A/h - Amplitude
In a watch with automatic winding, the centrifugal and gravitational forces are used as an energy source. A semicircular weight called the
or balance weight winds the spring through the arm movements of the person wearing the watch. As an automatic watch is continuously being wound, the tension spring has a sliding clutch instead of an end hook. When the watch has been wound completely, the spring descends and overstraining is circumvented.
Chronograph or chrono
This watch tells the time and is also equipped with a timer mechanism or stopwatch. A chrono can be easily recognized by the extra push buttons, which release, stop and reset the chronograph hand. This hand turns once a minute, like a second hand on an auxiliary watch face. Further small hands count the minutes, half hours, hours and even tenth of seconds respectively.
The GMT function for wristwatches was originally developed in the 1950s for pilots. Their job regularly took them back and forth between different time zones, so they needed a timepiece that did not constantly have to be set to the new local time. The acronym GMT refers to Greenwich Mean Time: the official ‘world time’ until 1928. Today it has been replaced by UTC or Coordinated Universal Time, however most watchmakers still use the older terminology when referring to watches with a second time zone. How do GMT watches work? Two hour hands show the time at your place of origin and your destination simultaneously. The additional hour hand is not read via the dial with its 12 hourly markers, but rather using the exterior ring or bezel, which has a 24-hour marking. So you read the time either ‘inside’ or ‘outside’ the dial, depending on the time you wish to know.
Helium escape valve
The helium escape valve was specially developed for use by professional divers. During deep sea dives lasting several days, divers operate from diving bells. Prior to surfacing, these bells are filled with a mixture of helium and oxygen. The helium molecules are lighter than air and can therefore penetrate the watch in sufficient quantity to push out the crystal at atmospheric pressure levels. This can be avoided by opening the valve during resurfacing, which allows the helium to escape, while preventing water from entering the watch. Please keep the helium valve closed when the watch is in contact with water.
Mother of pearl
Iridescence is an optical phenomenon that gives mother of pearl its characteristic shine and produces a rainbow of different colours depending on how light hits it. The inside of certain seashells is made up of multiple thin layers of material, which are responsible for creating this shimmering effect. Incidentally, pearls are created in a similar process. The thin overlaying layers break and reflect light differently, resulting in a colour spectrum that you can also find in a rainbow.
PVD stands for physical vapour deposition and offers the ultimate in robust and long-lasting colour and composition. In the PVD process the watch case or strap is placed in a sealed, pressurised chamber in which a material is vaporised, creating a saturated atmosphere. The basic substrate stainless steel becomes completely saturated by vaporised molecules, creating an even and deep deposition of colour. In contrast to traditional plating or lacquering techniques, which only coat the surface of the substrate, making it subject to abrasion and tarnishing through exposure to UV rays or moisture, a PVD coating does not discolour thanks to the complete penetration of the colour particles into the metal.
Super-LumiNova luminescent pigments are the latest patented development in the field of non-radioactive luminescent pigments. Thanks to their highly improved light storage capacity, these pigments can be used as luminescent markers on watch hands and dials. In essence, the photoluminescent pigments work like a light battery. After sufficient charging with either sunlight or artificial light, the stored light energy is discharged in the dark over a long period of time. This charging and discharging process can be repeated indefinitely and does not deteriorate or weaken over time.
The tachymeter scale on the watch face of a is used to measure the speed, e.g. of a car over a 1-km distance. The is activated when the vehicle passes the starting point and deactivated when the vehicle has reached the final point. The figure shown on the tachymeter scale corresponds to the speed in km per hour. The speed must be equal over the whole test distance.
A telemeter scale enables the calculation of the distance between an acoustic signal and its own position. Or, put more simply, it can be used to determine the proximity of a storm. To do this, the chronograph is started when lightning strikes and stopped at the first clap of thunder. It is then possible to gauge how far away the storm is by reading the telemeter scale and using the second hand as a counter. The scale is based on the well-known sonic speed value (343 m/s or 1,235 km/h), and was originally employed in a military context. It was used to determine the enemy's position via muzzle flashes and cannon fire.
Tritium gaseous tubes
Tritium is a colourless gas otherwise known as extra-heavy hydrogen. The name originates from the Greek word ‘tritos’ meaning third, and refers to the three components of the atom (3H). Tritium has been used for decades in all sorts of applications where constant, independent and long-lasting light sources are essential. On the dials of military watches you will often find a red, circular symbol with the notation ‘3H’ that refers to the use of tritium. In ‘civil’ watches, the abbreviation ‘T25’ denotes the same thing. In the past, luminous tritium was applied directly to the dial. Today’s watchmakers are more careful and fill the gas into fine tubes made from borosilicate glass, a highly resilient and ISO-certified glass used in chemical engineering. These Gaseous Tritium Light Sources (or GTLS) are not only exceptionally safe, they also guarantee the watch wearer at least ten years’ constant luminance – without any external energy source.