Scholars agree on the pivotal technological and social importance of the mechanical clock, but some believe that a medieval Chinese Buddhist monk invented the first water-powered mechanical clock, whereas others believe that a medieval European monk invented the first weight-driven truly mechanical clock.
Scholars have called the invention of the mechanical clock not only one of the most significant turning points in the history of science and technology but also one of the greatest achievements in the history of humankind. Although the term “clock” is now commonly used for a time-measuring instrument with a numbered dial and moving hands, some scholars frown on this usage, insisting that “clock” should be applied only to timekeepers that strike the hours by a bell (the Middle English clok directly descends from the Latin clocca, meaning “bell”). Devices to monitor time over both short and long periods go back to early civilizations. Ancient Babylonians, Egyptians, Greeks, and Romans developed sundials, water clocks (clepsydras), and sand clocks, and these “pre-clocks” were precursors to the mechanical clocks of the medieval Chinese, Arabs, and Europeans. The reason the medieval mechanical clock was so much more significant and influential than its predecessors was that it had the technological potential to evolve into a wide variety of timekeepers that would increasingly transform science and society.
Because many timekeepers have moving parts and because controversies exist over which country created the first mechanical clock, it is necessary to clarify the precise nature of this innovation. For many historians of technology, the mechanical clock has to be weight-driven, which means that it can work in subfreezing weather (unlike the water clock) and at night and on cloudy days (unlike the sundial). The mechanical clock also has to transmit the potential energy of a raised weight through a system of toothed wheels to a time indicator. This time-measuring mechanism—the escapement—is the crux of the mechanical clock. It consists of a rotating multinotched wheel whose cogs are periodically blocked and released by a device that rhythmically swivels back and forth and can thereby track time’s flow.
Joseph Needham, an eminent Sinologist, claimed that medieval Chinese artisans, six centuries before the Europeans, had developed the escapement as part of a long evolution of astronomical devices intended to model celestial motions. To keep their observational apparatus in synchronization with the revolving heavens, Chinese astronomers used water power to regulate the revolutions of a series of wheels. Needham was able to trace the history of these devices back to the Buddhist monk I-Xing
Even though Chinese hydromechanical clocks were vastly superior to clepsydras made in early medieval Europe, many scholars nevertheless believe that the first truly mechanical clock was invented in Europe
Some historians of technology argue that, by 1275, all the requirements for a truly mechanical clock were known. Some scholars believe that the breakthrough was made by Gerbert as early as the tenth century. He substituted a falling weight for falling water and devised a verge escapement. The descending weight caused a toothed wheel to rotate, and the verge (a spindle with pallets) engaged upper and lower teeth of the wheel alternately, causing the foliot (a rod with movable weights on each end) to oscillate. This stop-and-go mechanism, with its ticktock sound, has been called one of the most ingenious inventions in history. Other scholars point out that what was revolutionary in this mechanism was not the escapement, important though it was, but the oscillatory device, the rate of whose beats could be regulated to match nature’s timekeeper, the revolution of the heavens.
These European clocks initially served a religious purpose: They regulated the monks’s Mass time, prayers, meals, and work. In the late thirteenth century, clocks quickly spread from monasteries to churches, and clocks were built for St. Paul’s Cathedral in London and the cathedral at Canterbury. In the early fourteenth century, clocks were built in church towers in England, France, and Italy. The earliest mechanical clock that has survived was constructed in 1386 for Salisbury Cathedral in England.
Unlike the hydromechanical astronomical clocks of China, which had little influence on society, the fully mechanical European clocks had a revolutionary impact on science, technology, and culture. Lewis Mumford, an American social critic and humanist, saw the medieval mechanical clocks as the most significant contributor to the creation of the modern world. Clock time came to regulate not only work and prayer in monasteries but also all aspects of secular life. Some scholars see this time-organized society as a critical factor in the differentiation of Western from Eastern civilization. Critics of Needham’s claim that the Chinese first invented the mechanical clock point out that he anachronistically misused the term “escapement” for a periodic water scoop mechanism, which was admittedly an important discovery but not the same as the European oscillating-beat escapement. The Chinese hydromechanical clock was more accurate than the early European mechanical clocks, but the Chinese clock had no future, whereas the European clock made possible the scientific, technological, and societal revolutions that helped make the modern Western world. In the sixteenth century, when the Jesuit missionaries entered China (and West finally met East), Chinese statesmen and scholars were amazed by the Jesuits’s mechanical clocks, which they viewed as dazzling new inventions, unrelated to their largely forgotten horological tradition.
Initially, the European clock was an imprecise and unreliable instrument, but during the late Middle Ages and early Renaissance, it became more accurate and adaptable. When a coiled flat spring replaced the weight drive in the early fifteenth century, portable clocks became a reality. The later invention of the pendulum clock meant that fully mechanical timekeepers were increasingly more precise than any of their predecessors. These clockworks not only helped create modern science and society but also provided a philosophical model for the universe itself (the mechanistic worldview). Time measurement, once the province of obscure tinkerers and scholars, had become the catalyst in creating new ideas, new technologies, new societies, and, in the case of scientist Albert Einstein, a new vision of the universe.
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Cipolla, Carlo M. Clocks and Culture, 1300-1700. 1978. Reprint. New York: Norton, 2003. This treatment of the European invention of the mechanical clock and its effect on society is highly critical of Needham’s thesis that Chinese millwrights invented the first mechanical clocks. -
Landes, David S. Revolution in Time: Clocks and the Making of the Modern World. Rev. ed. Cambridge, Mass.: Harvard University Press, 2000. This book, the first comprehensive analysis of the mechanical clock’s invention and influence, has been called a “landmark.” Landes, who believes that Needham’s excessive Sinophilism blinded him to the true European provenance of the mechanical clock, explains in detail the origin, evolution, and impact of this great invention. This illustrated book contains an appendix on escapement mechanisms and seventy-eight pages of notes, with many references to primary and secondary sources. -
Needham, Joseph. Mechanical Engineering. Part 2 in Physics and Physical Technology. Vol. 4 in Science and Civilisation in China. New York: Cambridge University Press, 1965. This book, with its immense bibliography, contains a condensed but updated account of the Chinese invention of mechanical clocks that was initially made public in Heavenly Clockwork. -
Needham, Joseph, Wang Ling, and Derek de Solla Price. Heavenly Clockwork: The Great Astronomical Clocks of Medieval China. 2d ed. New York: Cambridge University Press, 1986. The authors argue that medieval Chinese astronomical clocks are the “missing link” between ancient water clocks and modern mechanical clocks. They survey the six centuries of mechanical clockwork in China that preceded the appearance of mechanical clocks in fourteenth century Europe.