In 1973 Michel Le Bellac and Jean-Marc Lévy-Leblond state that these equations are incorrect or misleading because they do not correspond to any consistent Galilean limit. Germain Rousseaux gives a simple example showing that a transformation from an initial inertial frame to a second frame with a speed of v 0 with respect to the first frame and then to a third frame moving with a speed v 1 with respect to the second frame would give a result different from going directly from the first frame to the third frame using a relative speed of (v 0 + v 1).