Courses and voussoirs

While talking about de Vandelvira (1585)’s Libro de trazas, Calvo López and Alonso-Rodríguez (2010, p. 70) says that once he has drawn the arcs that stand for the parallels, Valndelvira advises the reader that “las cuales dos cerchas cerrarás por do quisieres”; that is, ‘you can close these arcs as you will’”. This passage is rather illustrative of the two step subdivision of a surface first in courses, and these in voussoirs. While eluding to a roman type hemispherical vault, Calvo López and Alonso Rodríguez (2005) also illustrates a dome in which the first subdivisions are radial, and wythes are repeated two by two in a staggered bond. While inventive uses of this technique maybe found in a 450 year old dome in Cathedral of Murcia which exhibits a single spiral course, contemporary stereotomy also finds inspiration in courses perpendicular to the thrust lines as seen in MLK Jr Park vault.