The church of Notre Dame-du-Port at Clermont-Ferrand (Puy-de-Dôme)[82] (Fig. 12) (cir. 1100) has the Auvergnate characteristics just described. Its great fault lies in the darkness of the interior, a darkness more pronounced than that of the churches of Provence or Poitou because of the width and lowness of the aisles with the consequent distance of the lateral windows from the nave and the fact that they cannot be cut very high above the floor. The windows of the triforium are also small,[83] and their light is almost entirely confined to the gallery by its floor and by the smallness of the arches opening into the nave. This fault was remedied in the choir, where the light was most needed, by doing away with the triforium, and placing a clerestory beneath the half dome of the apse.[84] As a further improvement a lantern was placed over the crossing.[85] [Illustration: FIG. 12.--CLERMONT-FERRAND, NOTRE DAME-DU-PORT.] In certain churches of the school like Saint Sernin at Toulouse (nave twelfth century), the triforium was increased in size, perhaps in order that it might be used for congregational purposes, but more probably because larger windows were absolutely necessary in this portion of the church for the sake of the lighting. This theory is strengthened by the fact that Saint Sernin has double side aisles and the lateral windows are therefore too far away to light the nave. These added aisles are covered with vaults of regular Auvergnate character, even to the extent of half tunnel vaults beneath their roofs, and the remainder of the church corresponds to the structural standards of the school.[86] CHURCHES OF AUVERGNE WITH A CLERESTORY Although it might seem from the foregoing pages that the builders of Auvergne were very backward in structural technique, there are a number of churches in the school which have a clerestory in the nave. Among them is Saint Étienne at Nevers (Nièvre)[87] (end of the eleventh century),[88] in which the clerestory is obtained by raising the wall above the triforium arches just high enough to permit the introduction of comparatively small windows with their heads rising above the impost of the vaults.[89] The principle is the same as that in Provence, and no structural innovation is involved. The builders merely relied upon heavy piers and walls and salient buttresses to bear the added thrust which the tunnel vaults, thus raised, produced. That their reliance was not especially well founded is proved by the numerous cracks in the masonry. THE SCHOOL OF THE LOIRE