The scheme on which the plan of the dome and its accompaniments is set out in St. Paul’s is totally different from that in St. Peter’s (Figs. 454, 455). In the latter the space beneath the dome is penetrated by the nave and transept alone, irrespective of their aisles, which stop dead against the piers of the dome. In the former the same space is penetrated both by the nave and transept, and their aisles. To take another view. In St. Peter’s, the square occupied by the dome and its piers is surrounded on all sides by an aisle, low in the angles and lofty in the centres of the sides; or, in other words, the aisles failing to penetrate the dome, branch round its angles, while those of Sir Christopher Wren pierce directly through it. St. Paul’s has, externally, the advantage of the great corner piers rising from the ground, unencumbered by surrounding buildings; but internally, grandeur is sadly lost through the reduced span of the large supporting arches, by the want of bold simplicity in the piers, the meanness and irregularity of the smaller arches, and the confusion caused by the mode in which the portion above them is arranged. Externally, however, the outline of this dome is perhaps unequalled; and, even internally, if you look at general effect, and close your eyes to defects in detail, the impression produced is grand in the extreme. I have used up all the time at my disposal without having even reached one of the greatest classes of domical structures--those of the different Mahometan nations, from Morocco and Southern Spain, by Egypt and Turkey, to Persia and India. I the less regret this because I leave it wholly untouched for some one better acquainted with it than myself to take up: I will only offer two remarks upon it. The first is, that it is wholly an offshoot of the Byzantine style which was first adopted, and then developed by the infidel conquerors. The second is, that it is throughout, or nearly so, carried out with the pointed arch, and most usually with corbels instead of pendentives, giving in these two directions an extension to the developments which took place in Western Europe. I may also mention that, in splendour of decoration, it is impossible to conceive anything to go beyond it; though it is a style which seems alien to our Western and Christian prepossessions. We have seen that the cupola--the noblest of all architectural features--belonged by right to Roman architecture; was continued in the same style when it became Christian; was wonderfully developed in the Eastern and Christian Roman Empire; was continued in the Middle Ages in Italy, and transplanted into Germany and France; that it was taken up during the early days of the Renaissance from the unfinished Gothic cathedral at Florence and, through that semi-Mediæval, semi-Renaissance graft, was thoroughly adopted into the revived Classic styles. What I now want