The second and most iconic Patek perpetual calendar chronograph, the 2499, continued to feature the tachymeter in the first two of its four series, and these watches are considered to be the most desirable of the model. The 3970 created by Philippe Stern was actually 1.5mm in diameter smaller than its predecessor, the 2499, most likely because in the context of the '80s (Cartier Replica Watches) the idea of miniaturising a complication and diminutive case sizes were in vogue. As such, the 3970 and its split-second chronograph cousin the 5004 never featured a tachymeter. The exceptions to this are the unique execution dials of both watches made for rock legend Eric Clapton. These dials feature an Arabic 12 o'clock index with sensuously applied dot hour markers, and both a full seconds track and a full tachymetric scale.
But how do you fit this scale into a 36mm watch that already shows so much information and that features a subdial at six o'clock for both the date and moonphase indication? The solution is to me one of the greatest acts of dial design magic. The tachymeter track is abbreviated so that it disappears into the date ring from the dates of the 11th to the 21st. There are tiny markers for 130km and 110km, and nothing in between. But from a visual perspective, the speed between 130km and 110km can still be easily approximated depending on where the chronograph hand lands when you stop it. This allows you to place the minutely indexed full seconds track to the exterior of the watch replete with full 1/5th of a second markers, in accordance with the Lemania 2310's 18,000 vibrations per hour speed.
This way of abbreviating the tachymeter was something never done before in either of the 3970's antecedents. Looking at images of the 1518, you will see a fully articulated ring around the date indications at six o'clock, a fully realised seconds track and the tachymeter placed to the exterior, which makes it harder to read because the font for the speed is so small. The first two series of the 2499 use the same arrangement, though some dials feature an open date display that merges into the second track. With the unique dials of the 3970 and 5004, the inversion of the seconds track and tachymeter means that the tachymeter gains far greater visibility and is much easier to use. It also means that the print for the tachymeter can be far bolder, expressing a more performance-oriented character for the watch. Clearly, the scales used in these dials struck a chord with Thierry Stern, because when it came time to design the 5970, he used this exact design.
Practical Considerations
In designing his watch, Stern began with one critical criterion, which was to make his watch 40mm in diameter to aid visibility. Says Stern, "To me this was the perfect size of a modern classic. It also gave me significantly more space on the dial to focus on improving visibility." He explains, "My key focus was legibility. For that I needed more space than the 3970 allowed.roger dubuis replica The indication of the day and month were giving me so much trouble that I came very close to including a magnifier on the glass to enable them to be read easily. But that would have been too radical. Instead, I worked to make it as simple as possible and we tried around 20 different dials."
