=Notre Dame, Paris, and Amiens.=--The plan of Amiens is regarded as the typical example of French cathedrals. Comparing it with that of Notre Dame one observes that, while both are of the basilican type, the latter is distinguished by having double side aisles enclosing the entire nave, choir, and chevêt. The only other example of this is the =Cathedral of Bourges=. In Notre Dame the transepts do not project beyond the aisles. Further, in the vaulting of the nave the system is still one of square bays, embracing two aisle bays, having six divisions in the vaulting. In Amiens, however, the groin rib and pointed arch have taken the place of the sexpartite plan and the bays are oblong. The elasticity of this later system simplified the vaulting of the curved aisle of the chevêt, whereas in Notre Dame the awkwardness of the rhomboidal spaces was ingeniously evaded by dividing each into nearly equal triangles, which could easily be vaulted. Note in both plans the disposition of the buttresses in the outer walls. It is interesting to know that the area of Notre Dame is about equal to that of the Hypostyle Hall at Karnak, while that of Amiens is smaller, but the height of its nave is 140 feet as compared with 80 at Karnak. =West Fronts.=--In all French cathedrals a special feature of the exterior is the West Front, and a comparison of that of Notre Dame may well be made with the façade of Amiens, which marks the transition to the second style, the _Rayonnant_, and with that of Rheims, the upper part of which marks the transition to the third style, _Flamboyant_. The design of all three is constructively the same--a development of the Romanesque twin towers, connected by an arcade, while a rose or wheel window is placed above the central recessed door. The spires, which were intended to crown the towers, were never built. How they would have affected the appearance may be gathered from a comparison of the West Front of =Cologne Cathedral=--a cathedral that is “completely French in plan, uniting in one design the leading characteristics of the most notable French Churches.” (Hamlin.) It is in the West Front of =Notre Dame= that the structural purport of the design is most definitely pronounced. When we study the vertical elements of the design, we note the division of the façade into three vertical masses corresponding with the interior divisions of nave and double aisles. The division is made by the buttresses which sustain the longitudinal strain of the interior arcades and the outer walls and insure the stability of the towers. And this stability is also associated with a suggestion of upward growth, due to the three setbacks in the profile of the buttresses; which setbacks, it is to be noted, correspond to the three main horizontal divisions of the façade.