The first decades of the nineteenth century are characterized by the publication of numerous French engineering and architecture treatises. These treatises are important for the formalization of the solution of structural mechanics problems: in particular the tests of resistance in bending. It is a difficult path, bounded with Galileo's theories, with the mathematical and theoretical apparatus and with experimental tests as well. The proper solution to the problem is marked also by intuitions, errors and false ideas but, above all, by a huge experimental research in order to find the rules related to the strength of materials, which the design can be based on. The attention was focused on the works by Pierre Simon Girard, Jean-Baptiste Rondelet, Jean Henri Hassenfratz, Emiland Marie Gauthey, Joseph Mathieu Sganzin, Claude Louis Navier, preceded by a brief introduction to the works by Antoine Parent and George Louis Leclerc Comte de Buffon, to which constant reference is made. In this study reference is made to wood, whose mechanical characteristics let the observation on the mechanical behavior in bending possible.