1945 Breitling Chronomat Ref. 769

Why This Watch Matters The number "217012" on the dial of this chronograph represents a Breitling patent. No one else could make a slide rule chronograph like this back in the day. The Full Story Since its invention in the 17th century, the slide rule has been used to compute basic operations and more advanced rates and conversions, far before the computer came around. Using one was more or less common knowledge; if someone needed to do any applicable calculations, the slide rule was their best friend in doing so. When Breitling released the Chronomat in 1942, it was a really big deal to have a slide rule on a chronograph wristwatch. The utility of the Chronomat was immense. Breitling wan't the first to create a wristwatch with a slide rule, but the functionality was greatly improved by the addition of a chronograph complication, allowing easy measurement of average speed and heart rate, for example. Most Chronomats, including our example here, feature the number 217012 at six o'clock