Fra Giovanni's Intarsia Polyhedra

    Intarsia are mosaics made of pieces of inlaid wood.  They are a remarkable art form which reached a peak in northern Italy in the late 15th  and early 16th centuries.  Many outstanding examples of this period feature polyhedra.  Below are four intarsia panels by Fra Giovanni da Verona, constructed around 1520.  The first pair is in the Monastery of Monte Olivetto Maggiore (near Siena) and the second pair is from the church of Santa Maria in Organo, Verona.

    The first features a 72-sided sphere, a mazzocchio, and various instruments of the geometer.  The second features an "elevated icosidodecahedron," a complex nonconvex polyhedron which can be constructed by erecting a pyramid of equilateral triangles on each face of an icosidodecahedron.  The use of the mazzocchio goes back to Uccello.  The other polyhedra are based on Leonardo's drawings of "solid edge" models, published in Pacioli's influential 1509 book The Divine Proportion.

     
    Note that intarsia are flat panels.  The appearance of open cupboard doors is a trompe l'oeil effect of the masterful perspective.  The same effect is used in others of Fra Giovanni's panels.  The next one below features the same 72-sided sphere, along with an icosahedron and a truncated icosahedron. The panel after that features a cube with equilateral pyramids erected on each face, a cuboctahedron, and again the elevated icosidodecahedron.
     
    To construct intarsia, outline drawings are used as templates for cutting many  pieces of wood (perhaps a thousand or more in these examples). The cut wooden pieces are glued to a wooden substrate and varnished.  Different colors of wood provide the different shadings used.  Sometimes stains, bleaches, or heat were applied to the wood to provide a wider range of tones.

    Leonardo's printed drawings were clearly used to provide the outlines.  The identical viewpoint and perspective is used in each case, but Giovanni skillfully rotated the images and and adjusted the shadings appropriately.

     

    The examples above were all influenced on Leonardo's drawings in Pacioli's book. However, there were many spectacular intarsia before that time.  At right is one earlier example, featuring a mazzocchio.  It is just one panel from the richly intarsia-ized Studiolo of Urbino, in the late 1400's.


    Fra Giovanni's work is the most impressive of the art in my opinion.  Intarsia then died out as an art form in the mid 1500's.  This was part of the general trend away from geometric perspective, but also because the technique was denigrated as a "craft" compared to the "art" of painting.

    References: See the article by Tormey and Tormey and the book by Cromwell.  The first two images above were scanned from the Tormey article, and the third and fourth were sent to me by Peter Cromwell.


    Virtual Polyhedra, (c) 1998, George W. Hart