The passage helps us answer which of the following questions?1. What was the reason behind choosing 60 as the basis of astronomical calculations?2. When did the use of minute start among the general populace?3. Did the Greeks build on others' work in timekeeping devices?4. What was the reason that the Egyptians started developing timekeeping devices?
Choose your answer from the following options.
PASSAGE – III
The passage is followed by a question based on its content. Answer the question on the basis of what is stated or implied in the passage.
Why do we divide a minute into 60 seconds, an hour into 60 minutes, while there are only 24 hours in a day? Currently, the most prevalent numeral system is decimal (base 10), which possibly originated as it enabled easier counting with fingers. The civilizations that first split the day into smaller parts, nevertheless, used different numeral systems, notably duodecimal (base 12) and sexagesimal (base 60).
Most historians opine that the Egyptians were the first to divide the day into smaller parts. The first of the sundials they created were just stakes placed on the ground that indicated time by the length and direction of the resulting shadow. By 15th century B.C., they had developed a more advanced sundial. Without artificial light, humans at that time considered sunlit and dark periods to be two opposing realms. When sundials were used first, however, the Egyptians also first observed a group of 36 stars which divided the circle of the heavens. The clepsydra i.e. water clock, was also used to record time at night, and was perhaps the most accurate timekeeping device of its times.
Later the concept of a 24-hour day arose. The concept of fixed-length hours, however, originated in the Hellenistic period. Hipparchus proposed dividing the day into 24 equinoctial hours. Despite this suggestion, laypeople continued to use seasonally varying hours.
Hipparchus and other Greek scientists used astronomical techniques developed by the Babylonians. They made calculations in the sexagesimal (base 60) system. Although we do not know why 60 was chosen, it is convenient for expressing fractions, since it is the smallest number divisible by the first six counting numbers and also by 10, 12, 15, 20 and 30.
The Greek astronomer Eratosthenes used a sexagesimal system to divide a circle into 60 parts. Abou 100 years later, Hipparchus normalized the lines of latitude and also invented a system of longitude lines that encompassed 360 degrees. In his treatise Almagest, Ptolemy expanded Hipparchus' work by subdividing each of the 360 degrees of latitude and longitude. Each degree was divided into 60 parts, each subdivided into 60 parts. The first division, partes minutae primae, or first minute, became known as the "minute." The second segmentation, partes minutae secundae, or "second minute," became known as the second.
However, minutes and seconds, were not used for everyday timekeeping until many centuries. Clock displays split the hour into halves, thirds, quarters and sometimes even 12 parts, but never by 60. In fact, the hour was not commonly understood to be 60 minutes. It was not practical for the general public to consider minutes until the first mechanical displaying minutes appeared by 16th century. Even today, many clocks and wristwatches have a resolution of only one minute. Thanks to all this, modern society still thinks of time divisions in this manner.