Geometry and measures in the bell tower of Pietrasanta: a confirmation by the three-dimensional survey.

Abstract

It’s a simple rectangular brick that hides inside a coclide staircase that wraps around an ideal air column. From the earliest surveys appeared a compositional geometry that can be connected to a cultivated mind and brilliant as that of Mi-chelangelo Buonarroti, who was in Pietrasanta in 1520. The three-dimensional survey confirmed the hypothesis: the spiral staircase is set up on precise relations and according to simple geome-tries, but these generate complex surfaces. The point cloud reveals the proportional modules used , revealing the matrixes and confirming Mi-chelangelo’s authorship. The Ionic volute extru-ded in space that guides the auger, the conchoi-dal of Nicomede that models the internal void in the manner of classical columns, the Fibonacci spiral upward in the helix design, as well as canon Mensurius in Roman palms and the geometry of the plant set on a 18 palms paradigm are themes that characterize this architecture.