CONSTRUCTION XII. THE ARCH LOAD 179

method of the pure Byzantine and Italian Romanesque. But if we find too much stress is thus laid on the arches, we may introduce small second shafts on the top of the great shaft, a, Fig. 36, which may assist in carrying the roof, conveying great part of its weight at once to the heads of the main shafts, and relieving from its pressure the centres of the arches.

§ 3. The new shaft thus introduced may either remain lifted on the head of the great shaft, or may be carried to the ground in front of it, or through it, b, Fig. 36; in which latter case the main shaft divides into two or more minor shafts, and forms a group with the shaft brought down from above.

§ 4. When this shaft, brought from roof to ground, is subordinate to the main pier, and either is carried down the face of it, or forms no large part of the group, the principle is Romanesque or Gothic, b, Fig. 36. When it becomes a bold central shaft, and the main pier splits into two minor shafts on its sides, the principle is Classical or Palladian, c, Fig. 36. Which latter arrangement becomes absurd or unsatisfactory in proportion to the sufficiency of the main shaft to carry the roof without the help of the minor shafts or arch,

[Version 0.04: March 2008]