openings of Reims have but one mullion each, and all the tracery that branches out of it has the same section. But in the great openings of the clerestory of Amiens there are three mullions, the central one of which naturally requires to be stronger than the others, and its section is, as shown at c, Fig. 139, an amplification of the profile of the lateral mullions, whose section is given within the larger one. The three round members of the central mullion are carried out in the main tracery bars which branch from it, while the single round of the smaller mullions suffices for the tracery to which they give origin. There was little change wrought in this profile until, in the declining Gothic, sharp and multiplied arrises took the place of the rounds.
We have now examined the most characteristic profiles of the several members in which mouldings occur. The variations in proportion, in number of parts, and in the character of curves, are very great, no two profiles being ever quite the same, and yet, during the best period of Gothic, the leading types are few and simple, as well as rational and beautiful.
