The very first Longines ‘Aerochronometer’ was invoiced on the 30th of November 1928 to Longines-Wittnauer and pictured in Weems Air Navigation book of 1931. It was marked Échant[illon] Weems p[ou]r Navigation in the Longines archives It now rests in the Smithsonian, absent its crown, with the ultimate owner being none other than its original designer and architect, Philip Van Horn Weems. The other prototype made at the same time and written into the archive with the same pen and hand on that day is the piece marked Pour le Bureau (For the Bureau). The watch was for the Bureau Technique to keep. Somehow it slipped the net and found its way to the UK agent Baume.
The name heralded from Harold Gatty, the man described by Lindbergh as the ‘Prince of Navigators’, who originally used the term Aerochronometer to describe a timing device which offset aircraft speed inaccuracies when making navigational observations.
A celebrated navigator in his own right, Harold Gatty achieved international renown for his breathtaking June 1931 round-the-world flight success with Wiley Post, earning him the Distinguished Flying Cross from President Hoover. Gatty was no stranger to the front lines of aviation innovation; he worked at Wright Field, then a high-tech research and training facility for the U.S. Army Air Corps (USAAC), where he tested his own groundbreaking drift indicator. The Australian born Gatty ran Weems navigation training facility in San Diego in 1930 and later taught advanced navigation techniques at Wright Field to USAAC at personnel there, often working under the guidance of P.V.H. Weems.
It was precisely at this pivotal nerve center that Captain (later Major General) Albert Francis Hegenberger oversaw the Instrument and Navigation Unit from 1927 into the early 1930s. The Captain was already a legend for his 1927 Oakland-Honolulu flight and led the branch responsible for the development, improvement, and service testing of all crucial navigation instruments – a comprehensive remit that included octants, sextants, drift meters (like Gatty’s), and, most vitally, navigation watches.
Hegenberger’s division standardized the Weems second-setting model as a Type A-3 Navigation watch with the Materiels division allocating on June 3, 1931, and later sending 5 x Type A-2 navigation watches and 10 x Type A-3 Weems watches for service testing at Bolling, Langley, Scott, Brooks and Wright Field. The A-3 navigation watch test explicitly notes that the A-3 test “includes 2 special dial watches received from A.Wittnauer Co. on US Army Air Corps P.O 31-3402.”
The Type A-3 navigation watch requirements were developed, tested, and used by both the Bureau of Aeronautics Aircraft squadron’s battle fleet and the US Army Air Corps.
Rear Admiral Moffett, who was the chief of the Bureau of Aeronautics for the US Navy Department stated, “The suggestion… as to a moveable second-hand dial is considered to be a very valuable one, greatly facilitating the process of keeping a clock set to the exact time.”[1] Developed specifically for aviators with the Aircraft squadron’s battle fleet, it was officially designated as a “second setting navigation watch”[2] by the U.S Naval Observatory. It was later distributed by them to the US Naval air stations and fleet along with filling private and government orders for the next twenty odd years.
The central chapter on this new Longines Weems model allowed for the exact second to be set, relative to the hour and minute hands. The inner chapter ring disc could be rotated in either direction to gain an additional accuracy of +/- 30 seconds by using a radio signal or other known exact timepiece. Before 1928, watches were used with sextants for celestial calculations and accurate only to one minute.
This very first pair of Longines Weems Second-Setting watches (3585867 and 3585868), were both housed in all-silver cases using the 18.69N caliber which was first used in 1908. One of the pieces, 3585867 was the personal Aerochronometer of Weems. Both prototypes used repurposed 18.69N movements that originally heralded from Turkish dual time pocket watches that had been more than 10 years prior to the creation of the two Weems prototypes.
The unparalleled foresight and collaboration between John Heinmuller, Longines’ tenacious U.S. agent at Wittnauer, and Alfred Pfister, Longines’ brilliant technical director, ensured the Saint-Imier manufacturer secured its place at the forefront of aviation horology. Together, they are responsible for almost all of history’s most important pilot watch creations.
More than just the chief timer for the Fédération Aéronautique Internationale, John Heinmuller’s impact on aviation was profound. This remarkable watchmaker, pilot, and inventor not only meticulously recorded countless seminal flights but also cultivated deep, personal relationships with the “who’s who” of the skies. His tireless support and direct sponsorship of numerous aviation endeavors ensured Longines remained inextricably tied to the industry’s advancements and its unfolding future.
This extraordinary partnership yielded critical innovations, including the two early Weems second-setting creations and the groundbreaking prototype Hour-Angle watches. The latter famously featured the world’s first calibrated turning bezel, a revolutionary advancement that not only enabled but expedited the calculation of longitude and fundamentally shaped the future of pre radar air navigation.
Originally invoiced to Wittnauer on the 30 November 1928, it’s development and evolution was shaped by the man most responsible for conquering the challenges of 1920’s air navigation and beyond. Weems witnessed the first trans-Atlantic crossing by the US Navy’s ‘Nancy’ seaplanes in May 1919 whilst stationed on one of the navy ships below. This was described in the following passage.
“Twenty-five hundred feet below on board a station tracking ship, a young navigator, Lt. Cdr. Philip Van Horn Weems, U.S. Navy, gazed up and thought there must be a safer and simpler way than using a small armada of ships as beacons for the flight. Lt. Cdr. Weems, a brilliant, inventive and determined young man knew as he tracked that first flight that navigation was his destiny”.[3]
The air navigation techniques of dead reckoning, and pilotage were dramatically improved with the introduction of radio navigation. On 5th February 1924, Sir Frank Dyson, the Astronomer Royal, ordered the BBC to begin broadcasting the Greenwich Time Signal: the six pips that landed on the hour like a metronome of empire. Within weeks, supplementary signals followed from the United States Naval Observatory, France, Germany, and Japan. For the first time in history, a navigator anywhere within reach of a shortwave receiver could know GMT to within a fraction of a second. The Greenwich Time Signal, known as the BBC pips, enabled reliable time synchronization with a universally accessible, highly accurate, and consistent time reference signal that would soon be broadcast via multiple international radio platforms over the radio airwaves of the world directly into the cockpits of the men and women who helped write aviation’s history books.
Weems’s pioneering second-setting ideas first materialized with the modification of a Patek Philippe and a Hamilton torpedo boat watch. The first prototypes were modifications of two U.S. Navy torpedo-boat watches: one Hamilton and one Patek Philippe in late 1927. The edits were sanctioned by Rear Admiral J.M. Reeves, Commander, Aircraft Squadrons, Battle Fleet. These initial two pieces were used by Weems while training Charles Lindbergh in air navigation techniques in 1928. Unfortunately, their current whereabouts remain unknown. Building on this early work, Weems, in collaboration with master technician Dadisman of Jessop’s Jewelers in San Diego, modified Waltham Vanguard and Hamilton pocket 18 ligne pocket watches post production in 1928 and gave them the name Aerochronometer. This soon paved the way for the creation of an improved Longines second-setting wristwatch.
The modifications were done using the brilliant technician, Mr Dadisman, of Jessops Jewellers fame, in San Diego. There were a number of critical formative pieces in the development of the Longines Second Setting watch. This included Weems, his adjustable-rate clock ideas published in 1928, the Patek and Hamilton torpedo boat postproduction modified watches, the Longines technical department headed by Alfred Pfister and their dual time ‘Touran’ pocket watch which utilized a turning inner chapter. The other key playmaker was the brilliant John Heinmuller who acquired the nickname ‘Aero One’ and represented the US Longines agent.
His role at Wittnauer, the American agent of Longines, shaped, helped record and time the records of aviation’s golden age. A watch maker and innovative instrument creator, he was ably assisted by the brilliant technical head Pfister in St Imier who brought these incredible technical ideas to life.
It is important to note that Longines had already developed dual time pocket watches for the Egyptian and Turkish markets using a modified dual time 18.69N calibre first patented in 1911. Their own archive records clearly note the repurposing of Turkish 18.69N pocket watch movements originally destined for the agent Nacib Djezvidjian.
These Turkish pocket watch movements were made more than a decade prior to the delivery of the very first Weems. They were repurposed by Longines and used in the production of the first two Weems prototypes with serial number (3585867 and 3585868).
Two Turkish dual time pocket watch models used modified pin set 18.69N pocket watch movements with extra gear wheels. The first, with an inner dial had two time zones, two sets of hands, and the second pocket watch, signed Touran, featured an 18.5mm dual time turning inner chapter that mirrored the exact size of the turning disc of the prototype Weems pieces
Both pocket watch models are essential formative pieces in the evolution of the Longines 47mm Weems and the Touran lies in the Longines Museum.
Weems actual watch, the first made was invoiced on 30 November 1928 and delivered to the American agent Wittnauer . The confirmation that it is his watch comes from the unique chapter ring and the picture found in the first edition of Weems Air Navigation book published in 1931 where reference is made to it being Weems actual ‘Aerochronometer’.
The second piece made, was the very first Weems piece ever delivered outside America, and the watch was first made in 1929 and later invoiced to Baume, the UK agent on 21st June 1930.
The first two Weems prototypes have a number of unique qualities.
Both use an experimental 18.5mm chapter ring that is noted in the archives. This mirrors the inner chapter size of the Turkish dual time Touran pocket watch inner chapter.
Wittnauer order number 1395 followed for 72 Weems second setting pieces. The order was initially placed by John Heinmuller on behalf of Wittnauer the US agent for Longines. The order was placed on May 6, 1929 a few months before the Great Depression. The delivery was made in three tranches from February to May 1930. All of this order used chapter rings of 21mm diameter.
The size was later increased to 25mm in 1938 with the introduction of the ref 4356 and the 37.9 calibre.
Whilst we have no movement and lug profile picture of Weems actual watch, piece #2 has a movement stamped Patented 6 March 1911 that points to the repurposed dual time Turkish pocket watch movement from which they heralded. Both prototype pieces have consecutive serial numbers that are more than 10 years prior to their production in 1928 and 1929.
The archives note both prototypes used repurposed Turkish pocket watch movements with the patent stamp date mirroring that seen on the dual time Turkish pocket watch pieces.
Further, the lugs on 3585868 are much thicker and have much more downward curvature. This can be contrasted with the flatter lug profile production models of both the 1930 Weems and end 1931 Hour-angle production pieces.
Moreover, archive notes Dorage Rouge on this Baume delivery. This refers to the original gilt finishing of the Turkish dual time pocket watch calibers that were subsequently nickel plated on 3585867 and 3585868.
This differs to 1930 first production and subsequent Weems and Hour-angle models that were supplied with silver finish crowns. It is presumed Weems actual watch in the Smithsonian was fitted with a gilded crown.
The case hallmarks on the silver case of this second piece feature the following: a silver 925 stamp, AB for (Arthur Baume), an O which denotes the year 1929 and the other symbol recognizes imported silver along with a “1” stamp on the left of the case. The watch incredibly features its original pigskin strap and solid silver hallmarked buckle.
The hallmarks on it note the maker, EY Pearson & Son (mark registered in 1914), along with a London hallmark for 1929 and the Lion’s head stamp of the London assay office. Essentially meaning, the original buckle for the piece was made in London in 1929.
Another significant point of interest concerning this second prototype piece concerns the Longines cliché picture for this reference. The earliest pieces originally carried no reference, and Longines archives note a 1931 invoice to Perusset the South American agent of a Weems model 2106/5350 – the latter a cliché or picture number.
The Longines heritage department note they only have one archive cliché picture for the large 47mm Weems 18.69N reference in their archives. First and foremost, this cliché pic features a watch with the smaller 18.5mm chapter ring.
Secondly, the fonts on the two prototypes differ, and the cliche matches 3585868 making it the photographic ambassador for the 2106 reference.
Wittnauer’s order number 1395 was placed on the 6 May 1929 and was delivered between February and May 1930. All had larger 21mm chapter rings and all subsequent orders including the US Army Air Corps and Hour angle orders of 1931 used the 21mm chapter ring.
The who’s who of aviation would soon rely on a Longines Weems time piece or the improved Hour-angle creation that followed to help conquer the challenges of air navigation.
The creator who likely has claim to be called the grandfather of the GPS system created aviation’s pen-ultimate and most important tool watch upon which aviators and aviatrixes’ lives depended. Weems techniques and teachings lasted for almost three decades and celestial air navigation skills are returning in US Navy training courses in the event that the world goes dark.
Miraculously, the 92-year-old prototype that was the very first of its kind delivered outside America to England in June 1930 wrote its own chapter of aviation history. At some point in its life the watch was likely owned by a Millard Lee Rice of the US Navy.
A Weems Air Navigation book marked US Avigation, the original Longines box, and a US document case belonging to the airman who likely owned it was later collected from the owner below by the winner of the small UK auction.
At the time of collection, it was noted that the owner a US serviceman was based at Netheravon in Wiltshire and carried on a relationship with her great Aunt, a spinster during WWII.
The consignor’s recollection noted that his role was training UK personnel with Harvard aircraft prepping them for Spitfire sorties. The watch itself features in the TV program ‘Flog it’ above. Discoveries as to the historical importance of this Weems and its unique qualities were made in the years following its resale and with the help of Longines archives and museum.
It should be noted that P.V.H Weems was the ultimate owner of the very first Longines Weems prototype ever made. The watch was pictured in his Air Navigation book (first edition of 1931), and today, this watch lies in the Smithsonian. Incredibly, the ultimate recipient was not noted in Longines amazing archives.
Similarly, Lindbergh’s aircraft calotte, which was actually the world’s very first hour-angle timepiece, delivered in February 1929, and two Longines Hour-angle/Weems prototype wrist watches delivered to him in 1930, also lack comprehensive records in the archives concerning the ultimate recipient.
Born into a pre-radar world where air navigation hinged entirely on radio signals, this unique prototype Longines Weems second-setting watch became inextricably linked with the demands of the famous Greenwich Time Signal. Weems’s innovative concepts, initially repurposed from a dual-time Turkish pocket watch movement, found their practical realization through the concerted efforts of Longines’ American agent John Heinmuller and technical director Alfred Pfister. The radio’s BBC pips, when combined with the Weems’s ingenious mechanism, profoundly enhanced accuracy and certainty, defining this golden era of avigation. Without doubt this rare Flightbird is one of history’s most important aviation watches!!
[1] Air Navigation, Weems 1931 p401
[2] Air Navigation, Weems 1931 p401
[3] Weems & Plath, Weems & Plath Thermometers, Weems & Plath Hygrometers, Weems & Plath Barometers, Weems & Plath Weather Stations (weathershack.com)