Maxwell, preparing his dynamical approach to the Electromagnetism (Treatise, Vol. II, Parte IV, Cap.VI), reaches in the previous chapter the Hamilton equations by the impulsive method, attributed by him to Thompson and Tait. The state of motion of the system is given in terms of the generalized coordinates and their momenta, these seen as a result of impulsive forces conveniently applied from rest and from the actual configuration of the system. This approach ismuch more physical than the one provided by thevery rapid one through Legendre transformation and has the merit of allowing us to see the Hamilton equations as prescribing the mutual changes of positions and momenta - let them be understood as impulses of the applied forces - while in Lagrange's method deals only with quantities associated to the masses, position and velocities.
