Speedmaster Speedsonic

1974

ST 188.0001

The chronograph function is a mechanism for measuring time intervals. A chronograph watch can therefore be used to time events while displaying the time like any traditional watch.

Label given to a watch which has undergone precision tests and received a certificate from an official body (COSC).

Apertures which display both the day of the month (numerical) and the day of the week.

A tachymeter watch has a function for measuring speed. It is a chronograph with a graduated dial on which speed can be read in kilometres per hour based on a 1000 metre distance.