Glossary of Watch Terms.

elapsed time rotating bezel: A graduated rotating bezel (see rotating bezel") used to keep track of elapsed time. The bezel can be turned so the wearer can align the zero on the bezel with the watch's seconds or minutes hand. After a period of time passes, you can read the elapsed time off the bezel. This saves you having to perform the subtraction that would be necessary if you used the watch's regular dial.

escapement: Device in a mechanical movement that controls the rotation of the wheels and thus the motion of the hands.