LECTURE XVI.
The Transition.
Non-existence of the Dome in our old English architecture—Highly developed forms in France, Germany, and Italy, contemporary with our great Mediæval edifices—Suggestions for its introduction into our revived and redeveloped Neo-mediæval style—So-called Tomb of Agamemnon at Mycenæ—The Pantheon—Temple of Minerva Medica—Torre dei Schiavi—Temples of Vesta at Rome and Tivoli—Temple of Jupiter in Diocletian’s Palace, Spalatro—Tomb of St. Constantia—Baptistery at Nocera—Baptistery at Ravenna—Important domical development—“Pendentive Domes”—Early specimens—Pendentive domes the special characteristic of the Byzantine style—How this originated—Further domical developments—Cathedral at Florence—Churches of SS. Sergius and Bacchus, the Apostles, and St. Sophia, Constantinople.
IT has been my lot to deliver my lectures from this chair in groups so very detached from one another, as to render it impossible for my hearers to follow them as a continuous series. In spite, however, of this disadvantage, I purpose to make my present lecture form a natural sequence to the last which I had the pleasure of delivering three years ago.
My last course was on arched construction, and my last lectures were on vaulting. My present one will carry on the same subject into its culminating development—The Dome.
Strongly as my tendencies towards our own Mediæval architecture draw me towards the modes of vaulting which prevail in our own ancient buildings, and which formed the subject of my later lectures, I am bound to admit that the noblest of all forms by which a space can be covered is the dome; and, much more than this, that of all architectural forms it is the most sublime and the most poetic, and is susceptible of, and demands, the highest artistic treatment. I deplore, therefore, its non-existence in our old English architecture.
This regret, however, is diminished by the abundant evidence we possess that the dome, though absent from English buildings, was by no means held to be alien from the contemporary architecture of neighbouring countries, inasmuch as we possess it in highly developed forms over a large part of France, in Germany, and in Italy, erected at the same periods with many of our great Mediæval edifices.
If, then, I am departing from the line I had been taking in tracing out the history of old English architecture, I am not only supplying a hiatus in that history, but I trust that I may be able to offer suggestions for a more practical object—the supplying of that hiatus in our revived and redeveloped Neo-mediæval style.
In a former lecture, after defining a vault as the covering of a rectilinear space produced by the motion of an arch parallel to itself, I defined a dome as the covering of a circular space produced by the revolution of an arch round its central vertical axis. It follows that, if the arch so revolving is semicircular, the resulting dome is a hemisphere.
The revolving arch may, however, be of any form which an arch can assume. It may be elliptical, parabolic, hyperbolic, cycloidal; or it may be a pointed, a horse-shoe, or an ogee arch. Any one of these, or other forms of arch revolving on its centre, will generate a dome of its own sectional form. The plan, too, in spite of my definition, need not be a circle; it may be an ellipse, or of other forms.
I will not at this stage admit of square-planned, polygonal, or other straight-sided domes, because it may be doubted whether they are genuine domes at all, or whether they are not figures resulting from the intersection of a certain number of ordinary vaults. Anyhow, these are not generated by the revolution of an arch, so that if they are domes, my definition is at fault.