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拍品专文
Watches with equation of time are exceptional rarities, the present watch is also particularly attractive and of large size. The wonderful enamel dial with Arabic numerals has a large sector for the equation with corresponding sun hand and subsidiary dials for the date and the months. Part of a highly important watch collection for many decades, this horological treasure presents today's collectors with the opportunity to obtain a important and stunning example of a watch with equation of time.
The Courvoisier family of La Chaux-de-Fonds played an important part in Swiss watch and clock making. Several generations of the family were involved in the business through various associations. Josué-Robert with his son founded Robert Josué et fils; in 1781 the firm became J. Robert et fils et Cie. It was run by Captain Louis Robert and Louis Courvoisier. Robert's widow continued the firm from 1787 as J. Robert et fils, Courvoisier et Cie. In 1805 the name changed to Robert, Courvoisier et Cie and in 1811 to Courvoisier et Cie.
Equation of Time
For a watch with an equation mechanism, an indication of the date is always required because the equation varies continuously throughout the year. This information is useful when setting a watch to time given by a sundial. By adding or subtracting the equation for the day, as indicated by the hand, the sundial time could be corrected to mean time.
The equation of time in astronomy is the quantity that needs to be added or subtracted to switch from real time given by the sun, to the mean time; our time, which arbitrarily divided a day in 24 hours. The equation of time varies from one day to another, its value swings between around -16 to +16 seconds per day. By cumulating these differences, we obtain a variation between the real noon and the mean noon of more or less 15 minutes. The most important differences are, function of the years, toward February 12 (+14 minutes and 59 seconds) and November 3 (-16 minutes and 15 seconds). The difference is zero toward April 15, June 15, September 1 and December 24. It should be known that today, due to the summer time and the winter time, we live with a difference of two or three hours relative to the sun; our daily noon corresponding to the solar noon of Central Europe.
The equation of time also gives information about the equinoxes of spring (21 - 22 March) and autumn (22 - 23 September), as well as the solstices of summer (toward 21 June 21) and winter (toward 21 December). The equinox is the moment when the sun is on the plane of the equator, thus leading to days equal to nights. The solstice is the moment when the sun is in the farthest position from the equator, resulting in the longest day and the longest night. These dates determine the seasons of the year.
The Courvoisier family of La Chaux-de-Fonds played an important part in Swiss watch and clock making. Several generations of the family were involved in the business through various associations. Josué-Robert with his son founded Robert Josué et fils; in 1781 the firm became J. Robert et fils et Cie. It was run by Captain Louis Robert and Louis Courvoisier. Robert's widow continued the firm from 1787 as J. Robert et fils, Courvoisier et Cie. In 1805 the name changed to Robert, Courvoisier et Cie and in 1811 to Courvoisier et Cie.
Equation of Time
For a watch with an equation mechanism, an indication of the date is always required because the equation varies continuously throughout the year. This information is useful when setting a watch to time given by a sundial. By adding or subtracting the equation for the day, as indicated by the hand, the sundial time could be corrected to mean time.
The equation of time in astronomy is the quantity that needs to be added or subtracted to switch from real time given by the sun, to the mean time; our time, which arbitrarily divided a day in 24 hours. The equation of time varies from one day to another, its value swings between around -16 to +16 seconds per day. By cumulating these differences, we obtain a variation between the real noon and the mean noon of more or less 15 minutes. The most important differences are, function of the years, toward February 12 (+14 minutes and 59 seconds) and November 3 (-16 minutes and 15 seconds). The difference is zero toward April 15, June 15, September 1 and December 24. It should be known that today, due to the summer time and the winter time, we live with a difference of two or three hours relative to the sun; our daily noon corresponding to the solar noon of Central Europe.
The equation of time also gives information about the equinoxes of spring (21 - 22 March) and autumn (22 - 23 September), as well as the solstices of summer (toward 21 June 21) and winter (toward 21 December). The equinox is the moment when the sun is on the plane of the equator, thus leading to days equal to nights. The solstice is the moment when the sun is in the farthest position from the equator, resulting in the longest day and the longest night. These dates determine the seasons of the year.