[en] This paper attemps a completely logical derivation from Hamilton's principle to a purely eulerian principle. A logical step, which departs from the procedure adopted by Lin, has been taken. Since independent variations are to be taken on the velocity field, it is only natural to remove the constraints implying that the velocity is the derivative of the poarticle's position vector. This introduces a new vector multiplier enjoing a property of constant circulation along any segment fixed in the flow. This procedure yelds almost immediatly a general variational principle that can easily be specialized to the principles given by Bateman.
