74 



THE NATIONAL GEOGRAPHIC MAGAZINE 



the: inverted arches of the weees cathedrae 



This curious St. Andrew's Cross shows how builders of the Middle Ages could convert 

 a necessity into a beautiful architectural feature. During the construction of the central 

 tower (see page 73), it was discovered that the four piers supporting it were weak. A second 

 lower arch was built and a third inverted arch was then added. Thus the piers receive a 

 steady support along their whole height. 



I 



