Father Jean-Baptiste de La Chapelle, born about 1710 and probably died in 1792 in Paris. Before a large audience, he jumped into the Seine, eating, drinking, snuffing, discharging a pistol and writing while floating on the surface. He tried again, three years later, this demonstration before Louis XV near the royal hunting lodge in the forest of Senart, but his attempt failed when the current swept him away so fast that the king could not identify what happened to him.
His invention was a cork suit for soldiers, a precursor to the modern life vest. [Found here.]