Subscribe Email address:. Follow us facebook twitter youtube. Search Search for: Search. Ever Wonder Why? Search for: Search. Advertisements fund this website. Please disable your adblocking software or whitelist our website. Medieval astronomers were first to apply sexigesimal values to time. Full moons were tabulated using these same divisions by Christian scholar Roger Bacon in the 13th century. Minutes and seconds, however, were not used for everyday timekeeping for several centuries.
Mechanical clocks first appeared in Europe during the late 14th century, but with only one hand, following the design of sundials and water clocks. Minutes and seconds were but hypothetical quantities of time.
According to David S. While sextants and quadrants no telescopes yet had long been used to quantify the heavens, due to the movements of the sky their accuracy was limited to how well a user knew the time. Tycho Brahe was one such pioneer of using minutes and seconds, and was able to make measurements of unprecedented accuracy.
Many of his measurements required him to know the time to within 8 seconds. Thanks to documented evidence of the Egyptians' use of sundials, most historians credit them with being the first civilization to divide the day into smaller parts.
The first sundials were simply stakes placed in the ground that indicated time by the length and direction of the resulting shadow. As early as B. A T-shaped bar placed in the ground, this instrument was calibrated to divide the interval between sunrise and sunset into 12 parts. This division reflected Egypt's use of the duodecimal system--the importance of the number 12 is typically attributed either to the fact that it equals the number of lunar cycles in a year or the number of finger joints on each hand three in each of the four fingers, excluding the thumb , making it possible to count to 12 with the thumb.
The next-generation sundial likely formed the first representation of what we now call the hour. Although the hours within a given day were approximately equal, their lengths varied during the year, with summer hours being much longer than winter hours.
Without artificial light, humans of this time period regarded sunlit and dark periods as two opposing realms rather than as part of the same day. Without the aid of sundials, dividing the dark interval between sunset and sunrise was more complex than dividing the sunlit period. 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.
It took a long time before this happened. So next time you try to measure a minute by counting to 60, remember that people who lived thousands of years ago counted to 60 too! For further fun reading, check out Scientific American's article on how and why we measure the day. BY Michele Debczak. History WHY.
0コメント