Drawings illustrating the invention may also be provided. He sometimes employs devices of his own invention. Folk etymologies claim it as an American invention. Serendipity is a common occurrence throughout the history of product invention and scientific discovery. There is safe harbor in many jurisdictions to use a patented invention for research. The process worked in a way similar to the later invention of ball bearings. The work of making the invention practical was continued. Hanja uses traditional characters that came before the invention of simplified characters. He distilled this by a process of his own invention from crude oil. Nuremberg was an early centre of humanism, science, printing, and mechanical invention. There are a number of claims to the invention of the pile driver. Credit for the invention of the electric telephone is frequently disputed. The problem appears in different stories about the invention of chess. Philosophy Hall is listed as the site of the invention of FM radio. The Scots take enormous pride in the history of Scottish invention and discovery.