[59] It is true that fissures in a properly constructed vault are not necessarily alarming. Any vault may crack from unequal settlement of the supports. Gothic vaults are sometimes slightly ruptured in this way, but they are not thus endangered, because they are effectively buttressed. But fissures in a dome without abutments may be a sign of impending collapse. [60] _Ibid._, pp. 328–329. [61] _Ibid._, p. 388. [62] _Op. cit._, p. 399. [63] The principal work of Bramante’s immediate successors on the fabric itself appears to have been to strengthen the great piers, which seem to have been built too hastily, and on insecure foundations. Poleni tells that in order to strengthen these foundations, well-holes were dug under them and filled with solid masonry, and that arches were sprung between these sunken piers, consolidating the whole. _Op. cit._, p. 19. [64] _Ibid._, p. 19. [65] I call the end of the sanctuary “the east end” according to the nomenclature of the usual orientation. St. Peter’s, as is well known, does not conform to the general rule which has prevailed since the fifth century. [66] These vaults may have been begun by some of his predecessors. It is impossible to make out how far the building had been actually advanced by them. [67] The colossal order of the Temple of the Sun at Baalbek is so unique in scale, and so little known, that it does not influence our general notions of the size of a large classic order. [68] As it actually does in the western part of the nave built by Maderna. [69] _Le Vite_, etc., vol. 7, p. 249. [70] _Il Tempio Vaticano e sua Origine_, etc. Discritto dal Cav. Carlo Fontana, Rome, 1694, vol. 2, p. 406. [71] Letarouilly, _Edifices de Rome Moderne_, Paris, 1860, p. 350. [72] Milizia, _op. cit._, vol. 1, p. 144, affirms that it is by Bramante. [73] Cf. Fontana, _op. cit._, vol. 2, p. 363. [74] Bk. 3, p. 54. [75] _Op. cit._, vol. 2, p. 240. [76] _Op. cit._, vol. 2, p. 239. [77] _Memorie_, etc., vol. 2, p. 36. [78] _I Cinque Ordini d’Architettura._ [79] _Op. cit._, plate 32. [80] Bk. 1, chap. 1. [81] _Op. cit._, vol. 2, p. 30. [82] The drawings are found in the addendum to the edition of 1617, plates 7 and 8. [83] Recent investigations, the results of which are set forth by Signor Beltrami (_Il Pantheon_, Luca Beltrami, Milan, 1898), have shown that the existing portico is of later date than either the rotunda or the rectangular front against which it is set. [84] “A l’intérieur, pourtourné de pilastres également Corinthiens, deux parties de l’entablement qui n’ont pas leur raison d’être sous une voute, c’est-à-dire la frise et la corniche, par un raffinement peu habituel aux Italiens, ont été supprimées.” _L’Architecture de la Renaissance_, par Leon Palustre, Paris, Quantin, p. 72. [85] _Quatro libri dell’Architettura di Andrea Palladio_, Venice, 1581. [86] _Le Vite_, etc., vol. 2, pp. 432–433. [87] _Op. cit._, vol. 4, p. 444. [88] _Op. cit._, vol. 2, p. 537.