Lévy changed the assumption, "the directions of principal strains coincide with those of the principal stresses", stated by Saint-Venant, to "the directions of increments of principal strains coincide with those of the principal stresses" and that was also the first attempt of using an incremental flow rule.
In 1888 Lévy inaugurated a system of boat-traction by means of overhead cables. A trial system was installed between Joinville-le-Pont and Saint-Maurice; it consisted of an endless cable which was kept in motion by powerful steam-engines and to which boats were attached and thus kept at a speed of four kilometers an hour. The system proved unsatisfactory, however.
Selected works
Lévy is the author of several works, including:
"La Statique Graphique et Ses Applications à l'Art des Constructions" (1874; 2d ed. 1887);
"Sur le Principe d'Énergie" (1888);
"Étude des Moyens de Traction des Bateaux: Le Halage Funiculaire" (with M. G. Pavie, 1894)
