If you take a round disc, poke a hole in it somewhere off the centre, place a pencil in that hole and then role the disc along a straight edge-you've just looked at the secret to Cremonese arching.

This curve is called a Curtate Cycloid. Curtate Cycloids fit very well with the cross archings of Cremonese instruments. If one knows the height of the centre of the curve and the desired length, one can make templates for a proper violin arch at any point perpendicular to the centre line.

This points to an important aspect of Italian methods for violin making: everything is planned and engineered in a great violin. Nothing is left to chance-and it is the ability to use these methods, and to create one's own templates and designs, that separates the good makers from the great.