WW2 Hamilton GCT Navigators pocket watch, AN5740, cal 4992B Serviced
Patent 33106
Serial number AF43-15425
Contract No. W535ac-40783
Hamilton Greenwich Civil Time
 
This is a beautiful, functional piece of military history, used by the US forces during WW2.
 
It was known as a “Navigators Watch” as it was used by aviators. See the advert in the images which demonstrates the kind of use this pocket watch may have seen.
 
The pocket watch will often be seen in a case or a box that was intended to isolate it and protect it from shocks or accidental damage. Sadly this does not have the accompanying box, but they are very rare and make the pieces significantly more expensive in accordance with this.
 
The dial is 24 hours meaning it takes a full day for the hour hand to rotate. The minute hand still progresses around the dial as per usual. The watch also has a hacking feature, meaning the second hand stops when you pull the crown out. This ensures very precise time setting. The large, central second hand is a clear indicator of the importance of precise timekeeping in the display of the time. 
 
This particular example says AF which means it was issued to the Army Air Forces, with the 43 standing for the initial date of contract. There were 24,000 of these produced in this specific contract with the lowest case serial being AF43-7001. This example dates to 1944.
 
The movement was based on the 21 jewel, 16 size 992B movement. However, an extra jewel was added to support the second hand pinion, meaning the movement had 22 jewels and was called the 4992B. The movement has been recently serviced. 
 
 
Please see the images as these compliment and aid the description provided below.
 
Dial: 
The dial is original and has a black matte finish designed for contrast against the white writing. It is in good condition with no major scratching and quite an even tone overall. 
The dial is signed G.C.T to the centre, with a 24 hour inner hour track. The outer track is for the minutes and seconds which function normally.
 
Hands: 
The hands would appear to be original and are white in tone for visibility in the dark. They are in good condition with limited corrosion and no bending.
 
Glass: 
The glass appears to be original as it fits the profile of the watch very well. It has some light surface scratches. It is in good condition.
 
Crown and loop:
The crown is original and is in good condition, with some minor wear to the plating from use.
The loop is beautifully stylised and is original. It is in good condition with light surface scratching. 
 
Bezel:
The bezel is base metal, has a good coin edge finish and screws in place properly as it should, the thread is good. There are light scratches. Overall it is in good condition.
 
Case:
The case is base metal and is in good condition. There is some light wear to the plating in patches. There is light surface scratching consistent with age. There is one small dimpled dent to the bottom, visible in the images.
 
Caseback:
The case back is in good condition for its age with the manufacturer writing being clear, with minimal scratching and only minor wear to the centre of the plated finish. It has a coin edge which is in good condition. It screws in place properly as it should, the thread is good.
 
Inside of caseback:
The inside of the caseback is signed “Keystone”, “Base metal” with the serial number 904552. It is in very good condition.
 
Movement:
The movement was based on the 21 jewel, 16 size 992B movement. However, an extra jewel was added to support the secondhand pinion, meaning the movement had 22 jewels and was called the 4992B.
 
The movement is in very good condition for its age cosmetically. The movement has also been recently serviced.
It has a daily gain of +10 seconds a day, with an amplitude of 280 and a beat error of 1.4m/s.
 
Case dimensions: 
Case width: 51.5mm 
Case length: 51.5mm 
Case length with loop: 64mm 
Case length with crown: 57mm 
Case Depth: 18mm