Which two surveyors conducted the grueling decade-long geodetic campaign in the 1790s to measure the meridian arc?

Jean-Baptiste Delambre and Pierre Méchain

To physically realize the definition of the meter based on the Earth's meridian, an extraordinary and arduous geodetic survey was commissioned in the 1790s. This immense task of precisely measuring the arc of the meridian fell to two dedicated scientists, Jean-Baptiste Delambre and Pierre Méchain. Their measurement campaign spanned nearly a decade, covering the challenging distance between Dunkirk in the northern regions of France and Barcelona in the south. This effort was fraught with significant challenges, including navigating the political turmoil of the Reign of Terror, which subjected the surveyors to local suspicion, and overcoming profound technical difficulties inherent in such precise astronomical observations over vast distances.