Monday, October 6, 2014


Whenever anyone talks about Clock the very first thing comes in our mind is that it is a device used to measure time but hardly we thought about how it was invented and what was the reason that such a device was required to be designed. Let’s have a view over this.

The clock is one of the oldest human inventions. Earlier time was measured in terms of natural units. The basic need to develop such a device was to consistantly measure intervals of time shorter than the natural units: the day, the month or the year. Different peoples in different countries develop different time measurement device according to their own opinions. Following are some ancient clocks used in the past.


1. Sundial, an early clock, relies on shadows to provide good estimate of the hour on a sunny day.

2. In common sundials designs such as horizontal sundial, the sun casts a shadow from its style onto a surface marked with line indicating the hours of the day.

(Style is a time telling edge of the a thin cylindrical rod)

3. All sundials must be aligned with their styles parallel to the axis of earth's rotation to tell correct time.

4. Sundials cannot be used during cloudy weather or at night and also requires recalibration as the season changes due to change in direction of sun.


1. Candle clocks were mostly used in china, Japan, England and Iraq.

2. It is a thin long candle with evenly spaced markings (usually with numbers).

3. When the candle is burnt, it indicates what time it was, with the markings made on it.

4. Here observer initially would have to know how long it will take to burn from one marking to next, to know the exact time.

5. The most sophisticated candle clock known to date was those of Al-Jaziri in 1206.


1. The incense clock was invented in China between the years of 960-1279 and was very popular in Eastern cultures.

2. Burning incense was used to measure time, but there were many types.

3. Somewhere Colour of the smoke from the burning incense was used to know a period of time, as the colour of the smoke gets changed after a known passage of time.

4. Some incense clocks used smell to show the passing of time. They would be divided into sections of different smells, and when the observer noticed a particular smell, they could determine what time it was.

5. Some incense clocks would burn underneath of threads with weights attached. After a certain amount of time had passed, the thread was burnt due to the burning fire, causing the weight to drop onto a gong below. This was an “alarm” for the person who wanted to know what time it was.


1. It is also known by the name, Sand Glass, Sand Timer, Sand Watch or Sand Clock.

2. It has two connected vertical glass bulbs allowing a regulated trickle of material from top to bottom.

3. Once the top bulb is empty, it indicates an hour, that's why called as Hour glass. Then Sand glass is inverted to begin time again.


1. A water clock, also known as a clepsydra uses flow of water for time measurement.

2. It was originated in medieval Europe. Greeks began using them around 325 BC and also called as "Water Thieves".

3. There are two types of water clocks: inflow and outflow.

4. In an outflow water clock, a container is filled with water, and the water is drained slowly and evenly out of the container. This container has markings which are used to know the passage of time. As the water leaves the container, an observer can see where the water is level with the lines and tell how much time has passed.

5. Inflow water clock works also works basically the same way, except instead of water flowing out of the container, the water is filling up the marked container. As the container fills, the observer can see where the water meets the lines and tell how much time has passed.


1. Mechanical clocks tell time using gears. They have two important parts: a mainspring and a pendulum.

2. Mechanical clocks are wound with a key, and this tightens the mainspring. As the mainspring unwinds, its energy turns gears which cause the hands to move.

3. The pendulum keeps time and ensures that the gears move at the right pace: second by second.

4. Instead of a mainspring, some mechanical clocks have weights that pull the gears at the right pace. Mechanical clocks do not need electricity to operate. They can run off of the energy generated by their springs and weights.


1. During the later middle Ages, Crude wheel clocks came into use. Such clocks were driven by weights.

2. The principle of Pendulum clock was first given by Galileo but Pendulum clock was constructed by Christian Huygens in 1657.

3. In 1583, Galileo is said to have made his discovery by watching a lamp swinging from the roof of the Cathedral of Pisa and timing the oscillations by the beats of his pulse.

4. He found that a Pendulum of given length makes the same number of swings in a given time, no matter whether the breadth of the swing be large or small.

5. Galileo designed the Pendulum clock but could not construct it because he died before he could complete it.

6. The Pendulum clock was later invented by Christian Huygens in 1657.

7. In this Pendulum clock, an "escapement" allowed the hands of the clock to move an exact amount for each swing of the Pendulum. It kept time accurate with sun and stars.


1. Quartz clocks operate using the mineral quartz inside of a clock to keep time.

2. Like mechanical clocks, quartz clocks still use gears to count time, but they are electrical.

3. The mineral quartz is piezoelectric. This means that when a quartz crystal is squeezed, it generates a very small current of electricity. This also means that when electricity is passed through the quartz crystal, it vibrates.

4. Quartz crystals vibrate at the same frequency, meaning they shake the same number of times each second. Quartz crystals vibrate exactly 32,768 times each second!

All quartz clocks contain a battery to vibrate the quartz crystal and a circuit to count how many times the crystal has shaken.

5. The circuit then uses this information to create regular pulses of electricity. It generates one pulse every second. These pulses then make the gears of the clock move (if it is a mechanical clock) or power a digital display (if it is a digital clock). The quartz crystal in a quartz clock helps keep the clock accurate.

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