In 2009, when Patek Philippe presented the caliber CH 29-535 PS, its then latest proprietary chronograph movement based on classic principles (manually wound, column wheel, horizontal clutch), it was already clear that some day, it would be followed by a caliber with the acronym CHR, which stands for CHronographe à Rattrapante, the French term for split-seconds chronograph. That debut took place in 2012: Patek Philippe launched the Ref. 5204 split-seconds chronograph with a perpetual calendar, a watch type that adrenalizes collectors of the brand. Now, for the first time, the Ref. 5370 incorporates the fantastic caliber CHR 29-535 PS in its pure form without the added complication of a perpetual calendar. Because it is focused exclusively on time measurement, the Ref. 5370 has a decidedly masculine face that appeals to men for whom certain values are important, among them time, authenticity, tradition, functionality, precision, discretion, and timelessly sleek elegance. 

With the Ref. 5370, Patek Philippe also extended its range of pure split-seconds chronographs with a two-pusher model, a stopwatch with two pushers for the basic start, stop, reset functions and an additional on/off button in the crown for the split-seconds function. This contrasts against the ultra-thin Ref. 5959 monopusher split-seconds chronograph which has a single consecutive-action pusher for the basic start, stop, reset functions (3-phase column-wheel control) and an additional pusher for the rattrapante hand.

 
A stellar achievement by the dialmakers 

A glance at the dial illustrates what in Geneva is deemed functional beauty: fast and exact legibility without unnecessary embellishments that distract from the essence. Thanks to slender leaf-shaped hands with luminous coatings as well as the applied Breguet numerals in white gold, the time is eminently readable. Stopped times are also superbly legible with the slender chronograph and congruent split-seconds hands in rhodiumed steel as well as the instantaneous 30-minute chronograph counter hand in white gold and the white printed scales that stand out prominently against the black background. And it is not just black, it is intensely black, as is possible only with genuine enamel. This emphasis on tradition is reminiscent of the most fetching Patek Philippe pocket watches from the company's early history and of the roots of the Stern family which owns the manufacture; when they acquired Patek Philippe in 1932, the Sterns were already held in high esteem for the dials crafted by their "Cadrans Stern Frères" business. 

Enamel dials, then as now, challenge the skills of the dialmakers to the extreme. The solid white-gold dial of the Ref. 5370 split-seconds chronograph is first coated with black enamel by hand. The coating is melted in an oven at 850°C and then allowed to solidify to a glasslike consistency by controlled cooling. The result is an intense black that preserves its depth and gloss across centuries, as we know from ancient enamel artifacts found in Greece. At this point, small bores must be cautiously drilled into the hard, but also brittle, enamel to accommodate the tiny feet of the applied white-gold Breguet numerals. They contrast well against the black enamel as well as the white printed scales, one of which is a tachymeter scale calibrated to 1000 meters. It underscores the instrument-like personality of this split-seconds chronograph and contributes significantly to its masculine appeal. 

Power for tomorrow 

The caliber CHR 29-535 PS movement, developed and crafted in-house, has so far only been built as a version with a perpetual calendar. Now, to the delight of purists, it is available as a pure split-seconds chronograph that melds tradition with innovation. Its traditional facet is the underlying concept of a manually wound movement with column-wheel control and a horizontal wheel clutch that remains the benchmark for many friends of mechanical watches. To preserve this heritage in the 21st century, it was optimized in many respects and endowed with patented innovations that make this caliber the most progressive classic of its genre. 

• Clutch wheels with patented tooth profiles boost efficiency in power transmission and reduce wear. 

• The mesh depth of the clutch wheels is not adjusted with an eccentric next to the clutch lever; this is done much more precisely and easily with an eccentric column wheel cap at the outermost end of the clutch lever. 

• Self-adjusting hammers in jewel bearings simplify the servicing procedure. 

• The brake lever that stops the chronograph wheel is directly synchronized with the clutch lever. 

• The slotted minute-counter cam coasts the chronograph and split-seconds hands to a stop rather than abruptly blocking them. 

These new features of the mechanical chronograph are joined by innovations dedicated exclusively to the rattrapante function: 

• When lap times are stopped, a newly designed isolator uncouples the split-seconds wheel from the chronograph wheel to eliminate unwanted friction and prevent a degradation of balance amplitude while the split-seconds hand is immobilized. 

• The split-seconds lever that positions a ruby roller between two flat heart cam shoulders keeps the chronograph and split-seconds hands precisely aligned as long as they are superposed. 

These mechanisms are not only ingeniously designed but also lavishly finished by hand as befits a Patek Philippe movement. Most steel parts are painstakingly chamfered and their surfaces straight-grained; the split-seconds clamps are polished. The magnificent interplay of bright glossy and lustrous silky areas is enhanced with contrasting golden hues and sparkling red bearing jewels, showcasing watchmaking artistry that can be admired through the sapphire-crystal case back. This quality of finissage is expressly mandated by the Patek Philippe Seal, the watch industry's strictest set of  directives, as is the extremely high degree of accuracy that only tolerates deviations ranging between +2 and -3 seconds per day. 

A platinum case in point 

The CHR 29-535 PS caliber comes in a platinum case of befitting stature. As the movement itself, it is crafted in-house all the way from the original design and the blueprints to the 60-ton cold-forming presses, after which it is deburred, ground, and polished in time-consuming finishing processes. In the end, as is customary for all of the manufacture’s platinum cases, a flawless Top Wesselton diamond is immaculately set in the caseband at 6 o’clock. The last family-owned Genevan manufacture: Patek Philippe's creative department is in the family's hands as well: Sandrine Stern, the wife of manufacture president Thierry Stern, is at its helm. The Ref. 5370 is an opus of her design talent that has all the assets needed to become a grand classic. Its gently sculpted curvatures and contours interact in a sublimely harmonious way. The concave bezel merges the soft camber of the sapphire crystal with the case, and the oval chronograph pushers on either side of the new turban-style crown with the integrated rattrapante button are symbols of balanced polarity. The strap lugs feature reworked flanks that merge with the case in a gentle curvature and have a fine horizontal satin finish which emphasizes their slenderness. Additionally, the lugs do not merely taper out at the position of the strap bars but instead are terminated with fine cambered white-gold cabochons. Even though human nature is at odds with absolute perfection, Patek Philippe has once again come very close with the Ref. 5370. For the few individuals who will have the opportunity to wear it on their wrists, this latest creation of the Geneva workshops is a truly uplifting experience.