Hamilton 4992b 24 hour Military Navigation Master Watch
This is a very collectable military pocket watch by Hamilton that was made in 1944. Unusually it has additinal printing in the lower centre section of the dial that says "UAL 106381" this would appear to indicate that the watch was sold to United Airlines and the numbers correspond to the serial number of the movement. Hamilton factory records show that this watch was sold to the civilian market at wars end.
The 22 jewel movement in this watch is based upon the renowned 992B railroad watch, and in converting that movement into a centre seconds piece an additional jewel was used to support the centre seconds arbor. This movement is more or less state of the art for the time featuring 22 jewels, gold timing screws to the solid balance wheel, an Elinvar anti magnetic hairspring, a sprung micr-regulator, and full adjustment in 6 positions. The movement also has a "Hacking" feature whereby pulling the crown to timesetting position stops the watch. When the crown is pressed back to winding mode the watch instantly restarts. This feature allows for accurate time setting. Allow the seconds hand to advance to the zero, pull out the crown and the watch stops, advance the minute hand to the next full minute, then when that minute is reached depress the crown and the watch starts up. The time can thus be set to the precise second. This hacking feature also enables precise synchronisation with other timepieces. These watches proved to be so accurate in service that other timepieces within the same unit were in fact synchronised to, and set to this Navigation Master Watch. Hence the name.
The movement in this watch is in superb condition, running well and keeping accurate time.
The base metal case is in fairly good used condition as it does have quite a lot of plating loss to the rear cover which is fairly common for this type of case. There are no dents or dings and the military engravings to the rear cover are all legible.
The black 24 hour dial is in super condition as are the hands and the acrylic crystal.
This is a 24 hour watch, in that the hour hand revolves once in 24 hours, and the dial is marked accordingly. Thus 6 is where you may expect to find 3 on a normal dial, 12 is at 6, and 24 where you may expect to normally find 12. Reading the time takes a little thought!!
Overall, this is a highly collectable timepiece with unusual markings in very good condition, and running really well.