The Sacconi iso line layout for the
"belly" as an assumption to create
an "average" Stradivarius arch shape
This figure shows Sacconis attemt to construct a 3D model by 2D geometric layout for a "belly" arch shape . It seems obvious that it is a 2D-construction since all intersection points are positioned on circular arcs intersecting straight lines. The figure is divided into 4 sectors marked by the 4 congruent shaped "elements" on the surface. Within the waist sector circumscribed by these 4 element lines there is complete congruence of shape not only comparing left and right but also up and down.. The dividing angle marksout the image line of the congruent picture. It is not possible to find any connection between the "upper" and "lower" sectors. The center of the "element" image is not in the center of the arch shape. No equal "elements" can be found covering the "upper" and "lower" parts of the shell. Only a limited sector in the "waist" has this quality.