Thirteenth century masons worked out that if you want to fit a tapering octagonal spire exactly on top of a square tower you need tapering triangles known as broaches to fill in the corners. This church, at Frampton, Lincolnshire, is one of the first examples of this type of spire.
Tony
For more info: http://photoreflect.blogspot.com/2008/04/broach-spire.html
Tony
For more info: http://photoreflect.blogspot.com/2008/04/broach-spire.html