100th Auction
2019/11/15
Lot 74
Frères Rey & Cie. à Genève, 258 g, circa 1820
An important quarter repeating Geneva pocket watch with jumping centre seconds, calendar and equation of time "Minutes du Soleil" - with original wooden box
Case: 18k rose gold, signed movement protection cap. Dial: enamel, rose gold minute and hour hand, rose gold sun hand for equation of time. Movm.: brass full plate movement, 2 hammers / 2 gongs, chain/fusee, open barrel for striking train, double wheel duplex escapement, temperature-compensating balance spring, large three-arm ring balance, balance stop device.
Movement, dial and case of this impressive timepiece are immaculate. The pocket watch features a rare and fascinating complication – the equation of time. Quite unusually, the equation is displayed by means of a revolving disc in the centre of the dial. The date window with month and date sits at 12 o’clock.
Equation of time: This complication turns the "Raederuhr" into a sun dial. The "Raederuhr" shows midday every 24 hours. The sun dial on the other hand shows midday when the sun is at its highest point. Due to the inclination of the Earth's axis and the ellipticity of its orbit the sun is not always at its highest point at the same time. A clock with equation shows the extend of this deviation.
This construction includes a perpetual calendar with a kidney-shaped cam plate, where the radius of the disc mirrors the daily difference between local apparent and local mean time. A lever "reads" the circumference of the disc and a toothed rack sitting on the same axis as the lever interacts with a moving gear wheel. In very basic systems, the axis of this wheel is a pointer or a disc which indicates the equation of time; in more complex mechanisms, the wheel is connected to a differential gear which controls an extra minute hand on the main dial.
Calculation of the difference between local apparent and local mean time required the invention of the pendulum clock (in 1656 by Christiaan Huygens); it was first described in 1672 by English astronomer John Flamsteed. In 1705 Daniel Quare (1649 - 1720) started designing and building longcase equation clocks, first in England and later in France; the clocks either simultaneously displayed local apparent and local mean time, showed the equation of time or could be switched between the two settings.
Source: www.uhrenlexikon.de/begriff.php?begr=%C4quation&nr=1, as of 10/03/2019.
The brothers Rey were descendants of a very renowned watch- and clockmaking family in Geneva, which already appears in the records in the early 18th century. The brothers established their business in the early years of the 19th century with a workshop in Saint Gervais; on October 1, 1821 they filed for bankruptcy.
An important quarter repeating Geneva pocket watch with jumping centre seconds, calendar and equation of time "Minutes du Soleil" - with original wooden box
Case: 18k rose gold, signed movement protection cap. Dial: enamel, rose gold minute and hour hand, rose gold sun hand for equation of time. Movm.: brass full plate movement, 2 hammers / 2 gongs, chain/fusee, open barrel for striking train, double wheel duplex escapement, temperature-compensating balance spring, large three-arm ring balance, balance stop device.
Movement, dial and case of this impressive timepiece are immaculate. The pocket watch features a rare and fascinating complication – the equation of time. Quite unusually, the equation is displayed by means of a revolving disc in the centre of the dial. The date window with month and date sits at 12 o’clock.
Equation of time: This complication turns the "Raederuhr" into a sun dial. The "Raederuhr" shows midday every 24 hours. The sun dial on the other hand shows midday when the sun is at its highest point. Due to the inclination of the Earth's axis and the ellipticity of its orbit the sun is not always at its highest point at the same time. A clock with equation shows the extend of this deviation.
This construction includes a perpetual calendar with a kidney-shaped cam plate, where the radius of the disc mirrors the daily difference between local apparent and local mean time. A lever "reads" the circumference of the disc and a toothed rack sitting on the same axis as the lever interacts with a moving gear wheel. In very basic systems, the axis of this wheel is a pointer or a disc which indicates the equation of time; in more complex mechanisms, the wheel is connected to a differential gear which controls an extra minute hand on the main dial.
Calculation of the difference between local apparent and local mean time required the invention of the pendulum clock (in 1656 by Christiaan Huygens); it was first described in 1672 by English astronomer John Flamsteed. In 1705 Daniel Quare (1649 - 1720) started designing and building longcase equation clocks, first in England and later in France; the clocks either simultaneously displayed local apparent and local mean time, showed the equation of time or could be switched between the two settings.
Source: www.uhrenlexikon.de/begriff.php?begr=%C4quation&nr=1, as of 10/03/2019.
The brothers Rey were descendants of a very renowned watch- and clockmaking family in Geneva, which already appears in the records in the early 18th century. The brothers established their business in the early years of the 19th century with a workshop in Saint Gervais; on October 1, 1821 they filed for bankruptcy.
Sold
estimated
16.000—25.000 €
Price realized
15.700 €