Sur un Critérium astronomique certain de l'existence d'une couche fluide à l'intérieur de l'écorce terrestre

In a previous note, the author checked what would be the consequence, resulting from the hypothesis of the existence of a fluid core inside the Earth, on the nutation of its instantaneous axis of rotation: this one must be driven by a motion, the period of which is the same that the one of the nutation.