Showing posts with label Sexagesimal System of Time. Show all posts
Showing posts with label Sexagesimal System of Time. Show all posts

Monday, November 28, 2016

A Moment of Time

Two circular diagrams showing the division of the day and of the
week, from a Carolingian manuscript (Clm 14456 fol. 71r) of St.
Emmeram Abbey. The day is divided into 24 hours, and each hour
into 4 puncta, 10 minuta and 40 momenta. Similarly, the week is
divided into seven days, and each day into 96 puncta, 240 minuta
and 960 momenta.
A moment (momentum) was a medieval unit of time. The movement of a shadow on a sundial covered 40 moments in a solar hour. An hour in this case means one twelfth of the period between sunrise and sunset (see planetary hours). The length of a solar hour depended on the length of the day, which in turn varied with the season, so the length of a moment in modern seconds was not fixed, but on average, a moment corresponds to 90 seconds: A day was divided into 24 hours(of unequal lengths, twelve hours of the day and the night each), and an hour was divided into four puncta (quarter-hours), ten minuta and 40 momenta. The unit was used by medieval computists before the introduction of the mechanical clock and the base 60 system in the late 13th century. The unit would not have been used in everyday life. For our medieval counterparts the main marker of the passage of time was the call to prayer at intervals throughout the day.

The earliest reference we have to the moment is from the 8th century writings of the Venerable Bede. Bede describes the system as 1 hour = 4 points = 10 minutes = 15 parts = 40 moments. Bede was referenced four centuries later by Bartholomeus Anglicus in his early encyclopedia De Proprietatibus Rerum (On the Properties of Things). Centuries after Bede's description, the moment was further divided into 60 ostents, although no such divisions could ever have been used in observation with equipment in use at the time. Source: Wikipedia

Thursday, July 30, 2015

The Art of Measuring Time

Prague Astronomical Clock (HERE)
For thousands of years, devices have been used to measure and keep track of time. The current sexagesimal system of time measurement dates to approximately 2000 BCE, in Sumer. 

Most of the first clocks were not so much chronometers as exhibitions of the pattern of the cosmos. Clearly the origins of the mechanical clock lie in a complex realm of monumental planetariums. 

The medieval Prague Astronomical Clock at left was installed in 1410 - more than 130 years before Copernicus published ‘On the Revolutions of the Celestial Spheres’ in 1543. It is the third-oldest astronomical clock in the world and the oldest one still working (HERE)