ABSTRACT
On 1 May 1392, a conference of architects and engineers was asked if the construction of the new cathedral of Milan ‘ought to rise according to the square or the triangle?’ The local Lombard masons had laid out the building to a grid of squares and some of the piers had been raised ready to take their vaults, but the building committee had become alarmed at the height that was projected for them. The engineers’ response was ‘that it should rise up to a triangle or to the triangular figure, and not farther’.2 This confirmed a written proposal of 12 March the previous year that the cross-section be designed within an equilateral triangle. This was made by Annas of Freiburg and when Heinrich Parler replaced him in December of that year, he too at first proposed the equilateral triangle to determine the heights of the cathedral.3 In 1521, in the commentary on his translation of Vitruvius, Cesar Cesariano published a drawing of Milan Cathedral with its heights answering to a system of equilateral triangles (Fig. 46), adding that the ‘rule of the German architects‘ stipulated that the length and breadth of a church should be fixed by the vesica piscis (Fig. 47) – which is a circumscription of two equilateral triangles baseto-base – and that its heights should also be fixed by equilateral triangles.4
