Section on a large scale of the cupola, showing its construction; the lower part A A of the vault, from the springing to the summit of the arches, of about twelve feet high, is constructed of ranges of vases of terra cotta, in the form shown No. 6; these vases are placed perpendicularly one over the other, the point of the upper in the mouth of the lower; the remainder of the dome is constructed with small tubes of terra cotta, shown No. 5, placed almost horizontally, one within the other, and forming a spiral line from the base to the summit; these are also strengthened by another line of the same tubes, as well as several layers of the vases placed upright; the inside and the outside are covered with mortar.
Plan of the dome, showing the spiral line of the tubes.
Transverse section on the line B C of the plan; at the angles are eight large pillars which support the dome, and between them seven semicircular niches, pierced with a double range of columns. The dome is a circle inscribed in the regular octagon, small arches at the angle serving as pendentives.
8. Column from the ground floor of the Church of St. Viatli, Ravenna.
9. Column of the upper gallery of the Church of St. Vitali, Ravenna.
10. Column in the center of the windows of the dome of the church, etc.
Plan of the Church of St. Vitali; its form octagon within and without; the vestibule A is perpendicular to one of the angles; the entrance is at B, the choir at C; the paving of the center is a modern work in precious marbles; most of the surrounding chapels are posterior to the foundation of the church.