With Patek Philippe Extract from the Archives confirming production of the movement of the present watch in 1912. It was completed and encased in the nickel-chromed case in 1936 and sold on 28 September 1936.
This watch, the only example of a Patek Philippe oversize aviator's wristwatch with splittable centre seconds and hour angle dial known to have been made, is a sensational and most significant discovery to the world of watch collecting and scholarship. Until recently, there was no mention, discussion or illustration of such watch in literature.
In superb, unspoilt original condition, this rediscovered treasure immediately takes a most prominent position in the hall of fame of Patek Philippe's most remarkable, exclusive and technically intriguing wristwatches.
This hour angle wristwatch by Patek Philippe is understood to be a unique prototype, made upon special request in 1936, and can only be compared with another hour angle aviator wristwatch by Patek Philippe. These watches were intended to be worn outside the pilot's suit, thus their impressive size. In fact, with a diameter of over 56 mm., these are certainly the largest size wristwatches ever made by Patek Philippe.
The "hour" hand rotates once in 24 hours, indicating the degrees of arc against the center circle divided into 360. The "minute" hand rotates once every 4 hours and is read against the scale of 60. The two second hands revolve every 4 minutes, showing the angular minutes. Consequently, the time shown here reads 332 8.5', translating into 22 hours, 8 minutes and 30 seconds, the very time that all watches show in books and catalogues.
The present watch is fitted with a superb black lacquered dial on which all scales and the signature are in "negative". In fact, whereas traditional dials have a background colour with scales and signatures printed on top, the present technique features all scales and signatures carved into the plate and filled with off-white varnish. This manner must be regarded as the ultimate state of the art in dial manufacturing. Luminous material was used to highlight the Arabic numerals and the outer 60 degrees scale as well as the hands. It is a most noteworthy fact that the luminous material is all original and was never replaced. This becomes evident when comparing the black and white 1936 archival image of the watch with the actual watch today: As the luminous material was manually applied at the time of the dial's making, there are naturally a number of small imperfections which can be found, some over 70 years later, in the very same locations. Most notable to the beholders eyes is the lacking luminous material to the final end of the crossbar of the "4" at "45" where no material was applied - still absent today.
The present watch is furthermore fitted with a single button split seconds hand (actually a split angular minute hand), allowing the wearer to stop one of the arc minutes hand for record keeping purposes while allowing the movement (and the second hand) to continue running.
This complicated mechanism is based on an ébauche commissioned by Patek Philippe and made by LeCoultre, then further upgraded with the centre seconds hands and special motion work for the hour angle time indication by Victorin Piguet & Co. of Le Sentier. During the 1920s, Victorin Piguet was in charge of supplying to Patek Philippe most of the raw movements for complicated movements, including single button and split seconds chronographs, repeaters and perpetual calendars.
Astronomical navigation, for the purpose of positioning, has always been a key mission for navies. By using a sextant, precise chronometer (later deck watches), nautical tables and a spherical trigonometric calculation the navigator can precisely define a vessel's or, later, an aircraft's position. However, such calculations which were done manually until the 1930s took up to 30 minutes. As a consequence, and in combination with the ever increasing performance and cruising speed of airplanes, there was an immediate need to facilitate these calculations. Amongst the first ones to launch a practical attempt in resolving this dilemma were US navy official Philip Van Horn Weems and Colonel Charles A. Lindbergh, supplying practical ideas and drawings to Longines. The St. Imier based manufactory integrated their suggestions and produced, in small quantities, the first wearable hour angle wristwatch as of the late 1920s. The German hydrographic office launched numerous attempts during the 1930s to once more resolve the many challenges faced in conjunction with navigation and asked A. Lange & Söhne to develop and produce a number of prototypes of marine chronometers, deck watches and aviator's wristwatches for testing and observing. An important, later addition to these hour angle wristwatches was the split second hand allowing the wearer to stop one hand for recording purposes without stopping the movement. Research shows that in January 1936, A. Lange & Söhne was asked to produce two such examples fitted with splittable hands for angular minutes for studies.
Most interestingly, scholarship understands that in spring of 1936 both Patek Philippe and Vacheron Constantin were approached by a private to develop, produce and supply a very small series of hour angle wristwatches for testing.
The two examples by Patek Philippe are:
- Movement number 170'381, the present hour angle wristwatch with black dial and splittable centre seconds, never illustrated or mentioned in literature, offered here for auction the first time ever
- Movement number 170'383, also an hour angle wristwatch with black dial but fitted with simple centre seconds hand only, is extensively described and illustrated in Patek Philippe Wristwatches by Martin Huber & Alan Banbery, second edition, pp. 252 & 253. Sold at public auction in 1991, it is now on permanent exhibit at Patek Philippe's distinguished Museum in Geneva.
The three watches made by Vacheron Constantin are:
- Movement number 260'918, an hour angle wristwatch with silvered dial, shown (archival image) in The World of Vacheron Constantin by C. Lambelet/L. Coen, p. 403. Whereabouts unknown.
- Movement number 260'919, an hour angle wristwatch with silvered dial and simple time indication. Offered at auction and sold on 14 November 1998: Auktionen Dr. Crott, Frankfurt, lot 498, then 18 May 2004: Christie's, Geneva, lot 161, then 3 April 2005: Antiquorum, Geneva, "The Quarter Millenium of Vacheron Constantin, 1755 - 2005", lot 114.
- Movement number 260'920, an hour angle wristwatch with silvered dial and splittable centre seconds, comparable to the present watch but with separate split-button in the band. An archival image of this watch is shown in The World of Vacheron Constantin by C. Lambelet/L. Coen, p. 403. Whereabouts unknown.
Further developments of hour angle timekeepers include the famous Siderograph by Longines, developed with the help of Col. Charles A. Lindbergh and made in exceedingly small quantities as of 1939. With the introduction of radio navigation the purpose of hour angle watches become obsolete and has never grown beyond experimenting and a small number of prototypes.
We are indebted to Professor Herbert Dittrich, Konrad Knirim, Reinhard Reichel and Arnaud Tellier for their valuable assistance in researching this timepiece.