Time, Measurement of

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TIME, MEASUREMENT OF

TIME, MEASUREMENT OF. From being important in the mid-fifteenth century only to structured communities (monasteries, military camps, universities) and large-scale industrial undertakings (quarries, building sites, textile manufactories), measured time by the late eighteenth century had become the fundamental structural element of European social life. If the incidence of time control was felt more strongly in towns and industrial units than in the country, the sonorous hour indications of village church bells nonetheless brought it even to remote agrarian regions. This extension of time control in society was paralleled by major advances in the reliability and precision of time-measuring machines, but the causal relationship between the two is complex and only beginning to be investigated.

Time measurement was available in early modern Europe through the use of shadows (sundials and moon dials), gravity (water clocks, sandglasses, weight-driven clocks), or artificial force (spring-driven clocks and watches). Sundials and waterclocks derived from antiquity, mediated by humanist scholars; weight-driven clocks were an invention of medieval craftsmen, probably in the mid-thirteenth century. Spring-driven timekeepers can be claimed as an early modern invention, a response in the mid-fifteenth century to need for a portable timekeeper comparable with pocket sundials, which, known since antiquity, multiplied from the fourteenth century onward. Sandglasses were probably invented in Europe at about the same time as weight-driven clocks, in the mid-thirteenth century. For all, the ultimate time standard was that determined by the Earth's movements in relation to the Sun.

The various time-measuring instruments available had complementary functions. Sundials find time and display it; even if interrupted in their operation by lack of sunshine, they will immediately show time again once sunlight reappears. Weight- and spring-driven clocks and watches are timekeepers and time showers. Once set functioning, they count and display time without interruption. If deranged, however, they cannot of themselves find time again, but have to be set against a sundial. Throughout the early modern period, therefore, there was an essential complementary relationship between clocks, watches, and sundials, which are frequently found combined, or in close proximity to each other. Sandglasses are timekeepers but restricted to specific short periods, usually up to sixty minutes. They were used for measuring the often predetermined length of tasks such as university lessons, sermons, naval or military watches, and industrial activities.

Technical innovations in time-measuring machines during this period were many and fundamental. Although the usefulness of the force exerted by a coiled metal strip was recognized from at least the thirteenth century, it was not until the invention in the mid-fifteenth century of devices such as the fusee and the stackfreed, which equalized the force exerted as the spring uncoiled, that it could be useful in time measurement. Despite this, the behavior of sixteenth-century clocks and watches was affected by so many mechanical insufficiencies as to be highly erratic if not closely surveyed by the clock keeper, who was a regular appointment in towns and royal and noble establishments. Watches in the sixteenth century were as much valued as jewels as timekeepers, and public clocks were as important as symbols of social and economic status and for the astronomical/astrological indications they offered as they were for telling time. Indeed their behavior in the latter respect is frequently criticized in late-seventeenth and eighteenth-century literature.

The mathematical analysis of natural phenomena that characterized seventeenth-century research into the natural world, however, led to important innovations. Galileo (1564–1642), having recognized the isochronous nature of a pendulum, also recognized its potential as a controller for clock mechanisms and produced initial designs. Concurrently, but probably independently, Christiaan Huygens (1629–1695) produced different designs for this purpose and not only published its theory in his Horologium Oscillatorium (1672) but in 1676 revealed the isochronal properties of a flat spiral spring when applied to a watch balance.

These two fundamental innovations reduced the running error of clocks and watches from some twenty to thirty minutes a day to only a few minutes. Such precision allied with increased reliability in the performance of timekeepers, resulting from improvements in lubrication, bearings, and tooth profiles, meant that timekeepers now became viable machines for use in longitude determination, a task that had been proposed for them as early as 1532. Although immense technical difficulties remained to be overcome, by the 1780s viable longitude timekeepers existed and could be simplified for general use. Similarly, in the late eighteenth century, newly reliable timekeepers became an integral part of the development of timed industrial activity, and of the development of interlocking, time-tabled transport systems. None of this affected the watch as a status symbol, but it did transform its appearance as emphasis shifted from the watch as conspicuous jewel to the watch as elegant precision timepiece. Precision in the eighteenth century became the hallmark of quality, the equitable operation of the new timekeepers, of which Paris, London, and Switzerland were the chief producers, being both source and reflection of a new, absolute, Newtonian time.

See also Calendar ; Clocks and Watches ; Galileo Galilei ; Huygens Family ; Newton, Isaac ; Scientific Instruments .