Section of a rivet and microphotograph of scoriae

Cut in half along its length, this rivet reveals that the direction of the fibres (the wire) runs according to its shank (left). At the end of the rivet (right), the wire turns abruptly at a right angle with respect to the rivet shank, just before the area where the hammered end broke away. According to Dr Foecke, these piles of filaments bent at right angles constitute an area of great weakness.