GIRARD-PERREGAUX. A RARE AND EXEPTIONAL MEN'S 18K ROSE GOLD AUTOMATIC ANNUAL CALENDAR WRISTWATCH NO.6 Model: 1966 Equation of Time Date: 08/03/2018 Case reference: 49583-52-131-BK6A Movement: Signed, 44-Jewels, Cal. 3300-0010, 18K gold oscillation weight Dial: Signed, white, gilt applied baton hour markers, gilt leaf hands, subsidiary dial for days at the 2 o'clock position, subsidiary dial for seconds at the 9 o'clock position, month aperture at the 7 o'clock position, subsidiary dial for EOT indicator Case: Signed, polished 18K rose gold, snap on exhibition back, OR No. 6 Strap: Signed, black leather, signed 18K rose gold deployment clasp Size: 40mm Accompaniments: Girard-Perregaux wooden box, user manual, paperwork (International Warranty Card) An Equation Of Time (aka EOT) complication indicates the difference between “true” solar time (that of nature) and “mean” solar time (that of man). As the earth orbits around the sun in an elliptical (oval) shape & the axis is tilted – there are only 4 days a year when the day is exactly 24 hours long April 15th, June 14th, September 1st and December 24th. All other days of the year the days are shorter or longer – depending in the position of the earth. This watch will show the difference between the “mean” time & the “true” time. Since the duration of the days are fixed year after year (at the same location) a watch can be manufactured to replicate the correction via a shaped cam which elongates & shortens the days accordingly (40mm.)