The subject of this lecture is horology, the science of measuring time. The【D1】______has come a long way since ancient times. It

The subject of this lecture is horology, the science of measuring time. The measurement of time has come a long way since ancient times. It began with such devices as the sundial, where the position of the sun’s shadow marked the hour. Daylight was divided into 12 temporary hours, which were longer in the summer and shorter in the winter, simply because the amount of daylight changes with the seasons.
    The earliest sundial we know comes from Egypt, which was made of stone. Sundials were used through the classical world, and with time, evolved into more elaborate devices that could take into account seasonal changes and geographical positioning and reflect the hours accurately. This was quite an achievement in technology. Today, sundials can be seen as decorative pieces in many gardens.
    In the 11th century, the Chinese invented the first mechanical clocks. They were large and expensive, and certainly not intended for individuals. However, this is the type of clocks we are familiar with today. There have been many developments in clocks and watches since then, and they’ve been greatly improved. However, if your clock or watch makes a ticking sound, then it could well be based on the mechanical movements the Chinese developed a thousand years ago!
    However, timekeeping has moved on from the mechanical clock. Time has become so important that there is a series of atomic clocks around the world which measure International Atomic Time. Even though many countries have their own calendars, globalization has made it essential that we measure time uniformly. This standard was set in 1958. Now these atomic clocks are situated in over 70 laboratories all over the world.