Lectures on the rise and development of medieval architecture; vol. 2

by Sir George Gilbert Scott

Of its successors the name is legion. It would be useless for me to attempt to enumerate even the most successful of them. I will therefore content myself with a brief description of the two most typical—those of St. Peter’s, at Rome, and of our own St. Paul’s.

I am not aware of any dome of great scale erected in the interval between Brunelleschi’s dome at Florence and that of Michael Angelo at Rome. The latter, however, was the crowning result of the efforts of successive architects, especially of Bramante and Sangallo. In one sense it does, and the other it does not, show evidence of this lengthened period of development.

Fig. 452.—Section looking North, St. Peter’s, Rome. (From Fergusson).

Its unity of design would bespeak it as the work of one master-mind, while its perfection may mark it as the result of oft-repeated trials.

Though founded in idea on the dome at Florence, that of St. Peter’s differs from it in many most important and essential particulars (Fig. [452]). In the first place,—while that at Florence is supported from the very floor upon an octagonal wall merely pierced by comparatively narrow arches, that at St. Peter’s is essentially a pendentive dome, rising from four colossal piers which give it a square base, and united with the four arms of the church by arches, or rather vaults of vast span. These arches, it is true, are not so wide as to reduce the pendentives which rise from between them to triangular forms, but are set so far apart as to leave a portion of the ideal circle between them, and to give the pendentives a horizontal base.

This was necessary to give strength to the piers for the support of so gigantic a structure, but in no degree interferes with the pendentive character of the dome.

Again, at Florence the octagonal wall rises to the very base of the dome, while at Rome the drum, from the pendentives upwards, is circular. At Florence it is pierced only by rather ungainly circular windows, while at Rome it is colonnaded within and without, and beautifully decorated within. At Florence the dome is of that doubtful kind which has straight sides, carrying up the octagonal form to the very top, while at Rome the dome is circular and perfect. Both are in some degree alike in construction, being double, with a space between, not two domes, as at our St. Paul’s, but one dome formed of two shells partially connected; a mode of construction well suited to the support of the crowning lantern.