12/29/2023 0 Comments Who invented the clock![]() Some sundials may also be set vertically on the sides of buildings, and a wide variety of different designs have been employed over the centuries. In a typical horizontal sundial, the Sun casts the shadow of a gnomon (a thin vertical rod or shaft) onto a horizontal surface marked with lines indicating the hours of the day. The sundial, or shadow-clock, which measures the time of day by means of a shadow cast by the Sun onto a cylindrical stone, was widely used in ancient times, and can give at least a reasonably accurate reading of the local solar time. The clock is one of the oldest human inventions, and a bewildering array of different mechanisms have been employed over the millennia. ![]() Ancient Clocks Sundials were one of the earliest kinds of clock The ancient Greeks and Babylonians counted the day from sunset, as do orthodox Jews and Muslims even today the Egyptians reckoned the hours from sunrise in ancient Umbria the new day began at noon. The modern convention of starting the day at midnight, in the Roman style, is perhaps an arbitrary one, although a widely used one for all that, and the hour at which the day is considered to begin has varied throughout history and across different cultures. The first reference to clocks using 12 hours before noon and 12 hours after noon (all equal) comes from England in about 1380, although splitting the day into AM ( ante meridiem, or before midday), and PM ( post meridiem, or after midday) actually dates back to Roman days. The advent of mechanical clocks institutionalized the use of 24 equal hours per day. This meant of course that daytime hours were not necessarily of the same length as nighttime hours (except at the equinoxes), and hours at different times of the year would also vary in length. Prior to that, other than for some technical astronomical purposes, the day was usually split into 12 equal hours and the night into 12 equal hours, a practice dating back to ancient Egypt (although in practice, the night was often divided into 3 or 4 “watches” for security reasons). Our present system of dividing the day and night into 24 equal hours was instituted around the 14 th Century. The standard sexagesimal system of time measurement – 60 minutes in an hour, 60 seconds in a minute – also owes its ancestry to the sexagesimal system used in Sumer and Babylonia from around 2000 BCE, in which 60 was the base number for most mathematical and counting purposes. Although a 10-hour clock was briefly popular during France’s experiment with metric time measurement after the French Revolution, the 12-hour clock – a convention dating back to ancient Egypt and Babylon – has continued to be the norm, along with 24-hour clocks for some (mainly military and astronomical) applications. We use clocks to divide the day into smaller increments. ![]() If the principle behind a clock is relatively simple, the technological and engineering challenges involved in building a clock of any accuracy are relatively complex, and much of the history of clocks in the last two millennia has revolved around the invention of more and more complex machines that are able to overcome the intrinsic problems of friction, temperature differences, movement, magnetic fields, size, etc, in search of the ultimate in accurate, reliable and practical timekeeping devices. Other kinds of clock mechanisms, from the passage of water out of a vessel to the swinging of a pendulum to the vibration of a quartz crystal or the oscillation of a microscopic atom, are really just more manageable and more accurate variations on the same idea. The rotation of the Earth is a good example of something that is both repetitive and predictable, and indeed the turning of the Earth, as measured by the position of the Sun in the sky, was the first method mankind used to estimate the time of day. Really, a clock can be anything that repeats itself in a predictable way. ![]() Watches are sometimes distinguished from clocks in general, but really a watch is just a portable clock, usually worn in a pocket or on the wrist. A chronometer is an exceptionally precise mechanical timepiece, designed to be accurate in all conditions of temperature, pressure, etc, especially one used at sea. The English word “clock” comes from the Celtic words clocca and clogan, both meaning “bell”. Clocks of one sort or another have been around for thousands of yearsĪ clock is any free-standing device or instrument for measuring or displaying the current time.
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