The Clerestory
It would have been a simple matter to make the height of the clerestory equal to d/4. It is short of this by about 5½ inches.26 On the exterior, the top of the parapet is at exactly 1½ times the height of the string course at the base of the clerestory measured from the floor (Figure 8). The designer avoided the simple solution here as he did in rejecting the 37' module for the distance between the arcades (Figure 5). The pentagon in Figure 9 has side equal to half the bay length. This determines the height of the clerestory up to the lower edge of the top course, which adds a further foot to give the total height. The two top vertices of the pentagon and the centre line divide the length of the clerestory bay exactly into quarters (Triangle PQR is isosceles). The vertical lines passing through these vertices define the outer edges of the windows, and their corners where the verticals intersect the lower edges of the pentagon. The outer vertices give the notional positions of the outer columns, and then the other columns are positioned by symmetry.
Chords of the pentagon define the tops of the capitals, and the apices of the lancets. The springing line of the capitals is given by the semicircle shown in red, with a radius of half a bay length. The height of the shafts including their bases and capitals is half a bay length. Due to the pentagonal geometry, a golden rectangle is present, shown in yellow. A square, shown in violet, relates the lower edge of the window openings to the lower edge of the sloping sill.
The centre lines of all the arches are given by dividing the length of the bay into six (Figure 9). This measure also gives the width of the windows. It follows that QS is one twelfth of a bay length. The width of the stone backing to the shafts is one twenty-fourth of a bay length.
Chords of the pentagon define the tops of the capitals, and the apices of the lancets. The springing line of the capitals is given by the semicircle shown in red, with a radius of half a bay length. The height of the shafts including their bases and capitals is half a bay length. Due to the pentagonal geometry, a golden rectangle is present, shown in yellow. A square, shown in violet, relates the lower edge of the window openings to the lower edge of the sloping sill.
The centre lines of all the arches are given by dividing the length of the bay into six (Figure 9). This measure also gives the width of the windows. It follows that QS is one twelfth of a bay length. The width of the stone backing to the shafts is one twenty-fourth of a bay length.