We investigate the possibility that the Newtonian potential becomes progressively Harmonic when distances increases, as suggested in the Friedman’equations. Transition between the two potentials is describe by the forces of Darboux. Model doesn’t need dark matter or dark energy, allows to conserve energy and angular momentum and leads to flat curves of rotation at the periphery of galaxies. Dark matter is replaced by an increasing of ratio gravitational/inertial mass linked to the modification of potential.