The word perpetual, simply being something that happens frequently to the point of seeming endless and uninterrupted. In the watch world, there is such a vast array of different complications in timepieces. Chronographs, moon-phases, day-dates, split-seconds, tachymeter - so many complications for so many reasons, but the one we rarely talk about due to its high manufacturing cost and overall rarity is the perpetual calendar movement.

In looking at the start of this article, the literal definition of perpetual is something without end, but what would that mean in a watch movement? The primary function of a perpetual calendar is to keep track of minutes, hours, days, dates and years (including leap years), all while being completely mechanical. From personal experience, trying to wrap my head around something that seems so vastly complicated, no pun intended, was difficult at first. Once we pulled the sheet away from the mysteries of the perpetual calendar, it all started to make sense. Patek Phillippe, Audemars Piguet, and A. Lange & Sohne are the most notorious brands known for creating these magnificent movements. We will focus on the Patek Phillippe Grand Complications ref. 5320G Self-winding Perpetual Calendar strictly for a visual so you can see just how beautiful these movements are.

Patek Cal. 324 S Q / Credit: Patek Phillipe

The complicated movement goes back as far as the late 1700s. Invented by English watchmaker Thomas Mudge in 1762, the inventor of the detached lever escapement. The perpetual calendar was originally intended for pocket watches. A century passed, and Patek Phillippe created their version of this complicated movement. However, it would take approximately 25 additional years for Patek to have the rights to the patent to create their high-complication for smaller-scale watches, primarily the wristwatch in 1889. What came from this is a watch that will track up to four years accurately without any adjustment. How does it work does this complex movement work though?

Patek Phillipe Grand Complications ref. 5320G / Credit: Patek Phillipe

This high-complication is a mechanical marvel in its own right. Demonstrating years going by with supreme accuracy without a battery is incredible, but easily explained. Essentially, the movement tracks the month and dates by an internal mechanism or wheel (which rotates every four years) to precisely register the rest of the day, month, and year change indications. A perpetual calendar movement has separate mechanisms for each calendar indicator. Since there are mechanisms for each indicator, there needs to be something to make them synchronize. That is where the grand lever comes into play. The lever sits on top of all the mechanisms then passes through the axis for the watch hands creating a synchronized mechanism. While that explains how the movement works, how does it accurately track the day, date, month, and year? First, the movement recognizes that there are 28 days in each month. Every 25th day of each month, the movement proceeds to figure out how many extra days are needed for that month based on a program wheel inside the watch. The program wheel also dictates changes for the leap year, so no need to worry about that.

Ultimately, the perpetual calendar is an engineering marvel and is at the top of the movement scale. While these movements are rare and cost a pretty penny, it is clear why these are the highest class of watch mechanics available.

By: Tyler Frederick

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