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The first watches appeared shortly after 1500, early examples being made by Peter Henlein, a locksmith in Nürnberg, Ger. The escapement used in the early watches was the same as that used in the early clocks, the verge. Early watches were made notably in Germany and at Blois in France, among other countries, and were generally carried in the hand or worn on a chain around the neck. They usually had only one hand for the hours.

The mainspring, the element that drives the watch, consists of a flat spring-steel band stressed in bending or coiling; when the watch, or other spring-driven mechanism, is wound, the curvature of the spring is increased, and energy is thus stored. This energy is transmitted to the oscillating section of the watch (called the balance) by the wheeltrain and escapement, the motion of the balance itself controlling the release of the escapement and consequently the timing of the watch. A friction drive permits the hand to be set.

One of the main defects of the early watches was the variation in the torque exerted by the mainspring; that is, the force of the mainspring was greater when fully wound than when it was almost run down. Since the timekeeping of a watch fitted with a verge escapement was greatly influenced by the force driving it, this problem was quite serious. Solution of the problem was advanced almost as soon as the mainspring was invented (about 1450) by the application of the fusee, a cone-shaped, grooved pulley used together with a barrel containing the mainspring. With this arrangement, the mainspring was made to rotate a barrel in which it was housed; a length of catgut, later replaced by a chain, was wound on it, the other end being coiled around the fusee. When the mainspring was fully wound, the gut or chain pulled on the smallest radius of the cone-shaped fusee; as the mainspring ran down, the leverage was progressively increased as the gut or chain pulled on a larger radius. With correct proportioning of mainspring and fusee radii, an almost constant torque was maintained as the mainspring unwound.

The going barrel, in which the mainspring barrel drives the wheeltrain directly, is fitted to all modern mechanical watches and has superseded the fusee. With better quality mainsprings, torque variations have been reduced to a minimum, and with a properly adjusted balance and balance spring, good timekeeping is ensured.

Up to about 1580, the mechanisms of German watches were made almost wholly of iron; about this time, brass was introduced.

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