Maxwell sur les articles de Riemann et de Lorenz :
« From the assumption of both these papers we may draw the conclusions,
first, that action and reaction are not always equal and opposite, and second, that
apparatus may be constructed to generate any amount of work from its own
resources. For let two oppositely electrified bodies A and B travel along the line
joining them with equal velocities in the direction AB, then if either the potential or
the attraction of the bodies at a given time is th at due to their position at some
former time (as these authors suppose), B, the foremost body, will attract A
forwards more than B attracts A backwards. Now let A and B be kept asunder by a
rigid rod. The combined system, if set in motion in the direction AB, will pull in
that direction with a force which may either continually augment the velocity, or
may be used as an inexhaustible source of energy. »
James Clerk Maxwell, 1868.