It has a date function, automatic winding, 31 jewels, and a power reserve of 50 hours. The El Primero is a three-register column wheel chronograph displaying a 60-second chronograph register, a 30-minute counter, and a 12-hour counter. Rolex automatic calibers were set to beat at 19,800 vph well into the late 1970s and even early 1980s. This was an unusual and difficult feat for the day as most watches then beat between 18,000 (2.5 Hz) and 21,600 vph (3 Hz). With componentry inside the movement running at such a high pace the lubricant can dry up more quickly, and the parts themselves can suffer more wear and tear. Having a watch oscillate so many times per hour also has its drawbacks. All else being equal, which they are not, higher frequency creates a more accurate movement. The more oscillations the watch is able to make per second – or per hour – the faster the watch is able to recover and in turn get back to keeping accurate time faster. A watch that is knocked will have its balance disrupted for a short moment and then will need time to get back to normal running speed. Why would a watch manufacturer want to speed that up? The more often the balance oscillates, the less impact external forces will have on timekeeping. When it swings back, it makes a full oscillation (two vibrations or semi-oscillations). Picture a clock’s pendulum: as the pendulum swings one way it makes a vibration. Vph, (“vibrations per hour”), today often measured in Hertz (Hz), indicates how many times per hour the balance wheel rotates two vibrations (semi-oscillations) equal one full oscillation. So what does the number 36,000 actually mean? See Measuring The Time Between The Seconds: The Truth Behind High-Frequency Movements for the long answer or read on for the short answer.

View through the display back of a modern Zenith El Primero Zenith El Primero: a 36,000 vph high-frequency feat

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