What did Jean-Antoine Lépine invent in the 18th century?

Jean-Antoine Lépine is renowned for his significant contributions to watchmaking, particularly for the invention of a calibre that utilized a single plate and bridges. This innovation was pivotal because it streamlined the watch's construction, allowing for a thinner case and more efficient assembly. His design provided a new standard in horology, influencing the development of watches throughout the 18th century and beyond. The use of a single plate helped reduce the overall size of watches, which was instrumental in crafting more elegant and compact timepieces that could cater to the growing demand for portable watches during that era.

While other choices mention impactful inventions in horology, they do not accurately represent Lépine’s specific contributions. The timekeeping device for ships, the chronograph mechanism, and the automatic watch movement are attributed to different inventors and advancements in the field of watchmaking. Thus, Lépine's innovation of the calibre with one plate and bridges stands out as a defining moment in watchmaking history.