The ‘Weems’ navigation watch
(From the collector’s point of view)
I recently came into the possession of a watch which was on my personal wish list for a long time. As an Omega enthusiast and aviation in general, this was a kind of watch I only knew from books. And now I had the opportunity to purchase this piece of history. After making an offer which couldn’t be refused, the watch moved from the previous owner’s wrist to my wrist. I saw this particular Omega watch a long time ago and I was happily surprised by the condition of the watch. The watch was in completely original condition, so probably nothing has been replaced over the years. Both crowns were original and the dial and hands had the right patina. The case back has an engraving which didn’t ring a bell. This needed some research. The research started with Lt. Com. Phillip van Horn Weems.
Phillip van Horn Weems was born on a farm in Tennessee U.S.A. in the year 1889. Weems graduated from the Naval Academy in the year 1912, with specialization Navigation. Due to his interest in Aviation navigation, and later on astronautics, he was always busy to simplify navigational problems for fast airplanes and vessels. In the year 1928, he took a month leave from the Navy to teach Astronomical navigation to Charles A. Lindbergh for his first solo flight.
Since the cooperation of Weems and Lindbergh there is one watch brand which helped in the development and production of one of the most well-known navigation watches, Longines. This Swiss watch brand was founded in the year 1832 by Auguste Agassiz and was famous for measuring the time for the famous Lindbergh flight. Auguste Agassiz was present at the departure from Long Island New York and at the arrival at Le Bourget Paris. Longines later on developed and produced together with Lindbergh, and probably Weems too, the famous ‘Hour Angle’ watch.
During his period as Lieutenant Commander with the US Navy, P. Weems developed in cooperation with Longines (Wittnauer in the USA) a mechanism for wristwatches to easily compensate the time difference which acts in different less accurate wristwatches. You need to understand that back in the days, in the 1930’s, navigation on land and sea was done by mainly looking at the stars in the sky. By using a sextant and a precious time measuring device it was possible to determine a position. As a time measuring device they mainly used ship chronometers. These instruments were very precise and calibrated by the most eminent observatories in the world. Alas due to small time differences large distant failures could occur in determining the course. Especially for pilots, alone in an airplane and no use of a chronometer, this was a problem. In those days wristwatches were not very accurate and it was not possible to stop the secondhand. This could cause big issues to determine the course.
On the 23rd of July 1935, Weems registered a patent numbered 2008.734. A quite complicated looking technical drawing of a dial with, at first sight, many rotating discs and hands.
How does it work
The explanation is as followed: if there wasn’t a possibility to manually set the secondhand, but you could turn the scale towards the secondhand, therefore the time difference on both movements could be set equally. In this way, you quickly can see the time difference and use it as input for the calculation. The rotating bezel with a 60-second marking turned together with the second hand until the one-minute signal was given.
In the early 1940’s the British Government realized that developments in Europe could lead to the Second World War. Because of these developments, the Air Ministry was asked to enlarge the fleet of Supermarine Spitfire aircraft. This meant that there should be more complete equipments for the Fighter Pilots. The English watch company Goldsmiths & Silversmiths Company Ltd. was asked to deliver watches according to specific guidelines. The references chosen by the Air Ministry were: 6B/159 and 6B/234, both classified as navigational watches. After the specification Mk VIIA came MkVIII.
The explanation is as followed: if there wasn’t the possibility to manually set the secondhand, but you could turn the scale towards the secondhand, therefore the time difference on both movements could be set equally. In this way, you quickly can see the time difference and use it as input for the calculation. The rotating bezel with a 60-second marking turned together with the second hand until the one-minute signal was given.
Since February the 5th of the year 1924 the BBC broadcasted a ‘timesignal’, an idea of astronomer Sir Frank Watson Dyson and the Head of the BBC, John Reith. The beeps originally came from two mechanical clocks to be found in the Royal Greenwich Observatory. These signals were to be heard worldwide and were accurate on the second. You can still hear them on the website of Wikipedia.
In the early 1940’s the British Government realized that developments in Europe could lead to the Second World War. Because of these developments, the Air Ministry was asked to enlarge the fleet of Supermarine Spitfire aircraft. This meant that there should be more complete types of equipment for the Fighter Pilots. The English watch company Goldsmiths & Silversmiths Company Ltd. was asked to deliver watches according to specific guidelines. The references chosen by the Air Ministry were: 6B/159 and 6B/234, both classified as navigational watches. After the specification Mk VIIA came MkVIII.
The first watch was built by Longines. The watch needed to have a movement which could be fine adjusted manually and a, for that time unique, central second hand. The first models were the same watches which were designed for the Lindbergh’s Hour Angle. The inner disc, however, was replaced by one with a 60-second scale. The watches had the same size with a diameter of 74,2 mm.
Just before and during World War II, the Americans also choose the Weems navigation watch. Although the numbers were bigger and the watch should have a central second hand. The specification was the same as the RAF 6B/234. Again the same as the US Air Force type A-11, with the only difference that these watches had a second stop. Therefore a rotating lunette was not necessary. They also had the Arabic numerals and more often a black dial.
The diameter of the Weems Longines watch was quite smaller than the Longines Hour Angle. The maker of the case was not prescribed, hence there are different brands who made these watches. The Weems watches had two sizes: the bigger reference 6B/234 and A11 watches with a diameter of 34 mm and the smaller reference 6B/159 (Mini Weems) with a diameter of 31 mm. The Omega watch, subject of this story, has a diameter of 34 mm but meets the 6B/159 MkIIA specification. After some research, I found out that there were about 2000 pieces ordered. It’s not known how many actually were delivered and how many still are around there.
The reference 6B/159 with specification MkVIIA needed to meet the following demands (Building Specification G.535): the movement needed to be wound by the crown instead of using a separate key. The movement should run for a minimum of 36 hours (fully wound). The hands should be made of blued steel en the case should have a rotating lunette. The case could be made from steel, chrome or hardened brass. The dial needed to be light silver or white (like enamel). The deviation needed to meet the following requirements: after three hours +/- 3 seconds, after six hours +/- 5 seconds, after twelve hours +/- 8 seconds and after 24 hours +/- 15 seconds. The Longines caliber L10 LXW with central second meets these requirements.
The reference 6B/234 with the MkVIII specification (Building Specification G.633) could have the same case but should have some different specifications in the movement and the dial. The movement could be a hand wind movement with a power reserve of 36 hours but could have a bigger diameter. The movement should have a minimum of 18 jewels which was less than the standard in the 6B/159 reference. It should have a Swiss echappement. The dial could be black now. The deviation needed to meet the following requirements: after three hours +/- 5 seconds, after six hours +/- 10 seconds, after twelve hours +/- 15 seconds and after 24 hours +/- 30 seconds. So this was less accurate than the reference 6B/159.
If during service/ maintenance these specifications were not realized than the 6B/159 reference could be downgraded to a reference 6B/234. This had to change in the protocol and on the case back. If 6B/234 references didn’t meet the required specifications, this should be removed from the system and destroyed. These regulations are to be found in the Aviation Instruction Manual. These manuals are sometimes for sale and I have a few in my collection.