Chapter 22

According to Fontani, this cupola exceeds that of the Vatican, both in height and circumference by four braccia; and although supported by eight ribs only, which renders it much lighter than that of the Vatican, which has sixteen flanking buttresses, it is nevertheless more solid and firm. Thus it has never required to be supported by circling hoops of iron, nor has it demanded the labors of the many engineers and architects who have printed volumes upon the subject. The construction of this cupola is remarkable in these particulars--that it is octangular, that it is double, and built entirely on the walls, unsupported by piers, and that there are no apparent counterforts.]