It is difficult to imagine that thousands of years ago people lived without concern for the exact hour of the day.
Keeping time through the ages
Given the modern world's preoccupation with time, it is difficult to imagine that thousands of years ago people lived without concern for the exact hour of the day. Humanity's obsession with timekeeping seems to have coincided with the movement of early humans from bands of hunter-gatherers to communities that relied on agriculture. Knowing precisely when to plant and when to harvest became perhaps the most important piece of information in a society.
Most histories of timekeeping suggest the phenomenon dates back at least 6,000 years, to the Middle East and North Africa, with the Egyptians among its pioneers. Obelisks, their sun-cast shadows tracking the course of a day, were among the first timekeeping devices. A more sophisticated development was the Egyptian shadow clock, which used an elevated crossbar to cast a shadow on a long stem marked with time divisions. These were further refined into sundials, which threw their shadows on square or circular boards to indicate the time of day.
It didn't take the Egyptians long to figure out that, in the absence of the sun, time stood still ? and what to do about it. About 3,500 years ago, they invented the water clock, which told the time at night by dripping precise amounts of water into a calibrated container. Simple, but effective, water clocks were still being used in some parts of the world as recently as a century ago. Millennia passed before the next big step forward in timekeeping and, when it arrived, it was possibly as significant as any advance before or since: the invention of the mechanical clock.
The first examples, dating from the early 1300s, relied on gravity to pull weights, attached to various wheels and gears, which in turn moved an hour hand. Revolutionary they may have been, but by modern standards their accuracy was poor: they could be off by as much as half an hour each day. The 16th century saw the invention of spring-powered clocks and during the following hundred years inventors discovered pendulum power. Major improvements in accuracy followed during the 1600s and 1700s, to the extent that some clocks could keep time to within a second a day.
Then, as now, miniaturisation was the name of the game and the pocket watch was born. Time-keeping devices became a symbol for the progress of the age. The 18th century French philosopher Rene Decartes even compared God to a watchmaker, fashioning the mechanics of the world and winding up its motion. Not that everyone was so high-minded: inevitably, watches also became fashion statements. Elaborate miniature paintings were crafted on the enamel covers of some pocket watches, while others were encrusted with precious stones ? the forerunners of the high-end watches of today. Many Huguenots, French Protestants, fled their homeland and settled in Geneva in Switzerland, a centre of the Reformation, where they became prominent pocket-watch artists, often painting pieces for watches made in other European cities, such as London.
Although watches were developing aesthetically, accuracy could not be ignored either. As Britain and France battled for control over the seas in the 18th century, maintaining as close to exact time over long distances became even more important. Precise measurements of time aboard a ship were required for vessels to attain its exact nautical position. By measuring the sun's angle from the horizon at its zenith, or high noon, ship captains could determine their latitude. But only by determining the time at two distinct locations could a ship determine its precise longitude. The difference between the standard time kept aboard a marine chronometer and the real time of high noon aboard a ship as it travelled east or west could be used to calculate a ship's exact position.
Small discrepancies in time measurements could become huge errors in determining distances, causing ships to run a ground or encounter enemies. The task of keeping exact time on the seas was made all the more challenging by the constant changes in temperature, pressure, and humidity aboard a ship that could easily interfere with a time piece's mechanics. In 1714 the British Parliament offered a £20,000 prize, $12,000,000, in today's terms, to whomever could invent a precise marine chronometer. John Harrison, a British inventor, spent his entire life trying to come up with such a timepiece. To compensate for changes in temperature that might effect a clock's springs, Harrison invented a timepiece with bimetallic strips to protect them. To account for the ships swaying on the sea, Harrison developed caged roller bearings. But it was not that simple: it took Harrison 31 years of trial and error to develop such the time piece. These time pieces were so state of the art that they could account for nearly a third of a ship's initial cost.
But for the British Empire, it was worth it. Winning the Seven Years' War and gaining control of the seas allowed Britain to become the ascendant world power. The next big step forward in timekeeping, the development of quartz clocks, would not be Empire making but it was still significant. Most clocks and watches sold today employ quartz technology, which is cheaper and more accurate than mechanical movements. When bent in an electric field, quartz, or silicon dioxide crystals, vibrate and produce a near-constant electrical pulse. After a year, a quartz watch should be off by about only 10 seconds, an inaccuracy its mechanical equivalent can accumulate in the space of three or four months.
And yet, at the most prestigious end of watchmaking, mechanical watches still demand the highest prices. More than 99 per cent of the 700,000 or more watches made annually by Rolex, one of the most expensive brands, are mechanical, even though the company was involved with the development of quartz technology in the 20th century. "People choose what they see as the horological art of the mechanical watch, or they want something more precise," said Dominique Tadion, Rolex's head of public relations.
"Some tend to say that ladies like quartz, but I don't pick that up. And if you're out in the desert and your battery falls out, your rotor will help you." A modern high-end Swiss watch-assembly plant feels more like a science laboratory than a factory, with staff sat at high tables, dressed in white coats and wearing protective gloves. Ever present is the hiss of the tiny suction pipes used to remove dust ? the watch's biggest enemy ? as the devices are assembled and sealed.
Although based on technology that has been superseded, Rolex insists the mechanical watch is not stuck in a time warp. The company has a research and development department staffed by 240 engineers, 40 of whom have PhDs in disciplines such as mechanical engineering and physics. "We never close doors in terms of new models, in terms of precision and lubrication," said Mrs Tadion. The most accurate clocks of all are atomic, making use of the fact that electromagnetic radiation is emitted by each atomic element at a particular frequency. Dr Harold Lyons constructed the first atomic clock using the microwave frequencies of ammonia in 1948. Today atomic clocks are based on a number of different elements, including caesium, hydrogen and rubidium. Nasa has relied on these clocks to keep all of its missions in sink.
Atomic clocks are now so accurate ? to within 30 billionths of a second a year ? that they are used to co-ordinate time internationally. The countries of the world may not be in harmony politically, but in terms of time they are always perfectly in sync. @Email:email@example.com