History

Watches evolved from portable spring driven clocks, which first appeared in the 15th century. Portable timepieces were made possible by the invention of the mainspring. Although some sources erroneously credit Nürnberg clockmaker Peter Henlein (or Henle or Hele) with inventing the mainspring around 1511, many references to 'clocks without weights' and two surviving examples show that spring powered clocks appeared in the 1400s. Henlein is also often credited with constructing the first pocketwatches, mostly because of a passage by Johann Cochläus in 1511
Peter Hele, still a young man, fashions works which even the most learned mathematicians admire. He shapes many-wheeled clocks out of small bits of iron, which run and chime the hours without weights for forty hours, whether carried at the breast or in a handbag
and because he was popularized in a 19th century novel. However, many German clockmakers were creating miniature timepieces during this period, and there is no evidence Henlein was the first. Also, watches weren't widely worn in pockets until the 1600s.

1969–present Quartz watches

The introduction of the quartz watch in 1969 was a revolutionary improvement in watch technology.[30] In place of a balance wheel which oscillated at 5 beats per second, it used a quartz crystal resonator which vibrated at 32,768 Hz, driven by a battery powered oscillator circuit. In place of a wheel train to add up the beats into seconds, minutes, and hours, it used digital counters. The higher Q factor of the resonator, along with quartz's low temperature coefficient, resulted in better accuracy than the best mechanical watches, while the elimination of all moving parts made the watch more shock-resistant and eliminated the need for periodic cleaning.
Accuracy increased with the frequency of the crystal used, but so did power consumption. So the first generation watches had low frequencies of a few kilohertz, limiting their accuracy. The power saving use of CMOS logic and LCD displays in the 2nd generation increased battery life and allowed the crystal frequency to be increased to 32,768 Hz resulting in accuracy of 5–10 seconds per month. By the 1980s, quartz watches had taken over most of the watch market from the mechanical watch industry.

1950–1969 Electric watches

The first generation electric watches came out during this period. These kept time with a balance wheel powered by a solenoid, or in a few advanced watches that foreshadowed the quartz watch, by a steel tuning fork vibrating at 360 Hz, powered by a solenoid driven by a transistor oscillator circuit. The hands were still moved mechanically by a wheel train. In mechanical watches the self winding mechanism, shockproof balance pivots, and break resistant 'white metal' mainsprings became standard. The jewel craze caused 'jewel inflation' and watches with up to 100 jewels were produced.

1920–1950 Wristwatches

At the beginning of the century wristwatches were mostly worn by women. In 1904, Brazilian aviator Alberto Santos Dumont asked his friend Louis Cartier to come up with an alternative that would allow him to keep both hands on the controls while timing his performances during flight. Cartier and his master watchmaker, Edmond Jaeger soon came up with the first prototype for a man's wristwatch called the Santos wristwatch. The Santos first went on sale in 1911, the date of Cartier's first production of wristwatches. During the First World War soldiers needed access to their watches while their hands were full. They were given wristwatches, called 'trench watches', which were made with pocketwatch movements, so they were large and bulky and had the crown at the 12 o'clock position like pocketwatches. After the war pocketwatches went out of fashion and by 1930 the ratio of wrist- to pocketwatches was 50 to 1. The first successful self-winding system was invented by John Harwood in 1923.

1900–1920 Better materials

During the 20th century, the mechanical design of the watch became standardized, and advances were made in better materials, tighter tolerances, and improved production methods. The bimetallic temperature compensated balance wheel was made obsolete by the discovery of low temperature coefficient alloys invar and elinvar. A balance wheel of invar with a spring of elinvar was almost unaffected by temperature changes, so it replaced the complicated temperature compensated balance. The discovery in 1903 of a process to produce artificial sapphire made jewelling cheap. Bridge construction superseded 3/4 plate construction.

1850–1900 Mass production

At Vacheron Constantin, Geneva, Georges-Auguste Leschot (1800-1884), pioneered in the field of interchangeability in clockmaking by the invention of various machine tools. 1830 he designed an anchor escapement, which his student, Antoine Léchaud, later mass produced. 1839 he invented a pantograph allowing some degree of standardisation and interchangeability of parts on watches fitted with the same calibre.
Watch manufacturing really changed from assembly in watchmaking shops to mass production with interchangeable parts, as from 1854, pioneered by the Waltham Watch Company, in Waltham, Massachusetts. The railroads' stringent requirements for accurate watches to safely schedule trains drove improvements in accuracy. The engineer Webb C. Ball, established around 1891 the first precision standards and a reliable timepiece inspection system for Railroad chronometers. Temperature compensated balance wheels began to be widely used in watches during this period, and jewel bearings became almost universal. Techniques for adjusting the balance spring for isochronism and positional errors discovered by Abraham Breguet, M. Phillips, and L. Lossier were adopted. The first international watch precision contest took place in 1876, during the International Centennial Exposition in Philadelphia (the winning four top watches, which outclassed all competitors, had been randomly selected out of the mass production line), on display was also the first fully automatic screw making machine. By 1900, with these advances, the accuracy of quality watches, properly adjusted, topped out at a few seconds per day.[29]
From about 1860, key winding was replaced by keyless winding, where the watch was wound by turning the crown. The pin pallet escapement, an inexpensive version of the lever escapement invented in 1876 by Georges Frederic Roskopf was used in cheap mass produced dollar watches, which allowed ordinary workers to own a watch for the first time; other cheap watches used a simplifed version of the duplex escapement, developed by Daniel Buck in the 1870s.
These improvements were mostly originated and applied in the United States, and as a result the American industry ousted that of Switzerland from its long-held position as worldwide leader in the low-to-middle-class market. The Swiss responded, towards the end of the century, by changing their emphasis from economy to quality.

1800–1850 Lever escapement

The lever escapement, invented by Thomas Mudge in 1759 and improved by Josiah Emery in 1785, gradually came into use from about 1800 onwards, chiefly in Britain; it was also adopted by Abraham Louis Breguet, but Swiss watchmakers (who by now were the chief suppliers of watches to most of Europe) mostly adhered to the cylinder until the 1860s. By about 1900, however, the lever was used in almost every watch made. In this escapement the escape wheel pushed on a T shaped 'lever', which was unlocked as the balance wheel swung through its center position and gave the wheel a brief push before releasing it. The advantages of the lever was that it allowed the balance wheel to swing completely free during most of its cycle; due to 'locking' and 'draw' its action was very precise; and it was self-starting, so if the balance wheel was stopped by a jar it would start again. Jewel bearings, introduced in 1702 by Nicolas Fatio de Duillier, also came into use for quality watches during this period.