Montigny mitrailleuse
The Montigny mitrailleuse was an early type of crank-operated machine-gun developed by the Belgian gun works of Joseph Montigny between 1859 and 1870. It was an improved version of the "Mitrailleuse", () invented by Belgian Captain Fafschamps in 1851 which was a fixed 50-barrelled volley gun.
René Baillaud
He invented the "paraboloïde" a precursor of the radar. This instrument made it possible to establish the position of planes without having to see them, using only the sound they produced. The precision of the instrument was such, that it was used during the first world war by the French military, to reppel night attacks from German bombers by pointing searchlights at them. This furthermore represented a rare technological superioty for the French. After this remarkable start in the fields of acoustics, he nonetheless decided to abandon this field. The reason being that his professor's own instrument didn't get chosen by the French military, and René feared he would have no academic future in this field. He then turned chronometry.