It is difficult from the statements in _Parentalia_ clearly to identify Wren’s different drawings which have been preserved, and to reconcile either the statements or the drawings with what is said by more recent writers, who do not always agree among themselves. The drawings embody widely different schemes which were the results of so many attempts to meet the wishes of the king and court on the one hand, and those of the citizens on the other. Of these there are two sets which may be considered as the principal ones. The first of these has a novel plan based on that of the Greek cross, but having the reëntrant external angles filled out to segmental curves struck from the corners of a square enclosing the whole. A great dome on a circular drum supported by eight piers rises over the crossing, a small dome on pendentives covers each of the spaces between the great circle and the curved enclosing walls; while the northern, southern, and western arms of the cross have each a square groined vault. The form of the vaulting over the eastern arm is not indicated on the plan, but the choir enclosure is shown in the form of a circle cut out on the east to open into the sanctuary, and on the west to communicate with the nave. The dome (Fig. 135) is in two shells of masonry, the inner one being hemispherical with a circular opening in its crown, and the outer one a pointed oval supporting a lantern. The drum is thick, and although the vault springs from very near the top, a strong continuous abutment in the form of a solid ring of masonry, with concave outline, is built up against it. The dome is kept solid up to the haunch of the inner shell, so that this inner shell is abundantly secured, while the outline of the outer shell, from the point where it clears the solid mass below, has a form that would exert a minimum of thrust, though it would hardly be secure without a binding chain. It is noticeable that the inner face of the drum is not vertical, but inclined inward in the form of a truncated cone, which considerably strengthens it against any tendency to yield to the force of thrust in the dome. [Illustration: FIG. 135.--Section of Wren’s rejected scheme for St. Paul’s.]