When it became a question of dividing this corner of the French Empire, the final act of the Congress of Vienna prescribed in Article 25 that in the former Department of the Ourthe the five cantons of St. Vith, Malmedy, Cronenberg, Schleiden, and Eupen, and the extreme point of the canton of Aubel to the south of Aix — la-chapelle, shall belong to Prussia and the frontier shall fol low the boundaries of those cantons in such a manner that a line drawn from the south to the north shall strike the said point of the canton of Aubel, and be continued to the point of contact of the three ancient depart ments of the Ourthe, the Roeure, and the Meuse.