Why does an hour have sixty minutes

We have ten of them and so ten and multiples of ten would seem to be the most natural counting system. So, why is this? The Babylonians used cuneiform for recording, a system of mark-making whereby a wedge-shaped piece of wood or reed was pressed into wet clay.

To create numerals, they used two simple shapes: first an upright single wedge-shape for 1 — repeated for 2, 3, 4, etc — and then the same shape angled twice to make a sideways v-shape for 10, and again repeated for 20, 30 etc, as on the right. The Babylonians made astronomical calculations years ago based on It was the Egyptians who made sundials, which were simply a stake of wood placed in the ground, that divided the day into smaller parts by the length and direction of the shadow.

Later the instruments were calibrated to divide the time between sunrise and sunset into 12 parts. Water clocks, or clepsydra , from as early as the BC in Babylon and Egypt, and probably from BC in China, consisted of a bowl or dish whereby the flow of water into or out of was measured, which indicated the time.

Based on the Longstaff's information former astronomers made choices. Their successors followed those choices teaching them to the next generator. We are most recent in that tradition. Longstaff A, "Why 12 months in a year, seven days in a week or 60 minutes in an hour?

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Improve this question. Frank Hubeny See Scientific American. There may be an historical explanation for this that might have philosophic interest. During the era when sundials were first used, however, Egyptian astronomers also first observed a set of 36 stars that divided the circle of the heavens into equal parts. The passage of night could be marked by the appearance of 18 of these stars, three of which were assigned to each of the two twilight periods when the stars were difficult to view.

The period of total darkness was marked by the remaining 12 stars, again resulting in 12 divisions of night another nod to the duodecimal system. During the New Kingdom to B. The clepsydra, or water clock, was also used to record time during the night, and was perhaps the most accurate timekeeping device of the ancient world.

The timepiece--a specimen of which, found at the Temple of Ammon in Karnak, dated back to B. Once both the light and dark hours were divided into 12 parts, the concept of a hour day was in place. The concept of fixed-length hours, however, did not originate until the Hellenistic period, when Greek astronomers began using such a system for their theoretical calculations.

Hipparchus, whose work primarily took place between and B. Despite this suggestion, laypeople continued to use seasonally varying hours for many centuries. Hours of fixed length became commonplace only after mechanical clocks first appeared in Europe during the 14th century.

Hipparchus and other Greek astronomers employed astronomical techniques that were previously developed by the Babylonians, who resided in Mesopotamia. The Babylonians made astronomical calculations in the sexagesimal base 60 system they inherited from the Sumerians, who developed it around B. Although it is unknown why 60 was chosen, it is notably convenient for expressing fractions, since 60 is the smallest number divisible by the first six counting numbers as well as by 10, 12, 15, 20 and Although it is no longer used for general computation, the sexagesimal system is still used to measure angles, geographic coordinates and time.

In fact, both the circular face of a clock and the sphere of a globe owe their divisions to a 4,year-old numeric system of the Babylonians. The Greek astronomer Eratosthenes who lived circa to B. A century later, Hipparchus normalized the lines of latitude, making them parallel and obedient to the earth's geometry.

He also devised a system of longitude lines that encompassed degrees and that ran north to south, from pole to pole. In his treatise Almagest circa A. Each degree was divided into 60 parts, each of which was again subdivided into 60 smaller parts. The first division, partes minutae primae, or first minute, became known simply as the "minute. Minutes and seconds, however, were not used for everyday timekeeping until many centuries after the Almagest.