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Development

A rise in accuracy occurred in 1657 with the addition of the balance spring to the balance wheel, an invention disputed both at the time and ever since between Robert Hooke and Christiaan Huygens. This innovation increased watches' accuracy enormously, reducing error from perhaps several hours per day to perhaps 10 minutes per day, resulting in the addition of the minute hand to the face from around 1680 in Britain and around 1700 in France.

The increased accuracy of the balance wheel focused attention on errors caused by other parts of the movement, igniting a two-century wave of watchmaking innovation. The first thing to be improved was the escapement. The verge escapement was replaced in quality watches by the cylinder escapement, invented by Thomas Tompion in 1695 and further developed by George Graham in the 1720s. Improvements in manufacturing – such as the tooth-cutting machine devised by Robert Hooke – allowed some increase in the volume of watch production, although finishing and assembling was still done by hand until well into the 19th century.

A major cause of error in balance-wheel timepieces, caused by changes in elasticity of the balance spring from temperature changes, was solved by the bimetallic temperature-compensated balance wheel invented in 1765 by Pierre Le Roy and improved by Thomas Earnshaw (1749–1829). The lever escapement, the single most important technological breakthrough, though invented by Thomas Mudge in 1754 and improved by Josiah Emery in 1785, only gradually came into use from about 1800 onwards, chiefly in Britain.

The British predominated in watch manufacture for much of the 17th and 18th centuries, but maintained a system of production that was geared towards high-quality products for the élite. The British Watch Company modernized clock manufacture with mass-production techniques and the application of duplicating tools and machinery in 1843. In the United States, Aaron Lufkin Dennison started a factory in 1851 in Massachusetts that used interchangeable parts, and by 1861 a successful enterprise operated, incorporated as the Waltham Watch Company.