Léon Brault (1839-1885) entered naval service as a young man and received a scholarship to attend l’Ecole Polytechnique in Paris. He was assigned to naval vessels from 1861 and was promoted to lieutenant de frégate in 1863 and lieutenant de vaisseau in 1867. While recovering from a bout of dysentery in 1868, Brault developed his ideas about hydrography and the representation of winds. He was granted permission to study the records of the Dépôt des cartes et plans. He returned to active service during the outbreak of war in 1870, only to be struck down again with dysentery.
By 1872, he was back at the Dépôt. He toured the five naval ports of France—Cherbourg, Brest, Lorient, Rochefort, and Toulon—reviewing thousands of journals and logs. His diligent research and intelligence impressed his superiors; in 1872 was named a chevalier of the Légion d’honneur. His first charts, of the Atlantic, appeared in 1874. His work earned him accolades at the International Congress of Geographic Sciences held in Paris in 1875, the first of several awards for his charts. In 1878 he was appointed Head of the Meteorology Bureau at the Dépôt. He died in 1885 at the age of 46.