Mechanical watches have always been one of man’s ultimate mechanical wonders, though they could be considered archaic technology, with cogs and springs. This trait makes them, till this day, one of man’s most complex machines. That being said, what appears to be rather simple in its look and overall purpose, is infinitely more complicated on the inside. It goes without saying that a mechanical wristwatch is of course much smaller than most other mechanics, thus making it inherently more fragile. You see, mechanical wristwatches consist of bridges, springs, and many gears, and these perfectly aligned elements can be thrown out of whack from unseen forces external to the timepiece.
While shock and changes in temperature can play a somewhat large part in this regard, one of the biggest unseen culprits is magnetic fields.
Magnetism and Accuracy
From the time of the first mechanical wristwatch, magnetism has been the bane of an accurate timepiece. As the presence of magnetism becomes increasingly predominant, so does the potential for magnetized watches. The effects of a weak magnetic field are more of a nuisance than one might think, as even a small field can throw your timepiece off track, pushing it a few seconds ahead. And the effects of a strong magnetic field can even render your timepiece more or less useless. Where can these magnetic fields be found you may ask? In today’s world they are almost everywhere: in speakers, microphones, computers, and even mobile phones.
So if everyday items such as these can cause problems, I shudder at the thought of the magnetic fields engineers or scientists may encounter, and the effects they must have on their watches. While it may not be completely clear who invented what when it comes to magnetic watches in the late-19th century, one thing is for sure: They would have had a bearing on early anti-magnetic wristwatches.
Anti-Magnetic Watches: Beginnings and Today
While it is not entirely evident who invented the first anti-magnetic wristwatch, the IWC Pilot’s Watch Mark XI, which was introduced in 1948, was certainly one of the earliest. The 1950s would also see the likes of Omega (with the Railmaster), Rolex (with the Milgauss), and even Jaeger-LeCoultre (with the Geophysic) introducing their own versions of anti-magnetic wristwatches. These were all-purpose tool watches, built with a protective soft iron layer (also known as a Faraday cage) around the movement to nullify the effects of magnetism.
Today, the Faraday cage is still being used, but in recent years, watchmaking materials have improved so much that most Swiss-made mechanical watches meet the minimum requirements of anti-magnetic standards. That being said, watch manufacturers are now producing amagnetic wristwatches, which are even more immune to magnetism. Today, Omega’s anti-magnetic timepiece is the Seamaster Aqua Terra >15,000 Gauss, which is impervious to >15,000 Gauss, but more importantly, it achieves this feat without the use of a Faraday cage. The movement (calibre 8508) is constructed entirely from non-ferrous materials, hence the high magnetism it can withstand.
Another brand still producing an anti-magnetic wristwatch is Rolex. In 1958, Rolex introduced the Milgauss, amagentic to >1000 Gauss (hence the name), working alongside CERN. Today they still make the Milgauss, albeit with some modern improvements. The Milgauss still utilizes a Faraday cage, however, you’ll also find Rolex’s latest technology in the timepiece such as their Parachrom hairsprings and other non-ferrous materials throughout the movement. These improvements probably make the Milgauss insusceptible to magnetic fields above >1000 Gauss, but perhaps Rolex has respected the tradition of the name.
One brand that has recently reintroduced their anti-magnetic timepiece, and that I happen to think is a stroke of genius, is Jaeger-LeCoultre. In 2014, Jaeger reintroduced a limited edition Geophysic 1958, which takes many design ques from the original Geophysic from 1958. Most importantly, the new Geophysic 1958 is also amagentic. The Geophysic is powered by the in-house calibre 898/1, which can withstand serious shock, but above all, still makes use of a soft-iron inner case that protects the movement from the effects of magnetism, just like its vintage predecessor.