The chronograph range of the Genevan manufacture ranks among the most eclectic of our era, extending from manually wound classics with horizontal clutches and the world's thinnest split-seconds chronograph with two column wheels to the monopusher chronograph with a minute repeater and an instantaneous perpetual calendar. Concurrently, with their ingenious patented time-zone mechanisms and inimitable aesthetic appeal, Patek Philippe World Time watches are among the most coveted timepieces in their category. Now, the new Patek Philippe World Time Chronograph Ref. 5930 brings together what is so compellingly complementary.

To date, only a single Patek Philippe World Time Chronograph is known, a one-of-a-kind piece crafted over 70 years ago. It is wristwatch No. 862 442 dated 1940 (Patek Philippe Museum Inv. P996) featuring a dial with pulsimeter and asthmometer scales, and it probably belonged to a physician. With the Ref. 5930, Patek Philippe is now adding the World Time Chronograph as a new member to its regular collection, simultaneously upgrading it to the 21st-century state of the art. This is an ambitious venture, because both the World Time watch and the chronograph have made epochal progress at Patek Philippe since 1940. The mechanisms have become more precise but also more complex, so it was challenging to integrate both functions into one movement.

A new mechanical microcosm

The development of a chronograph on which the sun never sets – because it always indicates all 24 time zones – is an adventure in space management. The classic World Time watch does not have a seconds hand, but the chronograph features a long trotteuse and a 30-minute counter. Where conventional chronographs have a scale graduated in fractions of a second, the World Time Chronograph has a moving city disk with place names that each represent one of the 24 international time zones as well as a moving 24-hour ring on which the time is indicated for the city that stands directly above it. So quite a few things are in motion on the dial of a World Time Chronograph, driven by mechanisms (self-winding chronograph movement, World Time mechanism) that must interact in total harmony. The difficulty of this venture is compounded by the Patek Philippe Seal directives which call for the conceivably thinnest and most elegant solution and apply to self-winding watches as well. At the same time, saving hundredths of a millimeter must avoid compromises as regards the quality and precision of the new movement. This is why each new Patek Philippe watch is subjected to months of painstaking tests to verify its long-term dependability and rate accuracy. The new World Time Chronograph Ref. 5930 passed these tests hands down.

Two proven mechanisms recombined

The elements of the new mechanical CH 28-520 HU movement are the self-winding CH 28-520 PS chronograph caliber with column-wheel control and a vertical clutch as well as the proven World Time module based on a concept developed by Genevan watchmaker Louis Cottier in the 1930s. Subsequently, Patek Philippe further optimized this ingenious solution and had two important refinements patented in 1959 and 1999.

The chronograph movement and the World Time mechanism were enhanced with extensive modifications. Axes were shifted, bridges thinned and newly designed, and component clearances changed such that the caliber CH 28-520 HU can legitimately be called a new movement. It embodies everything that belongs to Patek Philippe's proud watchmaking heritage while featuring technical and functional innovations that make it a latest-generation movement. This also applies to its operation, in line with Patek Philippe's commitment to user-friendliness. The chronograph has a start/stop pusher at 2 o'clock and a reset pusher at 4 o'clock that also doubles as a flyback pusher. When it is pressed while the chronograph is running, the sweep hand flies back to zero and a new time measurement is started automatically. Because the chronograph hand is powered via a vertical clutch, it can also be used as a permanently running seconds hand without risking undue wear and without affecting the rate accuracy and power reserve of the watch.

All the time in the world

The World Time function is also very easy to use: The hour and minute hands indicate the time in the city and time zone whose name is shown at 12 o'clock. The time in the 23 other zones can be quickly and easily determined with the city disk and the two-colored 24-hour ring which instantly tells the user whether it is day or night in the respective city and time zone. When traveling from one time zone to the next, pressing the corrector button at 10 o'clock advances the city disk and the 24-hour ring counterclockwise in one-hour steps as well as the hour hand clockwise, also in one-hour steps. The correction is finished when the city name of the destination time zone is at 12 o'clock. During this process, the World Time mechanism and the hour hand are uncoupled from the movement, so neither the amplitude of the balance nor the steady progression of the minute hand are affected. The chronograph hand also keeps moving without the slightest irregularity.

Mechanical complexity and sleek elegance

In the new Ref. 5930, the fusion of a chronograph and a World Time watch presents itself with a classic round case in 18K white gold. It features the same winglet-style strap lugs that were a key design element of the 1940s and 1950s World Time watches. The time-zone correction button is still at 10 o'clock and has the same rectangular profile as the two chronograph pushers. Their shape is a recurring theme in the manufacture's classic chronographs. Needless to say, the case is endowed with a sapphire-crystal display back that reveals the stunning beauty and flawless finish of the movement. The center of the rotor is decorated with delicate perlage, while the centrifugal mass itself features circular graining and an engraved Calatrava cross. The circular graining is repeated on the silvery bright rhodiumed bridges. Their polished chamfers, polished countersinks, and gold-filled engravings comply with the directives of the Patek Philippe Seal. They highlight beautiful contrasts against the gleaming red bearing jewels, the golden hue of the Gyromax® balance, and the purple-blue shimmer of the patented Spiromax® balance spring in Silinvar®; with its Patek Philippe terminal curve, it combines the concentric breathing of a Breguet hairspring with the svelte silhouette of a classic flat balance spring.

All displays at a glance

A look at the dial shows how seamlessly the two complications are integrated. The outermost display element in blue lists the 24 city names that each represent an entire time zone. It has been updated with new cities for some time zones – for instance Dubai instead of Riyadh or Brisbane instead of Nouméa – and takes into account the fact that Moscow changed its local time from UTC+4 to UTC+3. A small gap between the city disk and the 24-hour ring accommodates the seconds scale for chronograph measurements. It is a narrow white circular scale with fourth-of-a-second graduations. This subdivision reflects the movement frequency of 4 hertz (28,800 A/h), which allows times to be stopped to an accuracy of one-eighth of a second. The 24-hour ring, which continuously rotates counterclockwise, doubles as a day/night indicator. It has bright numerals on a dark background and a moon symbol for the nocturnal hours as well as dark numerals on a bright background and a sun symbol for the daylight hours. The center of the dial is designed along the lines of the World Time watch tradition. It sports a subtle manually guilloched decoration interrupted only by the 18K white-gold index markers and the 30-minute chronograph counter. This subdial stands out with a delicate white- gold surround, the white minute scale, and the discreet circular-grained finish. The design is not only an artistic exploit but also assures optimized legibility.

The new Patek Philippe World Time Chronograph Ref. 5930 launches in 2016 in a version with a white-gold case and a blue, hand-guilloched dial center. It is worn on a hand-stitched matt navy blue alligator strap with large square scales to match the dial. An 18K white-gold Calatrava fold-over clasp keeps the watch comfortably secured to the wrist.