Key Features
A pocket-sized high-precision naval navigation chronometer with official US Navy markings. The GCT Greenwich Civil Time model is designed to store the exact time of the prime meridian, which allows longitude to be calculated when compared with the position of the sun. The watch was mounted on a spring suspension and was used as a deck chronometer.
Movement Grade 4992B of an especially high class of precision on 22 jewels, central seconds with a stop function when the crown is pulled out. Serial numbers begin with “4C” and are cataloged for the US government. The back cover has military markings, military order number and serial number.
Antique pocket watches with a 24-hour time indication are quite rare, and this example with a central second and a top-class movement is a very valuable, collectible device. Everything works perfectly, and the watch runs like new.
Servicing and Guarantee
This timepiece has been serviced with full disassembly. There is a 3-month guarantee, subject to the usage and care guidelines.
Overview
Body: 
(9/10 near perfect).
Watch face: (9/10 near perfect).
Movement: (9/10 near perfect).
Accuracy: (10/10 like new).
Case
- Original circular case with ridged finished rounded edges.
- Chrome case.
- Slightly convex mineral crystal.
- Screw-done front welt and caseback.
- Numbers of the military order punched on cover.
- “Contract Number” on cover.
Dimensions:
- Width w/o crown 51 mm.
- Ring height 68mm.
Dial and Hands
- Original black dial.
- Full daily 24-hour markings.
- Plain military style numerals with 5-minute markup.
- Additional red daily 13 – 24-hour markings.
- “G.C.T.” signature.
- Original, ‘spade’ style white painted steel hands.
- Long, thin centre second hand.
Movement
- Swiss-made movement.
- Anchor escapement.
- 22 jewels.
- Manual winding.
- Antimagnetic split balance with thermocompensation and adjusting screws.
- White elinvar spiral with isochronous Breguet hairspring.
- Precision micro-controller.
- Power reserve more than 33 hours.
- Plates and bridges with Geneva wave.
Servicing and Guarantee
- Fully serviced.
- Mechanics in full working order.
- 3-month guarantee.
- Guarantee Terms and Conditions.
Links and Resources:
Longines Wittnauer Marine Chronometer with 24-hour Display.
