Here we have an uncommon example of a WW2 Air Ministry RAF Issue Pocket watch Chronograph, stores reference 6A/390. It was for use by pilots and navigators during missions during WW2.
The dial is black with the contrasting white 1/5th seconds track, large luminous Arabic numerals and 30-minute counter and constant seconds. The hands are of Skeleton style and are white painted, with the radium luminous in-fill. The 30-minute counter hand is white with the arrow tip and the constant seconds hand is also white. The central second hand has the tear drop counterbalance.
The case is formed of Nickel and measures 51mm x 51mm. It is of open face style with the snap-on bezel and double hinged case back. It has the elongated crown tube with the onion style crown and loop. The pin set for the hands is to the right.
The case back is clearly marked to the rear with the ‘AM’ initials and crown, with the 6A/390 stores code. The inside of the caseback is signed with the serial number ‘129150’. The inner case back snaps open to reveal the perlage finishing on the underside.
The movement is a Lemania 19NP chronograph movement. It operates at a frequency of 18,000 BPH with a 35-hour power reserve. It displays the hours, minutes, constant seconds, central chronograph 60 seconds and a 30-minute counter.
It has the gilt finishing which is a bright and even tone. It is in very good condition, having been recently serviced. It has a daily variation of within 15 seconds per day.
Due to the need for fast turnarounds and provision, multiple makers will have produced these pocket watches, with varying levels of quality. With this having a Lemania movement, it will be one of the better-quality examples.
A stores issue publication of the time states that if a Weems wristwatch with central seconds is not available, the 6A/390 should be used. Another publication details the specifics of the 6A/390 Chronograph watch Mk. II. It states it is to be used in connection with navigation. The dial is finished in black and the hands and numerals finished in white, or treated with luminous paint. It is of 30-hour keyless winding type with the chronograph movement.
The centre second-hand the hand on the top sub dial make one revolution in one minute and 30 minutes respectively. The chronograph is controlled by depressing the winding knob. Successive pressings of this, start, stop and reset the chronograph hands.
The design and construction of the chronograph is such that the centre second hand should indicate correctly to within one fifth part of a second, and the starting and stopping errors should not exceed one fifth part of a second.
It is stated that the pocket watch should not exceed 60 seconds variation within 24 hours.
Please see the images as these compliment and aid the description provided below.
A further condition report is below.
Dial:
The dial is in decent condition. The white signing is good and clear. The gloss tone has aged, and areas are matte. The luminous on the hour markers and hands has losses with age.
Hands:
The hands are original. They are of Skeleton style and are white painted. The white paint has aged and has areas of rust. The luminous in-fill is original with losses.
Glass:
The crystal is a replacement which is in good condition.
Loop:
The crown, stem and loop are original and are in strong condition.
Case:
It is an open face pocket watch, with a snap-on front. The front snaps on tightly. It has light surface scratching associated with age and some discolouration mainly to the bezel.
Caseback:
The case back is double hinged. The outer back has the clear and defined issue markings. One side is slightly bent, meaning the back closes but leaves a gap on this side. The hinge is good and strong. The inner back is good, sealing tightly with a good hinge.
Movement:
The movement is a Lemania 19NP chronograph movement. It operates at a frequency of 18,000 BPH with a 35-hour power reserve. It displays the hours, minutes, constant seconds, central chronograph 60 seconds and a 30-minute counter.
It is in very good condition, having been recently serviced. It has a daily variation of within 15 seconds per day. It has an amplitude of 315 degrees and a beat error of 0.2m/s.
Case dimensions:
Case width: 51.25mm
Case length: 51mm
Case length with crown: 67.5mm
Case length with crown loop: 74.5mm
Case Depth: 18mm