4th

Clocks
A particularly old invention , however it is still used and even developed along the years.
The pocket clock was invented in the 16 century and has developed throughout time to a several types of clocks . The most common clocks are the Wall Clock and the Hand Watch.

The Wall Clock
It is a hanged clock usually on the wall and sometimes on top of towers and in public places, such as the Big Bang in London. This kind of clock was invented in the 17 century by Galileo Galile and was first built with pendulum at the bottom of the clock. The clock could easily "find out" what time is it by using the pendulum cyclic motion to measure a certain time usually in seconds.

The Hand Watch
It was invented at the beginning of the 20th century and was designed in a way that allow to wear it on your hand which will allow you to know what time is it at any certain moment. Comparing to the Wall Clock this watch is very cheap and contains an electronic system. This watch is mass product because of his many ups such as , small , cheap , doesn't cost so much power (electricity) and efficient.




The sources of my work :

http://he.wikipedia.org/wiki/%D7%A9%D7%A2%D7%95%D7%9F_%D7%99%D7%93

http://he.wikipedia.org/wiki/%D7%A9%D7%A2%D7%95%D7%9F#.D7.A6.D7.99.D7.95.D7.A0.D7.99_.D7.93.D7.A8.D7.9A_.D7.91.D7.94.D7.AA.D7.A4.D7.AA.D7.97.D7.95.D7.AA_.D7.94.D7.A9.D7.A2.D7.95.D7.9F