Technical: Antimagnetic Watches
A mechanical watch is a complex machine, made up of hundreds of tiny parts, intricately engineered to tell the time and remain accurate despite everything thrown its way during usual, daily wear. But when daily wear becomes unusual, and the watch is exposed to extreme environments, it's inevitable that the machine might need some fine tuning to compensate.
All mechanical watches make use of a balance wheel that contains a hairspring; it regulates the movement, and keeps the watch telling the time accurately. When magnetised, the performance of this delicate coil is significantly impaired. The higher the magnetic field, the faster the spring will oscillate the balance wheel, causing the watch to run too fast—and if the intensity of the magnetic field is high enough, it can stop the watch outright.
Of course, most of the natural magnetic fields around us aren’t strong enough to drastically affect a watch’s accuracy, but as technology has developed, the sources of magnetic fields have increased. This came to the attention of the watchmaking world in the 19th century, during a period of rapid progress in electrical science, and a new understanding of electromagneticism. As our use of electricity began to increase, watchmakers realised, the implications for mechanical watches could potentially be disastrous. This was particularly relevant for those who worked in highly magnetised environments—scientists and engineers, for example—who would be unable to wear a mechanical wristwatch without magnetic waves causing utter havoc with its delicate inner workings.
As early as the 1840s, horological pioneers were experimenting with antimagnetic watches. The first solution was the simplest one—make the components of the movement out of non-magnetic materials. There is no real consensus on who created the first anti-magnetic timepieces, but certainly, Vacheron Constantin had begun to experiment with using palladium in the construction of its hairsprings and balance wheels during this period.
As with most things, however, there’s more than one way to skin a cat. In 1836, the English scientist Michael Faraday invented a way of shielding an object from electric fields with a cage formed of conductive material. Watchmakers in the 1940s and ‘50s found that they could use this principle and fit a ferromagnetic shield around a watch movement, deflecting magnetic energy away from the delicate components.
This paved the way for the creation of some truly exemplary watches. The groundbreaking Jaeger-LeCoultre Mark 11 was commissioned by the British Ministry of Defence as a reliable timepiece for its pilots, who would be sitting mere metres from the powerful engines of their aircrafts. The Rolex Milgauss, which remains a popular model in the prestigious brand’s collection to this day, was named specifically after its ability to withstand a magnetic flux density of 1,000 gauss, and was used with great enthusiasm by scientists and engineers.
