The RAF expansion schemes from 1934 to 1939 provided the opportunity for forward planning for the RAF and this was accelerated after the declaration of war in 1939.
One item which needed to be procured was a hacking watch for pilots to assist with accurate navigation. This needed to be simple to use for dead reckoning navigation, not elaborate based on star shots and sidereal time using the siderograph featured above.
British and American air forces held joint meetings regarding the design of the American A-11 watch, which in Britain was sourced for the RAF and labelled the 6B/159.
The watch was to have a hacking facility, and the Weems second setting rotating bezel had provided this in a robust way, helping to simplify avigation for about 10 years. The Weems A-11 was initially manufactured in accordance with US military specification 27834, published in August 1937.
The British military deemed the A-11 Weems model too small at 27mm diameter, but Longines had produced a 34mm version since 1937, as shown below.
The 1939 Longines Weems model, serial number 5940884, is a 34mm diameter model, with blued spade hands, and red sweep second hand. The bezel lock is at 4 o'clock.
The 27mm diameter type A-11 was standardised by the United States Army Air Forces in May 1940, and had leaf hands as did the commercially available second setting watches at the time. The bezel lock is at 2 o'clock.
The RAF purchased 34mm pilots watches from 1940 onward, and engraved the case back with the part number 6B/159. Open ended leather straps were fitted prior to issue. This watch was also known as the Mk. VIIA. Early watches had a Weems rotating bezel, but later hacking movement models dispensed with this.
The Weems 6B/159 with specification Mk. VIIA needed to meet the following requirements of 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 and 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.
About 7000 Weems 6B/159 watches were produced to this specification, and they were individually numbered xxxx/40 on the case back.
There were five manufacturers of these timepieces; Longines, Omega, Jager-LeCoultre, Zenith and Movado. Omega, Zenith and Movado used the same case.
The Longines Weems is thought to be the most common, and the Movado the least common.
The watches were ordered in early 1940, and delivered in the first half of 1940.
The original January 5, 1940 order note for 2000 Omega Weems CK 2129 watches, 6B/159 is shown below.
And a compilation of the issued versions of these watches is shown below.
6B/159 Weems models.
Longines 6B/159 Weems
The Longines Weems 6B/159 models are numbered in the approximate range 1800/40 to 3700/40. A typical serial number of the watch movement is 5934652 for case 2340/40. This makes the movements a few thousand earlier in production than the smaller A-11 Longines Weems, e.g. with a serial number 5938556 for case 40-662.
6B/159 Longines Weems cal 12.68N with original flanged crown. The spade hands are identical to the 34mm diameter 1939 model seen above.
The back cover is marked with "Goldsmiths & Silversmiths" who procured the watches. "AM" stands for the Ministry of Air Force (Air Ministry).
The case serial number for all five manufacturers of 6B/159 watches runs sequentially, and the model above is 2340/40.
Observed serial numbers for the Longines models range from at least 1893/40 to 3691/40.
Another 6B/159 dial shown below with original crowns. The spring bars were fixed.
6B/159 Longines Weems
A few dials have been seen with an open 6 and 9.
Civilian models exist outside the 6B/159 order, and serial number 5992610 is shown below, with baton hands, from about 1940. The case back was sterile.
Other 34mm cases exist, a Longines Weems with lumed baton hands below is one of the last Weems with serial number 7523472 of 1947.
Below is a US Navy Academy embossed dial from the early 1940's, with baton hands.
Below is a RCAF sub seconds issue with a white dial. Serial number 6155664 calibre 10L of about 1940.
And a black dial model from about the same time, with smaller sub seconds, sold by Antiquorum in December 2004.
Finally, a 34mm version with no bezel lock, and the cal 12L fitted, serial number 6481439, about 1942, and dial with baton hands.
The Longines A-11 watch was produced just after the 6B/159, and is smaller at 27mm. Just over 1000 were thought to be made, as case numbers run to at least 40-1075. The dial is usually sterile, but rarely is signed Longines. Leaf hands were used.
The movement was cal 10L, and signed U.S. ARMY A.C.
The issued instruction manual featured the signed dial of the time.
A gold filled U.S.Navy presentation model from 1942 carried the cal 10L, movement signed U.S. ARMY A.C., so this signed movement was not confined to only A-11 watches.
Other 27mm Longines Weems continued to be produced outside the A-11 range.
A stick hand signed model below.
Serial number 6576547 from about 1942 had baton hands.
Serial number 6580945 had applied Breguet numbers.
A black dial model with baton hands is shown below.
An advertisement in January 1947 Flying magazine indicates that the leaf hand model continued in production until after the war.
The Longines 6B/159 model is seen below on the wrist of Sub Lieut (A) W N Jones, RNVR, Observer Fleet Air Arm, in Malta.
While Longines produced watches before and after the war, the other 6B/159 manufacturers only produced watches in 1940. The Zenith and LeCoultre are shown below alongside the Longines.
Zenith 6B 159 Weems
The Zenith Weems has thicker numerals on the bezel. It has one spade hand and an hourglass syringe hand. The Omega, Zenith and Movado 6B 159 all used the same case, with a cam lever set into the case at 4 o'clock to lock the bezel.
The model number 6B 159 is engraved on the case back without the / .
The movement was the Zenith 106, and case numbers are seen in the range 5586/40 to 6301/40. Zenith movements are sometimes re-cased in Movado cases, (and vice versa), as the cases are identical.
Movado 6B 159 Weems
The Cal 150MN movement was used in this model, with a spade hour hand and a tapered syringe second hand.
Observed case numbers range from 406/40 to 1579/40, with either stainless steel or plated bezels.
A Movado on a Bonklip strap is shown below.
Sometimes the Movado Weems is seen with 83817 on the dial in purple dye, or faded purple dye as shown on the 2 examples above. There is no explanation for this.
The Movado dial sometimes unsigned.
The bezel lock mechanism housing for this case is shown below.
Movado later produced a black dial Weems model in 1950, with cathedral hands, 17J cal 127 movement and about 36mm diameter.
Omega 6B 159 Weems
This watch has the Cal CK2129 movement, with 2000 ordered as noted above.
Omega case numbers have been observed in the range 3634/40 to 5580/40
The dial has a spade hour hand and a thin needle pointer second hand.
The dial is signed OMEGA with the Omega symbol.
LeCoultre Weems (6B/159 and A-11)
LeCoultre made 34mm diameter watches for the RAF labelled 6B/159, and for the USAAF labelled A-11. The cases were identical.
The 6B/159 case numbers observed are in the range 7155/40 to 8530/40, and about 600 USAAF A-11 watches were made.
The 6B/159 case back read "S. S. & S" for Samuel Smith & Sons, who procured the watches for the Air Ministry.
The LeCoultre models have the most dial variations. Blued leaf hands were used, but the dial can have radial numbers, and can be sterile.
The bezel has numbers every 5 minutes, the only 6B/159 watch to do so.
As for the Movado, 83817 in purple dye is sometimes seen on the dial.
A USAAC model is shown below, case number 468. Many case numbers were not engraved on this series, other than the LeCoultre 5 digit case number.
In about 1942 Wittnauer brought out a 27mm diameter Weems watch, signed Wittnauer, or Wittnauer Weems.
The movement was a Wittnauer 10TS, based on the Revue 56.
Production continued through and after the war, and a variety of dials exist.
Baton hands, gold filled.
The case back was sterile, but often personalised.
Stick hands gold filled.
Wittnauer 10TS movement
24 hour dial
24 hour dial black
Below is a NOS Wittnauer in original box with price tag $43.76 attached.
The Weems bezel was a robust way to provide a hacking facility on a watch, but it was crude compared with newer movements which allowed hacking directly. Throughout WW2 and soon after, the need for hacking watches meant that the Weems bezel continued in production, but as demand diminished, the Weems bezel disappeared.