An essential handbook for watchmakers, watch collectors, and watch enthusiasts. A treasure trove of knowledge for the repair of old watches. The standard work for watchmaking education. One can buy and sell watches, and even engage in their manufacture, without any knowledge of their mechanism. However, it is important to remember that ignorance is never a desirable virtue. Guided by these considerations, R. Lavest, then director of the watchmaking school at the Technikum in Le Locle, the cradle of Swiss watchmaking, authored this highly competent textbook in 1945. The work served as accompanying literature for an introductory course on watchmaking, aimed at all related professions such as salespeople, retailers, and wholesalers. It is structured in a very understandable manner, both linguistically and content-wise, and is well-illustrated.