The new Lange 1 Tourbillon Perpetual Calendar in White Gold makes February 29th a holiday for friends of fine watchmaking.
February 29 is the secret holiday for the owner of a watch with perpetual calendar. For on this date the gregorian calendar gives us an extra day. This is necessary because the Earth does not revolve around the Sun in exactly 365 days, but in 365 days, 5 hours, 48 minutes and 45 seconds. This means that we miss a quarter of a day a year. So that we do not celebrate one day Christmas in the summer, an additional day compensates for the difference between the sun and the calendar year every four years.
Again this year, the timers with eternal calendar can show again what is in them. And indeed twice. Not only do they have to correctly reflect the transition from the 28th to the 29th of February, but they must also move right to the 1st March at the end of the day. What sounds simple is a great technical challenge. It is important to develop a mechanical program that records the different lengths of the 48-month cycle in a four-year cycle. As a rule, this task is carried out by a wheel with 48 teeth, in which the information on the duration of the month during a four-year cycle is permanently stored in the form of differently deep incisions.
In the Lange 1 Tourbillon perpetual calendar model, the product developers from A. Lange & Söhne went a completely new way. They moved the monthly display to a large circulating ring that rotates around its own axis in 30-degree increments every year. The construction is equipped with different recesses for the respective month lengths and with a complex scanning mechanism, which also takes into account the switching periods. In addition, all the ads of the perpetual calendar are jumping forward and can be clearly read at any time. The power of the relay is slowly built up over a period of 24 hours. The shifting therefore does not affect the gear. The mechanism is designed in such a way that it has to be corrected by one day in 2100.
