Linked with the name A. Lange & Söhne, the UP/DOWN display has a long-standing tradition. In 1879, Lange received Imperial Patent No. 9349 for the development of this indication, which was implemented in historic pocket watches and marine chronometers. The subject was a “device in pocket watches for recognising whether the watch is wound or unwound and for indicating how much time remains before it reaches the totally unwound state.” This was the official moment of birth of Lange’s characteristic UP/DOWN power-reserve indicator.
Wound or unwound The UP/DOWN power-reserve indicator
The power-reserve indicator was useful especially for precision watches that were relied on for navigational purposes and other scientific applications. It indicates the state of wind and reminds the owner to rewind the watch before it stops running. In the display, the “AUF” (UP) denotes the fully wound and “AB” (DOWN) the fully unwound state of the mainspring. It is a traditional hallmark of A. Lange & Söhne watches.
The 1815 UP/DOWN features a special mechanical implementation of the display. It is no longer a modular addition to an existing movement but instead is integrated directly into the confined space of the movement with a specially designed planetary gearing. The result is a thinner silhouette and more elegant proportions. The compact ensemble is based on a 1940 patent granted to Otto Lange, a grandson of the manufactory’s founder.