"Peter Henlein... makes from a little iron a pocket clock with a lot of wheels."
Johannes Cocleus, historian
The world's first portable timepiece, which came to be known as a "pocket-clocke," was made in Nuremberg, Germany, between 1504 and 1508 by the former apprentice locksmith and clockmaker Peter Henlein (c. 1479-1542). The miniaturization of timepieces began with the invention of the coiled spring in Italy in the late 1450s along with the development of various escapement mechanisms. However, the real breakthrough proved to be Henlein's invention of the balance spring, which greatly improved the precision of a watch's spring-driven interior.
Henlein's new pocket watch measured only a few inches in diameter, chimed on the hour, and could run for up to forty hours before it required rewinding. It was driven by scaled-down steel wheels and hand- forged springs that, despite representing a huge technological leap forward, were nonetheless persistently inaccurate. The coiled springs unwound at a varying speed, causing the watch to slow as the mainspring unwound. Early springs also had a maddening tendency to break when tightly wound, although later refinements such as cam springs were added to compensate for inherent irregularities.
It took Henlein ten years to develop his first pocket watch (this and his subsequent timepieces would go on to become known as his "Nuremberg eggs"). The high cost of the innovation saw the pocket watch become largely a status symbol of the upper classes, yet the popularity of the pocket watch was to continue for 400 years, not least as a formal gift of readily perceived worth, until the invention of the wristwatch in the early twentieth century.
