Calibre 19.73

Notes

The 19.73 was the first Longines chronograph calibre designed from the ground up to be a chronograph calibre rather than being adapted from an existing time only calibre. It had an instantaneous jumping minute counter and was very commercially successful in medical, military, and sports timing applications. Derivatives of this movement would be produced by Longines for 31 years and the subsequent 18.73 and 13.33Z chronograph movements are based upon a similar architecture.