[46] Exs., Issoire (Puy-de-Dôme), Saint Paul, see Enlart, I, p. 269, Fig. 102, or Choisy II, p. 209. Toulouse (Haute-Garonne), Saint Sernin, see Choisy, II, p. 212. Culhat (Puy-de-Dôme), Ch. Lasteyrie, p. 250, Fig. 241. Parthenay-le-Vieux (Deux-Sèvres), Notre Dame, ill. in Choisy, I, p. 205, etc.
[47] Enlart, I, p. 267, Fig. 100 and Lasteyrie, p. 413, Fig. 430.
The clerestory at Vaison is hardly worthy of the name, for its windows are cut entirely above the imposts of the vault, which is of pointed section, and therefore does not acquire thickness so rapidly as to render the windows too deep to admit a reasonable amount of light. The construction of such a clerestory consists merely in taking advantage of the pointed form of vaulting without presenting structural advances. Its windows are necessarily small and deep set and the system is not a satisfactory solution of the lighting problem.
[48] Revoil, II, pl. XVIII.
[49] Semicircular vaults were sometimes used, however. Example, Saint Paul-Trois Châteaux (Drome), Cath. (first half of the twelfth century), Lasteyrie, p. 412, Fig. 429, etc.
[50] Choisy, II, p. 206, Fig. 14.
[51] Enlart, I, p. 268, Fig. 101.
[52] Choisy, II, p. 205, Fig. 13.
[53] Lasteyrie, p. 250, Fig. 241.
[54] See statement to that effect in Rivoira, II, p. 106.