[155] This was especially important to the Lombard builders, who always preferred the semicircular arch, which could thus be employed for all six ribs of the vault and would cause the crown to be domed up just high enough to permit the construction of the entire vault by means of a simple centering from rib to rib. See Porter, Cons. of Lombard and Gothic Vaults.
[156] See Porter, Cons. of Lombard and Gothic Vaults.
[157] Illustrated in M. H.
[158] Illustrated in Porter, Cons. of Lombard and Gothic Vaults, Fig. 19.
[159] See Porter, Cons. of Lombard and Gothic Vaults, p. 13.
[160] Examples include: Laval (Mayenne), La Trinité; LeMans (Sarthe), La Couture; Poitiers (Vienne), Cath. (portion); Poitiers, Sainte Radegonde; Brantôme (Dordogne), Ch.; Lucheux (Somme), Ch.; Airaines (Somme), Notre Dame.
[161] They are, perhaps, the earliest of the Anjou group. Enlart (Vol. I, pp. 435, note 1 and 445, note 1) gives an earlier date for Lucheux and Airaines, but the appearance of their vaults does not seem to bear out this assertion.
[162] See Choisy, II, p. 277 and p. 276, Fig. 8—A. B. C.
[163] Enlart, I, p. 437, Fig. 205.
[164] Enlart, I, p. 444, Fig. 210. See also p. 446, note 1.