Peter Henlein, a locksmith and burgher of Nuremberg, Germany, invented a spring-powered clock around 1510. It had only one hand, had no glass cover, and was rather imprecise because it slowed down as the spring unwound. In fact, Henlein went so far as to develop the first portable watch; it was six inches high. People usually carried it by hand, or wore it around their necks or in large pockets. The first reported person to actually wear a watch on the wrist was the French mathematician and philosopher, Blaise Pascal (1623–1662). He attached his pocket watch to his wrist with a piece of string.