture. It was acquired by the Metropolitan Museum of Art in 1982 as part of the Jack and Belle Linsky Collection.

Full-length view of the longcase astronomical regulator in its gallery setting.
Full-length view of the longcase astronomical regulator in its gallery setting. — The Metropolitan Museum of Art. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.metmuseum.org
Category
Clock · Longcase astronomical regulator
Maker / attribution
Ferdinand Berthoud
Reference
Not recorded
Catalogue / lot identifier
1982.60.50
Source-reported date
ca. 1768–70
Source-reported place
France

Source-reported attribution and specifications are not independent authentication. A listing does not establish present ownership, current display, availability or permission to reproduce.

Object description

Movement and Functionality

The movement is constructed with two square brass plates held by five cylindrical pillars. It comprises a weight-driven going train featuring maintaining power and a spring-driven striking train. Regulation is provided by a Graham-type dead-beat escapement acting upon a heavy bimetallic gridiron pendulum. The pendulum, designed to compensate for temperature-induced variations, incorporates brass and steel rods.

The regulator is engineered to indicate both mean time and true solar time. An epicyclic equation mechanism, described in the maker's 'Essai sur l’horlogerie', utilizes a kidney-shaped cam mounted behind the calendar dial. A spring-loaded arm follows the cam's profile to regulate the motion of the solar time hand. The clock operates for approximately thirty-four and a half days on a single winding.

Evidence for this section
  • “regulated by a Graham-type dead-beat escapement and the heavy gridiron pendulum”
  • “The train drives the epicyclic system for the equation mechanism”
  • “As the clock has a duration of thirty-four and one half days”

Case Construction

The case for the regulator is the product of collaboration between clockmaker Ferdinand Berthoud and master ébéniste Balthazar Lieutaud. It is constructed from an oak carcass finished with ebony veneer and brass inlay. Decorative gilt-bronze mounts are applied throughout, featuring a classicizing vase ornament atop the hood.

The trunk includes a glazed panel that exposes the length of the pendulum. While the design shares features with other regulators in a series—such as the use of Neoclassical elements—this example includes unique details like the Chinese fretwork patterns on the base. The bezel framing the dial is designed in the form of a serpent biting its tail, accompanied by vegetal spandrel ornaments.

Evidence for this section
  • “All four clocks are signed by Balthazar Lieutaud”
  • “The Versailles, Wallace, and Metropolitan cases are made of ebony veneer”
  • “Chinese fret motifs on the base of the Metropolitan’s regulator”

Provenance and Condition

The clock is identified in the records of the Metropolitan Museum of Art as part of the Jack and Belle Linsky Collection. It was previously documented in the 1955 Art Treasures Exhibition in New York. A 1959 sale record indicates that the object was previously owned by Thelma Chrysler Foy and Madame Jacques Balsan.

Regarding its physical condition, the base of the wooden structure required replacement upon the museum's acquisition due to severe damage. The ball finial currently positioned on top of the vase is believed to be a later replacement. The movement was cleaned and repaired to a running state, though it is currently not kept in operation to preserve its condition.

Evidence for this section
  • “The Jack and Belle Linsky Collection, 1982”
  • “In 1959, it was sold by Thelma Chrysler Foy in New York”
  • “The ball finial on top of the vase is probably a replacement.”

Open research questions

  • What specific maintenance would be required to restore the equation mechanism to full operational status while protecting the calendar disk?
  • Are there remaining traces of the original blued steel mean-time hand on the internal mechanism?

Source evidence

Recorded claims and source quotations for Longcase astronomical regulator
FieldSource-reported valueSource quotation
MakerFerdinand Berthoud“Ferdinand Berthoud, Maker”
Dateca. 1768–70“ca. 1768–70”
Case makerBalthazar Lieutaud“All four clocks are signed by Balthazar Lieutaud (ca. 1720–1780)”
Dimensions90 1/2 × 21 × 12 3/4 in.“Overall: 90 1/2 × 21 × 12 3/4 in. (229.9 × 53.3 × 32.4 cm)”
MaterialOak, ebony, brass, gilt-bronze, enamel“Case: oak veneered with ebony and brass, with gilt-bronze mounts; Dial: white enamel; Movement: gilded brass and steel”
Accession Number1982.60.50“1982.60.50”
Mechanism typeGraham-type dead-beat escapement“regulated by a Graham-type dead-beat escapement and the heavy gridiron pendulum”

Visible details

  • Case features linear styling with decorative Chinese fretwork motifs on the base.
  • White enamel dial includes Roman hour numerals and Arabic minute markers.
  • Hinged bezel frame is modeled as a snake biting its tail.
  • Kidney-shaped cam component modulates the solar time display.

Research qualifications

  • The ball finial atop the hood is noted as a probable replacement.
  • The clock is not currently maintained in running condition due to installation and maintenance constraints.

Photograph identity and source facts were screened before import; rights clearance remains pending.

Consulted source

Longcase astronomical regulator

Reviewed 2026-10-26 · Record eabaee3e8c

Terms in this record

Glossary explanations for terms named in this object’s record.