Dividing the day

The sun clock, the oldest used object for the man to measure the time, functions observing it change of position and length ofthe projected shades for the Sun in the different periods of the day. Located in Egypt, the first clocks, that date approximately of 3500 B.C., were composites only for a pillar, called gnomon, and could show the two halves of the day (the noon was the moment of the lesser shade). Later, scales of measures had been added in return of the column so that the days could be divided in shorter periods. The first evidence of division of the time in equal parts date of 1500 B.C.