The pinnacle after Roriczer
A pinnacle generated from one square: rotated squares give the widths of spire and finial, multiples of the side give the heights.
The rules it illustrates
A pinnacle from one square. Draw a square the width of the pinnacle; inscribe a second square on the mid-points of its sides, and a third on the mid-points of the second. Turned back into line, the squares give the widths of the body, its panels and the spire; every height is a multiple of the first side.
Where it appears in the book
In the chapters Romanesque and Gothic.