Combined underwater watch and depth indicator

摘要

The watch has a casing fitted with a transparent dial under which are concentric indicating discs. In the middle of the casing is the timing mechanism which operates a disc carrying a ring shaped scale, and the mechanism also rtates a second scale around it. This carries a marking member which is moved around the inner scale at a constant angular speed. An externally toothed ring on the outside of the casing can be rotated to alter the position of the working member independently of the watch mechanism. Inside the time scale is a small scale marked in metres.