Automatic wristwatch with date

Description — British Museum

Automatic wristwatch with date Strap Brushed stainless steel and gold plated link strap. Case Stainless steel case with screw in case back. Gold screw-in crown at 3 o'clock. Automatic helium valve at 10 o'clock. Black ceramic rotating bezel, with arabic numerals (10-50) with gold edging. Sapphire crystal. Dial Black dial with horizontal grooved pattern. Luminescent indexes for hour markers. Date aperture at 3 o'clock. Luminescent hour and minute hand, seconds hand having luminescent arrow-head tip. Movement Automatic movement based on Selita SW 200 26-jewel movement.

Curator's comments — British Museum

The watch came in a large black cardboard and faux-leather presentation box. The box was not registered, but photographs were taken and are attached to this record. For a similar presention box from TAG Heuer see object 2018,8024.2 The watch has a rapid date change, helium release valve, is waterproof to 500m and has a power reserve of 38 hours. The balance frequency is 28,800 vph The helium escape valve (found at the 10 o'clock position on this watch) is a feature found on some diving watches. When diving to depths over 250ft divers travel down in a diving bell which is saturated with helium and hydrogen. The helium atoms are very small and can enter the divers watch. On returning to the surface as the watch depressurises the build-up of helium inside the watch could cause the crystal to pop off. The helium escape valve can be opened during decompression to release the helium safely.