Amiens, the retracing of the ground plan

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mankind has never thought anything important until it was written in stone.

Victor Hugo

Floor plan of Amiens Cathedral - Credit: Gothika - CC-BY-SA

On this page, we'll test our triple-enceinte system on Amiens Cathedral. Let's take a look at the floor plan. After measuring the distances between the different speakers, we'll look them up in the Table. I'll give you the results straight away. As in the case of Reims, we can see that segment A is obtained by a circular arc with origin O passing through the center of the Table (fig. 2a). The procedure is identical. Segment B, on the other hand, is drawn differently. Its origin is still located at point O, but its end is defined here by a three-part segmentation of the Table (fig. 2b).

At first glance, this construction may seem curious or arbitrary, but recall the process used to partition a Gothic chevet. This involved drawing a rectangle made up of three squares. As the base of the chevet is equal to the width of the table, there's no need for further division (fig. 3). Simply keep and extend the existing lines to draw segment B in a single gesture (the same principle is used in Chartres).

Fig. 3 - Unified layout of the chevet and Table d'Amiens

The green segment remains, determined here by the half-height of the Table. The length of the transept is obtained by a triple transfer of segment C.

Figure 6 shows the layout of the three enclosures, with their natural extensions and respective proportions. The angle dividing the apse corresponds to the diagonal of a rectangle, as explained above: the blue segment is equivalent to 3x the green segment.
Only five lines (dotted lines) have been added to mark the intermediate bays. They are equidistant, set by the green segment, so it was very easy to draw them. Note that the sixth bay of the nave is wider than the others. This element is not shown on the drawing. Figure 7 completes the tracing by drawing pillars at each line intersection and buttresses when the intersections are outside the line. Figure 8 shows the floor plan of Amiens Cathedral.

Figs. 6, 7, 8 - Amiens Cathedral retraced (excluding western mass and apsidioles)

In relation to the bare outline of the triple enclosure, segments are transferred to give the building its characteristic Latin cross shape, with one branch longer than the other. However, this shape is merely a symbol which, while it affects the building's footprint, has no influence on the sacred proportions of the sanctuary ordered by the triple enclosure. I explain this in the book. You'll also find a floor plan and elevation of Chartres Cathedral.