Chester Carlson (1906-1968), US physicist and in- ventor of xerographic photocopying. Carlson worked as a printer before studying physics. During the Depression he decided that invention was the way to prosperity, and set about trying to find a cheap, dry method of copying documents. He focused on a scheme using an electrostatic charge to cause powder (toner) to stick to paper, and produced his first copies in 1938. Over the next six years 20 companies turned down his patents, but in 1944 he found commercial backing. In 1959 the first Xerox photocopying machine was brought out and Carlson went on to enjoy phenomenal financial success.