The clock is an instrument for measuring time. It tells us at any moment what time it is. But what really measures time for us is the sun, or rather the movements of our earth around the sun. We divide time up into years, months, weeks, days, hours, minutes, and seconds. Now what we call “a year” is simply the time it takes our earth to go once right around the sun. A month is simply the twelfth part of a year; and when we divide the year into twelve parts because it takes about a month for the moon to go round the earth. A month is really a “moon-th” – a moon period. What we call a day, is simply the time it takes our earth to spin round once on itself. For convenience, we again divide this day into twenty-four hours and every hour into sixty minutes, and every minute into sixty seconds. A week is seven of these days, and so four of these weeks make a month, as reckoned by the moon.
In the early days, men had to watch the sun and moon to know the time. But the sun and moon could only tell them about days and months; not about hours and minutes. The first plan to tell the time more correctly was the sun-dial; which was a round plate of metal ruled in line to show hours and minutes, with a stick standing up in the center. The time was told by watching the shadow of this stick as it moved around the marked plate or dial.
The English king, Alfred, measured the time by burning marked candles. Another plan was the sand-glass, or hourglass, which was so made that some grains of sand would take a certain time (say an hour) to fall from one vessel into another.
But the clock is the best instrument for measuring time. The first clock was made in France in the 14th century. It was moved by hanging weights. The clock, moved by spring, was first made in the 16th century. A clock is a wonderful machine. A wound-up spring drives a number of wheels so made that they move the hands round the face of the clock, and these hands as they go round point correctly in turn to the figures on the face marking the hours and minutes. Now a day we have a quartz clock which runs with help of battery cells. Of course, a clock does not mark years and months and weeks, but it marks all the hours and minutes of one day.