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 of the Florentines of the fifteenth century. Their civic pride and large resources called for an imposing design which should make the dome a dominant architectural feature of their city. It was decided that it should be raised upon the top of a high drum, and the task to which Brunelleschi appHed himself was to fulfil this requirement.

Of the vast and soaring dome which he succeeded in erecting many opinions have been held, but all beholders are impressed with its grandeur. It has been common to speak as if the master had been chiefly inspired by the ancient monuments of Rome, and had taken the Pantheon as his principal model. But although he came to his task fresh from the study of the ancient Roman monuments, and undoubtedly had the Pantheon much in mind, yet the dome which he produced has little in common with that great achievement of imperial Roman constructive skill. In general it follows, though with great improvements as to outline and proportions, the scheme of Arnolfo as illustrated in the fresco of the Spanish Chapel; but the model to which it most closely conforms, notwithstanding the obvious and essential points of difference, is that of the Baptistery just described. There can, I think, be little question that this monument supplied the chief inspiration and guidance to both Arnolfo and Brunelleschi. A comparison will show that the dome of the cathedral, with its supporting drum, is, in fact, little other than a reproduction of the Baptistery of San Giovanni in a modified form, and enlarged proportions, raised over the crossing.

But while taking the scheme of the Baptistery as the basis of his own scheme, Brunelleschi was obliged to make some daring changes in order to give his design the external character which he sought. This great dome (Plate I), like that of the Baptistery, is octagonal in plan and pointed in elevation. It rises from the top of the octagonal drum, and consists of two nearly concentric shells of masonry, with an interval between them. Eight vast ribs of stone rise from the angles of the drum and