Born Mar. 7, 1857, in St. Aubin-sur-Aire; died Feb. 1, 1938, in Bussy, Haute-Marne. French geodesist; member of the Paris Academy of Sciences (1910).
In 1874, Lallemand graduated from the Polytechnic School. From 1884 until 1928 he was head of the French National Bureau of Surveying. He was president of the International Union of Geodesy and Geophysics from 1919 to 1933. His chief works dealt with high-precision leveling. He proposed a new instrument for determining average sea level.